Can I interpolate rainfall data from stations outside of watershed for the watershed? I have only few station inside the watershed so I want to use the stations outside if I can to get better results

Yes, you can interpolate the rainfall from stations outside the watershed. However, the quality of the interpolation will depend on the distance between the stations and the watershed, the prevailing weather patterns, and to some extent the topography.

For example, it probably wouldn't be appropriate to use a station on the rainy side of a mountain divide in estimating rainfall in the rainshadow. One way to get an idea on how good you estimates are is to compare the actual rainfall at a station with the interpolated rainfall at that location, when you leave it out of the dataset.


How much would the Greenland landmass isostatic rebound contribute to long term climate change? In reading the question What would the geology and climate of a supposed landmass near the pole be like, assuming a thoroughly warmer planet?, it came to mind that another factor may cause a shift in the long term climatic patterns should the Greenland Ice sheet continue melt - the effects of a 'taller' Greenland, due to its isostatic rebound.

According to the Polar Field Services website,

  The enormous weight of the ice down-warped the land surface, causing the material underlying these land masses to slowly flow away. The physics are similar to the reasons a balloon deforms when you press down on it. In the same way that the balloon reshapes itself when you remove your hand, the land actually pops back up over several thousand years when the weight of expansive ice sheets no longer weighs down the underlying area. In Greenland, where the ice sheet is currently receding, the island is actively rebounding.

Given that there are already peaks of up to about 3.7km in altitude, my related questions are:

How high would these peaks go?
What effect would a 'taller' Greenland have on climatic patterns?

Be warned this is a general (and speculative) answer, but it was getting too long to be a comment: The bulk of Greenland's ice mass is centred over inland/central Greenland. If you were to take all the ice away today, much of central Greenland would actually be below sea level, by several hundred metres in fact:

Glacial isostatic rebound would seek to equilibrate the loss in mass by 'popping' Greenland back up, but it appears that we'd be starting from at or below sea level over much of the island! I'm afraid I don't have any figures to hand over what the total isostatic adjustment might be in the centre, but I would be skeptical of it producing peaks any higher than the current ice sheet level - so the net effect on atmospheric circulation in this region may be small.

Interestingly, the post-glacial isostatic adjustment going on in that region is not as simple as may be expected, some areas over Greenland are actually still sinking, due in part to the movement of former ice mass from the Arctic into the seas around Greenland (as water). The figure below indicates that the areas to watch are actually Canada and Scandinavia, at least for now.

For the existing tall peaks that are rebounding, in general terms you could potentially expect more orographic precipitation enhancement as they became higher, more erosion, which could lead to greater drawdown of CO2 from weathering...the arm-waving speculation goes on... (but see this question.)

From a regional climate aspect, I would perhaps be more concerned over the decrease in albedo on Greenland from the loss of its ice cap. Also, the potential effect of changing surface moisture fluxes to the atmosphere, should central Greenland end up becoming a series of lakes and islands (rather like Finland in its post-glacial state today).


Understanding pushbroom sensors Does a push broom scanner scan a path perpendicular to the direction of satellite travel? I am confused because its detectors are arranged across track even though it scans along track.

Does the image of the pushbroom scans a path perpendicular to the direction of satellite travel?

Not really. There is no "scanning" in a push broom sensor. A push broom sensor does not have any moving parts; compare with the related whisk broom sensor which does indeed scan a path perpendicular to the satellite's motion. The difference between the two is that a push broom sensor has multiple identical sensors arranged in a line (orthogonal to the nominal direction of travel) while a whisk broom sensor has but one sensor. The line of sensors in a push broom sensor eliminates the need for scanning.

Both types of sensors form an image by forming image lines and then pasting those image lines, one after another, into an image buffer. A push broom sensor forms an image line by exposing all of the sensors to light simultaneously. A whisk broom sensor forms an image line by taking a series of snapshots, rotating the sensor a bit between each snapshot. With both kinds of sensors, the satellite's motion between capturing individual lines is what enables an image to be formed.


Could this cloud be artificially formed? This photo was taken at 3000 m above sea level in an open field, during the day.

There's not much context, but my guess is that this was a cavum cloud (a.k.a. punch hole or fallstreak), that was caused by an aircraft.  The UK Met Office describe how these form:

They form in clouds of supercooled water droplets, water below 0 °C but not yet frozen. These water droplets need a tiny particle, a nucleus, to freeze or to be cooled below -40 °C.
Aircraft punching through this cloud layer can cause air to expand and cool as it passes over the aircraft wings or propeller. This change in temperature can be enough to encourage the supercooled droplets to freeze and fall from the cloud layer in this distinctive pattern.

The Cloud Appreciation Society have a gallery with loads of examples.  The NASA Earth Observatory blog also has a nice satellite image from over the Southern US with multiple occurrences at the same time, which also features in Heymsfield et al (2011) Formation and Spread of Aircraft-Induced Holes in Clouds, Science:

(NASA image by Jeff Schmaltz, using MODIS data from LANCE/EOSDIS Rapid Response.)


How much oil is created each year? We all know that oil is an essentially nonrenewable resource over human time scales. However, I am currently working on an activity for high schoolers that teaches them to predict how long humans can continue extracting oil before running out (and what a sustainable rate of extraction would be).

To that end, does anyone know roughly how much oil is created each year, (in the entire crust, no matter how inaccessible)?

I can't provide numbers, but a hopefully reasonable outline for your own calculations:

All that is required for oil to form is a source-rock brought to the right depths in a sedimentary basin and the oil migrating into a host-rock. If it is economically profitable (See Footnote) it goes into the global reserve calculation. (Petroleum Sedimentology Winfried Zimmerle, H. Zimmerle)

All you need to calculate the oil production is an estimate of the volume of host-rock that is currently under those conditions in sedimentary basins around the world.

As you can see there is a staggering area of Earth covered by sedimentary basins, and all those basins have a certain volume under oil generating conditions.

You will probably also need a rough estimate of how much oil can come out of an average source-rock, and how much will be trapped in economically profitable host-rock traps. Maybe a factor that takes into account the basin type, would also help to improve the calculation (Compressional basins would have a lot of antiform traps, while extensional basins have tilted bed traps).

I have the feeling that the total oil inventory of Earth is probably a Logistic function. Once all the oil traps are filled all the excessive oil is lost to migration or too much heat. Empty traps would mean that oil would find a place to accumulate. So it might even be a self-stabilizing system (but not in human-time-scale, but let's see how long we last).

I think that this would yield an order-of-magnitude answer. It is possible that somebody already made these calculations and I would love to see the numbers.

Footnote: Oil, like all resources, follows mining economics. If you earn money, you mine, if you loose money, you leave. This also means that if more money can be earned, there are also more deposits worth the effort. Calculations with today's reserves are almost useless, because they can't predict what people will be willing to pay for oil in the future. Even if mining becomes unprofitable, we might produce synthetic oil, just because it is a convenient chemical (energy stored in relation to mass, diffusivity, and danger). We kind of already have that with rapeseed oil, which sadly can get a better price to power rich countries cars, than feed poor countries people.


Lake inflow-outflow problem The evaporation from a lake is to be calculated by the water balance method.   Inflow to the lake occurs through three small rivers, A, B and C.   The outflow occurs through the river D.   Calculate the evaporation from the lake surface during summer (May – August) if the water level was +571.04 m on May 1 and +571.10 m on August 31.   The lake surface area is 100 km$^2$.   The precipitation P during the period was 100 mm. Average inflows and outflow are given below:

              River      Catchment(km2) Average Q(m3/s)
                A             150        15
                B             120        20
                C             130        17
                D                        45

This is the way I have attempted it:

Total Inflow ( by A, B, C) $= 52\ \mathrm{m^3/s}$.
Outflow (by D, assuming that D is fed by the lake) $= 45\ \mathrm{m^3/s}$.
Inflow - Outflow = Change in storage (which is in turn change in elevation × area)
Net Inflow into the lake = Inflow by 3 rivers + Precipitation
$$
= (52\ \mathrm{m^{3}/s} \times 122 \times (30\ \mathrm{days}+31+30+31)\times24\times60\times60 + 0.1\ \mathrm{m}\times100\times10^3 \mathrm{m}^2)
$$
Total Outflow = Outflow + Evaporation
$$
                = (45\times122\times24\times60\times60 + E),
$$
where E is the component to be found.
Change in storage = Change in elevation × Area
$$
                  = (571.10 - 571.04)\times100 \times 10^6 E = 0.68\ \mathrm{m}
$$

Everything you did looks reasonable.  There is one error in the 'net inflow into lake' line where you take the area of the lake to be $100\cdot10^3\ \text{m}^2$ instead of $100\cdot10^6\ \text{m}^2$, but that might just be a typo.

In general, this type of problem is much easier to work (especially when you think you've made an error) by keeping everything symbolic.  For your problem I would define the variables

$i$: inflow into the river in $\frac{\text{m}^3}{\text{s}}$
$o$: outflow from the river in $\frac{\text{m}^3}{\text{s}}$
$r$: inflow from rain in $\text{m}$
$e$: evaporation in $\text{m}^3$
$\Delta h$: change in height of the lake in $\text{m}$
$A$: area of the lake in $\text{m}^2$
$\Delta t$: time period in $\text{s}$

The equilibrium equation is then

$$\text{sum of inflows}-\text{sum of outflows}=\text{change in storage}$$

which is written in terms of the defined variables as

$$i\ \Delta t+r\ A-o\ \Delta t-e=\Delta h\ A.$$

You can check that this equation at least makes sense in terms of units by observing that all of the terms have units of volume, i.e. $\text{m}^3$.  Finally, you can rearrange the equation to solve for the variable of interest;

$$e=(i-o)\Delta t+(r-\Delta h)A.$$

At this point you can plug in the numbers.


Why are there waves in seas towards shore - even in night? Waves are mostly caused by Friction of wind on surface of water.

Wind blows from sea to land in day and land to sea in night due to pressure and temperature difference.

So it is intuitive why there are waves towards shore in day, but even in night there are waves towards shore. Sometimes even stronger than waves during the day.

Why is that?

Ocean waves (and also in mediterranean type seas and larger lakes, but on a smaller scale) are generated by two processes:

locally generated waves ("wind waves"), which follow the direction of the wind;
waves generated further out in the sea (i.e. "swell waves"), which do not necessarily follow the direction of the wind.

