NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Evaluating the design of an Earth Radiation Budget Instrument with systen simulations. Part 1: Instantaneous estimatesA set of system simulations has been performed to evaluate candidate scanner designs for an Earth Radiation Budget Instrument (ERBI) for the Earth Observing System (EOS) of the late 1990s. Five different instruments are considered: (1) the Active Cavity Array (ACA), (2) the Clouds and Earth's Radiant Energy System-Instrument (CERES-I), (3) the Conically Scanning Radiometer (CSR), (4) the Earth Radiation Budget Experiment Cross-Track Scanner (ERBE), and (5) the Nimbus-7 Biaxial Scanner (N7). Errors in instantaneous, top-of-the-atmosphere (TOA) satellite flux estimates are assumed to arise from two measurement problems: the sampling of space over a given geographic domain, and sampling in angle about a given spatial location. When angular sampling errors vanish due to the application of correct angular dependence models (ADMs) during inversion, the accuracy of each scanner design is determined by the instrument's ability to map the TOA radiance field in a uniform manner. In this regard, the instruments containing a cross-track scanning component (CERES-I and ERBE) do best. As errors in ADMs are encountered, cross-track instruments incur angular sampling errors more rapidly than biaxial instruments (N7, ACA, and CSR) and eventually overtake the biaxial designs in their total error amounts. A latitude bias (north-south error gradient) in the ADM error of cross-track instruments also exists. This would be objectionable when ADM errors are systematic over large areas of the globe. For instantaneous errors, however, cross-track scanners outperform biaxial or conical scanners for 2.5 deg latitude x 2.5 deg longitude target areas, providing that the ADM error is less than or equal to 30%. A key issue is the amount of systematic ADM error (departures from the mean models) that is present at the 2.5 deg resolution of the ERBE target areas. If this error is less than 30%, then the CERES-I, ERBE, and CSR, in order of increasing error, provide the most accurate instantaneous flux estimates, within 2-3 W/sq m of each other in reflected shortwave flux. The magnitude of this error is near the 10 W/sq m accuracy requirement of the user community. Longwave flux errors have been found to have the same space and time characteristics as errors in shortwave radiation, but only about 25% as large.
Document ID
19950038867
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Stowe, Larry
(NOAA/NESDIS, Washington, DC United States)
Ardanuy, Philip
(Research and Data Systems, Greenbelt, MD United States)
Hucek, Richard
(Research and Data Systems, Greenbelt, MD United States)
Abel, Peter
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Jacobowitz, Herbert
(NOAA/NESDIS, Washington, DC United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1993
Publication Information
Publication: Journal of Atmospheric and Oceanic Technology
Volume: 10
Issue: 6
ISSN: 0739-0572
Subject Category
Meteorology And Climatology
Accession Number
95A70466
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available