What does supersaturation with respect to ice mean? I've been reading about the Bergeron process, a process that generates much of the precipitation in the middle latitudes by generating ice crystals at the expense of water droplets. The part I don't understand is the supersaturation with respect to ice versus with respect to water.

From Earth Science by Tarbuck, Lutgens, and Tasa:
"When air is saturated with respect to water, it is supersaturated with respect to ice . . . Thus, ice crystals cannot coexist with water droplets because the air always 'appears' supersaturated to the ice crystals. Hence, the ice crystals begin to consume the 'excess' water vapor . . ."

I don't exactly understand what supersaturation relative to water and ice mean, even though they've attempted to explain it. My first thought is that maybe on the ice surface, the affinity for water vapor molecules is higher than in air, so water vapor molecules are more likely to be deposited on the surface, hence why the relative humidity with respect to the ice is higher. However, in my thinking, "with respect to" would mean which surface the water vapor is getting deposited on, when clearly the statement says the thing being deposited ("with respect to water"). Can someone explain this clearly for me?

The saturation vapour pressure defined by the American Meteorological Society:

The vapor pressure of a system, at a given temperature, for which the vapor of a substance is in equilibrium with a plane surface of that substance's pure liquid or solid phase; that is, the vapor pressure of a system that has attained saturation but not supersaturation.
The saturation vapor pressure of any pure substance, with respect to a specified parent phase, is an intrinsic property of that substance, and is a function of temperature alone. For water vapor, the saturation pressure over supercooled liquid differs appreciably from that over ice.

When water vapour exists over a body of supercooled liquid water, water is constantly exchanged between the liquid form and the water vapour form.  When this reaches equilibrium, there is equal phase change in both directions.  If the air becomes saturated, no more water vapour can be added to it, for it will condensate to the liquid form immediately.  At this temperature, the vapour pressure is the saturation vapour pressure with respect to water.  Remember that water can exist well below 0°C — clouds are typically not completely frozen until temperatures drop to around -40°C, although it depends on many factors and the details are subject to ongoing research.
When water vapour exists over a body of ice, there is a phase exchange.  At a certain temperature and pressure, the air is saturated, any water added will precipitate as ice.  At this temperature, the vapour pressure is the saturation vapour pressure with respect to ice.
By "Body of" you should probably not so much think of a frozen lake or liquid ocean but rather of small cloud droplets or ice particles.
This graph from Vermont State College shows the saturation vapour pressure over water or ice:

Source: Vermont State College
As your source stated, this difference is important for meteorology as it affects the formation of clouds and precipitation.
Now as to why the saturation vapour pressure is different with respect to water than with respect to ice is another question.  You may find more expertise for that on Chemistry Stack Exchange than here on Earth Science.  My atmospheric science textbooks in any case don't go into detail there.


How much oil was consumed worldwide since it was started to use massively in the mid 19th century? According to this article from 2015 How much oil is left on Earth

1.5 trillion barrels of crude oil reserves were left in the world by end 2015

But how much oil was already consumed worldwide since it was started to use massively in the mid 19th century? Is it most of it or a small part of it?

PS: I'm not sure if this question is for Earth Science SE or for Economy SE, if you think it's in the wrong SE please move it.

Cumulative world oil production at the end of 2017 was approximately 1.36 trillion barrels.


Which parts of the ocean have been explored? So there's a sea, right by my house. How do I know if it's been explored, and what info do we have about it?

According to the internet, about 5-10% of the world's oceans has been explored.

Is there a map that shows which parts of the ocean have been explored, and which haven't? Does it show what has been discovered about X part of the ocean etc.? Where can I find such information?

If I just google "Unexplored parts of the world", it'd drive me to very specific and popular parts of the earth, many of which have actually been explored (to a certain point), such as the Mariana Trench etc.

The simplest way to find out the basic information about your nearby ocean is to check Google Earth, which has an Ocean layer that often includes details about noteworthy features and discoveries.

This story from Scripps Institution of Oceanography explains some of the updates that were made in late 2015:

  The new global gravity map, recently published by [geophysicist David] Sandwell and
  colleagues in the journal Science, was used in combination with
  available depth soundings to provide a more detailed picture of the
  mountains and valleys along Earth’s most unexplored expanse – the
  ocean floor.

This essay in Scientific American helps explain some of the extent of our knowledge:

  So the “95% unexplored” meme doesn’t really tell the full story of our
  exploration of the oceans. When it comes to having a large-scale map,
  the ocean floor is perhaps not as unexplored as we might think, with
  100% coverage to a resolution of 5km and 10%-15% coverage at around
  100m resolution. That 10%-15% is similar in resolution to the current
  global maps of Mars and Venus.

  But our exploration of the oceans depends on what we want to know
  about them. If our questions are: “What does it look like down there?”
  or: “What’s going on down there?”, then the area that has been
  “explored” is arguably even less than the 0.05% mapped so far at the
  very highest resolution by sonar.

The areas mapped in most detail will be near coasts and common ship routes. Oceanographic vessels run their sonar systems almost continuously, so the maps will have lines of very high resolution detail running through them (artifacts that are often interpreted to look like lost cities or roadways).

But surprising discoveries are still made. It was only in 2012 that a Scripps expedition found a methane seep that was later determined to support an elaborate chemosynthetic ecosystem just 20 miles off the coast of Del Mar in Southern California.


What are the most common minerals at the Earth's surface? I know how to find out the first few most common minerals, and I know how to find a list of 6800 minerals that one geologist found as a microscopic grain in this one meteorite. I can't seem to find a good reference for the top few hundred minerals that actually occur in macroscopic quantities in near-surface rocks.

Sorting by frequency would be great. A reference including subsurface rocks or other planets would be an interesting bonus.

I can't seem to find a good reference for the top few hundred minerals that actually occur in macroscopic quantities in near-surface rocks.

That's because such a list does not exist. The 'first few most common minerals' you mentioned, aka the 'rock-forming minerals' account for 99.9% (at least, depends on definition) of the minerals you will find in near-surface environments. It also depends on location - the minerals you will find in a limestone are will be completely different from the minerals in granitic areas.

I also don't completely seem to understand what you mean by 'macroscopic quantities'. Are you referring to minerals that are large enough to be seem by the naked eye or that are abundant in quantity regardless of their size?


Convert NO2 concentration in Sentinel-5P data from mol/m2 to μg/m3 on the ground level Sentinel-5P satellite provides high-resolution data products on concentration levels for several atmospheric trace gases (NO2, SO2, O3
, and others), which are measured in mol/m2 within the total or tropospheric column. Is it possible to deduce concentrations for a specific slice of the troposphere?

Namely, I'm interested to get NO2 raster to work in GIS, where each pixel of it will contain NO2 level in μg/m3, 0–50 meters above the ground. I've already read Product User Information, Algorithm Theoretical Basis Document, and Input Output Data Definition related to the corresponding Sentinel-5 NO2 product. However, it didn't give me an idea of how to get μg/m3 for the near-ground level. Is it feasible at all? I guess it is, as in the Copernicus European air quality portal, which uses Sentinel-5P data for the air pollution forecast, I see that they show NO2 concentrations in μg/m3.

Is there some workflow to do it?

A screenshot from the Copernicus European air quality portal:

P.S. I have good experience in remote sensing of land surface and geographic information systems, but I've never worked with weather/atmosphere data before.

...measured in mol/m² within the total or tropospheric column. Is it possible to deduce concentrations for a specific slice of the troposphere?

Not really, since you have a crucial bit of information missing: the vertical distribution.

Your alternatives are:

Combine satellite data with a model to estimate near-surface NO₂.  The model may be able to estimate what surface conditions may be associated with what total column conditions, depending on other factors.
Stick with total column data.
Use a different data source, preferably ground-based measurements.  Although a limb sounder does a much better job at getting a high vertical resolution (at expense of horizontal resolution), below 50 metre is too close to the surface.

Measuring the vertical distribution with a down-looking sensor is difficult.  You can get some information with vertical sounding by having many closely-spaced channels along a spectral line, but the vertical resolution is going to be very poor, in particular from space.  Vertical sounding is common practice for temperature and water vapour, but if you search for NO₂ vertical sounding, you will find mostly, probably exclusively, ground-based measurements.  I've tried to do CH₄ sounding and you're lucky if you can get 2 degrees of freedom of signal (DOFS), meaning a rough split in "lower half" or "upper half", but usually you get much less than that:

Source: Holl et al., (2016)

TANSO-FTS is a spectrometer carried on a satellite, PEARL-FTS is a ground-based instrument looking up.  Now this was for CH₄ (not NO₂) and for a station in the Arctic at night.  Hopefully you're not trying to do this in the Arctic and not at night, so if you try to retrieve profiles from a spectrometer (AIRS, IASI, CrIS) you can do a better job, but near-surface, probably not.  Looking up, such as PEARL-FTS does, tends to be easier than looking down because you don't have a background surface to deal with.

There are plenty of  instruments that can retrieve NO₂ total column:

Source: WMO Oscar

However, to get a good quality profile from space you need a limb sounder, such as these:

Source: WMO Oscar

A limb sounder gets a much better vertical resolution, but a much worse horizontal and temporal resolution (there are no geostationary limb sounders, and the concept wouldn't make much sense).  You can find a limb viewing geometry illustration here:

Source: Riese et al. (2014)

The best signal to noise ratio are from solar occultation limb sounders such as ACE-FTS, but those can only measure at sunrise and sunset.  And close to the surface is difficult with any limb sounder, solar occultation or not, so it is unlikely that a limb sounder would even work in your case of measurements within 50 metre from the surface.

Depending on your scientific background, I would either look for model data or use ground-based measurements.

Holl, G., Walker, K. A., Conway, S., Saitoh, N., Boone, C. D., Strong, K., & Drummond, J. R. (2016). Methane cross-validation between three Fourier transform spectrometers: SCISAT ACE-FTS, GOSAT TANSO-FTS, and ground-based FTS measurements in the Canadian high Arctic. Atmospheric Measurement Techniques, 9(5), 1961-1980.
Riese, M. & Oelhaf, H. & Preusse, P. & Blank, Joerg & Ern, M. & Friedl-Vallon, Felix & Fischer, H. & Guggenmoser, Tobias & Höpfner, Michael & Hoor, Peter & Kaufmann, M. & Orphal, Johannes & Ploeger, Felix & Spang, Reinhold & Suminska-Ebersoldt, O. & Ungermann, Jörn & Vogel, B. & Woiwode, W.. (2014). Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) scientific objectives. Atmospheric Measurement Techniques. 7. 1915-1928. 10.5194/amt-7-1915-2014.