During the night, you are probably seeing swell waves. Of course, some wave energy is generated also in the opposite direction by the wind blowing offshore, but one can only "see" these waves further out in the sea if the wind is strong enough (see the definition of fetch).

Also check the Figure [1] below for clarification on how swell is generated (the longer period wave energy travels faster than the energy of the shorter period waves, so the initial "random" wave field disintegrates into regular swell).

Shallow water wave processes like diffraction and refraction will curve the paths of the waves that start reaching the coast and "feeling the bottom". The waves appear to be heading almost perpendicular when they reach the coast, even if 1 km out to sea they're moving almost parallel to the long distance coast.

How the waves appear at the coast to the observer depends on the direction of the local wind. Generally, if the local wind blows in the same direction as the waves (i.e. onshore wind), the waves appear "mushy" as the wind helps to break the waves (see example image). If the local wind blows in the opposite direction of the incoming waves (i.e. offshore wind), the waves maintain their shape due to opposing wind and they break later (see example image). These conditions are favourable to surfers.

[1] Holthuijsen, L. H. Waves in oceanic and coastal waters. Cambridge University press, 2010.


How and when was the $\mathsf{CO_2}$ scrubbed when Earth was still primordial? How and when was the $\mathsf{CO_2}$ removed in primordial Earth atmosphere? What is the main mechanism of this removal of $\mathsf{CO_2}$? Is it dissolving in water? Or rock weathering? Or was the bulk of $\mathsf{CO_2}$ actually removed by early life?

As you probably realise, the Earth's early atmosphere was mainly composed of CO2, as are the atmospheres of Mars and Venus to this very day. You are right in thinking that most of this CO2 was removed by biological activity; if all the earth's fossil fuels and limestone rocks were converted back into CO2, we would have an atmosphere similar to that which existed nearly 4 billion years ago. It was this same biological activity which built up the oxygen level to its present 21 percent. The process continues right up to the present day. The CO2 content of the atmosphere is to some extent self regulating: the higher the levels, the more vigorously plants and photosynthetic micro-organisms grow, extracting more and more carbon dioxide from the atmosphere, but this natural process could be swamped if the build-up of CO2 exceeded the capacity of plants to remove it. It is not generally known that algae and phytoplankton in the sea remove more CO2 and generate more oxygen than all the rainforests.


Interpolating Merra reanalysis Merra re-analysis ara available for  a coarser horizontal grid with resolution of 0.625 × 0.5 degrees providing differents parameters : Precipitation, Temperature ....This been said, I want to interpolate continuously theses parameters ( More precisely : For each coordinate I want to know elevation, Precipitation , and other parameters ( Look the following example ).

Time step  // Latitude // Longitude // Elevation // Precipitation  ...

1    ................ 30    .............     -7     ..................   1500 ...................       x             x    x ....x

1       ...............          30.25   .........     -7   ...................     x x ..........................x

1  .................             31.11  .....      -6.63    ...................xx.......................X

If you have an idea how to interpolate these data I would be grateful.

I strongly recoment using interp2 funtion from Matlab or any other equivalent in other languages. I have used it to do similar tasks.


What is the temperature of the flowing water in icy river? Boundaries of the question:

The question is about rivers where water flows in cold area of the earth. Whether it's because of the winter or it's simply cold all year long. Usually, the top layer of the river freeze and water underneath continue to flow freely.
The question is about the temperature of the liquid water only. So, the temperature of the solid water is irrelevant to the question.
This question is only about fresh water rivers only. So salty rivers are not part of the question.

The question itself:

What is the temperature of the flowing water in icy river?
More precisely, does the temperature of the water drop below 0 °C?
If it does, is this common?
If it doesn't, does it get close to it at all?

Attempted research to find the answer :

I had in mind that the current allowed the water to stay liquid, but that might be wrong because there is no proof to it.
However, this answer says:

  For flowing water to freeze, the temperature would have to be
  exceptionally cold.

Which seems to agree that current can lower the freezing point.

I found a great document about the temperature of the water within lake, but didn't find any reliable answer for rivers.

EDIT
I have come to believe that temperatures don't typically fall below 0 °C, based upon aggregating the following information...

Rivers freeze completely once the heat lost exceeds the rate of water
replacement.
Most lakes and rivers don't freeze solid because water,
ice, and snow are good insulators and poor conductors of heat. The
portions of a lake or river that is exposed to the cold winter air
freezes, and this ice insulates the water below from
further rapid freezing.
Earth is warming the water from below.

Using this, we can probably conclude that water won't cool down enough during it's journey down the river. Thus, the water would need to be already colder at the start of the journey. We know that the start is a lake with calm water. So, it's unlikely to happen because the lake would freeze completely and stop flowing out into the river.

This is a complex question.

I will assume the following to be able to frame an answer properly:

Let's take a general cold area as a baseline, such as the High Arctic or 70°+ N latitude;
The reference for this example can be Pond Inlet, on Baffin Island, an example where long-term records are available (72° N). The following data assumptions will be based on the normals provided by this station. But what is discussed is likely to be valid for a large area of the High Arctic - like 70°+ N latitude;
In this area, the normal (1981-2010) mean annual air temperature is -14.6° C is fairly representative
Also, in this area, the normal yearly degree days to reach thawing (TDD - the sum of daily average temperatures above 0° C) is 473 degrees.
The bulk of the TDD sum (473 degrees) occurs during June, July and August; only 2 degrees in May, 31 in September and 1 in October, so thawing is most likely minimal outside these three months. As a consequence there are two fairly distinct seasons: the thaw season (summer, duration 3 months) and the freezing season (winter, duration 9 months).
Pro-glacial rivers are not considered (river taking their source from glaciers, different story)
Lakes are not considered (different story)

This all means that the cold region's rivers are not thermally static through time. Even in the High Arctic, an icy river can be frozen along both its vertical and horizontal profile during a good part of the long winter, and thaw completely during the short summer. But other considerations exists.

Let's examine what can happen when the snow thaw is sometime in June. The discharge signature for a river in the High Arctic is nival, with a discharge peak occurring during early summer due to the massive input of snowmelt water, and additional weaker responses from the small rain amounts. This looks like this:

Source:  Woo (2012) Permafrost Hydrology, fig 10.14; from river McMaster, 74° N.

So what basically is happening here?

Peak is during June.
Afterward, once the snow had melted completely, the discharge lowered drastically.
By late August, there is almost no more water in the river, and it may be completely recessed.
Then winter arrives.

During the next several months, snow will accumulate in the landscape. In a landscape there are snow sources and snow sinks (Pomeroy et al. 1997);  sources may be higher lands, outcrops, plateaus, or exposed areas, and sinks lower areas, such as depression or channels. Our typical nival river will be a sink in this context.

Because of this, it is not only patches of ice that will be found in the river channel, but tightly packed snow that builds up at the base when it is a thick layer (or is looser when the snowpack is thin). In any case snow will be most likely metamorphized in structure as a result of surface thaw and the water snowmelt infiltration -> snow percolation -> re-ice events during the winter.

What is happening in June, in more detail?
Let's analyse this further with a more detailed (though raw and unprocessed) graph from a small stream in a gully near Pond Inlet, with resolution available up to the nearest day:

Source: Stream temperature and water pressure in a stream located in a gully on Bylot Island, 85 km from Pond Inlet; raw, partial data from my PhD work. Temperature in blue, scale on the right, and pressure in black, scale on the left. Dates on the x-axis.

By looking at the pressure line (in black), it can be interpreted that there was no water until June 16th when the pressure increased drastically. Temperature (in blue) stayed at -2 °C until the 17th. Water was infiltrating into the snow at this time, contributing to the slowly rising pressure, but the water did not reach the sensor until the 17th when the temperature starts rising. During the 18th, temperature rises to -0.5 °C, then hovers in these negative temperature for almost 24 hours. This supercooled water temperature is due to a mix of factors, such as increased pressure from the water on snow, the release of latent heat due to the metamorphized snow thawing, and the near zero temperature of the water, in balance with the snow.

When a critical mass of water accumulates near the logger emplacement in the stream channel, the bulk of the snow melt and water then shifts to positive temperatures, still near zero, with diurnal/nocturnal shifts (blue line becoming wave-like).

Note: This small stream is minimally impacted by the geothermal flux (heat flowing up from the ground below).

Summary, in relation to the questions:

Temperature will be mostly above zero; but may be under and near zero for short periods when the water is mixing with snow and ice in a channel;
Yes - as shown in the second figure, water was at -0.5 °C for about 24 hours;
I think it is common, as thawing temperatures do reach very high latitudes such as Ward Hunt Island (83° N), and thus this process likely concerns a large area, including probably the entire Canadian Archipelago (lowlands at least).  But this transition process does not last long at any location. Additionally, it is worth noting that High Arctic rivers are difficult to access, monitor, and study, so it is difficult to generalize this with confidence; other factors or contexts could exist where conclusions may differ.


Earthquakes at plate boundaries I was looking into tectonic plate boundaries and earthquakes with pictures like these

One thing that is quite obvious is that some of the plate boundaries have very thin zones of earthquakes, whereas the zones near India, Chile, Australia,.. are much more spread out. What is the cause of this?

Thanks,

Kim

The cause is partly geometry and partly process. Subduction zones generally take oceanic crust and upper mantle down into the deeper mantle, but the angle of the subduction zone varies greatly. For example, the Tonga Trench is very steep, giving rise to a 'tight' earthquake zone. At its shallowest, the two plate boundary isn't even a subduction zone at all, but becomes obduction, overthrusting oceanic crust/mantle over the plate, as happened with the Oman ophiolite. Then there are ocean-continent collisions, such as western South Americas. Because the continental crust is much less dense than oceanic crust, it is more buoyant, so you get a broader subduction zone than you would with a back arc overlying ocean-ocean collision. Finally, there are continent-continent collisions, typified by India-Tibet, where none of the crust can sink very deep, so you get a stack of imbricate over-thrusts, as in most of Tibet and the Himalayas, all linked to earthquakes over hundreds of kilometres width, as in the Nepalese quake of last year.

Also consider the tectonics involved. Where two tectonic plates slide against each other there may be little or no subduction, but stress release in the transcurrent fault can still create major earthquakes - think the San Andreas Fault, or New Zealand. Kim points out the thickness of earthquake zones such as those north of Australia. It isn't just in southeast Asia. We can see similar complexities in the Eastern Mediterranean, the Caribbean and elsewhere, where there are many micro-plates jostling in a complex pattern. They only seem like one seismic zone because of the scale of your diagram. There is yet a different story in the Rift Valley of Africa.

