| Popis: |
Since August of 1994, the Defense Meteorological Satellite Program (DMSP) has had on-orbit two satellite platforms (F-11 and F-12) which carry the special sensor microwave water vapor sounder (SSM/T-2). The sensor consists of 5 channels: three located symmetrically about the 183 GHz water vapor absorption line, one at 150 GHz and a 91.65 GHz window channel. Calibration of the SSM/T-2 on both platforms was undertaken to verify the absolute accuracy of the microwave measurements. Initial findings show a discrepancy between measurements from the SSM/T-2 and an independent aircraft-mounted instrument of only 1-1.6 K at 183 GHz. Basic channel information obtained from radiative transfer modeling provides an insight into the surface and atmospheric contributions to the channel observations and the sensitivity of the channels to various atmospheric phenomena. From the modeling and calibration studies a number of interesting channel signatures were observed in the SSM/T-2 measurements including the effects of the underlying surface, fractional cloud coverage and type, and precipitation occurrence. The signatures of clouds and precipitation (over water and land) have been identified and efforts to derive detection algorithms have been made. |
