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### Proceedings Paper

Monitoring GOES Imager visible-channel responsivities using empirical distribution functions of Earth data
Author(s): David Crosby; Jeanette Baucom; I-Lok Chang; Charles Dean; Dejiang Han; Larry McMillin; Michael Weinreb; Xiangqian Wu
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Paper Abstract

Although the visible channel of the Imagers carried by NOAA's operational Geostationary Operational Environmental Satellites (GOES) has no onboard calibration device, the decrease in the responsivity of this channel over time must be known if we are to make the data in this channel useful for detecting trends in the signals from the Earth. Therefore, some external method is required to provide this information. In this paper, we examine an external technique for monitoring responsivity changes based on empirical distribution functions (EDFs) of observations of the Earth's full disk. A time series of instrument outputs (in digital counts) at fixed levels at the tops of the EDFs is produced. A nonlinear least squares technique is then employed to adjust the time series for solar and seasonal effects and to fit it with an exponential, whose argument provides the rate of degradation of the responsivity. This technique assumes that the probabilistic structure of the signal from the earth does not change over time. The resulting time series and estimated responsivity degradation rates for the visible channels of GOES-8 and -10 Imagers will be presented. These results are similar to those obtained earlier with a star-based technique, thus increasing our confidence in the results of both techniques. The EDF technique and the star-based technique are synergistic, as they use very different approaches and data sets. Also, the star based technique works at the low end of the Imager's output signal range, whereas the EDF technique works at the high end.

Paper Details

Date Published: 22 August 2005
PDF: 9 pages
Proc. SPIE 5882, Earth Observing Systems X, 58820O (22 August 2005); doi: 10.1117/12.616933
Show Author Affiliations
David Crosby, QSS Group, Inc. (United States)
Jeanette Baucom, Aerospace Corp. (United States)
I-Lok Chang, QSS Group, Inc. (United States)
American Univ. (United States)
Charles Dean, QSS Group, Inc. (United States)
Dejiang Han, ASRC Aerospace (United States)
Larry McMillin, NOAA/NESDIS/ORA (United States)
Michael Weinreb, General Dynamics Advanced Information Systems, NOAA/NESDIS/OSD (United States)
Xiangqian Wu, NOAA/NESDIS/ORA (United States)

Published in SPIE Proceedings Vol. 5882:
Earth Observing Systems X
James J. Butler, Editor(s)