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Proceedings Paper

Footprint size and cloud-clearing error relationships derived from NAST-I top of the atmosphere radiance measurements
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Paper Abstract

We discuss the relationship between instrument footprint size, field-of-regard sample density, and cloud clearing technique on measured top of the atmosphere radiance error under partly cloudy conditions. The cloud clearing technique (N*) uses the linear relationship between observed radiance and the amount of cloud in a field-of-view. We extrapolate radiance observed for two adjacent fields-of-view possessing differing cloud amounts to the cloud free value (i.e., zero cloud). Options include techniques to compensate for “black” or “gray” clouds, where a single channel N* may not provide adequate spectral correction. Spectrally dependent error statistics are developed from partly cloudy samples of varying footprint size and sample patterns. Data were collected by the NPOESS (National Polar-orbiting Operational Environmental Satellite System) Aircraft Sounding Testbed-Interferometer (NAST-I) flying on the NASA Proteus or ER-2 high altitude research aircraft, and include tropical, temporal and arctic flight sections. Analysis shows that larger sounder footprints contain more cloud contamination and higher cloud clearing errors; these errors can be significantly reduced by techniques that utilize high-spectral and -spatial resolution coincidently collected radiance measurements from sensors like MODIS. Data also indicates that full area sampling results in smaller cloud clearing errors than small footprint sampling on a wider spaced grid.

Paper Details

Date Published: 16 February 2004
PDF: 12 pages
Proc. SPIE 5235, Remote Sensing of Clouds and the Atmosphere VIII, (16 February 2004); doi: 10.1117/12.511131
Show Author Affiliations
Gail E. Bingham, Utah State Univ. (United States)
Steven A. Arnesen, Utah State Univ. (United States)
Gregory W. Cantwell, Utah State Univ. (United States)
William L. Smith, NASA Langley Research Ctr. (United States)
Daniel K. Zhou, NASA Langley Research Ctr. (United States)

Published in SPIE Proceedings Vol. 5235:
Remote Sensing of Clouds and the Atmosphere VIII
Klaus P. Schaefer; Adolfo Comeron; Michel R. Carleer; Richard H. Picard, Editor(s)

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