Explanation for growing circular echo on weather radar? Does anybody have an explanation for the growing ring/growing circular echo that I occasionally see on weather radar? Attached is a gif of a NEXRAD loop showing areas around Denver, CO, Aug. 2, 2015 3:46 PM to 4:32 PM local time.

You are seeing the gust fronts or outflow boundaries of the thunderstorms around Denver.  The rainfall from the storm provides an evaporative flux that cools the air it falls into (preserving $\theta_e$ of air descending from aloft).  This cool air is more dense than the surrounding air at and near the surface and spreads out as a density current.  The cooler the air (relative to ambient air) the faster it will spread out.  You experience the passage of the boundary as the gusty wind conditions that often precede a storm.

The movement of this density current causes the warmer air it displaces to rise (which can initiate further convection) and this concentrates and lofts insects, which is what you are seeing on radar.  In radar nomenclature you will hear these features referred to as "fine lines".


What is the maximum value of Easting in UTM coordinates? What is the maximum value of Easting in UTM coordinates?

In many websites I found the answer of maximum value is about 834000 meters, but if you convert some of these coordinates below the value will be much higher than that.

Latitude: 61.44 Longitude: 25.40 --> Converted in UTM: Sector: 35 V  Northing: 414668 Easting: 6812844

Latitude: -47.04 Longitude: -73.48 --> Converted: Sector: 18 G Northing: 615471 Easting: 4789269

You are correct about the maximum value, you just have the easting and northing backwards.

In your first example, the easting is 414668 m and the northing is 6812844 m. The convention is eastings first. You can think of UTM coordinates as $(x, y)$ pairs, and they are sometimes labelled as such. Here's the conversion offered by one converter:

As you say, eastings are usually less than 834 000 m, and more than 160 000 m.

Note than some UTM zones are non-standard widths. Also, you will sometimes see coordinates referenced to some neighbouring zone, which isn't a good idea but is sometimes convenient, so the numbers can be unexpectedly large. Lastly: be aware that in the US you may sometimes come across UTM coordinates in other units, such as feet. Horrible.


Applications of differential/integral calculus in crystallography (teaching undergraduates)? I'm a mathematics professor who is seeking to find interesting, application-driven ways of teaching freshmen college students differential/integral calculus. I am in no way versed in crystallography or much of earth science beyond the usual education that the average non-expert gets, but I did enjoy and do well in a single-semester college geology course, and rocks and minerals have always fascinated me. I am wondering if the crystallographers and earth scientists here might know off-hand applications of tangent lines, derivatives, optimization, integration, etc., in crystallography. I've been browsing, and it certainly seems that vectors and linear algebra and group theory are central in this field, but it has been difficult to find uses for undergraduate calculus skills in the field. Please help?

This site may give you some ideas. In particular, look at the Petrology and Geochemistry section:

  Metamorphic phase diagrams show which minerals are stable under
  various temperatures and pressures. The slopes of the boundaries
  between the areas where different minerals are stable depend on the
  properties of the minerals (like the entropy and the molar volume).

  And... well, mineralogy, petrology, and geochemistry are full of ideas
  taken from chemical thermodynamics. And thermodynamics is full of
  multivariable calculus. (How does changing the pressure change the
  amount of calcium in garnet vs the amount of calcium in plagioclase?
  The question is a partial derivative.) From my own favorite,
  metamorphic petrology, there are all kinds of techniques for using
  metamorphic minerals to tell stories of heating and burial and cooling
  and exhumation. And none of the techniques would be possible without
  calculus. (Or, in many cases, differential equations.) I'm sure
  igneous rocks and ore deposits have similar uses of thermodynamics.

Here's an example of a metamorphic P-T Diagram with the source link with more examples:

Source:  https://serc.carleton.edu/research_education/equilibria/metamorphic_diagrams.html


Earthen dam with rock fill and clay core I want to know how to determine water table height and phreatic line in earthen dam with rock fill and clay core.

Okay have a look at this article it may be some use, it's the Journal of GeoEngineering, Vol. 8, No. 1 April 2013 Pgs 27-32 so you may be able to get a hard copy if the link fails, it talks about clay core dams and seepage calculations thereof, including phreatic pathway estimation.

If I remember correctly rock fill in earth dams is treated as earth for the purposes of working out seepage lines etc... as it is generally small enough (particle size), relative to the dam as a whole, to have little or no effect on total mean permeability.


Why is q used for specific humidity? $q$ is the symbol used for specific humidity in many textbooks and papers (at least in meteorology and climatology, I'm not familiar with it in other disciplines). Where does this symbol come from, and what does it stand for?

The specific humidity q is a quotient - mass of water vapor in mass of moist air. The mass is expressed per volume, i.e. the density of water vapor $\rho_v$ and the density of dry air $\rho_d$ are used for the definition of the quotient $q$ known as specific humidity:

$$ q = \dfrac{\rho_v}{\rho_v+\rho_d} $$


Cell Size of Salt Pan Tessellations Salt Pans (such as in Badwater Basin of Death Valley, California) often show a tessellation pattern which forms presumably due to contraction of the deposited salt crust forming irregular cracks towards which the salt crust bends upwards and creates ridges. The cells of this tessellation have a characteristic size of 1-2 meters. I wonder whether a simple model exists which can explain the size of the cells, i.e. why they are 1-2m in size as opposed to 5cm or 10m.

If someone has researched this in the past, I would be interested in some references. Otherwise, some ideas or speculations are appreciated. Some related questions: would the cell size change with a different salt (Badwater Basin is covered predominantly by NaCl)? Does the composition of the underlying soil or rock matter? Does it rather depend on the diurnal temperature time-course characteristic of the place?

Surace,

Here are two references:

http://www.iup.uni-heidelberg.de/institut/forschung/groups/ts/soil_physics/research/pms/cracks
Coupling analysis of pattern formation in desiccation cracks, [2016, Sayako Hirobe and Kenji Oguni]

Best,
Jannes


Is climate change a vicious circle? My question refers to the current process of climate change. CO2 is rising, which leads to the greenhouse effect, which raises temperatures. This leads to more wildfires, which reduces number of trees, increasing CO2 and reducing CO2 capacity absorption. Ice caps start to melt, which reduces sunlight reflection (less snow), trapping more heat on atmosphere. Water rises, taking over land and trees, further enhancing the CO2 absorption capacity. Oceans acidify, lowering their CO2 absorption capacity too. Etc etc.

It seems the process of climate change is a "vicious circle", with a lot of feedback loops reinforcing the trends.

Is this the case? Are there counteracting forces that go against this circle?

Related questions which imo do not provide an answer to this one: here, here.

There are indeed a lot of positive feedback mechanisms, i.e. a warm climate leads to a warmer climate. From this Wikipedia article, they are:

Carbon cycle feedbacks
Cloud feedback
Gas release
Ice-albedo feedback
Water vapor feedback

However, there are also a few negative feedbacks (same source):

Blackbody radiation
Carbon cycle
Lapse rate
Impacts on humans

Now the question is: what is the net budget between positive and negative feedbacks? To assess this, climatologists use some metrics, the main ones being "transient climate response" (TCR) and "equilibrium climate sensitivity" (ECS). From Knutti et al. (2017):

TCR is defined as the global mean surface warming at the time of
doubling of CO$_2$ in an idealized 1% yr$^{−1}$ CO$_2$ increase
experiment, but is more generally quantifying warming in response to a
changing forcing prior to the deep ocean being in equilibrium with the
forcing. Based on state-of-the-art climate models, and instrumentally
recorded warming in response to CO$_2$ and other anthropogenic and
natural forcings, the Intergovernmental Panel on Climate Change's
Fifth Assessment Report (IPCC AR5) assessed that the transient climate
response is 'likely' (>66% probability) to be in the range of 1 °C to
2.5 °C.
By contrast, the equilibrium climate sensitivity (ECS) is defined as
the warming response to doubling CO$_2$ in the atmosphere relative to
pre-industrial climate, after the climate reached its new equilibrium,
taking into account changes in water vapour, lapse rate, clouds and
surface albedo. [...] The estimated range of ECS has not changed much
despite massive research efforts. The IPCC assessed that it is
'likely' to be in the range of 1.5 °C to 4.5 °C.

Which basically means that the climate will get warmer in the future, until it will eventually reach some kind of equilibrium.


What is the most cost-effective solution to climate change based on scientific evidence? Please don't answer without citing scientific research which has a general consensus or article from a reputable source based on verifiable research citations.
I recently read this article about a 2017 PNAS study from Griscom et al (link below) that "estimated natural carbon solutions (NCS) (essentially ecosystem regeneration) have the potential to provide up to 37 percent of the CO2 mitigation that we'd need through 2030, for a 66 percent chance of holding warming to below 2°C."
More specifically, what is the most cost-effective solution? Most geoengineering solutions have significant risks or unknowns which greatly reduce their benefit. Reducing fossil fuel use immediately will reduce short-term economic output with replacing with renewables and alternatives. Maybe simply paying drivers incentives to use alternative vehicles is most-cost effective, as transportation is the largest percentage of greenhouse gas emissions in the US (EPA).
So what is the most cost-effective and how much money would it take to get it done? Global energy-related CO2 emissions were 33.1 Gt CO2 in 2018 according the [IEA report][6]. Apparently from the Griscom study, 10 USD MgCO2e−1 is the "current cost of emission reduction efforts underway and current prices on existing carbon markets" from 2017. 1Gt = 1Pg = 1000Mt = 1000Tg = 10^9 tonnes metric, and 1Mg = 1 tonne, so our CO2 emissions cost us 10*10^9 or 10 billion USD per year. For reference, global GDP is at US$84.84 trillion for 2018, meaning reducing our entire emissions to zero would cost all of 0.0001% of global GDP.
As as corollary, if all benefits of NCS to uncalculated ecosystem services were included, would they be the most cost-effective, and what is the average ROI on research investment to calculate them?
To the Mods: I've changed the title to match the narrow question specified in the body of the question. I've provided an answer that is very specific using calculated figures from cited references. What else would you like to make the question more narrow?
Griscom et al, https://www.pnas.org/content/114/44/11645

In researching my question to provide what is known so far I found the following information. I won't accept my own answer unless it gets the most upvotes.