The above are just some sketchy simplifications of a revolution in geological understanding that started in the late 1960s, and which are still continuing. It's not possible to give a detailed explanation in this forum, but there are many excellent and fascinating textbooks. Warning - you can get hooked. Then it becomes a lifetime study.


How to relate the backward trajectories with offline particular samples? To correlate chemicals in aerosols emanating from certain sample points, backward trajectory analysis is usually applied for identifying the potential geographical source region.

In this figure from Characteristics of aerosol pollution during heavy haze events in
Suzhou, China, the trajectories are clustered into several groups. The different fractions of chemicals (e.g. organic matter, sulfate) in each group shows the impact of different regions.

It represents an easy approach  to research the impact of regional transportation for the particulate matter in certain receptors.

The trajectories are calculated for certain times (e.g 0:00, 6:00, 12:00, 18:00 for each day).
Offline PM samples with its chemical species are usually collected for 24 h

How can I relate the samples with trajectories with different temporal scale?

Most atmospheric science researchers use back-trajectory analysis in qualitative sense to explain source of a pollutant. And as pointed out by the questioner, it is not possible to associate trajectories calculated at a particular time to the measurement that is average of say several hours.

However, quantitative analysis of observed concentration with back-trajectories is possible and is used to identify emission sources and their strength.

For the quantitative analysis, a large number of back-trajectories are simulated (of the order of 100000) from the place of measurement, however each trajectory is initiated with slightly different initial condition.

Let me explain with an example. Suppose PM2.5 concentration was measured on a certain date as 24 hour average at location given by co-ordinates x, y and z. Assuming that air was well mix in region surrounding x, y and z given by x-dx to x + dx, y-dy to y+dy and z-dy to z + dy, backtrajectories will be simulated, each with slight different x,y and z but within volume given by 2dx*2dy*2dz. Also, the number of trajectories simulated will be equally distributed in the volume and time period (24 hours in this example) to which observation represents. The simulation will result in distribution of trajectory with some grid-boxes visited by several trajectories whereas others may have no trajectory or very few trajectories. Emissions in the grid-boxes which are more frequently visited, have more potential to contribute to observed concentration. In other words, the concentration being measured at x, y, z will be proportional to sum of amount of time spent by each trajectories multiplied by emission flux in that grid box.

More detailed description of backtrajectory analysis and its application to related to observed quantity are available in following articles.

Gadhavi et al., 2015, Evaluation of black carbon inventories using a Lagrangian dispersion model - a case study over Southern India, Atmos Chem Phys, vol. 15, 1447-1461, doi: 10.5194/acp-15-1447-2015.
Seibert and Frank, 2004, Source-receptor matrix calculation with a Lagragian particle dispersion model in backward mode, Atmos. Chem. Phys., vol. 4, 51-63, doi:10.5194/acp-4-51-2004


Why is Mauna Kea taller than the maximum height possible on Earth? We can calculate the maximum possible height of the mountain on earth.
If the elastic limit of a typical rock is $3 \times 10^8\ \mathrm{N/m}$ and its mean density is $3 \times 10^3\ \mathrm{kg/m^3}$, then the breaking stress is $h\,\rho\,\mathrm{g}$, where $h$ is height, $\rho$ is the density of the rock, and $\mathrm{g}$ is the acceleration due to gravity. Then

$$ h = \frac{\mathrm{elastic\ limit}}{\rho\,\mathrm{g}} $$

Putting the values we get,

$$ h = 10^4\ \mathrm{m} $$

which is the maximum possible height. Now Mount Everest is within this limit, but Mauna Kea is 10,210 m tall (measured from its oceanic base).

Does this suggest that rock types at the base of this mountain are different?
Or does the presence of water have an effect?

Since over half of the height of Mauna Kea is under water, you need to consider the buoyancy effect. Instead of a density of $3 \times 10^3\ \mathrm{kg/m^3}$, the underwater portion has a net density of $2 \times 10^3\ \mathrm{kg/m^3}$. That will significantly increase the potential height of such a mountain. Add in all the other uncertainties (is Mauna Kea made of rock with "typical" elastic limit and density? is it even homogenous? are there dynamics involved? and what about Naomi?) and there's no reason to see its height as a contradiction.


About meddies: what are they? How do they form? How are they maintained? A "meddy" is usually described as a Mediterranean Water eddy. While many meddies have been observed in recent years, I would want to know what are the common characteristics of such features (temperature, salinity, depth, lifespan)? What are the conditions that cause the formation of meddies? How are they preserved for so long as they may last for about 2 years and cover distances up to one thousand kilometers?

Meddies are anticyclonic (rotating clockwise) lenses of warm salty Mediterranean Water that travel through the North Atlantic between ∼500 and 1500 m depth. They are observed as large temperature, salinity and velocity anomalies (Richardson et al., 2000). Meddies are typically 40–100 km in diameter with their core being 500–1000 m thick.

Meddies separate from the Mediterranean Undercurrent (the main Mediterranean outflow) as it flows through abrupt topographic changes like major canyons. Each year between 15–20 meddies are formed off southern Portugal predominantly at two sites (Bower et al., 1997): Cape St. Vincent (37° N) and Extremadura Promontory (39° N). They can be detected by their surface signature in surface temperature and sea level anomalies (Oliveira et al., 2000). A large percentage of the meddies formed collide with large seamounts decay while some travel west on the north side of the seamounts and then travel southwest near Cape St Vincent toward the Canary basin with translation speeds of a few cm/s and clockwise rotation periods of 4 to 6 days (Richardson et al., 2000).

(P.L. Richardson: "Tracking Ocean Eddies", American Scientist 81, 261--271, 1993. Fig 10. http://josvg.home.xs4all.nl/Dundee/meddies/index.html)

Meddies can have maximum salinities around 36.5 and maximum temperatures around 13°C and they are observed as large anomalies (salinity anomaly ~1 and temperature anomaly ~4 °C) as they travel westward into cooler and fresher water. During their trip, the Mediterranean water inside the meddy slowly mixes with the surrounding Atlantic water and the salt anomaly progressively weakens until the meddy dissipates. The main processes causing mixing occur at the boundary of a meddy where the largest gradients of temperature and salinity exist and are double-diffusion and thermohaline intrusions as large as 25 m thick (Meunier et al., 2015).

From Tychensky et Carton, 1998. (http://outreach.eurosites.info/outreach/DeepOceans/station.php?id=10&page_inc=fact)

Meddies average lifespan is around 1.7 years although some were observed for more than 5 years (Richardson et al., 2000). During that time they travel distances up to one thousand kilometers and their maintained mostly because the core of the meddy tends to have a doubly-stable stratification (Armi et al., 1989). Up to 29 meddies may coexist in the North Atlantic at the same time (Richardson et al., 2000).

From Univ. of Delaware (http://www.spaceflightnow.com/news/n0603/21whirlpools/)


What is a mud diapir and how does it form? Mud diapirs are relatively common features in seismic reflection images. What is a mud diapir? How is it different from a mud volcano? What are their common characteristics (size, age, composition)? How are they formed and preserved?
 Source http://steveholbrook.com/

This is an excellent question, and a topic about which there is a lot of literature. In addition to the volume linked above, I can also recommend:

Geological Society of London Special Publication 216: http://sp.lyellcollection.org/content/216/1

Another good place to start is the extensive body of work done by Chris Morley and Pieter van Rensbergen that examines shale diapirs on seismic as well as in outcrop (good outcrop examples are surprisingly rare). Some good papers, in addition to the above two books, include:

Morley, C. K., P. Crevello, and Z. H. Ahmad, 1998, Shale tectonics and deformation associated with active diapirism: the Jerudong Anticline, Brunei Darussalam: Journal of the Geological Society, London, v. 155, p. 475-490.
van Rensbergen, P., C. K. Morley, D. W. Ang, T. Q. Hoan, and N. T. Lam, 1999, Structural evolution of shale diapirs from reactive rise to mud volcanism: 3D seismic data from the Baram delta, offshore Brunei Darussalam: Journal of the Geological Society, London, v. 156, p. 633-650.
van Rensbergen, P., and C. K. Morley, 2000, 3D seismic study of a shale expulsion syncline at the base of the Champion delta, offshore Brunei and its implications for the early structural evolution of large delta systems: Marine and Petroleum Geology, v. 17, p. 861-872.
Barber et al., 1986, Mud Volcanoes, Shale Diapirs, Wrench Faults, and Melanges in Accretionary Complexes, Eastern Indonesia, in AAPG Bulletin.
Stewart, S.A. & Davies, R.J. (2006) Structure and emplacement of mud volcano systems in the South Caspian Basin. AAPGBull., 90(5), 771^786.

If I was to summarise all of the work I have seen over the past 15 years, I'd say that there are three major concepts for shale diapirs:

1) That they are large masses of mobilised shale - essentially big masses of shale, akin to salt diapirs. Note this is starting to fall out of favour, but is still relevant in some places, such as the Niger Delta.

2) Shale diapirs are emplaced in a means more akin to igneous intrusives, undergoing fracturing and stoping of overburden rocks due to their high overpressures. As such, shale diapirs are considered to be more like country rock that has been heavily fractured and invaded by gases and mud. This generates the chaotic seismic character.

3) Shale diapirs may be simple artefacts caused by complex structure. Features interpreted on seismic as diapirs have been drilled into in several places, but these well penetrations typically did not encounter indications of mobile or previously mobile shale. This has led to suggestions that many 'diapirs' may just be zones in which the bedding is at high angle, and/or heavily affected by fault processes and gas, leading to zones of poor seismic resolution.

My personal view is that there is evidence for all three of the above scenarios, depending on the regional basin and tectonic history.

I'm sorry this doesn't really answer the question, but I hope it gives you enough threads to research this in more detail.

Good Luck!

Mark


Where to get temperature sounding model forecast data? I want to know the current lapse rate for a given point in the US. In other words, I want "live" temperature data at various altitudes. Live is flexible -- I'm generally OK with a forecast which is valid for the current point in time. Where can I get this data, preferably in a format that's easy to ingest into Python?

