Remote Sensing of Tropospheric Temperature Structure by Means of Passive Microwave Radiometry.
Final rept. 1 Sep 68-31 Aug 70,
CALIFORNIA UNIV BERKELEY RADIO ASTRONOMY LAB
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The spectrum of emission from the low-frequency wing of the 5-mm oxygen band as observed at the ground provides data on the temperature profile in the lowest 10 km of the atmosphere. The vertical temperature profile follows from the inversion of the integral equation of radiative transfer. The quality of such an inference depends on a the noise in the data, b the absolute radiometer calibration errors, c the natural resolution of the kernel in the integral equation, and d the accuracy with which the gaseous absorption coefficients are known. To investigate the feasibility of this remote sensing, the authors built a scanning radiometer to operate in the interval 50-60 GHz. Observations at 3-5 frequencies were made concomitantly with weather balloon flights at the Oakland, California, weather station. Inversion of the data yielded profiles which agreed with the balloon observed temperatures within 2-3 degrees K RMS. These profiles were more accurate than the daily mean profiles for the station for the particular months. They also exhibited temperature inversions. The limitation in the accuracy resulted from the radiometer noise of 1 degrees -2 degrees K, so that item a above dominated. In order to improve the results and to investigate the extent to which items b, c, and d above would fundamentally limit the technique, development of a new multi-channel radiometer system was begun. Author