Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter
Surface longwave radiation fluxes dominate the energy budget of nighttime polar regions, yet little is known about the relative accuracy of existing satellite-based techniques to estimate this parameter. We compare eight methods to estimate the downwelling longwave radiation flux and to validate the...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20030020801 2023-05-15T14:52:56+02:00 Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter Chiacchio, Marc Francis, Jennifer Stackhouse, Paul, Jr. Unclassified, Unlimited, Publicly available [2002] application/pdf http://hdl.handle.net/2060/20030020801 unknown Document ID: 20030020801 http://hdl.handle.net/2060/20030020801 Copyright, Distribution as joint owner in the copyright CASI Earth Resources and Remote Sensing Journal of Applied Meteorology; 41; 306-318 2002 ftnasantrs 2019-07-21T02:28:55Z Surface longwave radiation fluxes dominate the energy budget of nighttime polar regions, yet little is known about the relative accuracy of existing satellite-based techniques to estimate this parameter. We compare eight methods to estimate the downwelling longwave radiation flux and to validate their performance with measurements from two field programs in thc Arctic: the Coordinated Eastern Arctic Experiment (CEAREX ) conducted in the Barents Sea during the autumn and winter of 1988, and the Lead Experiment performed in the Beaufort Sea in the spring of 1992. Five of the eight methods were developed for satellite-derived quantities, and three are simple parameterizations based on surface observations. All of the algorithms require information about cloud fraction, which is provided from the NASA-NOAA Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) polar pathfinder dataset (Path-P): some techniques ingest temperature and moisture profiles (also from Path-P): one-half of the methods assume that clouds are opaque and have a constant geometric thickness of 50 hPa, and three include no thickness information whatsoever. With a somewhat limited validation dataset, the following primary conclusions result: (1) all methods exhibit approximately the same correlations with measurements and rms differences, but the biases range from -34 W sq m (16% of the mean) to nearly 0; (2) the error analysis described here indicates that the assumption of a 50-hPa cloud thickness is too thin by a factor of 2 on average in polar nighttime conditions; (3) cloud-overlap techniques. which effectively increase mean cloud thickness, significantly improve the results; (4) simple Arctic-specific parameterizations performed poorly, probably because they were developed with surface-observed cloud fractions; and (5) the single algorithm that includes an estimate of cloud thickness exhibits the smallest differences from observations. Other/Unknown Material Arctic Barents Sea Beaufort Sea NASA Technical Reports Server (NTRS) Arctic Barents Sea |
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Open Polar |
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NASA Technical Reports Server (NTRS) |
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ftnasantrs |
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topic |
Earth Resources and Remote Sensing |
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Earth Resources and Remote Sensing Chiacchio, Marc Francis, Jennifer Stackhouse, Paul, Jr. Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter |
topic_facet |
Earth Resources and Remote Sensing |
description |
Surface longwave radiation fluxes dominate the energy budget of nighttime polar regions, yet little is known about the relative accuracy of existing satellite-based techniques to estimate this parameter. We compare eight methods to estimate the downwelling longwave radiation flux and to validate their performance with measurements from two field programs in thc Arctic: the Coordinated Eastern Arctic Experiment (CEAREX ) conducted in the Barents Sea during the autumn and winter of 1988, and the Lead Experiment performed in the Beaufort Sea in the spring of 1992. Five of the eight methods were developed for satellite-derived quantities, and three are simple parameterizations based on surface observations. All of the algorithms require information about cloud fraction, which is provided from the NASA-NOAA Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) polar pathfinder dataset (Path-P): some techniques ingest temperature and moisture profiles (also from Path-P): one-half of the methods assume that clouds are opaque and have a constant geometric thickness of 50 hPa, and three include no thickness information whatsoever. With a somewhat limited validation dataset, the following primary conclusions result: (1) all methods exhibit approximately the same correlations with measurements and rms differences, but the biases range from -34 W sq m (16% of the mean) to nearly 0; (2) the error analysis described here indicates that the assumption of a 50-hPa cloud thickness is too thin by a factor of 2 on average in polar nighttime conditions; (3) cloud-overlap techniques. which effectively increase mean cloud thickness, significantly improve the results; (4) simple Arctic-specific parameterizations performed poorly, probably because they were developed with surface-observed cloud fractions; and (5) the single algorithm that includes an estimate of cloud thickness exhibits the smallest differences from observations. |
format |
Other/Unknown Material |
author |
Chiacchio, Marc Francis, Jennifer Stackhouse, Paul, Jr. |
author_facet |
Chiacchio, Marc Francis, Jennifer Stackhouse, Paul, Jr. |
author_sort |
Chiacchio, Marc |
title |
Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter |
title_short |
Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter |
title_full |
Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter |
title_fullStr |
Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter |
title_full_unstemmed |
Evaluation of Methods to Estimate the Surface Downwelling Longwave Flux during Arctic Winter |
title_sort |
evaluation of methods to estimate the surface downwelling longwave flux during arctic winter |
publishDate |
2002 |
url |
http://hdl.handle.net/2060/20030020801 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Arctic Barents Sea |
geographic_facet |
Arctic Barents Sea |
genre |
Arctic Barents Sea Beaufort Sea |
genre_facet |
Arctic Barents Sea Beaufort Sea |
op_source |
CASI |
op_relation |
Document ID: 20030020801 http://hdl.handle.net/2060/20030020801 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766324347342946304 |