Thermodynamic profiling provides continuous temperature, humidity and cloud liquid profiles during clear and cloudy conditions. The thermodynamic profiler radiometrically observes microwave radiation intensity at multiple frequencies, along with infrared and surface meteorological measurements. Historical radiosonde and neural network or regression methods are used for profile retrieval. Wind profiling radar provides horizontal winds. We compare radiosonde, thermodynamic and wind soundings to evaluate continuous profiling accuracy. Forecast and observed thermodynamic profiles are also compared. Thermodynamic profiling, particularly when combined with wind profiling radar and advanced assimilation methods, provides continuous soundings needed for improved local high resolution modeling and forecasting. We also describe "slant" observations of integrated GPS signal delay and their potential to extend local forecast improvements to regional scale. Applications include improved forecasting of high resolution dispersion and transport, short-term precipitation and fog.
We describe a passive microwave radiometer that provides continuous unattended atmospheric temperature and humidity profiles up to 10 km in height, and low resolution liquid water profiles. Profile accuracies in cloudy and clear conditions up to 7 km height are better than 2.5 K (temperature) and 1.1 g/m<SUP>3</SUP> (humidity) as determined by statistical comparison with radiosondes. The microwave profiler observes 12 channels in the 20 to 60 GHz range, 1 infrared channel, and surface temperature, pressure and humidity. Retrieval coefficients for specific locations are derived using local radiosonde data and a neural network or regression analysis. The commercial microwave radiometer design has logged more than a million hours in locations ranging form the arctic to the tropics. We provide examples of microwave profiler soundings in various locations and weather conditions, and comparisons with radiosondes. We discuss recent high resolution water vapor field analysis results based on simulated slant GPS and microwave profiler data.
The global positioning system (GPS) is based on a constellation of 24 transmitter satellites orbiting the earth at approximately 21,000 km altitude. The original goal of the GPS was to provide global and all-weather precision positioning and navigation for the military. Since this original concept was developed, several civilian applications have been conceived that are making use of these satellites. GPS/MET is one such application. GPS/MET is sponsored by NSF, FAA, NOAA, and NASA. The goal of GPS/MET is to demonstrate the feasibility of recovering atmospheric temperature profiles from occulting radio signals from one of the 24 GPS transmitters. On April 3, 1995, a small radio receiver was launched into a 750 km low- earth orbit and 70 degree inclination. As this receiver orbits, occultations occur when the radio link between any one of the 24 GPS transmitters and the low-earth orbiting (LEO) receiver progressively descends or ascends through the earth's atmosphere. With the current constellation of GPS transmitters, approximately 500 such occultations occur in each 24-hour period per LEO receiver. Several hundred occultations have been analyzed to date, where some type of confirmational data has been available (i.e., radiosonde, satellite, numerical analysis gridded data). In this paper, we present a brief outline of the method followed by a few typical temperature soundings that have been obtained.