Intersensor calibration of DMSP SSM/Iapos;s: F-8 to F-14, 1987-1997
Colton, M.C.; Poe, G.A.
Geoscience and Remote Sensing, IEEE Transactions on
Volume 37, Issue 1, Jan 1999 Page(s):418 - 439
Digital Object Identifier 10.1109/36.739079
Summary:The Defense Meteorological Satellite Program (DMSP) operational
special sensor microwave imager (SSM/I) marked its ten-year anniversary
on the launch date of the first SSM/I (F-8), June 19, 1987. After F-8,
the DMSP has launched five more SSM/I's, F-10 (December 1990), F-11
(November 1991), F-12 (August 1994), F-13 (March 1995), and F-14 (April
1997), leaving the last SSM/I for a candidate launch in 1999. Built by
Hughes Aircraft Co., these instruments have proven to be the most
reliable and well-calibrated, space-based, passive microwave imaging
radiometers to date, allowing the data to be used quantitatively for
both operational and climatological applications. The remarkable
stability of the SSM/I sensors also provides the opportunity to quantify
the incremental brightness temperature differences to which the SSM/Is
can be intercalibrated, thus establishing the “noise floor”
for intercomparisons. This paper summarizes the prelaunch and postlaunch
performances of each new sensor determined during calibration and
validation (cal/val), starting with the formal, multiyear cal/val effort
conducted by both government and public institutions under the direction
of the Naval Research Laboratory (NRL) and sponsored by the joint Air
Force/Navy DMSP. Sensor-specific components, orbital configuration, and
systematic relative errors are examined that contribute to the total
system calibration. In particular, a large (1-3 K) but correctable
left-right scan asymmetry of SSM/I brightness temperatures was observed
in the data and traced to an antenna field-of-view (FOV) intrusion by
the spacecraft (start of scan) and a glare suppression sensor (end of
scan). These effects were found to be correctable to first order using a
pixel-dependent spillover correction. Empirical statistical distribution
functions for rain-free ocean pixels were constructed for the entire set
of SSM/Is and formed the basis for assessing intersensor calibration.
Manufacturer-derived sensor-specific antenna pattern correction (APC)
coefficients were found to be the source of large intersensor
differences for several channels, e.g., 1-2 K for the 22-V channel
View citation and abstract |
Cart
