The upper-air data were examined for a few cases of heavy rainstorms over Japan, in expection of finding internal gravity waves generated over the storm areas. Among the cases, there was one case where variations of temperature, relative humidity and horizontal wind velocity in the troposphere showed features of internal gravity waves in the downstream of heavy rainfall (*150mm/day) area. The horizontal and vertical wave lengths of the variations were *400km and *3km, respectively. The amplitudes of temperature, humidity and wind velocity variations were estimated as *2K, *20% and *4m/sec respectively. But, no wave-like variation was detected in geopotential height. The wave-like variations were not found from the observational data 12 hours later.
A dual-channel microwave radiometer that measures precipitable water vapor and cloud liquid was operated during the 1979 Severe Storms and Mesoscale Experiment (Sesame). Conventional retrievals of vapor in the presence of clouds with high liquid content were not satisfactory. To correct these retrievals, an adaptive retrieval algorithm is developed and applied to the Sesame data. During clear conditions, or conditions of light clouds, the new recoveries are quite close to those obtained by conventional statistical inversion; however, during heavy liquid-bearing clouds the recovered vapor agrees better with radiosonde data.The vapor-liquid radiometers were operated at Lawton, Oklahoma, from March 29, 1979, to June 8, 1979. The two radiometers used for these measurements have center frequencies of 20.6 GHz and 31.65 GHz. The former is near the peak of the water vapor line at 22.2 GHz; the latter is located in the absorption window between the water vapor line and the oxygen band at 60 GHz. Both radiometers are coupled to a single offset parabolic antenna designed to produce equal beamwidths for these two frequencies ]. This has special significance when measuring cloud liquid, since both beams should contain the same cloud column. The switching radiometers, whose specifications are given in Table 1, have been described in detail by Guiraud et al. [ 1979]. These radiometers differ from the traditional Dicke design by adding a second reference source to the switching sequence. The antenna, radiometers, and computer are located in a small air-conditioned building. The antenna points through an aperture in the wall of the building to a flat aluminum reflector aligned at 45 ø to the zenith. Energy from the zenith is reflected from the flat reflector into the antenna. To form a low-loss window to the microwave energy, the aperture in the side of the building is covered with two sheets of Mylar, each 2 mil thick. An aluminum cowling shields this window from Paper number 80S0516. 947 948 WESTWATER AND GUIRAUD the Lawton, Oklahoma, area we use two sources of radiosondes for our vapor comparison. The most dependable are the standard releases made by the National Weather Service at Oklahoma City, Oklahoma, at 0 and 12 GMT, but unfortunately, these are approximately 80 mi (---130 km) to the northeast of the radiometers. At Fort Sill, Oklahoma, local radiosonde releases are made by the U.S. Army and are used for atmospheric artillery corrections. o •4 II I < RADIOMETRIC RETRIEVAL OF WATER VAPOR 949
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