The SSM/T-2 sensor is a five channel, total power microwave radiometer with three channels situated symmetrically about the 183.31 GHz water vapor resonance line and two window channels. This instrument was flown on all DMSP Block 5D-2 satellites starting with F11 launched in 1991. SSM/T-2 is designed to provide global monitoring of the concentration of water vapor in the atmosphere under all sky conditions by taking advantage of the reduced sensitivity of the microwave region to cloud attenuation.