19 August 1993 Assessment of calibration errors on AMSU-B
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Abstract
The Advanced Microwave Sounding Unit B (AMSU-B) is a five channel microwave radiometer due to be flown in conjunction with AMSU-A on the TIROS-N series of satellites. The instrument provides two 'window' channels centered on 89 GHz and 150 GHz and three channels centered on 183.31 GHz which are used to determine the atmosphere's humidity profile. AMSU-B is a total power radiometer which is required to achieve a temperature sensitivity of 1 K to 1.2 K according to channel. It has a scan period of 8/3 seconds; during each scan it acquires 90 Earth view pixels, 4 cold calibration pixels and 4 hot calibration pixels. The calibration data are, in effect, used to determine the gain of the radiometer during that scan period. The sources used for calibration are an on-board, ambient temperature black- body target for the hot calibration, and deep space for the cold. The radiometric performance of the instrument is dependent on the accuracy to which it is calibrated during each scan period. The required calibration accuracy is +/- 1 K with a random component due to short term fluctuations of not more than +/- 0.2 K. This paper addresses the assessment of in-orbit error sources which effect calibration over the mission duration. The emphasis has been placed on errors in the bias values over life and errors associated with orbital variations of the hot and cold calibration target. The conclusions of the assessment are presented.
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Janet E. Charlton, Janet E. Charlton, Mark L. Jarrett, Mark L. Jarrett, A. R. L. Tatnall, A. R. L. Tatnall, } "Assessment of calibration errors on AMSU-B", Proc. SPIE 1935, Microwave Instrumentation for Remote Sensing of the Earth, (19 August 1993); doi: 10.1117/12.152587; https://doi.org/10.1117/12.152587
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