Early-orbit performance of the special Sensor Microwave Water-Vapor Profiler (SSM/T-2 B4) and Special Sensor Microwave Air-Temperature Sounder (SSM/T-1 B3)

The SSM/T-1 B3 and SSM/T-2 B4 units were successfully launched on August 29th, 1994. The SSM/T-2 instrument is a five channel, microwave total-power radiometer. It has three channels near the 183.31 GHz water vapor resonance line and two window channels (91 GHz and 150 GHz). The SSM/T-1 is a cross-track step scanning seven-channel Dicke microwave radiometer instrument. It operates in the oxygen absorption region at center frequencies of 50.5, 53.2, 54.35, 54.9, 58.4, 58.9, and 59.4 GHz. At a nominal orbit at an altitude of 833 km, brightness temperatures from the SSM/T-1 and SSM/T-2 instruments are used in the AFGWC´s (Air Force Global Weather Center) weather prediction models. The SSM/T-2 ground processing software provides profiles of relative humidity, and absolute humidity, and water vapor mass at six mandatory pressure levels. The SSM/T-1 ground processing software estimates air temperature profiles at fifteen pressure levels and the tropopause. The SSM/T-1 f33 and SSM¯-2 B4 units are functioning properly as a microwave temperature sounder and a water-vapor profiler, respectively. The radiometer sensitivities agree with ground based measurements. The nominal radiometer gains and the resultant dynamic ranges of all channels indicated that the SSM/T-1 unit could measure brightness temperatures between the cold path at 2.7 Kelvins and the warm load of 330 Kelvins