A new article in the Encyclopedia of Atmospheric Science, 3rd Edition, was contributed by AER Principal Scientist Stephen Leroy on GPS meteorology. The article introduces how GNSS signals are used for atmospheric science, climate science, and meteorological science purposes. The signals of the Global Positioning System encounter refraction in the Earth’s atmosphere. In ground-based GPS meteorology, GPS signals are observed at a ground station and the data can be inverted for precipitable water with an accuracy of 2% and a precision of <2%. In GPS radio occultation, GPS signals are observed in low-Earth orbit after traversing the atmosphere in limb-sounding geometry, and the data can be inverted for profiles of the microwave refractivity, pressure, temperature and water vapor. Between 8 and 30 km (8,000 and 30,000 m), the retrieved refractivity is precise to 0.2%. Both ground-based GPS and GPS radio occultation are ideally suited to climate monitoring and numerical weather prediction.
Figure 1. Distribution of GNSS ground stations for years 2000 (a), 2010 (b), and 2020 (c). These stations can measure column-integrated water vapor with near absolute accuracy at 5-minute intervals. Also shown is a time-history (d) of the number of such stations worldwide.
Figure 2. Distribution of all 13,350 radio occultation soundings for April 9, 2023, on a longitude-latitude map (a) and in solar (local) time of sounding by latitude (b). On that day, seven different radio occultation missions were operating, consisting of 36 different satellites.
Citation: Encyclopedia of Atmospheric Science, 3rd Edition
Chapter in Section 10: Observational Methods - Satellite GPS Meteorology
S. Leroy
In Publication