More details:

I'm currently using a lapse rate constant to try to estimate the temperature at various altitudes, but would like to use something more sophisticated. I'm a pilot, so I initially thought about using the Temps & Winds Aloft product, and then interpolating between the sporadic sites, but then I found the models on NOAA's site. But:

I'm not clear on which one is best for my use case. Op40 seems to be a good default. But the HRRR model seems even better, specifically due to the higher resolution.
I'm not sure where raw data in a format that I can use. If, e.g., I create an interactive skew plot for Op40 on the NOAA site, I can then click the Get Text button and get the type of info I'm interested in:

But if I choose the ASCII Text on the first page I get a GSD file which doesn't seem to follow NOAA's own file format. And it looks like HRRR comes in a grib2 format, which also doesn't seem to be as simple as lat/lon,altitude,temp. It seems like these files provide something more raw which then needs to be simulated against to get the temps? I found some python libraries, but could use a pointer on the approach I need to take.

The GSD file is just a text (ASCII) file, which you can read with almost anything you want. Since you are using python I would recommend looking at Pandas and especially the pandas.read_csv functionality.

I am using this URL as an example now:
https://rucsoundings.noaa.gov/get_soundings.cgi?data_source=Op40&latest=latest&start_year=2019&start_month_name=Dec&start_mday=3&start_hour=7&start_min=0&n_hrs=1.0&fcst_len=shortest&airport=50%2C-90&text=Ascii%20text%20%28GSD%20format%29&hydrometeors=false&start=latest

From the ruc soundings you referred to. Here I just entered lat=50 and lon=-90 to pick something. You see this in the URL in "airport=".
You can download the data you need with wget or curl and put into a file with a better name (sounding.txt) like this:

wget "https://rucsoundings.noaa.gov/get_soundings.cgi?data_source=Op40&latest=latest&start_year=2019&start_month_name=Dec&start_mday=3&start_hour=7&start_min=0&n_hrs=1.0&fcst_len=shortest&airport=50%2C-90&text=Ascii%20text%20%28GSD%20format%29&hydrometeors=false&start=latest" -O sounding.txt

Then you can write a small python program to fetch the data you need and read the data with pandas.

I also want to note that if you are going to use grib2 you will be able to easily change the model since grib2 is a standard format for NWP data. This will be a little more complicated, as it is a bit more tricky to read. grib2 is a binary format that is very good for storing large datasets. I refer to eccodes from ECMWF if you want to look more into this.


Is it possible to estimate the size of a meteorite from its remains? I live near this ophiolite (Sasso di San Zanobi, Firenzuola) and they used to say it is a meteorite.
There is no evidence of a crater but let's pretend it is the remain of a meteorite: how big would the original meteorite have been?

Meteors enter the atmosphere at speeds ranging from 11 km/sec, to 72 km/sec. Those speeds are so large that if a meteorite were to hit the surface at that speed, the energy released would be more then enough to to vaporize the meteorite on impact, therefore leaving nothing of the original impacting body. However, during their fall, meteorites slow down due to the friction with the atmosphere. The friction is proportional to the square of the meteorite radius (its cross-section), but the mass is proportional to the cube of the radius (its volume). This means that the larger the meteorite the less it slows down and the faster it hits the surface.

Past a given size, the atmosphere doesn't provide enough breaking power. Therefore, all meteorites larger than that limit vaporize during the impact. To have a sense of how big is that size limit you can simply have a look of the larger meteorite on Earth: the Hoba meteorite.

(image taken from TripAdvisor and submitted by user huys25)

Therefore, what your picture shows is not a meteorite (there would be also other reasons beside the size to say so), nor the remains of one. The remains of large meteorites often reduce to small fragments that broke from the main body before impact, or impactites. Impactites are small pieces of rock that might contain meteorite materials but are not unaltered pieces of it.

Said that, once a meteorite is found the calculation of the original size considers the final size, the speed and angle of impact (computed from crater geometry) and the meteorite composition among other parameters.

There are many online calculators that allow you to have a rough estimate of the size of a crater that a meteorite like that would leave. For example the Convertalot Asteroid Impact Calculator. From the picture it looks like porous rock, so plugging in a density of 1.5 g/cm$^3$ and impact angle of 45°, a fairly low speed of 20 m/s, and a diameter of 20 m, it would have produced an impact crater 177 meters in diameter and 44 meters deep. Definitely a landscape feature difficult to miss.

Finally, from the shape of what you show in the picture, I don't see how it can be associated to a meteorite, as it doesn't look like one at all. In that line, it could resemble the central peak of an impact crater. Like the one visible at the center of Tycho crater on the Moon.

(Image source: Wikipedia - Tycho crater on the Moon: mosaic of images, made by Lunar Reconnaissance Orbiter. Width of the image is 120 km.)

However, if the central peak were that well preserved you would expect the rim of the crater to be well preserved too, and from what you say, that doesn't seem to be the case.


Does a registry for fallen meteors exist? Is there any kind of like an officially monitored list of falling asteroids, meteors, etc and objects entering earth's atmosphere?

The short answer is "yes" and the links are provided below.

Fireball reports: https://www.amsmeteors.org/fireballs/fireball-report/
Classified meteorites: https://www.lpi.usra.edu/meteor/


Does the long-term ice-core temperature record provide reasonable evidence that the current temperature trend is not anthropogenic? When looking at the long term ice-core temperature record, it very clearly shows a ~100,000 year cyclical trend with warming spikes and gradual cooling. To the untrained eye, it seems that such a trend has not been significantly deviated from so far (in the present day). This would indicate to me that the current upward temperature trend is not human-caused. What refutes that idea?

Also a relevant question: what is the confidence of this temperature record and what are the probable deviations from the temperatures indicated in that graph?

No, ice cores do not refute human-caused warming.  In fact, they support it.  Your logic really doesn't follow because the rate of warming now compared to some arbitrary previous date is not  related to whether the warming is driven by humans.  Instead, it is important to consider the natural variation of physical factors that affect climate (collectively known as Malenkovitch cycles; http://en.wikipedia.org/wiki/Milankovitch_cycles ), and then recognize any large deviations from those cycles.

An image of the EPICA and Vostok ice cores versus age obtained from http://en.wikipedia.org/wiki/Ice_age , clearly shows influence of the Malenkovitch cycles.  The most notable of which is the strong cycle that is approximately 70,000 years and is associated with geologic ice ages. In fact, the Earth is historically on average much cooler than it is now, and the retreat of glaciers has been periodic but not sustained.  We were supposed to have cooled off some time ago, but clearly we are not in a global cooling period. Many would even argue that humans started affecting the climate over 7,000 years ago when land management and fire was wielded prevalently.

In order to attribute climate change to humans, climate models are run with and without anthropogenic climate forcing.  When they do so, climate models run without anthropogenic forcing are unable to duplicate the current warming trend.  I've attached an image of this from the IPCC AR5 Technical Summary draft which shows a full climate simulation, one without anthropogenic climate forcers, and one with no aerosol forcing for comparison.

Finally, I thought someone might value this link that discusses climate change atrribution:
http://www.realclimate.org/index.php/archives/2014/08/ipcc-attribution-statements-redux-a-response-to-judith-curry/comment-page-4/


How much of earth's molecular oxygen in the atmosphere is due to plants? I know plants form a critical part of the earth's biosphere, including molecular oxygen production. Molecular oxygen makes up ~20% of our atmosphere.  How much of the earth's molecular oxygen in the atmosphere is due to plants? Is there a minimal level of plant life necessary to maintain levels of oxygen so that land mammals can live? Also, are land plants mostly important or are underwater plants a significant source of atmospheric oxygen?

The oxygen in the atmosphere was produced by cyanobacteria during the Great Oyxgenation Event, around 2.3 billion years ago. Cyanobacteria produced & still, produces, to a lesser extent, oxygen by photosynthesis. Plants did not exist during the Great Oxygenation Event, but these day plants replenish atmospheric oxygen by removing carbon dioxide by photosysnthesis, like cyanobacteria. According to David Biello, The Origin of Oxygen in the Earth's Atmosphere the production of oxygen by cyanobacteria during the Great Oxygenation Event took one billion years.

During the Carboniferous period, about 350 million years ago, the amount of oxygen in the atmosphere increased to 30% because the rate of burial of organic matter prevented it from reacting with atmospheric oxygen, History & Significance of Oxygen in the Atmosphere

According to Wallace S. Broecker our atmospheric oxygen supplies are vast:

  Simply put, our atmosphere is endowed with such an enormous reserve of this gas that even if we were to burn all our fossil fuel reserves, all our trees, and all the organic matter stored in soils, we would use up only a few percent of the available $\ce{O2}$. No matter how foolishly we treat our environmental heritage, we simply don't have the capacity to put more than a small dent in our $\ce{O2}$ supply.

From Atmospheric oxygen - Broecker


Calculating mean time spent precipitating for a specified period/area? I would like to calculate the prior probability of active precipitation currently taking place at any random moment during a year.

The area I’m looking at (London, UK) has averages of 601.7mm of rain and 109.6 precipitation days per year (according to https://en.m.wikipedia.org/wiki/Climate_of_London).

I haven’t been able to find any historical data for “time spent raining”, nor for average the distribution of rain intensity (which would also help me estimate this), for any area. Is this data publicly available anywhere?

Check with the Met Office to see what data is available.

My experience, from elsewhere, is that weather data: temperature, pressure and precipitation are recorded at important weather stations at half hourly intervals, with the data being in the format shown below

With data in format it is easy to determine the  "time spent raining" to a precision of half an hour.


How does the energy of tornadic winds compare to floodwaters? I have been watching The Weather Channel for a month straight following the hurricanes. One of the meteorologists warned people not to drive into floodwaters, saying that water moving at about 6 miles per hour has the same amount of power as an EF5 tornado.

How did they figure that out?

The force exerted by a moving fluid (gas or liquid) per unit area is
proportional to its density $D$ and to the square of its velocity $V^2$.
The power delivered by a moving fluid (gas or liquid) per unit area
is proportional to its density $D$ and to the cube of its velocity $V^3$.

Water is about $800$ times as dense as air.
So water moving at $(\frac{1}{800})^{1/2}$ or about $\frac{1}{28}$ as fast as air exerts the same force per unit area,
and water moving at $(\frac{1}{800})^{1/3}$ or about $\frac{1}{9}$ as fast as air delivers the same power per unit area.

Or in other words air must move $800^{1/2}$ or about $28$ times as fast as water to exert the same force per unit area, and $800^{1/3}$ or about $9$ times as fast to deliver the same power per unit area.

