Sensitivity of Millimeter and Sub-Millimeter Wave Channels to Clear Air211 Temperature and Water Vapor Variations

摘要

The brightness temperature observed from above the Earth's atmosphere is211u001esensitive to parameters such as pressure, temperature, water vapor, and 211u001ehydrometeor content. In order to determine optimal sounding strategies for future 211u001ehigh-resolution, passive, microwave instruments, a study of the potential clear-211u001eair sounding capabilities of all significant microwave oxygen and water vapor 211u001eabsorption lines in the frequency range from approximately 10 to 1000 GHz has 211u001ebeen undertaken. The study uses a second-order statistical climatological model 211u001ecovering four seasons and three latitudinal zones: low, middle, an high 211u001elatitudes, and a wide range of altitudes (up to approx. 70 km). The 211u001eclimatological model was developed using data from three sources: the Upper 211u001eAtmosphere Research Satellite (UARS) HALogen Occulation Experiment (HALOE) 211u001einstrument, the TIROS Operational Vertical Sounder (TOVS) Initial Guess Retrieval 211u001e(TIGR) radiosonde set, and the NOAA Advanced Microwave Sounder Unit (AMSU) 211u001eradiosonde set. Variations in the vertical sensitivities of brightness 211u001etemperatures due to statistical variations of water vapor and temperature with 211u001elatitude and season around each line are considered, and useful channel sets for 211u001egeostationary microwave vertical sounding are suggested.