
A New Global Swarm of Weather-Sensing Satellites - cryptoz
http://www.theatlantic.com/technology/archive/2015/01/a-new-global-swarm-of-orbiting-weather-sensors/384935/?utm_content=buffer9f1b1&utm_medium=social&utm_source=linkedin.com&utm_campaign=buffer&single_page=true
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josephhardin
This is interesting, but not as groundbreaking as they make it out to be.
People are already using GPS signals to calculate things like available liquid
water. For instance, see
[http://www.suominet.ucar.edu/](http://www.suominet.ucar.edu/) .

One of the main problems with something like this is that you get an
integrated quantity, with no easy way of backing out the exact elevation this
occured at. If you get a dense enough network, sure you may be able to work it
back out, but you also don't really get a sense of the drop shape.

For comparison, the most advanced satellite weather system we have is the
Global Precipitation Measurement(GPM) constellation. This uses a series of
radiometers and radars to provide a much more detailed picture, that also
includes 3d data. See
[http://www.nasa.gov/mission_pages/GPM/main/](http://www.nasa.gov/mission_pages/GPM/main/)
for more information.

If you stick to ground radar, you can get even more impressive by using
polarization. By transmitting dual polarized signals, we can actually get a
measure of the shape of the raindrops(based on the difference in power
returned by the two polarizations). The US NEXRAD network recently upgraded
it's radars to be dual polarization capable(finally). This also provides us
with the ability to differentiate between ice and rain(Something we couldn't,
strictly speaking, do before). We can also separate out the signals caused by
bugs(which can be a huge issue), as well as other sources of signal
contamination.

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valevk
Do you know whether such techniques are also used for researching other
planets than earth?

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josephhardin
I'm really not sure. I mostly just keep up with terrestrial weather.

