IEEE 22- Design and Evaluation of the First Special Sensor Microwave Imager/Sounder


The first Special Sensor Microwave Imager/Sounder
(SSMIS) was launched in October 2003 aboard the Air Force Defense
Meteorological Satellite Program (DMSP) F-16 Spacecraft.
As originally conceived, the SSMIS integrates the imaging capabilities
of the heritage DMSP conically scanning Special Sensor Microwave/
Imager sensor with the cross-track microwave sounders
Special Sensor Microwave Temperature and Special Sensor Microwave
Humidity Sounder, SSM/T-2 into a single conically scanning
24-channel instrument with extended sounding capability to
profile the mesosphere. As such, the SSMIS represents the most
complex operational satellite passive microwave imager/sounding
sensor flown while, at the same time, offering new and challenging
capabilities associated with radiometer channels having common
fields of view, uniform polarizations, and fixed spatial resolutions
across the active scene scan sector. A comprehensive end-to-end
calibration/validation (cal/val) of the first SSMIS initiated shortly
after launch was conducted under joint sponsorship by the DMSP
and the Navy Space and Warfare Systems Command. Herein,
we provide an overview of the SSMIS instrument design, performance
characteristics, and major cal/val results. Overall, the
first SSMIS instrument exhibits remarkably stable radiometer
sensitivities, meeting requirements with considerablemargin while
providing high-quality imagery for all channels. Two unanticipated
radiometer calibration anomalies uncovered during the
cal/val—sun intrusion into the warm-load calibration target and
antenna reflector emissions—required significant attention during
the cal/val program. In particular, the tasks of diagnosing the root
cause(s) of these anomalies as well as the development of ground
processing software algorithms to mitigate their impact on F-16
SSMIS and hardware fixes on future instruments necessitated
the construction of extensive analysis and simulation tools. The
lessons learned from the SSMIS cal/val and the associated analysis
tools are expected to play an important role in the design and
performance evaluation of future passive microwave imaging and
sounding instruments as well as guiding the planning and development
of future cal/val programs.