Title :
Deep-space calibration of the WindSat radiometer
Author :
Jones, W. Linwood ; Park, Jun D. ; Soisuvarn, Seubson ; Hong, Liang ; Gaiser, Peter W. ; Germain, Karen M St
Author_Institution :
Electr. & Comput. Eng. Dept., Univ. of Central Florida, Orlando, FL, USA
fDate :
3/1/2006 12:00:00 AM
Abstract :
The WindSat microwave polarimetric radiometer consists of 22 channels of polarized brightness temperatures operating at five frequencies: 6.8, 10.7, 18.7, 23.8, and 37.0 GHz. The 10.7-, 18.7-, and 37.0-GHz channels are fully polarimetric (vertical/horizontal, ±45° and left-hand and right-hand circularly polarized) to measure the four Stokes radiometric parameters. The principal objective of this Naval Research Laboratory experiment, which flys on the USAF Coriolis satellite, is to provide the proof of concept of the first passive measurement of ocean surface wind vector from space. This paper presents details of the on-orbit absolute radiometric calibration procedure, which was performed during of a series of satellite pitch maneuvers. During these special tests, the satellite pitch was slowly ramped to +45° (and -45°), which caused the WindSat conical spinning antenna to view deep space during the forward (or aft portion) of the azimuth scan. When viewing the homogeneous and isotropic brightness of space (2.73 K) through both the main reflector and the cold-load calibration reflector, it is possible to determine the absolute calibration of the individual channels and the relative calibration bias between polarimetric channels. Results demonstrate consistent and stable channel calibrations (with very small brightness biases) that exceed the mission radiometric calibration requirements.
Keywords :
calibration; geophysical techniques; microwave measurement; radiometers; remote sensing; 10.7 GHz; 18.7 GHz; 23.8 GHz; 37.0 GHz; 6.8 GHz; Naval Research Laboratory experiment; Stokes radiometric parameters; USAF Coriolis satellite; WindSat conical spinning antenna; WindSat microwave polarimetric radiometer; cold-load calibration reflector; deep-space calibration; homogeneous brightness; isotropic brightness; main reflector; ocean surface wind vector; on-orbit absolute radiometric calibration; polarized brightness temperatures; Antenna measurements; Brightness temperature; Calibration; Frequency; Laboratories; Microwave radiometry; Oceans; Polarization; Satellite broadcasting; Sea measurements; Calibration; WindSat; radiometer;
Journal_Title :
Geoscience and Remote Sensing, IEEE Transactions on
DOI :
10.1109/TGRS.2005.862499