I found this ranked list from 'Project Drawdown' (PD) that states Managing Refrigerants is the number one solution by GT CO2 reduction by total, but with an unknown cost. Offshore wind turbines (OFTs) seems to be the best solution by total reduction. Electric vehicles (EVs) has the highest savings, but with also the highest cost.

Dividing the reduction amount by the savings leads to OVTs at 11.4 GT CO2 reduction per trillion USD a year (GCR/TUY), then Solar Farms (SFs) at 7.35 and EVs at 1.11 for the top three by savings. However, if all are calculated and ranked, the most reduction by savings is Tree Intercropping at 778 and methane digesters small at 137, the most reduction by cost is Nuclear Energy at 18254 and then Solar Water at 2033, but including the costs with negative numbers (not sure what that means) it's Landfill Methane at -1374 and Solar Farms at -458 GCR/TUY.

I'm not sure if they're including the cost of nuclear accidents or waste storage, since waste storage at least in the US has not been reconciled, and may not be fast enough, so using Solar Water at 2.033 GCR/BillionUY, it would cost 16.3 billion USD per year to reduce the CO2 we emit for energy. Based on a single strategy, that's 2.11 dollars per person in the world (7.7 billion) and $12.50 for every person in the developed world (1.3 billion). Is this correct?

In the PD FAQs they state, "Carbon pricing is a policy mechanism to implement solutions and not in itself a solution to global warming. It is the single most impactful policy proposal that would accelerate the adoption of every solution enlisted."

Adding a few other solutions I've found:

CO2 recapture in concrete can reduce it's emissions by 40% (it is 8% of global) and also the energy used. https://www.solidiatech.com/
Red mud as a carbon sink, using the hydroxides from aluminum smelting because of the high solubility of CO2 in them.
Relying on rock weathering from carbonic acid in rain and because "Coccolithophores account for half of the calcium carbonate creation in the ocean", some kind of phytoplankton farms harnessing their "potential for carbon sequestration but also for the production of high value products, such as fatty acids and pigments."


What is the line crossing the Pacific Ocean that is shown on maps? The picture below shows an imaginary line on the globe which crosses the Pacific Ocean and works as a rough separator of the Eastern and Western hemispheres.

What is this line called in English? I'm trying to find the history behind its funny shape.

It's the international date line and marks the boundary between the time zones that are +12 and -12 hours from UTC / Greenwich. It should follow the +/-180 degree meridian line, but zigs and zags to include territories or islands within a "day" thus the Aleutians islands are in the same time zone as the Hawaiian islands.


What are the top 21 meetings regarding climate change? I was at an academic conference recently and one of the presenters mentioned examining certain variables before and after the top 21 climate change meetings.

Unfortunately I was not able to get a hold of her after the conference and I have no background in earth science/climate change. Does anyone know what she could have been referring to?

I am aware of the COP and CMP only held by the UN.

As Isopcycnal Oscillation has noted in the comments, you've probably misheard, and what they were talking about was COP 21 (not "top 21"), the 21st summit of the UNFCCC parties in Paris, December 2016.


Why is there Uranium in Earth's Crust? Uranium's density is greater than most elements, so you would expect it to settle to the bottom of a volume of fluid. In the case of the Earth, which was molten in the beginning, you might then expect uranium to have settled to the core.

What stopped all of the Uranium from sinking down, so that we still have the deposits in the crust? Or more widely, why do we have heavy elements in the crust at all?

Uranium is primarily lithophilic (it readily combines chemically with oxygen), but also is chalcophilic (it readily combines chemically with sulfur). It definitely is not siderophilic (it does not readily dissolve in molten iron). The first two means that uranium compounds are easily formed, which are of course much less dense than is pure uranium. That uranium is not siderophilic means that the mechanisms that led to the differentiation of the Earth had a lesser effect on uranium than it did on metals that easily alloy with iron.


Petroleum and coal formation I was wondering why are coal and petroleum being both fossil fuels are found at different places i.e. coal at land and petroleum at sea.

Coal, oil and gas can be found anywhere on Earth: on land and on sea.

The Japanese once mined coal from beneath the sea floor, using Hashima Island as the base of operations. The island is only 6.3 ha in size.

The British also mined coal from under the sea, in the north east of England.

As for oil, the following picture from USGS shows the current oil-prone petroleum basins in the world, outside of the USA.

The following oil basins are all on land:

Russia
Arabia, Kuwait, Iraq and north Africa
China
Eastern Europe
The Canadian oil sands and other plays in the province of Alberta, Canada
Colombia
The oil fields of east Texas, USA
The former oil fields in Pennsylvania

When oil & coal deposits formed they each had different mechanisms of formation. Coal is derived of plant material that once lived on land, died, formed peat, which then got buried.

Oil however, owes its origins to algae & plankton that lived in the oceans. When they died they sank to the bottom of the ocean and deposited in waters with very low, if any oxygen. Eventually, these deposits were covered by sediments. If the deposit was subject to a significant amount of geothermal heating gas deposits formed, otherwise oil deposits formed. Movements of the Earth's crust then repositioned some of the deposits which is why some coal is now under the sea and some oil is now on land.


What would be the extent of the feedback on climate of unattended deaths event? Being given that decaying corpses will stop emitting digestive metane, but would release huge amount of methane during their decaying process, I was wondering if this could be considered among the Climate change feedback loops?

To illustrate this, let's just say that scenarii for year 2050 include possibility that population (and livestock) would collapse in a decade. We may have something like 200'000'000 tons mammals decaying in a 5-10 years span... This is not even a quarter on below image, but already so many methane released at once!

Edit: I am not looking for existing signs, I am thinking of the effect of billions of mammals death on the greenhouse effect caused by the consequent huge methane release.

(copied from https://media.treehugger.com, credits XKCD)

Mass of Earth's atmosphere: $5 \times 10^{18} kg$

Concentration of methane in Earth's atmosphere: $1866 ppb$

Mass of methane in Earth's atmosphere, present day: $9.3 \times 10^{12} kg$ = 9,300,000,000 tons

If all those dead mammals were composed entirely of methane, they would increase the atmospheric concentration of methane by about 2%. They aren't, and (as @trond hansen commented) most of their carbon would be converted to $\ce{CO_2}$ with a 30-fold smaller global warming footprint.

So, I think it's safe to say the impact of decomposing mammals would be relatively small.

Worry more about effects on plants, which constitute 80% of the Earth's biomass; bacteria, which constitute 15%; and fungi, which constitute about 2%. The entire animal kingdom amounts to much less than half a percent of global biomass, and half of that is arthropods (which have their own concerns for the future).

(Source: figures from The biomass distribution on Earth, Yinon M. Bar-On, Rob Phillips, and Ron Milo, PNAS June 19, 2018 115 (25) 6506-6511; first published May 21, 2018 https://doi.org/10.1073/pnas.1711842115)


Why would India have so much thorium on its beaches? The recent BBC News article Why India Wants to Turn its Beaches into Nuclear Fuel includes the passage:

The tropical beaches of India probably bring to mind sun-dappled palms, fiery fish curries and dreadlocked backpackers, but they also hold a surprising secret. Their sands are rich in thorium – often hailed as a cleaner, safer alternative to conventional nuclear fuels.
The country has long been eager to exploit its estimated 300,000 to 850,000 tonnes of thorium – quite probably the world’s largest reserves – but progress has been slow.  Their effort is coming back into focus amid renewed interest in the technology. Last year Dutch scientists fired up the first new experimental thorium reactor in decades, start-ups are promoting the technology in the West and last year China pledged to spend $3.3bn to develop reactors that could eventually run on thorium.

The caption to a stock image of a beach says:

Kerala's beautiful beaches hold 16% of India's thorium reserves, a major potential power source - if only scientists can find the right way to exploit it.

Question: why would India have so much thorium on its beaches, apart from the fact that India has so many beaches of course?

why would India have so much thorium on it's beaches...?

Because monazite. Monazite is a rare earth element phosphate, with the formula CePO4 (where Ce stands not only for cerium, but all of the are earth elements and yttrium as well). It is one of the main ore minerals for the rare earths. It's a very common mineral in granites and similar rocks, and it's very resistant to erosion.

Therefore, it commonly accumulates in placer deposits, together with other resistant minerals such as quartz, magnetite, zircon, rutile, etc. Essentially, nature breaks down the rocks and concentrates those minerals in mineral sands (sometimes known as black sands). These sands are not unique to India, and many examples can be found across the world. Essentially you find them where ever you have sandy beaches developed in areas of granite mountains (in the case of monazite).

Why thorium? Because monazite shares the same crystal structure with a mineral called cheralite: CaTh(PO4)2, and the two components (monazite and cheralite) can exist in the same mineral via solid solution. Some monazites can contain 20 and 30% thorium! Granite-derived monazite is particularly rich in Th, unlike carbonatite-derived monazite which usually has little Th. The Th is usually an unwanted by-product, with monazite mined primarily for the rare earths. But, if you're looking for the Th - this is something that you actually want.


National Weather Service "average daily/yearly" (temp, rainfall) life cycle? Does anyone know the "life-cycle" of the averages used for daily and yearly temperatures and rainfall by the National Weather Service?

I have lived in the same (semi-desert) area for over 40 yrs, and have seen the yearly rainfall average go from 13 inches per year to 24 inches per year and back down to 18 inches per year over that period of time.

Unfortunately, I failed to pay attention to the specific "whens" of this phenomenon...

Simple math tells me that this is NOT possible if we are using total data - only possible if we use an interval. But, I cannot find any reference to such an interval ... .  Same things I have been seen with average temperatures ... .

Climate normals are computed over 30 years.  Not sure why that number of years was chosen specifically.  Perhaps a recent incentive is to identify climate changes (though it actually would make warming appear less significant when looking at anomalies).  But, given that those trends have only gotten interest in the past few decades, the only historical reason I can fathom is to sooner allow more sites to be used.  30 years is a fair number of data points statistically, but for daily normals, it should still have a significant error range.  It would seem a 50 or mean year normals length might be more useful at this point, though indeed climate changing might be comparable to the confidence interval.

But regardless of why they chose that value, that should be the period they are reporting.