Thus water moving at $6$ mph exerts the same force per unit area as air moving at about $170$ mph (a $170$ mph wind), and delivers the same power per unit area as air moving at about $55$ mph (a $55$ mph wind).

So it is not the power of 6 mph water that equals that of an EF4 (not EF5) tornado, but the force.
$6$ mph water has the same power as a 55 mph whole gale.


How to convert mol m-2 s-1 CO2 emission to Megaton day-1 (MtCO2 per day)? I am working on the global CO2 emission using a model dataset. The model provides the CO2 emission in mol m-2 s-1. How to convert mol m-2 s-1 CO2 emission to Megaton day-1 (Mt per day)?
Regards

Do the calculation for 1 mol of CO$_2$
1 mol of CO$_2$ weighs 49 grammes = 0.0049 kg
86400 seconds in a day, so 864000 * 0.0049 = 423.36 kg/day/m$^2$
The surface area of the globe is 5.1 x 10$^{14}$ m$^2$ - so 423.6 * 5.1 x 10$^{14}$ = 2.16 x 10$^{17}$ kg/day
Convert from kg to Megatons, 10$^9$ kg in a Megaton  - so we get 1 mol CO$_2$/m$^2$/second = 2.16 x 10$^8$ Megatons/day
This assumes, as farrenthorpe commented, that the molar emission rate represents a rate evenly distributed over the globe - if, for instance it only represented terrestrial emissions, or emissions in a particular region the calculation would need to take that into account.


Why does radioactive dating work on specific rocks? As I understand it, radioactive dating measures time by what portion of a radioactive isotope has decayed. Weren't all the natural radioactive isotopes created during the formation of the solar system? So how does radioactive dating age a specific rock, instead of just the number of years since the formation of the solar system?

There are other, mostly chemical processes which alter the isotope ratios. Isotope dating uses a combination of them. This is why it can not be used always, for any radioactive isotopes, only in special circumstances. It also requires very sensitive measurements (below in the second example, close to induvidually count lead atoms in microscopic zircon crystals).
For example, in carbon dating, C14 is continuously generated in the atmosphere due to the cosmic radiation, and builds in the biosphere, where it decays. If a plant stops accumulating carbon ( = it dies), its C14 ratio starts to decay.
Another example, this time about isotopes which were created really with the Solar System. The mineral zircon ($\rm{ZrSiO_4}$) accumulates uranium and thorium atoms in it crystal structure, but strongly rejects lead. This rejection can happen as it freezes. After it is solid, the lead atoms created by U/Th decay do not go away any more. Thus, all the lead in the zircon crystals of the soil of Moon, were created since it frozen. This makes possible to know, when did that zircon solidify ($\approx$ when formed the crust of the Moon).


Does the geographic North Pole move? The magnetic North (or South) Pole moves due to activities in the inner of Earth. And earthquakes can tilt the Earth's orientation a tiny bit. But can and does the axis' orientation relative to the surface change too? A major impact could surely do it, but could the Earth's inner activities?

I don't mean precession, nor tectonics or continental drift, but the movement of the rotation axis. Could for example the geographic North Pole move to Greenland? (Not Greenland moving to the NP)

Yes, it's called polar motion.

The rotational pole moves continuously, as you can see from the right-hand side of this figure (below) by the Earth Orientation Centre (EOC) and the International Earth Rotation and Reference Systems Service (IERS). The figure shows about 650 days of time; mjd is modified Julian day and time goes along the locus in the polar motion diagram.

The left-hand side of the figure shows Length of Day, and I think that's chiefly why they are making these refined polar measurements — to keep track of leap seconds, etc.

It's been established, by Fong et al. (19996), among others, that earthquakes could change the earth's rotational axis, by redistributing mass on a large scale. Their table 1 shows [the sort of effect that individual earthquakes theoretically have — edited after comment from David Hammen] on the length of day; $\Psi$ is the excitation vector:

The EOC's website lists other geophysical excitations, among them:

Atmospheric angular momentum
Oceanic angular momentum
Hydrological excitation function
Axial angular momentum of the core

References

Chao, Benjamin Fong, Richard S. Gross, Yan-Ben Han (1996). Seismic excitation of the polar motion, 1977–1993. Pure and Applied Geophysics, September 1996, Volume 146, Issue 3, pp 407-419. DOI 10.1007/BF00874727

Update: This article on some new research in this field is worth a read.


How is there enough $\ce{O2}$ in the atmosphere to breathe if you are in a desert with no plants? Humans depend on $\ce{O2}$ for breathing. The source of $\ce{O2}$ is photosynthesis by plants or cyanobacteria in the ocean.

How is it, that when people travel through deserts or the Arctic / Antarctica, they able to breathe? Is it due to Earth's wind currents blowing $\ce{O2}$ from the nearest ocean?

Look at it this way: According to the American National Center of Atmospheric research, the Earths atmosphere weighs 5.148 x 10^^18 kg., and that atmosphere is composed of about 20.8 to 20.9% oxygen (depending on moisture content of the air). So the Earths atmosphere contains about 1.07 million trillion kgs of oxygen.

The 7.5 billion (or so) humans on the planet, each converts an average of about 0.73 kg of oxygen per day, converting most of it to exhaled CO2. So the planetary consumption of oxygen by humans, as a percentage of the total available, is about 100 x 0.73 x 10^^9 / 1.07 x 10^^18 %.

That is, about half of one millionth of 1% of the Earths available oxygen, a level of oxygen deficiency that is almost instantly dispelled by turbulent mixing in the troposphere (i.e.by 'weather'). So no, there is no chance of gasping for oxygen in deserts or polar wastes.

Now gasping for air 8000 metres up a mountain, or in a crowded disco with cigarette smoke and poor ventilation - that is another question!


Can a microGPS tracker trace the path of an underwater drainage conduit? The Devil's Kettle is a pothole in the rock where a small river disappears underground in the Judge C.R. Magney State Park in Minnesota. Would it be possible to trace the path of the drainage conduit by throwing in a small waterproof GPS tracker?

GPS units require a clear view of the sky to fix their position. Because unlike radio signals used for communications, once the GPS signal have bounced in a wall becomes useless for computing the receiver's position. Therefore, the GPS would loss fix shortly after entering the pothole.

The studies made in the area that determined the point at which the water reenters the river, claim that the flow of water keep objects at the bottom of the pothole, explaining why they never resurface. So there is a high chance that you wouldn't see your GPS ever again.

However, if your GPS were to resurface, it would fix its position again soon after regaining a clear view of the sky. So, if you recover it (or if it had the capability to transmit its position in real time), you won't see a record of the track followed by the device, you would see only the entry and exit point.

For such problems, similar to a car going trough a tunnel, the GPS is usually augmented with inertial navigation systems that can estimate the displacements and compute the position by dead reckoning from the last GPS fix. Despite that the turbulence within the water flow in the pothole would make very challenging to keep track of the trajectory of the device underground, a sophisticated enough device should be able to do it.


How long until Earth's core solidifies? How much longer does Earth have until the core turns solid?

Does global warming change these estimates at all?

Global warming has to do with the surface only, and at best involves changes of 20 degrees at the outside extreme, in comparison to the earth's core, which is as hot as the surface of the sun.

For complete accuracy, and to reflect what a commenter has pointed out, the inner core is solid already, but this is because of the extremely high pressure of the overlying layers of the outer core (which IS liquid), and the mantle. See the Wikipedia articles concerning the Inner Core, and the Outer Core.  Note that it is the outer core which creates the earth's magnetic field.

The answer is that the earth's core will never be solid.  And I do mean NEVER.  Now, that being said, there is only one way it could ever happen and that is if the earth happened to get thrown out of its orbit to become a nomad planet.  Then it might have time for its core to cool.

The reason I say this is because it will take longer for the earth's core to turn solid than it will take for the sun to run out of nuclear fuel and expand to engulf the earth.  At that point, the earth will be vaporized as it spirals out of its orbit into the sun.  The core would soon turn into incandescent gas.  This will occur something like 4 to 5 billion years from now.

If by some chance the earth were to become a nomad planet, free to cool in its own good time, then it would take a long long time.  See Energetics of the Earth by John Verhoogen, available online via Google Books.

The main factor slowing down the cooling is radioactive decay of long living atoms, namely Uranium-238, Uranium-235, Thorium-232, and Potassium-40, with half-lives of roughly 4.47 billion years, 704 million years, 14.1 billion years, and 1.28 billion years, respectively. From the half-lives of these isotopes and a comparison with the age of Earth, you can see that internal heat production via radioactive decay will likely persist at near current levels for quite some time to come. Verhoogen gives 5000 K as the core temperature now, and a 250 K cooling since the formation of the Solar System, 4.5 billion years ago.  If it really does cool at that rate (55 degrees per billion years), it would take something like 91 billion years to cool to 0 Kelvin.

But don't worry, it won't happen, as I said.

Edited to add detail


Where can I find a data set containing wetland loss by decade I am trying to find a reputable source that lists how many  acres of wetland are destroyed each year on average in each decade, specifically in the Continental US. I found some secondary sources, but many of them are conflicting, and didn't list primary sources. Are there any primary sources that list the amount of wetland destruction?

Start with US Fish and wildlife services National Wetlands Inventory site.
Site has links to :

Wetlands Mapper.
National Wetlands Inventory home page
Status and Trends web page
Download Seamless Wetlands Data


Seismic amplitude distribution Recorded (or raw) and processed pre/post-stack seismic data (relative amplitudes) usually display a standard normal distribution, albeit with a very small amount of skewness.

What would be possible causes and/or significance if amplitudes did not retain a mean value of zero (or very nearly zero)?

I'm sure there are several possible reasons.

I'm not a seismologist, this is an amateur answer only.

Tidal forces

Local acceleration has very small long-term drifts due to tidal forces from the Sun and the Moon. These will have periods of roughly 1 day as the Earth rotates. Most seismometer data will have been run through a high-pass filter with a much higher cutoff frequency than this (of course along with other filtering). This might be implemented with some baseline restoring function other than a simple filter.

Real changes in local g due to displacement in the Earth

Prompt gravity signals -- changes in local g as mass distribution in the Earth changes -- have been detected, and this kind of measurement may become more widely used in the future. Of course a typical seismometer will not be sensitive to pick this up, unless of course your seismometer is sitting atop a substantial geological event!

