First observations from DMSP SSMIS (Invited Presentation)

The first Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager/Sounder (SSMIS) was launched on 18 October, 2003. The conically scanning instrument will replace SSM/I, SSM/T-1 and SSM/T-2, combining both imaging and sounding capabilities of current operational instruments. It also improves temperature sounding capability by profiling from the surface to 0.03mb (~80 km altitude) and by increasing horizontal spatial resolutions to 37.5 km for lower air and to 75 km for upper air.

Following challenging development and deployment efforts, SSMIS passed early orbit checkout and is now undergoing detailed Cal/Val. SSMIS has demonstrated outstanding imagery, displaying high spatial resolution with relatively uniform coverage across ground track scans. First results from the new upper atmospheric sounding channels are being analyzed. They rely on magnetically sensitive oxygen bands in the 50-60 GHz regime. Sensor calibration issues under study include geolocation offsets, polarization contamination, banding effects, end-of-scan effects, Doppler compensation performance. Performance of newly designed temperature and moisture retrieval software will also be addressed. Extensive matchup comparisons with radiosonde and lidar data indicate that system requirements may be achieved at many atmospheric levels for parameters including atmospheric temperature and moisture. Adjustments or alternative procedures may be required to meet performance goals for other levels.

Cal/Val relies on a variety of ground truth measurements, including conventional radiosonde matchups, precisely collocated temperature and water vapor profile measurements by the Aerospace/DMSP lidar located at Barking Sands, Hawaii, by the JPL NDSC lidars at Table Mountain, California, and at Mauna Loa, Hawaii, aircraft-based underflights with frequency-matched microwave radiometers, aircraft-based dropsonde measurements, and by collocated data from SSM/I, SSM/T-1, SSM/T-2 and AMSU. Extensive matchup data are being collected and archived by Aerospace personnel at Air Force Weather Agency (AFWA), and by NRL personnel at FNMOC. Temperature and water vapor profiles from operational radiosonde network as well as numerical meteorological forecast models are also gathered to provide broader spatial and temporal coverage. Radiative transfer calculations simulating brightness temperatures are in excellent agreement with most tropospheric temperature and moisture sounding channels.