If you wanted to verify these values, I was able to find pages to get the 1961-1990 normals (use the find command within this file to determine station id), 1971-2000 normals, and of course 1981-2000 normals.
Or a more robust option would be to use NWS' great ClimateNow data portal (select your local NWS office).  There you can look at annual data for the entire record length, search for specific values, or compute normals for any period you wish (select your station, then Monthly summarized data, and then the mean at the bottom is your normal over the time period you selected) (can also change to avg temp).

I know these portals can be a bit complex to some, so if you wish to mention the area, I can pull the values and edit the answer.  And then you can see just how much the normals have changed :-)


Differences between hydrothermal vents on Earth and Europa Hydrothermal vents are common in areas subject to volcanic activity at the bottom of Earth's oceans. Meanwhile, hydrothermal vents are believed to exist on Jupiter's moon Europa and maybe in other moons of the Solar System. Vents on Earth are beginning to be understood and the complex ecosystems associated with them provide many new and fascinating discoveries. My question is what are differences between vents in the two systems?

At the moment, the question is unanswerable, because nobody knows if the vents exist - or even if there is an ocean under Europa's icy exterior (although the idea is reasonably well-accepted). At the moment, they're hypothetical, and until a mission is sent to Europa to observe the depths of its oceans, we won't know much about them.

Well, there actually is one difference. On Earth, hydrothermal vents are the byproducts of tectonic activity. They occur near where tectonic plates meet - for example, in the Mid-Atlantic Ridge, or the Pacific Ring of Fire. On Europa, however, the source of the vents is thought to be tidal interactions with Jupiter, which provide enough heat to keep the ocean from freezing solid, like the moon's exterior.

There is one interesting difference regarding the impacts of vents, described in part of this paper (starting at the bottom of page 7, then jumping in more detail to page 10), which is that Earth's oceans are stratified (i.e composed of distinct layers, stemming from effects of heating, cooling, and convection), whereas Europa's ocean may be unstratified and uniform. On page 10, the authors explain this by saying:

  Earth's ocean is stratified because it is both heated and cooled at different locations along the upper surface. Water cooled at the poles slides beneath warm tropical water, forming stable stratification. If the dominant source of buoyancy in Europa's ocean is heat input at the base, the situation is more reminiscent of a pot of water on a stove, or of convection in the Earth's liquid core. The fluid should be convectively unstable everywhere, and stable stratification should not occur.

The authors say that they can apply this unstratified model to plumes from vents and therefore better explain ocean dynamics on Europa.

Sources:

National Oceanic and Atmospheric Administration

Woods Hole Oceanographic Institution

"Hydrothermal Plume Dynamics on Europa: Implications for Chaos Formation" by Goodman et al.


How were the sea levels around western Europe during the Medieval Warm Period? The Medieval Warm Period (MWP) or Medieval Climatic Anomaly was a time from about 950 to 1250 when climate was warmer than in the timespans immediately before and after.

My question is if this warming lead to significant changes in sea level and how these looked like around western Europe, how the sea levels developed during this time.

Since the change in temperature was not globally uniform, it is of course possible that the sea level changes didn't amount to much.

In the global sense the sea level data are not entirely consistent, but then, there are always going to be apparent variations when you are comparing proxy data from different sources. As far as Europe is concerned sea level rose between 1.0 and 1.6 metres throughout the Medieval Warm Period - or maybe as much as 2.0 metres by some of the more extreme estimates. Following this was the 'little ice age' (actually not an ice age at all), when sea level fell by almost as much. See for example the graphs of Behre 2004, and Puls, 2008, (German North Sea coast),both of which are reproduced in Kwaad's paper, which is a good overview.

http://www.kwaad.net/SeaLevel-MiddleAges-LittleIceAge.html

Whatever sea level change you regard as definitive, the important point is that these were just minor variations superimposed upon a major sea level trend. Overall the post-glacial sea level, from about 8000 years ago, was a rapid rise from -50 metres (or so), flattening off during the last two millennia, and now massively accelerating again, primarily due to human-induced climate change.


Does volcanic activity fluctuate? According to this person's surmises, volcanic activity appers to be increasing.
However, according to this report, volcanic activity is probably not increasing.
My question is:
Does Volcanic activity fluctuate?
If it does, what would cause this fluctuation in volcanic activity?

Image cited by both:

Image: Smithsonian National Museum of Natural History, Global Volcanism Program

Is this fluctuation or recording increase?

This is probably an observational effect that is quite common in the Earth Sciences. In scientifically progressing societies there is a higher proportion of observations due to a number of effects:

awareness of science (not interpreting it as a wonder)
ability to record events
ability to observe (think 12 hour day in the factory vs. free weekend)
technology to do remote observations
...

This is also why more and more meteorites are observed falling. In the middle ages you were either too busy to care, took it as a wonder, or found a meteorite, but had no ability to write it down. Similar scenario for volcanic eruptions. I could imagine that actually all those ships, airplanes, and oudoor-activities (no offense) lead to more observations of eruptions, but that people were to busy recording and writing them down. The geologists of their time were probably busy finding war-necessary resources.

Sources:

http://www.volcanodiscovery.com/de/volcanoes/faq/is-volcanic-activity-increasing.html


Modified blackbody model of earth. What is wrong with it? I have made a modified blackbody model that predict earth temperature distribution with high accuracy. It doesn´t include mass or gases. It is based on the initial thought that all energy above surface is solar heat, and heat transfer must apply to the system. Just some simple modification to the perfect blackbody surprisingly enough gave very accurate results.

I answered a question with these equations, but a moderator deleted it for unknown reasons. It is only numbers, and no speculation, so I really can´t understand why.

The greenhouse effect uses The Stefan-Boltzmann equation to add fluxes, stacking them, and that is not allowed in thermal physics. It is a balance equation and should only be used for "net" transfer.

I show why it is wrong to use an average value of solar irradiation over the whole surface area, it is because intensity is instantaneous. You cannot use average, because that means that the sun would only be ~5C. Or -18C depending on what solar average you use. Solar heat is about 105Celsius at TOA, that makes a big difference. I show how surface temperature and atmosphere temperature distribution is connected to the solar constant all the way.

It is not shown here, but the model also show direct and total irradiation at zenith, with accuracy. Anyway, since it was deleted without explanation, I get the feeling of censorship, since it falsifies the greenhouse effect. Now I ask you. What is wrong with it?:

I use Stefan-Boltzmann equation and temperature. Solar heat is absorbed according to the geometric difference between the blackbody and earth, two volumes with shells.

$TSI/(4/3^2)$.

And since only half the surface area is irradiated,

$(1/2∗TSI)/(4/3^2)=383W/m^2$

or 286.7 Kelvin. The effective temperature is found by heat transfer to the surface and inverse square law,

$1/4∗(TSI−((1/2∗TSI)/(4/3^2)))=244W/m^2$, or 256 Kelvin.

Tropopause temperature:

$((1/2∗TSI)/(4/3^2))−(1/4∗(TSI−((1/2∗TSI)/(4/3^2)))=138W/m^2$

or 222 Kelvin. As you can see, heat dominates everything, and just modifying the blackbody to observed differences, absorption in depth of a volume + irradiation of only half the surface, gives a accurate distribution of temperature.

The numbers are, from my POV, unquestionable. Such a good fit falsifies the greenhouse immediately, especially since no experiments show the effect where cold gas can increase the intensity of the heat source heating it, which the theory claims. So, what are your opinions?

The premise that the Stefan-Boltzmann equation is used for greenhouse gases is wrong. The Stefan-Boltzmann equation is used for irradiance output, not energy input. The ground warms the atmosphere, and the atmosphere releases energy into space.

I suggest looking at the one-dimensional energy balance model. See http://kurs.uib.no/acdc/filer/219.BYQINh.pdf


Are marine fossils in the mountain happens due to lower sea levels? https://9gag.com/gag/aBme0M2
This one says it is

I am not sure whether to ask this in geology or biology.
How does marine fossils show up in mountains?

Leonardo was wrong about this.  It is not due to sea level dropping (except in very isolated cases), it's due to the land rising.  Sedimentary rocks that form in sea beds are often uplifted by tectonic processes to form mountains and plateaus.  See e.g. https://en.wikipedia.org/wiki/Sedimentary_rock


Great Smoky Mountains National Park Why is it that Spring in the Great Smoky Mountains National Park is the peak season for forest fires both man made and lightning caused when it rains so much in the spring and it is so wet there in the Spring so how can forest fires possibly form and even be the peak season for fires there?

With fires, the forest cover and climate generally control what are the worse seasons for fires, add to this the human factor, accidental and prescribed burning.  For purposely ignited fires spring and fall are the major seasons, spring because the ground is often still damp but the fine fuels on the surface are dry enough to burn, making the fire easier to control, fall because the fuel is generally dry but the weather is getting colder and wetter with winter approaching making the fire easier to extinguish and reducing the time required to monitor the fire.

In the case of the Smoky mountains, it appears that the weather is more damp, humid, in the winter and summer, additionally, summer has more moderating green moist vegetation that is not present in the spring or fall.  The following excerpt from the Great Smokey Mountains Fire management plan directly mentions the spring and fall seasons (See page 16).  Great Smoke Mountains Fire Management Plan

  The annual fire weather cycle is more a function of seasonality and temperature than
  precipitation. Warm temperatures and exposed fuels during the dormant seasons of spring and
  fall condition the fuels for easy ignition and spread. In contrast, during the winter, cold
  temperatures prolong the wetting effect of the precipitation, and in the summer, heavy sheltering
  of fuels by tree foliage (coupled with high humidity) makes for poor ignition conditions under
  normal circumstances. Exceptions to the norm have occurred. Atypical dry spells in any
  season can result in more fires and/or unusually higher fire intensities. In 1987, and again in
  2007, extreme summer-time droughts made the normally fire-resistant hardwood forest
  susceptible to fire. Numerous lightning- and human-caused fires in and near the Park burned
  thousands of acres during summer months in those years.


What data does a skilled meteorologist look at to predict thunderstorms? An uneducated layman like me would just look at CAPE numbers and make rough guesses on possible thunderstorms. In a related but non-duplicate question, vertical wind shear is discussed.

If we are talking about predicting afternoon thunderstorms at or near a single location (8 hours ahead), what are the rules of thumb that skilled meteorologists follow to estimate the likelihood of the condition based on three possible sets of data:

when they have no more data on their hands than those produced by mesoscale models like WRF.
when a radiosonde is launched in early morning.
when a weather radar is added to the mix.