See:

Prompt gravity signal induced by the 2011 Tohoku-Oki earthquake - could this really be useful for warnings?
Earthquake-induced prompt gravity signals identified in dense array data in Japan
Gravity sensors might offer earlier warning of earthquakes

Instrumental effects

Drift due to thermal changes
Tilt due to geological changes (the z accelerometer is no longer pointing in the same direction)
Tilt due to improperly mounted seismometer that was shaken loose by the earthquake
others...


Are the cores of every mountain range igneous? Every volcano is a mountain, but not every mountain is a volcano. Still, it strikes me that--at least for the mountain ranges I can think of in this moment--they all seem to have igneous cores. Is this generally true, or are there plenty of examples of mountain ranges with sedimentary or metamorphic cores?

Many mountain ranges do not have igneous cores. The front ranges of the Rocky Mountains in British Columbia are created by thrust faults that push sedimentary strata up to form the mountains. The driving force for this motion is a subduction zone located 100's of kilometres to the west. I believe that the Himalayas mountains are formed in a similar fashion.

See the following Wikipedia article: Geology of the Rocky Mountains


Why are storms relatively short on Earth? From reading articles and the such it is clear that other planets such as Jupiter have storms that lasts months over months. However on Earth, storms last much shorter. In fact, the longest storm was Typhoon John which lasted a mere 31 days. Such long storms are commonly found on other planets. So why don't we have long storms?

The main driving force for storms to form at all are the equator-pole temperature gradients. The main reason  for them to stop is friction between the lower atmosphere and earth's surface. This friction counteracts geostrophic balance (the balance between the pressure gradient and the coriolis force). Longer storms can only sustain themself through latent heat release, which can act as a secondary driver (and is the reason that Hurricanes/Typhoons can last rather long). However, at the latest at landfall this mechanism stops and the storm will decay. On gas-planets, however, there is no surface, therefore friction is much less (only the friction between different layers of the atmosphere, which is much less). Once a storm develops, with a low pressure centre, there is no (or hardly) any friction which counteracts geostrophic balance. This allows the storms to exist much longer.

As to other non-gas planets:
Mars and Mercury have a very thin atmosphere, therefore, as far as I know, there is no weather as on earth anyway. As for Venus, which has an atmosphere, I do not know.

Note that also on Earth, some weather circulations last much longer than the couple of days that storms last, for example the polar vortex, which lasts the whole winter (and is far away from the earths surface). Especially if you compare the gas-planets, you might also see them as "storms" in the wider sense.

references:

(lack) of atmospheres on Mars and Mercury: https://en.wikipedia.org/wiki/Atmosphere_of_Mars, https://en.wikipedia.org/wiki/Atmosphere_of_Mercury

no surface on Jupiter: https://en.wikipedia.org/wiki/Atmosphere_of_Jupiter

disturbance of geostrophic flow due to friction: https://en.wikipedia.org/wiki/Ageostrophy

formation of storms in general: "An Introduction to Dynamic Meteorology - James R. Holton", Chapter 9, and 11


How did plants adapt to $\small\sf{CO_2}$ levels past 400k years? Why won't they do it again? (Description from climate.nasa.gov: This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric $\small\sf{CO_2}$ has increased since the Industrial Revolution. (Credit: Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.))
I'm not sure where and why has all $\small\sf{CO_2}$ gone every 100.000 years and out of where has $\small\sf{CO_2}$ come?
But if $\small\sf{CO_2}$ came from burning trees or volcanoes and disappeared because plants adapted then I have this question:
Plants somehow tolerated these 100.000 year $\small\sf{CO_2}$ changes over time which is very evolutionary small time. So perhaps adaptation was just about changing plants' composition percentages which is very flexible. When some rare $\small\sf{CO_2}$ eating trees came to be more frequent. But if that's true why can't plants change their composition again to adjust for human $\small\sf{CO_2}$-emissions pace?

I'm not sure where and why has all CO2 gone every 100.000 years and out of where has CO2 come?

The amount of CO2 in the atmosphere for the last 400000 years is very strongly correlated with temperature.

Temperature change (blue) and carbon dioxide change (red) observed in ice core records.
Image source: https://www.ncdc.noaa.gov/paleo/globalwarming/temperature-change.html.

Glaciations currently occur at roughly one hundred thousand year intervals, driven primarily by Milankovitch cycles. So what causes the strong correlation between temperature and carbon dioxide levels? The primary reason for this marked correlation is that carbon dioxide dissolves in cold water much more readily than it does in warm water.

As a glacial period starts, the oceans gradually get colder worldwide as ice gradually spreads over the Northern Hemisphere. This enables oceans to absorb carbon dioxide from the atmosphere. Atmospheric CO2 drop as a glaciation proceeds. The plot shows that both temperature and CO2 levels drop rather slowly over the course of a glaciation, and then both rise rather quickly as the glaciation ends.

One reason for this is atmospheric carbon dioxide levels. The Milankovitch cycles triggers the end of a glaciation. The warming oceans cannot hold as much carbon dioxide as they could during the depths of the glaciation and release carbon dioxide to the atmosphere. This exacerbates the warming, releasing even more carbon dioxide into the atmosphere. This makes the escape from a glaciation much steeper than the entry into one (Shakun 2012). A nice graph from the cited paper:

Upper plot: CO₂ concentration (yellow circles), global temperature (blue), and Antarctic temperature (red).
Lower plot: Simulation results that show that Southern Hemisphere temperatures tends to lead but global temperatures tend to lag CO₂ levels.
Image source: http://www.nature.com/nature/journal/v484/n7392/fig_tab/nature10915_F2.html.

  But if CO2 came from burning trees or volcanoes and disappeared because plants adapted then I have this question:

  Plants somehow tolerated these 100.000 year CO2 changes over time which is very evolutionary small time. So perhaps adaptation was just about changing plants' composition percentages which is very flexible. When some rare CO2 eating trees came to be more frequent. But if that's true why can't plants change their composition again to adjust for human CO2-emissions pace?

Your question is a bit moot since the increases in CO2 did not come from burning trees or volcanoes and did not disappear because plants adapted.

Jeremy Shakun, et al., "Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation," Nature 484.7392 (2012): 49-54.


Was Russia's original territory unfavorable for agriculture? How favourable were the soil and climate in Russia's landmass of the 1500s for growing crops in comparison with Northern European countries?

The area outlined covers several climatic zones. The northeastern part was, and to some extent still is, permafrost at shallow depth, so obviously this was not good for agriculture. Further south most of the area outlined is covered in podzols, which are generally sandy and nutrient poor. Therefore, where water availability is not a limiting constraint (and we have no rainfall records for the 1500s), and where it is not too cold, the soils could have supported agriculture- but only just. They would most likely not have been high yielding. Even today, such soils need a lot of extra nutrients and additional organic carbon to give good results. Politics apart, maybe this is why much of Russia has remained so poor for so long?


At what altitude do winds exert the most force? Imagine I want to make a floating wind turbine like the Altaeros BAT, which is tethered and uses helium. What would be the best height to keep such a device deployed? I know that wind velocity decreases near the ground due to friction with the Earth's surface. Though, the density of air decreases with height, so the force of high winds aloft are lessened.  Considering these issues, at what altitudes do the winds exert the most force for a tethered wind turbine to produce the most energy?  Please disregard the energy required to keep the turbine afloat.

".....the density of air decreases with height, so the force of high winds aloft are lessened." I can personally vouch for the difference between a 60mph wind at sea level, and one at 14,000 feet! However, however, the single biggest difference between the two altitudes isn't so much the force of that wind, but the consistency of that wind speed, which seems to matter most to wind generation.

Here's how a wind turbine engineer would think of this problem:

From The Engineer's Toolbox- Power generated from the wind

Theoretically power in moving air - or wind - can be calculated

P = 1/2 ρ A v^3
  =  1/8 ρ π d^2 v^3

where
P = power (W)

ρ = density of air (kg/m3)

A = wind mill area perpendicular to the wind (m2)

v = wind velocity (m/s)

π = 3.14....

d = wind mill diameter (m)


Why is there a daily inequality for low tides? I understand why there is a daily inequality for high tides. What I do not understand is why the low tides are not equal. The data all seems to be somewhere along the lines of but the theory seems to point to
That is, a greater daily inequality for high tide and none for low tide. I know that there are things to consider besides the moons influence, but the data pretty clearly rises above the noise in its consistency.

The water for high tides needs to come from somewhere; the mean sea level should stay approximately constant, as long as wind is neglected. That way tides are a kind of oscillations.

In the first of the two diagrams a low low tide is followed by a high high tide, and a high low tide is followed by a low high tide. That way the mean sea level, averaged over one low tide - high tide period remains constant:

In the second diagram you need to average over two low tide - high tide periods to get a constant mean:

The first diagram can be explained by the superposition of semi-diurnal tides, while
the second diagram needs an additional diurnal constituent. Depending on the amplitude and phase shift of the diurnal constituent relative to the semi-diurnal constituent we can get different resulting oscillations.

More about tides and their constituents.


Dynamic meteorology - calculating air temperature based off falling air I'm not sure if this is the correct place to ask this. Basically I have an exercise in dynamic meteorology that is set up like this:

  1 kg of dry air is falling with a constant speed of 0.5 cm / s and 0.1
  w/kg of heat is extracted. Does the air volume temperature rise, fall
  or does it remain unchanged?

Here's how I tried to solve it:

$w = 0.5 \frac{cm}{s}$

$J= -0.1 \frac{w}{kg}$

$T? $

$J = Cp \frac{dT}{dt} - \alpha  \frac{dp}{dt}$

$J = Cp \frac{dT}{dt} - \frac{1}{\rho}  \frac{dp}{dt}$

$\frac{dp}{dt} = \frac{\delta p}{\delta t} + u  \frac{\delta p}{\delta x} + v \frac{\delta p}{\delta y} + w \frac{\delta p}{\delta z} = w \frac{\delta p}{\delta z}$

(because $\frac{\delta p}{\delta t} + u  \frac{\delta p}{\delta x} + v \frac{\delta p}{\delta y} = 0$)

$ \frac{\delta p}{\delta z} = -\rho g$

$\frac{dp}{dt} = w \frac{\delta p}{\delta z} = w -\rho g$

$J = Cp \frac{dT}{dt} - \frac{-1 w \rho g}{\rho} = Cp \frac{dT}{dt} + \rho g$

$$\frac{dT}{dt} = \frac{J-gw}{Cp} = \frac{-0.1 \frac{w}{kg} - 9.81 \frac{m}{s^2}   0.5 \frac{cm}{s}}{1004.5 \frac{J}{K * kg}} $$

Here's where I get lost. Any help?

