3 ms·
You also have satellites with GPS receivers, so that they can measure the effects when the GPS signal skims the atmosphere. This allows humidity and temperature
by mnw21cam 12y ago
You also have satellites with GPS receivers, so that they can measure the effects when the GPS signal skims the atmosphere. This allows humidity and temperature to be measured with very high accuracy, with a very good vertical resolution.
http://en.wikipedia.org/wiki/GNSS_radio_occultation http://en.wikipedia.org/wiki/GNSS_radio_occultation
- mturmon 12y agoYou're making a good distinction here. The research on using GPS occultation for sensing water vapor that I'm most familiar with uses two satellites, and does not use ground stations. I am biased here, because I know the people who are developing this technology, so I'd be welcome to further information on this point! E.g., I took a look at the thesis abstract pointed to by @kubiii, but it wasn't specific enough to tell what their exact sensing method was. There are some generally good-quality summaries of GPS radio occultation here: http://geooptics.com/?page_id=148 http://geooptics.com/?page_id=148 The main advantages of GPS occultation for H2O sensing are that it's relatively bias-free (compared to microwave radiometers), that it can see through clouds, and that it has better usable vertical resolution.
- mnw21cam 12y agoYes, that's exactly it. Two satellites - one is a standard GPS satellite, and the other is a satellite with a GPS receiver.