Background: I am curious about actual procedures/decision templates used at various rocket launch sites.

For same day forecasting of afternoon thunderstorms, I'd start with the morning observations and the 12Z† model runs (I choose 12Z because that is the morning here in the Americas.  For Europe you might be more interested in the 00Z or 06Z runs to start your day).  In particular I'd start with the output of the 12Z GFS and NAM, and then give that some time to propagate into the RAP and finally the HRRR models which are initialized from each other starting with GFS.

For observational data, I'm interested in the 12Z balloon launch, surface fields (temperature, dew point, winds, pressure), upper air data (850 mb temperature, 500 mb wind and vorticity, 300 mb wind) and satellite imagery (for cloud cover).

At 12Z the morning soundings are going often going to have the remnants of a nocturnal inversion and the previous days boundary layer.  Give cloud cover and surface temperature and moisture advection you can get a rough idea of how that boundary layer will evolve.  An hour or two after 12Z the GFS and NAM will start coming in and you can look at forecast soundings and how the model thinks things will evolve.  Around 15-17Z I'm looking at the HRRR for some additional guidance.

CAPE and wind shear only tell part of the story.

Image credits: Pierre_cb via Wikipedia. Licensed under GFDL 1.2+/CC-ASA 3.0U.

CAPE (convective available potential energy) is a measure of buoyancy and its opposite, CIN (convective inhibition) is a measure of the negative buoyancy a parcel must overcome to reach its level of free convection.  You can have a lot of CAPE, but more than a little CIN can keep any thunderstorms from firing.  If you have no CIN on the other hand but lots of CAPE you'll generally get a mess of storms everywhere but nothing organized.  The bulk 0-6 km wind shear is a good predictor of the type of storms you can anticipate.  Little shear tends toward air-mass thunderstorms while lots of shear tends toward supercell thunderstorms.  In between these two are multi-cell thunderstorms.  The shear will also influence whether multiple storms along a boundary stay discrete or build upscale into a linear feature (e.g. squall lines or QLCS).

What the above things tell you is whether the environment favors convection and what type of convection.  It does not tell you if there will be a storm or not.  You can have a perfect environment for storms, but unless something acts to initiate convection, you won't have a storm.  Storms like to initiate along boundaries (cold fronts, dry lines, gust fronts, etc).  You can also initiate with daytime thermal boundary layer convection eroding CIN until parcels can freely convect.  Upper level divergence can also promote initiation by providing large scale ascent.

Putting this together, I'm looking at observations and model output to identify favorable storm environments.  I'm also looking at them for features that promote initiation.  As we near showtime, I'll also be looking at radar.  On the radar I'm looking for evidence of convergence zones (radar fine lines, fronts, etc) to narrow down where I'd expect storms to fire.

† The Z suffix is shorthand for the historical Zulu time zone, which in modern times we call GMT or Greenwich Mean Time.  All meteorological products are referenced to this time zone and this is done for simplicity.  For example, no matter where you are on Earth, you know balloons are going to go up at 12Z and 00Z, and that the GFS will come out at 00,06,12 and 18Z.  The conversion to local time exactly that as from GMT or UTC.  For example 12Z on the east coast of the USA (in eastern daylight time, EDT, at the time of this writing) is GMT-0400, so 12Z - 4 = 08, or 8 AM EDT (and 7 AM EST the other half of the year).


Convert satellite image data (GOES 15) into solar irradiance values? I have GOES 15 satellite image data (GVAR_IMG) for a project that I am working on.  The files are end in .BAND_01, .BAND_02, etc.

I use the Panoply tool to view these files, but am looking for an online tool or software to convert this data into solar irradiance values.

It is far too complex a process to estimate surface irradiances utilising satellite data. No software takes just satellite images as input and gives out irradiances.

I am pasting link to an article that describes algorithm to convert geostationary satellite measurements to surface reaching solar irradiance.

Gadhavi et al., 2008; doi: 10.1029/2007JD009308

To summarise following are most important aspects in estimating surface radiation budget.

Calibration constants to convert photon counts measured by satellite sensor to radiance
Parameterisation scheme to convert narrow band satellite radiances to broadband radiances.
surface optical characteristics as function of wavelength, sun elevation and season
Geophysical parameters like cloud amount, aerosol amount, ozone, etc. (Essentially these are the real satellite input in whole process).
Radiative transfer model to estimate irradiances using inputs received from satellite and other sources.

There are few web-site where one can directly get final output of irradiance values. See following link.
https://data.noaa.gov/dataset/surface-radiation-budget-surfrad-network-1-hour-observations


What would it take to confirm or refute the Snowball Earth Hypothesis? Since Harland's sedimentary work and Budyko's models in the 1960s, geologists have hypothesized that the Earth may once have been completely frozen. There are various lines of evidence for this event.

What would it take to conclusively confirm or refute this hypothesis, short of going back in a time machine?

In order to confirm the snowball earth hypothesis, we'd need at least:

A paleogeographic model which extends to greater than 650ma and has been shown be be conclusively accurate throughout that entire period. (i.e. one we can trust)
Sedimentation structures/patterns (or other paleoclimate proxy data), consistent with a glaciation event, tied into the same time period, from the north pole to the south pole


What geologic features could this video game environment be modeled from, and how do they form? I have been playing this game for a while and I like the city's setting. It seem to be placed on a rock platform, or a mesa maybe, connected to the mainland on the bottom-left. It also has some connection in the top left and middle right.

I would like to know what this structure is called so I can find some real-life such occurrences in order to draw some fan-art for this game.

I would also like to know, if possible, what sort of parameters does nature require to make such an effect. What kind of climate, rock combinations, that sort of thing.

Looking at the landscape, it almost appears to be a highland, with steep valleys carved by a misty river - which suggests possible waterfalls.  I am reminded of Victoria Falls, on the border of Zimbabwe and Zambia (part of the landscape pictured below)

Image source

The geological processes that formed these features is summarised in the webpage The Geology of Victoria Falls as a series of tectonic and erosional activity over an ancient basaltic bedrock, forming a series of near parallel gorges (shown below and from the webpage linked before).


How to interpret seismic interferometry data? Here is a screenshot of coseismic interferometry measurements of the 2015 Nepal earthquake. What does it mean?

The star is the epicenter of the earthquake. The screenshot was taken from the UNOSAT live crisis map.

It is a differential InSAR image that shows wrapped phase in radians which is a measure of the change in range (or distance) between the ground surface and a (more or less) fixed point in space from which the radar images were acquired (keep in mind that two SAR images are required to create an interferogram). To get the actual range change you have to unwrap the interferogram.

You can think of the fringes as contour lines. Areas where spacing between the fringes is tight, represent areas with high deformation, e.g., near the fault. The wavelength of the radar determines the fringe spacing.

A better looking interferogram for the Nepal earthquake is at http://topex.ucsd.edu/nepal/ (made using SAR data acquired by the L-band ALOS-2 satellite operated by the Japanese Space Agency, JAXA).


Before the Great Oxygenation Event, where was the oxygen? Today, the oxygen in the atmosphere is about 1018 kg.
The estimated carbon biomass of the earth is about 4×1015. Less than 0.5%.

Estimated fossil fuels are around 5 times as much as existing carbon biomass. If these estimates are appropriate, then probably before the oxygen was released it was not locked up in carbon compounds.

Oxygen could have been extracted from inorganic stuff and cycled through the biomass.

Which reduced minerals were left behind? Not silicates and carbonates. Little magnetite crystals?

Maybe there was more SiO4 before (things like olivine), and living things tended to produce silicates with less oxygen (things like kaolin)? There isn't a whole lot of silica dissolved in seawater at any one time, but there's a whole lot of silica available and it could add up eventually. Silicates with more oxygen weathered away, and silicates with less oxygen were deposited?

Maybe there's so much free oxygen today because some H2 got produced, and it rose right out of the atmosphere and got swept away. So there's less water and more oxygen than there used to be.

Maybe the biomass estimates, and the fossil fuel estimates, don't actually tell us about the carbon, and there is lots of reduced carbon elsewhere.

I'm speculating, does anybody have good answers?

the great oxygenation event was caused by the evolution of photosynthesis, photosynthesis turns CO2 and water in to sugar and oxygen. so the oxygen came from CO2 and water.

keep in mind CO2 levels were many many times higher (~20X) than today. Hydrogen was not released it was combined with carbon and oxygen to make sugars


Amplitude scaling in seismic inversion I've been testing how amplitude scaling subsequently affects the results of gapped/non-gapped deconvolution and an impedance inversion algorithm called BLIMP (Ferguson and Margrave, 1996). Indeed, scaling the amplitude of the input seismic data (whether linearly or non-linearly) greatly affects the final result of both deconvolution and inversion. I am confused by this.

Let's look at the convolution model in its full mathematical form:

$$ s(t) = [R(t) \ast W(t) + N(t)] \times A(t)$$

where $s(t)$ is the observed seismic trace, $R(t)$ is the reflectivity time series (or perhaps impulse response if you want a more realistic/complicated situation), $W(t)$ is the source wavelet, N(t) is the additive, random noise component, and finally $A(t)$ is the amplitude. Also, note that $\ast$ denotes convolution and $\times$ denotes multiplication. I understand the convolution model in this mathematical context, but I am failing to transfer that knowledge to grasp how amplitude could so greatly affect deconvolution or inversion calculations.

If anyone has any papers, personal insight, or both to provide, please do so.

You can think of this amplitude term as being part of the wavelet term such that your definition of the wavelet is: "the necessary filter/operator to convert true reflectivity into the arbitrarily scaled seismic data". This scalar depends on the data itself and therefore must be obtained empirically. In fact, it is very likely that the scalar is frequency dependent. Your best bet to obtain the full wavelet, including its scalar, is by using a well where your reflectivity is known and applying the method of White and Simm (2003) or any other similar method.

Anyway, doing any sort of deconvolution or inversion with the wrong wavelet scalar will leak all error from this into the solution. You are pretty much asking: "What is the necessary (for example) acoustic impedance such that when I do this faulty forward modeling, I get the measured seismic data?".


What periods of the fossil record are most lacking in specimens? What parts of the fossil record are most lacking in specimens? That is, if you were to trace the evolution of a modern mammal (humans, for example) from abiogenesis to now, which periods are the most lacking in fossils? Where are the biggest gaps in our evolutionary history.