Well.. W/kg = J/(kgs) = Nm/(kgs) = (kgm/s^2)m/(kgs) = m^2/s^3 So, J and wg have same unit, and also your final answer has correct unit, Kelvin per second. Your final answer says the parcel`s temperature will drop, even without cooling term J(you will find this strange because it should be heated by adiabatic heating). It is because you set w=0.5 instead of w=-0.5. I hope this helps you :)


What determines a mineral's hardness? Mohs Hardness Scale is basically a measurement of the hardness of a material, or more specific, a rock or mineral. But I have never been able to figure out why some minerals are harder than others.

The hardness of minerals is diagnostic because the hardness is determined by the strength of bonds and the structure of the mineral lattice. Hardness is basically the stress required to create and grow extended lattice defects such as micro-fractures, stress twins, and dislocations.

Diamond, quartz, and framework silicates, such as feldspar, are hard because they have a three-dimensional lattice of covalently bonded atoms. Native metals are soft because they have close-packing lattices of metallic bonded atoms.

Hardness is an intrinsic property of a mineral like density or refractive index.


Is it possible to have a busier tropical storm season in the eastern Pacific basin than in the western Pacific basin? It is known that hurricane activity in Atlantic basin is less active than in East Pacific basin in seasons past, but for the 2005 and 2010 seasons, the Atlantic basin is busier than western Pacific basin.  However,I have never heard of the eastern Pacific basin having a busier season than the western Pacific basin, is that possible?

There are many determinants of tropical storms. The most important is to have sea surface temperatures of >27 deg C. Obviously, this will increase in extent, though not necessarily in frequency, with global warming, and increased incidence of El-Nino events. Shallow sea, as in the western Pacific, warms up faster than deep sea, as in the eastern Pacific. Hence there are always likely to be more tropical storms in the west Pacific.
The second determinant is for the air mass to have a 'start-up' rotation, which is a function of latitude. That is, almost no tropical storms at the equator, but many in the tropics, as air masses pick up Coriolis rotation.


(Why) Is there more landmass on Earth's Northern hemisphere than the Southern Hemisphere? This Question on Worldbuilding is based on the presumption that there is a greater amount of landmass on the Earth's Northern Hemisphere than there is on the Southern Hemisphere.

While researching to form an answer to this question, I found it difficult to find a map that accurately portrays which hemisphere actually has a greater landmass, and started thinking about the actual nature of the question - assuming there is a greater concentration of landmass in the Northern Hemisphere than the South, why is that?

Does it have anything to do with the rotational procession of the Earth? Is it more related to the Earth's natural fault lines?  Or is there something else that influences a greater accumulation of land mass on our Northern Hemisphere (if that is, in fact, an accurate assumption)?

It would be a strange coincidence (but of course possible) if the landmass would be exactly evenly divided between the northern and southern hemispheres, as defined by the equator. However, you can cut the globe with another plane and form two hemispheres that have the same landmass, eg. any vertical plane that goes through the Geographical centre of Earth.

Calculation of Geographical centre of Earth by whuber at GIS stackexchange

The landmass distribution is largely depending of the location of the continental plates, but Global Paleogeography maps also suggest that the breakup of Pangaea follows other laws than an even distribution between north and south hemisphere.

The problems to find a map that accurately portrays which hemisphere actually has a greater landmass, is probably related to the fact that many popular (and in many ways useful!) map projections are not made to show area relations. Use a globe or equal area projection to compare the size of landmasses.

This might also be an interesting article for you and a starting point for further research: Riguzzi et al. (2009) Can Earth's rotation and tidal despinning drive plate tectonics?. The authors argue that there is a correlation between tectonic movements and rotation of the Earth and the Moon's revolution plane. Tomographic data of slab dip angles support the point and this might also be part of an explanation why earthquakes and volcanism varies along the latitudes and might be rare in the polar regions.


Pyroclastic density currents interpretation How to interpret bubble voids in pyroclastic density currents? You may see the case on the photo attached. It is; Miocene, densely welded, crystal bearing, LT. Do they have to occur on the top of the current?

The name of the cavities are lithophysae. They show that the current has high volatile content. Vapor phase devitrification is the origin of litophysae. Pyroclasts in the curremt maintain their volatile content till compaction. volatiles escapes from the clasts during deposition to the weakness zones of the flowage. After exsolution, the laminae (source of the volatile) will be compacted and vapor phase minerals tridymite, crystobalite and feldpspar crystallized.

The cavities don't have to be on the top of the pyroclastic density current. They may occur on the flowage shearing surfaces and a syn-depositional incident.

The answer is not complete but it may give some idea.


What is this weird looking structure in Ethiopian desert? I was surfing through Google Maps around Ethiopian desert region (close to the town of Werder/Wardheer) and I found this weird looking structure. It seems like a dried up lake bed, but I can't guess what the straight lines are going out of the circular thing. Any idea?

Zoom in for the clues. The lines are not radiating out from the village, but from the cattle kraals. These kraals are irregular enclosures built of acacia thorn, agave and other thorny bushes. The cattle are kept in these kraals at night to protect them from hyenas and packs of wild dogs. The cattle themselves are likely African longhorn or various local cross-breeds with Sebu. They are creatures of habit, walking out from the kraal in the early morning, and back in the evening. They follow the same track for several hundred metres before the cattle diverge in slightly different directions. In the more concentrated paths decades of hoof-prints erode the dusty soil, often in trenches to depths of 60 or 70 cm. When it rains, runoff drains into the paths where it collects as red mud, the latter being derived from the deep weathering of basalt. The cattle are led by villagers who each have allocated pasture land, hence the constancy of direction.

This is the most striking example I have seen. Often it is not as obvious because, at least in wetter areas, there is more local grass, and the cattle are tempted to disperse 'closer to home'. On the ground one can see these in many parts of East Africa, from the Simian highlands of Ethiopia to the Simiyu pastures of northern Tanzania.


References on hurricanes Would anyone know of references (available online or not) that give detailed explanations and especially the physics behind violent meteorological events such as hurricanes?

There are many generalized references, such as
http://moe.met.fsu.edu/~rhart/papers-hart/2006Hart.pdf
https://en.wikipedia.org/wiki/Tropical_cyclone
http://www.aoml.noaa.gov/hrd/tcfaq/tcfaqD.html
But I think the best is Kerry Emmanuel's presentation:
http://www3.nd.edu/~its/Emanuel.pdf
Is this sufficient detail for you? If not, then you probably need to do a course in tropical meteorology.


What does 'reghosted' mean in a seismic cube label? I came across to a seismic volume labeled as reghosted. In my understanding, a seismic survey is deghosted as part of a processing step. Then I wonder why one would like to reghosted the data? Is there any benefit in reghosted? Is it maybe reghosted something different than bring the ghost back to the data? Is there a visual inspection to know a data set is deghosted?

As you rightly say, data will normally be deghosted during processing.

However, sometimes the deghosting is performed by the acquisition company rather than the processing contractor. The most obvious example would be PGS Geostreamer data, where 'raw' field tapes supplied by PGS to the customer are the upcoming wavefield, with the receiver ghost already removed. This is because the process of combining the velocity sensor and hydrophone data to remove the sea surface reflection is PGS's secret sauce - in many ways building a multi-sensor streamer is the easy part. They work with the true raw data internally, but never supply it to anyone else.

This is normally fine, but if the data is later processed (or reprocessed) by someone else, then complications can arise. If this other processing company wants to perform Full Waveform Inversion, which involves modelling a synthetic wavefield and comparing to the recorded wavefield, then the absence of the receiver ghost will cause an issue. Since the boundary condition at the sea surface has to be reflective to model the multiples correctly. Thus, they may add the receiver ghost back into the data by making an assumption of the sea surface reflectivity and adding it back, creating a 'reghosted' dataset to compare to the synthetics within the FWI.

That said, this would be an internal working dataset for the processing company, not something that would be supplied to the client. So I am surprised you would come across it without knowing what it was, if you see what I mean.


If gypsum turns into plaster around 210 F, is there any natural plaster deposits or formations out there? For a while I have been working with gypsum I mined from a site in Utah, and I realized how low the temperature is to turn it into plaster, so I was wandering; has there ever been any cases of large deposits of gypsum being naturally heated into plaster and coming in contact with water?

Water is removed from gypsum hydrate about 300 F+ making it dry powder gypsum. Water is added to gypsum to make "plaster of Paris" , no particular temperature is involved. Not sure it answers the question , but gypsum commonly deposits in oil production tubing. The produced oil/water/gas  mix cools as it comes up the well tubing and deposits in the tubing,; very difficult to prevent or remove.


Do Antarctic research stations use any of the local resources, like water, or is everything flown in? There are serious ideas, if not quite yet plans, for space missions to the Moon and Mars to take advantage of in situ resources, such as producing oxygen for propulsion (e.g. for a sample return) out of Mars' atmosphere or from water ice on the Moon. This is of course considered because space flight is expensive per kilogram launched from Earth. There's some similarity with research stations in the Antarctic with fairly expensive logistics. So I wonder if they somehow are living off the land to cut costs.

Do research stations use the local water, or is even water for showering flown in by airplanes?

The Australian and Belgian Antarctic research stations use local resources for their respective water supplies.

Australia operates a number of stations. In the past, snow was melted but currently local melt water is processed and used. However, the Australian base, Casey, also melts ice and the Mawson base also melts snow.

  Getting freshwater in Antarctica is quite difficult and time consuming. The exact method used varies between stations. In earlier days, snow and ice was shovelled into large tanks and heated to form water. Today, Casey and Mawson pump water from a melt lake behind the station and store it in a heated tank house.
  Davis draws water from a local tarn which is processed by a Reverse Osmosis System which produces about 18,000 litres each 24 hours. The average station demand is around 10,000 – 14,000 litres a day. Macquarie Island draws water from a dam located about three kilometres from the station on the plateau and 200 metres above sea level. The water is pumped to two holding tanks.

Water saving appliances are installed wherever possible, but each person on station is asked to use as little water as possible.

Expeditioners are limited to three minute showers and, when water supplies are short, to only shower every second or third day. Other water saving measures are also followed, such as doing one large load of washing rather than several smaller loads, and turning off the taps while cleaning your teeth.

