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TitleUse of ScaRaB Measurements for Validating a GOES-based TOA Radiation Product
AuthorTrishchenko, AORCID logo; Li, Z
SourceJournal of Applied Meteorology and Climatology 37, 6, 1998 p. 591-605,<0591:UOSMFV>2.0.CO;2 Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 20042329
PublisherAmerican Meteorological Society
Mediapaper; on-line; digital
File formatpdf
AbstractLack of calibrated radiation measurements at the top of the atmosphere (TOA) between major space-borne radiation missions entails inference of the TOA radiation budget from operational weather sensors. The inferred data are subject to uncertainties due to calibration, narrow to broad-band conversion, etc. In this study, a surrogate TOA Earth radiation budget product generated from GOES-7 imagery data for use in the US Atmospheric Radiation Measurement (ARM) program was validated using measurements from the ScaRaB radiometer flown on board the Meteor-3/7 satellite. Comparisons were made between coincident and collocated short-wave and long-wave radiative quantities derived from GOES and ScaRaB sensors over an ARM experimental locale in the South Great Plains, Oklahoma, during April and July 1994. The comparisons are proven to be instrumental in validating the calibration and narrow to broad-band conversion used to obtain broad-band radiative quantities from GOES digital counts. Calibrations for both visible and infrared window channels have small uncertainties, whereas narrow to broad-band conversion of short-wave measurements contains large systematic errors. The caveat stems from use of a quadratic conversion equation, instead of a linear one as was found from ScaRaB narrow and broad-band measurements. The ensuing errors in the estimates of broad-band albedo depend on scene brightness, underestimation for bright scenes and overestimation for dark scenes. As a result, the magnitude of the TOA cloud radiative forcing is underestimated by about 14 W m-2 or 7.5% on a daytime mean basis. After correcting this error, the ratio of cloud radiative forcing (a measure of the impact of clouds on atmospheric absorption) derived from ARM measurements turns out to be 1.07 which is even in closer agreement with radiative transfer models than found from previous studies using original GOES products.

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