The biggest temporal gap would be (IMO) the Precambrian, specifically pre-Ediacarian. Accordingly the biggest gap in the evolutionary history is the origin of eukaryots, both because of the paucity of pre-Ediacarian formations but also because few of the early protists were likely to be fossilizable.

From the probable apparition of life ca. 3.8-3.5 Ga (e. g. 1 for a review of Archean fossils) to the Ediacarian (ca. 600 Ma) in which metazoans (i. e. "animals") are already diverse (e. g. 2), this is more than 3 Ga of life history for which we have very little fossils (though our knowledge of this fossil record increases currently thanks, in part, to our better understanding of the "chemical" fossil record).

1: J. W. Schopf, 2006. Fossil evidence of Archaean life. Philosophical transactions of the Royal Society, B., 361: 869-885.
2: S.Conway Morris, 1993. The fossil record and the early evolution of the Metazoa. Nature, 361: 219-225.


Is there major potential for vertical farming? You can take up way less square footage for the same amount of production
You can eliminate the need for pesticides
You can power the farms from renewable energy
You can significantly increase growing efficiency
You can significantly increase the nutritional value of plants

I see major opportunity in vertical farming due to these reasons. What do you guys think? Will we see vertical farming taking over the agricultural industry?

As our planet gets warmer less area will be avaliable for farming so vertical farming will be needed to supply food for a growing population.

Vertical farming will not replace traditional farming but it will be an addition to this.

Vertical farming can be effective in growing food by using less energy,We can use only the part of the light spectrum that plants need(UV-Blue-Red-IR)And avoid producing un needed green light(plants do not use the green part of the spectrum).

The use of water can be a lot lower in vertical farming as any evaporated water can be captured and recycled.

The need of plant nutrients can be reduced significantly,One only needs to add the nutrients the plants remove(so no runoff of nutrients at all).

The use of pesticides can be close to eliminated and this is good news for insects that are needed in the production of food and for the consumers of the food.

A very large part of the water used in prossesing of the product can be recycled and used to create more food,So less water will be wasted.

A lot of the organic waste can be used as animal feed directly(Roots stems and flowers material not usable for human consumption).

So the answer to your question is yes there is potential in doing this,How large potential there realy is i do not know but i think it might be significant.

The prosess uses more CO2 than it releases(if renewable energy is used) so it is cleaner for the environment,It can be done anywhere so less emission of CO2 during transport to the consumers.


What kind of lava tube feature is Cleopatra's Grave? Cleopatra's Grave is a natural feature inside (warning: PDF) Catacombs Cave in Lava Beds National Monument near Modoc, California.

Source: LookBeforeYouLive

My apologies, as this image is somehow in really bad color, like all the other images from that blog post. (I should really be grateful they got images at all, as this low image quality video provides some idea of the difficulty of reaching the location, which requires crawling through at least eight feet of one-foot-high passage and lots of three-foot-high passage, and the ceiling directly above it is about two feet high, so I can't complain about the quality!)

I saw it with my own eyes. Cleopatra's grave is an oblong feature on the floor of Catacombs Cave (lava tube) about three feet long and two feet wide and rimmed by apparently normal cave floor that raises up about an inch or so above the surrounding floor. Cleopatra's grave is composed of rock of a light grey color as opposed to the dark grey and slightly brown-tinged floor around it. It looks very smooth (I didn't touch it because of its historic paint) and it exhibits circular fractures running two complete rings around its outer edge. It is trivially identified by the rather recent red paint serving to mark the locations of the historic yellow paint applied by J.D. Howard himself calling it by name.

The surface has no visible crystals, and if I didn't know it was natural I'd have thought on seeing it that somebody had mixed up some really fine grout (think cement) and poured it. Furthermore, the surface exhibits no specular reflection and almost perfectly uniform matte reflection.

But what is it? Some kind of lava upwelling? A rafted block of unusual shape? Something else?

This is a locally-well-known feature that I'm hoping somebody here actually knows the answer to. But there is simply not another way of getting at it -- there's no way I'm going to test its hardness or otherwise risk damage to so much as the paint on it.

It's just average ropy lava called pahoehoe by geologists. It's similar to dough so it easily forms ropes like the ones around the side and bulbs like the central area which is similar to a pillow except that it's called a toe.

The colder black lava flows like ropes and the hotter red lava is smooth.

This is also from Cleopatra probably: https://media.gettyimages.com/photos/ropey-lava-from-volcanic-eruption-picture-id200432059-001

Another good image of a toe:

Source: Oregon State University


Does being under water provide any protection from a asteroid? Does being under or on water provide any protection from an asteroid hitting the opposite side of the Earth over being in or on land or in air? Why?

Will the shock wave follow the curvature of the Earth through the oceans?

I'm trying to go with the worst case survivable scenario.

Related:

  This is from a broad question that I am breaking up in 3 questions. Feel free to edit.

Scenario 3. In a submarine or capsule underwater?

Does being in the air provide any protection from an asteroid?

No. It depends on the severity. Water would be worse. If an asteroid hit in the ocean we would experience tsunamis the size we get from large magnitude earthquakes. The displacement of the water would be massive. It would also cause things like swimming pools sloshing around, common to the videos you see of hotels from the 2011 Japan earthquake. If it hit on the opposite side of the Earth, land would still be a better spot. Tsunamis can translate vast distances depending on the level of energy and surface deformation they create. Being in a submarine?  Again, no. A tsunamis can pass under boats. However, impact from an asteroid vs sea floor deformation from earthquakes are different functions. The submarine one, would require someone with a little more expertise.


How much of Earth's forested land is currently protected from logging/deforestation? Deforestation is an ongoing global problem. From this National Geographic webpage:

  The quickest solution to deforestation would be to simply stop cutting down trees. [However], financial realities make this unlikely to occur. ... A more workable solution is to carefully manage forest resources by eliminating clear-cutting to make sure that forest environments remain intact. ... The number of new tree plantations is growing each year, but their total still equals a tiny fraction of the Earth’s forested land.

How much forested land is currently protected from logging/deforestation?  How much is currently at risk?  How do tree plantations compare in overall size?  I'm hoping someone could answer these questions in terms of the main countries involved.

Here is what I have found thus far:

From http://www.earth-policy.org/indicators/C56

  Forests cover 31 percent of the world's land surface, just over 4 billion hectares. This is down from the pre-industrial area of 5.9 billion hectares. ... According to data from the U.N. Food and Agriculture Organization [below], deforestation was at its highest rate in the 1990s, when each year the world lost on average 16 million hectares of forest—roughly the size of the state of Michigan. At the same time, forest area expanded in some places, either through planting or natural processes, bringing the global net loss of forest to 8.3 million hectares per year.  In the first decade of this century, the rate of deforestation was slightly lower, but still, a disturbingly high 13 million hectares were destroyed annually. As forest expansion remained stable, the global net forest loss between 2000 and 2010 was 5.2 million hectares per year.

South America and Africa are clearly the biggest area of concerns due to illegal logging and corrupt governance.  Should we expect the rates of deforestation in those continents to continue "as-is"?  Or is there some percentage of forested areas that can be expected to last (e.g. perhaps some countries are less corrupt)? Furthermore, if the size of forested land on N. America, Asia, and Europe remains constant or grows, how much of that is due to tree plantations?

How much forested land is currently protected from
  logging/deforestation?

I doubt that could be answered with anything better than a rough guesstimate. We would first need to know how much land is OFFICIALLY/LEGALLY protected. Then we would have to subtract acreage to allow for illegal logging or general environmental destruction. There are also areas that aren't legally protected but nevertheless aren't logged simply because they're very remote, the terrain is too rugged, etc.

In addition, it's a moving target. Various governments around the world continually modify their environmental management policies and practices. A forest that's protected today might fall prey to a bribe from some giant oil company tomorrow.

  How much is currently at risk?

Again, that's very hard to answer. Forest destruction is an ongoing process around the world. Forests in the most remote regions are typically the safest, but they will become more vulnerable as surrounding forests are felled, new roads are built, more people move into these remote areas, etc.

Another factor to consider is war, or political corruption in general. So many governments have been destabilized (primarily by the U.S.), and so many governments are grappling with economic woes or fears of invasion. Not surprisingly, they're going to emphasize security and survival over the environment.

Of course, war itself can take a toll. Consider Vietnam, where the U.S. used Agent Orange indiscriminately. I believe the Soviets similarly wiped out much of Afghanistan's montane forests.

  How do tree plantations compare in overall size?

Are you asking how the land area that is devoted to tree plantations compares to the land area covered with wild forests?

Again, I don't know the answer, but please note that there are vast differences between plantations and wild forests. Plantations may be preferable to barren earth, but they don't begin to compare to "natural forests" in terms of biodiversity. Tree farms are to Nature what fast food is to cuisine.

I fear for Africa more than South America. The Amazon is obviously a cause for concern, but there is some political stability in South America, and there are environmental activists there.

In comparison, Africa appears to be lost. How many acres have been converted to genetically modified food? I've read about thousands of traditional African farmers being replaced by GMO, though there isn't much information on the subject.

Libya's destruction by NATO was an enormous blow for Africa (and the world). And for whatever it's worth, I believe Colonel Gaddafi was generally regarded as an environmentalist, at least in comparison to other African leaders. There have long been predictions that the next cold war will be fought between the U.S. and China over Africa's natural resources. In fact, the U.S. has troops stationed in just about every country in Africa, and I just read that China is building a military base there.

In summary, forest loss is a huge problem in South America, but there is at least some hope. I predict that it will be a much bigger problem in Africa in the long run.

  Furthermore, if the size of forested land on N. America, Asia, and
  Europe remains constant or grows, how much of that is due to tree
  plantations?

Once again I don't have a specific answer, but I can offer a good guess: Most of it. After all, native forests will continue to shrink, while tree farms will continue to multiply.

Sorry to be so negative. I actually believe there is hope, but things aren't going to change without a massive change agent.


Epicenter of earthquake at sea - is it a point on ocean surface or sea bed? When an earthquakes' focus is below the sea bed, is the epicenter given as a point on the oceans' surface at mean sea level, or as a point on the sea bed?

There is some ambiguity in the term 'earths surface' here that is causing confusion in the English Language Learners sister site, which I'm hoping the experts here can clear up.

I'm using the definition of epicenter found here.
Is the epicenter always directly above the hypocenter?

