[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/ .

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/ 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.

[valevk]

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

[josephhardin]

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