The Belgian, Princess Elisabeth base, melts snow to obtain water. The Belgians, as do bases from other countries, also use renewable sources of energy, namely, wind and solar, via wind generators and solar panels. The Australian base at Mawson has two wind generators that supply 95 percent of the stations energy requirements

The US base at Mc Murdo, operated a nuclear reactor for electricity generation, for 10 years, until 1972. It produce over 78 MWh or electricity and 13 million gallons (49.21 ML) of fresh water.

Diesel generators still produce much of the electricity used at Antarctic stations.

The French base, Dumont d'Urville, obtains fresh water by desalinating sea water.

Food is delivered to all the stations from outside because the Antarctic Treaty, bans the eating of anything originating from the continent. This prevents fishing and eating seals or penguins, or any other fauna or flora.

Waste water from bases is treated before being discharged.

The mining of minerals and the exploitation of oil and gas from Antarctica is still banned.


Hypotheses about Silurian carbon isotope excursions? The Silurian Period is now known to have undergone several significant positive $\delta^{13}C_{carb}$ excursions, namely the early Aeronian, Late Aeronian, Valgu, Ireviken, Mulde, Lau & Klonk events (see e. g. Cramer et al. 2011; Gradstein et al. 2012). It seems to me that those excursions where mainly studied in the context of chemostratigraphy and not paleoclimatology, though.

Is there any hypotheses on what could have triggered these excursions?
How come the short (ca. 24 Myr) Silurian be so unstable has to have so many significant excursions?

Sources:
Cramer, et al. 2011. Revised correlation of Silurian Provincial Series of North America with global and regional chronostratigraphic units and $\delta^{13}C_{carb}$ chemostratigraphy. Lethaia, 44: 185-202.
Gradstein, Ogg, Schmidt & Ogg (Eds). 2012. The geologic time scale. Elsevier, Amsterdam: 1144pp.

Even though many researchers now recognise that the Silurian palaeoclimate show signs of large fluctuations - resulting in the carbon excursions, the mechanism behind the climatic shifts is not well understood.

Recent research from Munnecke et al. 2014 (1) suggest that the carbon (and oxygen) isotope excursions that mainly affected low latitude palaeoenvironments, were probably due to climatic shifts between humid (low C) and arid (high C) climatic conditions. The possible consequences of these two climate regimes is shown below:

One of the only certain climatic regimes that occurred was in the early Silurian, where 3 of the 7 'Early Palaeozoic Icehouse' (EPI) events occurred (2).  Munnecke et al. 2010 (3) note that much of the Silurian is 'sandwiched' between the EPI and the greenhouse of the Devonian, possibly suggesting a prolonged transitional period between the 2 climatic regimes.

Some observations suggest that sea levels fluctuated very wildly, Munnecke et al. 2010 (3) states they were up to the order of 140 m.  This is partly related to recent oceanic circulation modelling performed by Servais et al. (4) who state that the palaeogeography of the time (large northern ocean and the Gondwanan land mass at the south pole - see below) would have possible resulted in a halothermal circulation, rather than the modern day thermohaline circulation, essentially due to the restrictions a possible Mediterranean-like production of denser water at the lower latitudes (as indicated in the diagram above).

Image source

So, in summary, the oceanic-atmospheric interaction of the Silurian is considered to be unstable (1)(3), with oxic and anoxic regions uncertain (4), but the effects were clearly seen with variations in the climate from humid to arid and large fluctuations in sea levels.

References

(1) Munnecke et al. 2014, Silurian climate development University of Nuremberg

(2) Page, A., Zalasiewicz, J., Williams, M., Popov, L., 2007. Were transgressive black shales a
negative feedback modulating glacioeustasy in the Early Palaeozoic Icehouse? In:
Williams, M., Haywood, A.M., Gregory, F.J., Schmidt, D.N. (Eds.), Deep-Time
Perspectives on Climate Change: Marrying the Signal from Computer Models and
Biological Proxies: Special Publication of the Geological Society of London. The
Micropalaeontological Society, pp. 123–156

(3) Munnecke et al. 2010, Ordovician and Silurian sea–water chemistry, sea level, and climate: A synopsis Palaeogeography, Palaeoclimatology, Palaeoecology

(4) Servais et al. 2014, Possible oceanic circulation patterns, surface water currents and upwelling zones in the Early Palaeozoic Special Issue:   EPGC - Early Palaeozic Global Change


Infared & Thermal imaging Let's say I have an infared picture of the earth from the space station, is it possible to measure the temperature of the picture area, and thus convert the infared picture I have to a thermal picture?

Temperature images are calculated from microwave and infrared data. So in principle yes.

See https://en.wikipedia.org/wiki/Satellite_temperature_measurements?wprov=sfla1


snow modelling using raster data with different resolution I am trying model to some snow processes for the whole US.
I do have daily climate forcing time series for a 1 x 1 km raster in a Lambert Conformal Conic Projection (netCdf format). The MODIS snow cover time series for a grid of 500 m in a sinusoidal projection (hdf format) and snow depth data in a 1 km resolution grid (binary .dat file) in a Geographical projection.

I would like to get the time series for each variable in a 1x1 and 2x2 km grid.
The question I have is how can this be achieved without using GIS Software. I know how to do this using ArcGIS, but since I do have a lot of files I think there must be a better way of doing this.

My model is in MATLAB, so if there is some toolbox that would achieve that it would be my first choice. However, I am open to other approaches and standalone tools.

To make sure I'm understanding correctly: You need to reproject some data from one coordinate system to another. Then you need to interpolate or resample it onto a grid.

If you are already familiar with MATLAB, then you can certainly use MATLAB. Look to the Mapping Toolbox for coordinate transforms (although it does not make life easy IMHO), and check out griddedInterpolant and scatteredInterpolant and their options for interpolation.

If you're more tool-agnostic it might be easier in R (check out the spatial, raster, and rgdal packages). Or, depending on your GIS system, there is probably a way to script or automate it there so that you do not have to work through the process manually for all your files.


Recursion relations of Associated Legendre Polynomials with Schmidt Semi-normalization Can someone please provides me with the recursion relations of Associated Legendre Polynomials when using Schmidt quasi-normalization? I need that in the context of Geomagnetism to obtain the Spherical Harmonics coefficients g and h.

FYI, the usual reference relied on for the equations used in geomagnetism is:

Langel, R. A. "Chapter four: Main field." Geomagnetism, edited by JA Jacobs (1987).

If it wasn't for lockdown I'd have copied from the book locked in my office to make sure I got it right...but until someone corrects me...
The Schmidt quasi/semi-normalisations for the associated Legendre polynomials are given by these recursions, in the form you'd actually use for calculations typically:

Note that if you use Schmidt normalisation of Legendre polynomials from a given software language to do calculations, you do not want to include the Condon-Shortley phase factor of . So check if it is included in the Legendre polynomial and/or normalisation formula.
Edit: Some links to open source geomagnetism compatible software for calculating Schmidt normalised associated Legendre polynomials.
Python: ChaosMagPy
Python/Fortran-95: SHTools


Why are January and February the coldest months although 21 December is the shortest day? My question deals with the northern hemisphere only, obviously. It seems to me that January and February are the coldest months of the year. Water temperature is even more 'retarded': the seas are coldest in February and March. Since 21 December is the shortest day of the year, why isn't (the end of) December the coldest time of the year, both in air and water temperature?

Short answer: air, land and water take a while to cool down (or rise in temperature; we see the same thing happening with July and August being the warmest months on average – not June, while June 21st is the longest day). In December, the fall just ended, and everything is relatively warm.
Also, depending on how far North you go, the difference between day length in December, January and February isn't that much. See this graph from Wikipedia:


Can we see lava in a divergent tectonic boundary? Can we actually see an orange line of lava if we look down to the crack of the divergent boundary of tectonic plates?

No, we can't. This is because of several reasons, mostly stemming from the fact that the plates are not diverging fast enough to keep the lava hot enough before it cools down.

If we go and look on diverging plate boundaries on land, such as on Iceland or East Africa, you don't have a "line" of lava. Instead, you have individual volcanoes located along a linear trend:

source: http://volcano.oregonstate.edu/vwdocs/volc_images/africa/africa.html

You see all the volcanoes along a line in the Ethiopia and Kenya region? It's not one "line of lava", but single volcanoes along a line.

If we think about divergent boundaries underwater, where the lava comes from a much shallower depth, we may think it might be possible to see this kind of feature. The problem is that water is extremely effective in cooling down lava. Here's an example video of what happens when there is lava underwater:

https://www.youtube.com/watch?v=hmMlspNoZMs

As you can see, the lava cools in seconds. It doesn't erupt fast enough to sustain a constant liquid lava "line" under water.

This is not something that happens on Earth. But on other planets, maybe. If we think of a planet where the surface temperatures are on the hundreds of degrees Celsius (such as Venus), the cooling of the lava may be slow enough for plate tectonics (if they exist on said planet) to catch up and provide enough magma to sustain a long-lived magma lake-river on the boundary.


What kind of climate could you expect in a mountainous area in a subtropical region? More specifically, I'm trying to work out climate analogues for my farm. It's at 5200-6200ft in South India. My area is a bit too small for the Köppen Map to correctly reveal patterns.

I'll be getting a weather station etc. soon, but it'll take a few months to a year before I have enough data to work with. But right now I have some experimental planting to do, so..

My question is, if you were at around 5800ft in a tropical/subtropical region of India, would the climate then be more like a temperate zone or an alpine climate, but with monsoons?

To put it another way, my question has a general aspect to it too, which is: what happens to a tropical zone as the land increases in elevation? Does it become more "temperate" or "alpine" for all practical purposes? And what "tropical" factors remain in effect (for example, sunlight, I'm guessing)?

If I sound confused about how this stuff works, I would love if someone could direct me to a guide of some kind too!

Further information: It's in the Nilgiri Hills, Tamil Nadu, in a region called Bengal Mattam. There's a small stream that runs through the farm, right at the border, all along the lowest point of our farm/the hillside. The stream then turns sharply and in one kilometer from that turning point, empties into an irregularly shaped reservoir, which is about 669 meters from one end to other, and about 250 on two other extremes. I'm guessing that won't count for much except increase humidity and dew?

Do any of the resources here help you with historical rainfall trends for your area? Those are probably going to be a better guide than any approximation based on your latitude, altitude, and terrain as to what you can grow. I say this because at 5800ft the mountains are going to control your weather way more than a lot of other factors that are important at sea level.