Technically the depth is distance below the ocean floor, but bear in mind that unless there happens to be a cluster of seismometers close to the earthquake (unlikely in the ocean environment), the accuracy of depth estimates is only approximate. If you look at the table of earthquake depths in, for example, the Tonga Trench, you will see a few really deep earthquakes and many times more 'shallow earthquakes' at a nominal depth of 10 km - meaning 'shallow-ish'.


Why is ocean surface velocity around 3% of wind velocity? Many introductory level textbooks suggest that, as a rule of thumb, the velocity of the ocean surface is around 3% the wind velocity at 10 meters above the sea surface.

For instance, Ocean Circulation by the Open University Press, page 39:

  Another useful empirical observation is that the surface current speed is typically 3% of the wind speed, so that a 10 m/s wind might be expected to give rise to a surface current of about 0.3 m/s

What are the mechanisms that result in this ratio? How universal is this relationship?

A very good analysis looking at the 3% relationship is an article by Weber (1983). His main result is that:

  We assume a fully developed sea, and take the eddy viscosity to be proportional to the friction velocity times a characteristic depth. Hence the total current (Ekman current plus wave-induced current) can be expressed as functions of the wind speed. The results show that the magnitude of the total surface current lies between 3.1 and 3.4% of the wind speed at 10 m height for winds between 5 and 30 m s−1.

The idea is that by including both the Ekman current (induced by the mean wind stress at the surface) and the wave-induced current (Stokes drift), the resulting total surface velocity can be easily represented as a function of wind velocity at 10 meters. Both Ekman and wave-induced currents are about the same size and add up to be around 3% of the wind speed. The assumptions include the full range for Ekman dynamics (homogeneous, not affected by boundaries), plus some about waves (non-decaying, small amplitude). In the real ocean, eddy viscosity is vertically variable, but, as it is the case with Ekman dynamics, the approximation is quite close to what is observed in the ocean. The approximations that Weber used are valid for a large range of wind values (5-30 m s−1) and they break down in weak wind (not fully developed waves) and strong wind conditions (whitecapping, wave breaking).

Weber, J. E., 1983: Steady Wind- and Wave-Induced Currents in the Open Ocean. J. Phys. Oceanogr., 13, 524–530.


Can anyone help me identify these rocks please? I apologize for any errors in my pictures or writing. My first post.

[

The first two images look like banded calcite to me.  The rock appears to have distinct cleavages, no clearly conchoidal fractures, and a slightly waxy luster on the weathered surfaces.  Sometimes this type of rock goes under the term onyx but traditionally onyx is a type of chalcedony.  If it is banded calcite a typical knife will easily scratch the surface, additionally it would fizz with some muriatic acid (or dilute HCl).  If it is type of chalcedony, then knife will have a harder time scratching the surface an may not if the knife is on the soft side.  Also the acid will not react with the stone.

Jan Doggen's suggestion will help you get better results for the other stones.


Can the clouds on Venus and Titan be categorized in the same way as clouds on Earth? E.g. are the clouds on Venus (and Titan) cumulus, stratus, cirrus, or some other type that isn't found on Earth?

Clouds on Venus

After a quick search, it appears the clouds found on Venus are different than Earth's:

  Venus is covered by a thick layer of clouds. These clouds are made
  mostly of sulfuric acid and are very fast moving, going up to 220
  miles per hour (350 km per hour). The clouds rotate 60 times faster
  than the planet rotates. The clouds circle Venus in four Earth days;
  the planet rotates around its axis in 243 Earth days. These
  quickly-moving clouds distribute the heat around the planet, making
  the night side hot also. V-shaped cloud patterns are visible in the
  middle latitudes when the clouds are examined in ultraviolet light.
  The clouds rain sulphuric acid (extremely acid rain), but this
  corrosive precipitation does not reach the surface. The high heat
  beneath the clouds (up to 220°C) evaporates the rain drops about 10
  miles (30 km) above Venus. SOURCE

Clouds on Titan

According to this release by NASA, Titan has "cirrus-like" clouds:

  Now, thin, wispy clouds of ice particles, similar to Earth's cirrus
  clouds, are being reported by Carrie Anderson and Robert Samuelson at
  NASA's Goddard Space Flight Center in Greenbelt, Md. The findings,
  published February 1 in Icarus, were made using the Composite Infrared
  Spectrometer (CIRS) on NASA's Cassini spacecraft.


Publicly available data set with ensemble forecasts and observations? I am looking for a publicly available, easy to download, small data set of ensemble forecasts (or reforecasts), with corresponding observations or reanalysis. We are planning to illustrate some methods for a small software package, so ideally, the data set should be available for the foreseeable future, or even better, freely distributable. Further, ideally, the data set would be given as SV or text file (anything that can be read easily without requiring additional software packages, as it would be the case with GRIB for example). Any suggestions?

By easy to download I mean: Ideally, without creating any login, for example directly possible within Python or R; small in the sense of a couple of months and data for only one location are enough; there should be some verifying observation or re-analysis associated with the forecasts

You can try if this looks simple enough. Still requires registration, but it is free for reasonable use: Global Ensemble Forecast System (GEFS).


Why is Paris still polluted during the Covid-19 shutdown? It does not seem that the air pollution level is getting any lower in Paris during the current shutdown due to COVID-19.

Why is that?

There are fewer cars. Are they only a small part of Paris' air pollution?

Where is the pollution coming from?

There are fewer cars. Are they only a small part of Paris' air
  pollution?

Recent evolution of European standard on emissions for private vehicle means that the average car is polluting orders of magnitude less than the average gasoline-burning heater.

Even for a city plagued by the widespread use of huge, inefficent cars (New York), the heating systems (heat and hot water) may account for >40% of the emissions https://blogs.ei.columbia.edu/2019/01/15/heat-pumps-home-heating/

A couple of emissions pie-charts for PM10 and PM2.5 for Paris in 2012 (from the report Inventaire régional des émissions en Ile-de-France Année de référence 2012 - éléments synthétiques Edition mai 2016 )

and


How probable is is that earth magnetic field will change 180 degrees at once? Today the Earth's magnetic field is moving a little bit. But is there going to be a point where the field suddenly radically changes direction? If so what is the cause of that? If not, then is the field changing all the time gradually?

The magnetic north pole (and presumably the south pole) currently moves around 40km/year, although within a year it loops around, may travel much further than that forwards and backwards. Here is a map of the movement from the past century and a half (source)
:

However, during a magnetic reversal, the pole may move up to 10 times faster than that, over a period of less than 100 years. Here's a map showing the relative movements (the numbers are thousands of years ago (kya)) (source)

]

The reason for reversals aren't very well understood (according to the previous link), and I'm in no way an expert in the field, but just for some fun speculation, I would wonder whether reversals might be related to this phenomenon. Obviously a liquid outer core is going to operate differently from a screwdriver, but the two systems both appear to be exhibiting a bistable rotation while floating in space.


What determines the spectrum of high and low frequency waves emitted by an earthquake? Does the shape of the fault that the earthquake originated from determine its ratio of high frequency to low frequency waves?

What about shallow-fault vs deep subduction zone earthquakes?

There are several factors that determine the spectrum of wave frequencies of earthquakes. They include the following:

1) Size of the earthquake. All other things being equal, the larger the earthquake, the larger the spectrum of frequencies.

2) The texture of the rocks or other materials. Hard materials have a wider range of frequencies than soft materials.

3) The ratio of "body" to surface waves. Waves emanating from the body of the earthquake have higher total frequencies (and greater variation), than waves emanating from the surface of the ground.


Why do ooids not grow larger than 0.5 mm? I know ooids form in high energy water, by rolling and building layers around a nucleation site, but I don't understand what limits their size.

What keeps these such a regular, small size?

I was unaware of a 0.5 mm maximum rule with ooid size. The Sam Boggs Jr. book on Principals of Sedimentology and Stratagraphy indicates that ooids can grow up to 2 mm. Grains larger than this are pisoids.  The size limitation may depend on how you define an ooid. To me, an ooid carbonate grain with a nucleus and concentric layers of calcite or aragonite.

The size is likely a function of the availability of calcium and carbonate ions in the water (calcite or aragonite saturation).  I think that microbial action also contributes to large grain size, but if microbes are involved, then you might call it an oncoid instead.

The similarity of ooid size is a function of similarities in the environment of deposition.

Microfacies of Carbonate Rocks by Erik Flugel is a great book that discusses these features in detail.


What is difference between partially penetrating stream and fully penetrating stream? If fully penetrating stream means, the stream penetrates fully to the depth of aquifer, then doesn't it mean that there is zero conductance or leakance? The leakance or conductance is a term used to accommodate no low conductivity sediments at the bottom of stream which usually serve as interface between stream and aquifer.  Can somebody show with sketches, what is difference between the two types also including leakance or conductance term.

Streams that are shallow relative to the thickness of the aquifer in which they lie. Such streams often are referred to in the literature as partially penetrating streams. Most streams are partially penetrating streams. Seepage between a partially penetrating stream and the contiguous aquifer occurs both horizontally and vertically through streambank and streambed materials.

Image Source:USGS

There are a few streams that are deep enough to penetrate the full thickness of the aquifer in which they lie. Such streams often are referred to fully penetrating streams. Seepage between a fully penetrating stream and the contiguous aquifer occurs horizontally through streambank materials.

Image Source:USGS


What evidence is there that plant evolutionary history "dances to a different beat" than that of animals? Floral transformations have been due to gradual replacement and
  piecemeal, not mass extinction. Plant “geoevents”; have not been
  synchronous with epochal animal originations/ extinctions and hence
  may not be attributable to the same causes.
  -Traverse (1988)

What evidence is preserved in the fossil record to support that the terrestrial plants were largely unaffected by Mass Extinction events? And what does this tell us about possible Mass Extinction scenarios?

I'm not going to give an extensive account on "mass extinction" epistomology here but I think the first thing one has to consider is the difficulty of studying numerically paleobiodiversity (mostly because of a gappy fossil record but also an historically unbalanced sampling effort and the rock availability for some of the time periods); although, along the years, we designed better tools to compensate for those biases (see the whole bibliography of John Alroy for instance), this is still a major issue.

Furthermore, the recognition of the "Big Five" (i. e. the five bigger mass extinctions of the Phanerozoic: End Ordovician, Late Devonian, Permian/Triassic boundary, Triassic/Jurassic boundary and Cretaceous/Paleogene boundary) basically derive from the work of Sepkoski (1978, 1979; Raup & Sepkoski 1981, etc...) who studied the diversity of marine biota and more specifically (judging by Sepkoski 1981) marine metazoans. As a consequence everything terrestrial and every non-metazoan (plants, protists, bacteria) are not included in the classic recognition of those events. It so happens that at least the P-T and the K-Pg events have been also recognized in some marine protists (namely foraminifera) and in terrestrial vertebrates (dinosaurs for the K-PG and many groups of 'pelycosaurs' for the P-T to name the more famous); but conceptually this is a significant bias as it may happen that the geological event driving one of those mass extinctions can only affect marine organisms (oceanic anoxia being the most obvious example).

That's for the epistemology part. Now the plants themselves: as you noticed with your quote of Traverse (1988) it is thought that the Embryophyta (i. e. land plants) have not been affected by the Big Five. This idea have since then been somewhat challenged (e. g. McElwain & Punyasena 2007) with evidences that plants indeed were affected by some of those extinctions but maybe not as drastically as what we think happened for marine faunas or terrestrial vertebrates.
It needs to be considered however that the earliest evidences for the existence of land plants date from the Silurian (see Kenrick & Crane 1997 for a short review). Their fossil record remains extremely gappy until the Carboniferous, basically, meaning that the first two of the "Big Five", if they happened to have affected land plants, can not be observed.
Additionally Angiosperms appeared in the early Cretaceous and diversified significantly toward the end of the Cretaceous, meaning that if the K-Pg event had an effect on the other land plants, the number of extinctions in those groups would be drowned by the number of originations in Angiosperms (I don't have any reference for that, it is just food for thought).

Finally, land plants are not the only group that doesn't dance to the beat imposed by the Big Five. For instance there is evidence that radiolarians (a group of marine heterotrophic planktonic protists with an extensive, continuous fossil record) were not affected by the K-Pg crisis (Hollis et al. 1995) nor by the T-J event (Kießling & Danelian 2011). There are still thought to have been, to some extent, affected by the P-T but there is no clear evidence (to my knowledge) for them being affected by the two previous crisis either.
And of course there is the multitude of groups with no (or minimal) fossil record (because they have no fossilizable parts for instance and thus are only recorded in extremely rare occasions) for which we have literally no idea of what happened to them.

References:
Hollis C., Rodgers K.A. & Parker R.J. 1995. Siliceous plankton bloom in the earliest Tertiary of Marlborough, New Zealand. Geology, 23: 835-838.
Kenrick P. & Crane P.R., 1997. The origin and early evolution of plants on land. Nature, 389: 33-39.
Kießling W. & Danelian T., 2011. Trajectories of Late Permian – Jurassic radiolarian extinction rates: no evidence for an end-Triassic mass extinction. Fossil Record, 14: 95-101.
McElwain J. C. & Punyasena S. W., 2007. Mass extinction events and the plant fossil record. Trends in Ecology & Evolution, 22: 548-557.
Raup D. M. & Sepkoski J. J. Jr, 1982. Mass Extinctions in the Marine Fossil Record. Science, 215: 1501-1503.
Sepkoski J. J. Jr, 1978. A kinetic model of Phanerozoic taxonomic diversity I. Analysis of marine orders. Paleobiology, 4: 223-251.
Sepkoski J. J. Jr, 1979. A kinetic model of Phanerozoic taxonomic diversity II. Early Phanerozoic families and multiple equilibria. Paleobiology, 5: 223-251.
Sepkoski J. J. Jr, 1981. A factor analytic description of the Phanerozoic marine fossil record. Paleobiology, 7: 36-53.
Traverse A., 1988. Plant evolution dances to a different beat. Historical Biology, 1: 277-301.


The higher value range for the same satellite product (NO2_OMI_TEMIS) I'm dealing with NO2 column density of troposphere, and my data source is TEMIS.

The NO2 level3 data can be derived from the original information of OMI instrument.

I have downloaded two types of data, .grd and .kml for the same month.

The data I have downloaded are uploaded here1, 2

KML data

I open it in Google Earth, the figure shows like this:

We can see the data range of NO2 trop. column is 0~20 which are idential to the templete figure on the website.

GRD data

I have not found any detailed information about this data.
In the contents of it, -999 is deemed as no_data place.

I use python to read and plot the spatial distribution.

filename  = './CH2O-NO2/no2_201306.grd'
def read_grd(filename):
    ncols     = np.array(linecache.getline(filename, 1)[6:10]).astype(float)
    nrows     = np.array(linecache.getline(filename, 2)[6:10]).astype(float)
    xllcorner = np.array(linecache.getline(filename, 3)[10:14]).astype(float)
    yllcorner = np.array(linecache.getline(filename, 4)[10:14]).astype(float)
    cellsize  = np.array(linecache.getline(filename, 5)[9:14]).astype(float)
    nan_value = np.array(linecache.getline(filename, 6)[13:17]).astype(float)
    longitude = xllcorner + cellsize * np.arange(ncols)
    latitude = yllcorner + cellsize * np.arange(nrows)
    value = np.loadtxt(filename, skiprows=7)
    value = value[::-1]
    return value, longitude, latitude, nan_value

no2,lon_no2, lat_no2, nan_value = read_grd(filename)
no2[no2 == nan_value] = np.nan

def isnt_NaN(num):
    return num == num

no2[isnt_NaN(no2)].max()
> 9999.0

  It seems that the high value in grd format data are out of the regular condition which can be learned from previous resarch (Hot spots of NO2 column are about 15~20 10^15 molec/cm2).

Does anyone familiar with the OMI-NO2 data? I don't know how to deal with the irregular value which are way too higher than realistic.

It seems that you are concerned that your values in the data go above the max value on the color bar shown in the kml file.  I wouldn't worry about that.  You are using the "level 3" monthly average product, which by definition is highly quality controlled.  For most of the globe, typical values will vary between 1 x 10^14 and 5 x 10^15 molec/cm2.  Values over 20 x 10^15 molec/cm2 only occur in highly polluted areas.  Very large values in the OMI NO2 product are realistic, especially in SE Asia, where the largest NO2 columns are obtained.  I have even seen values over 1 x 10^17 on occasion.  As the signal gets larger, there is actually more confidence in the retrieval.  Really it's the low values (e.g. less than 8 x 10^14 molec/cm2) that you should treat cautiously, as anything lower than that could be "noise".

In order to show the variance of values (which can span 4 orders of magnitude) across the whole globe, the color scale chosen works well.  Note that the color bar is a logarithmic scale, which helps give definition to the plots in the regions with typical values.  You could rewrite the kml file though, and pick a different max value, if you are interested in better plots of southeast Asia.

If you are interested in learning more about the product, I highly suggest you see Boersma (2011) and also refer to the user manual.


convert .srtm to xyz ord grd I need to plot bathymetry map of my study region and need to convert the .srtm to .xyz or .grd format to use GMT. I tried to do this with grdraster and xyz2grd, but got wrong results. I found that there is srtm2grd command in Linux but I do not have it in my commands. the data are in the following address: ftp://topex.ucsd.edu/pub/srtm30_plus/srtm30/data/

NOTE: This is not the solution to the question in the title but it solves the problem described in the question's text.

Alternative solution

I would download the netCDF files from the grd directory instead of the srtm files from the data directory on the FTP server. The netCDF files can directly be plotted by GMT.

Example

Based on this file: e020n40.nc

#!/bin/bash

outfile=pic.ps
infile=e020n40.nc
invar=z
colorfile=colors.cpt

gmt makecpt -Cviridis -D -T-5200/2400/400 > ${colorfile}

gmt psbasemap -R20/60/-10/40 -JM18 -B4/4"NSEW" -X+1.5c -P -K > ${outfile}
gmt grdimage ${infile}?${invar} -R -J -C${colorfile} -O -K >> ${outfile}
gmt pscoast -J -R -Di -W1,black -O >> ${outfile}

output (pic.ps imported into GIMP v2.8.22 in 60 dpi resolution and with strong antialiasing):


Plate Tectonics: Is it possible to have an ocean-continent divergent boundary I am procedurally generating planets for an open world space sandbox game. I am using a rough simulation of tectonic plates to create mountain ranges and other geological features.

A planet surface consists of several plates, which consists of tiles. The continental plates are randomly generated, with random initial elevation and drift velocities assigned.

Tile elevations are generated by multiplying an envelope ( e^{ -d^2 } ) with a function for different types of plate boundaries and relative drift velocities.

For the sake of realism, is it possible to have a land-ocean divergent plate boundary? I could not find anything online. There also doesn't seem to be any examples on Earth from what I could find. Is it safe to assume that divergent boundaries only occur between land-land and ocean-ocean plate boundaries?

Update

Here is a rendering from the project. Red and green lines depict convergent boundaries. Land-land convergent boundaries produce mountains. Land-sea or sea-sea boundaries produces subduction zones. Blue lines denote a divergent boundary.

I'm going to change the simulation so that divergent boundaries happen only at land-land and ocean-ocean boundaries.

Sorry for my ignorance about geology. I know this is a crude way to simulate plate tectonics.

The oceanic plates are themselves formed from the divergent boundary, so probably not. Even if a new rifting occurred exactly at the boundary, the result would eventually be that the ocean floor surrounds the divergent boundary.

A very simplified model of an ocean would have a divergent boundary in the middle. This oceanic spreading center might have basaltic volcanic islands along it, and two mirrored plates on each sides, pushing towards neighboring continental or oceanic plates.

I'm trying to think about any oddity that would fit your description, but can't really come up with a good example. Locally you might have the conditions in triple junctions eg. at Afar Triangle. Somehow, it could also describe parts of New Zealand and eastern Mediterranean, but it's very complex areas with more parameters controlling the rifting.

Earth is not controlled by any simple equation, its formed by 4.56 billion years of interaction between rocks, magma, life, atmosphere and even astronomic influence, so I'm not sure that divergent boundary never occurred between existing continental and oceanic plates, but at least it's very uncommon and couldn't last long.

A way to understand plate tectonics better, and maybe even a good inspiration for world building games, is to have a look at the (free) program Gplates that is used by students and scientists to simulate tectonic history. Don't worry about your ignorance, interest is more important than knowledge. The game might be a good inspiration for someone to learn more about something really awesome.