A satellite radiance‐bias correction scheme for data assimilation
Abstract Recently, much progress has been made in the direct assimilation of satellite radiance measurements in numerical weather‐prediction systems. In order to use radiances from the TIROS Operational Vertical Sounder (TOVS), biases between the observed radiances and those simulated from the model...
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crwiley:10.1002/qj.49712757418 2024-06-23T07:56:43+00:00 A satellite radiance‐bias correction scheme for data assimilation Harris, B. A. Kelly, G. 2001 http://dx.doi.org/10.1002/qj.49712757418 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49712757418 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49712757418 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Quarterly Journal of the Royal Meteorological Society volume 127, issue 574, page 1453-1468 ISSN 0035-9009 1477-870X journal-article 2001 crwiley https://doi.org/10.1002/qj.49712757418 2024-06-11T04:41:51Z Abstract Recently, much progress has been made in the direct assimilation of satellite radiance measurements in numerical weather‐prediction systems. In order to use radiances from the TIROS Operational Vertical Sounder (TOVS), biases between the observed radiances and those simulated from the model first guess must be corrected. The original scheme for TOVS radiance‐bias correction at the European Centre for Medium‐Range Weather Forecasts utilized a global scan correction, and a linear air‐mass correction, with the observed radiances from the Microwave Sounding Unit channels 2, 3 and 4 as predictors. The new scheme differs in two fundamental ways. Analysis of radiance data shows a significant residual scan bias which depends strongly on latitude for some channels. The new scheme applies a latitudinally dependent scan correction to take this into account. The air‐mass predictors are now computed from the background field, since the background field contains a more consistent representation of the air mass and surface characteristics than the observed microwave radiances. Four new predictors are used, 1000–300 hPa thickness, 200–50 hPa thickness, model surface skin temperature and total precipitable water. In particular, the skin‐temperature predictor is able to differentiate between ocean and sea‐ice, performing much better than the old scheme in the winter hemisphere. The use of model predictors is a change in philosophy away from correction of the observations to correction of the computed forward radiances. This leads to a natural extension where the gradient of the bias correction can be taken into account in variational retrieval schemes. Article in Journal/Newspaper Sea ice Wiley Online Library Quarterly Journal of the Royal Meteorological Society 127 574 1453 1468 |
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Wiley Online Library |
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English |
description |
Abstract Recently, much progress has been made in the direct assimilation of satellite radiance measurements in numerical weather‐prediction systems. In order to use radiances from the TIROS Operational Vertical Sounder (TOVS), biases between the observed radiances and those simulated from the model first guess must be corrected. The original scheme for TOVS radiance‐bias correction at the European Centre for Medium‐Range Weather Forecasts utilized a global scan correction, and a linear air‐mass correction, with the observed radiances from the Microwave Sounding Unit channels 2, 3 and 4 as predictors. The new scheme differs in two fundamental ways. Analysis of radiance data shows a significant residual scan bias which depends strongly on latitude for some channels. The new scheme applies a latitudinally dependent scan correction to take this into account. The air‐mass predictors are now computed from the background field, since the background field contains a more consistent representation of the air mass and surface characteristics than the observed microwave radiances. Four new predictors are used, 1000–300 hPa thickness, 200–50 hPa thickness, model surface skin temperature and total precipitable water. In particular, the skin‐temperature predictor is able to differentiate between ocean and sea‐ice, performing much better than the old scheme in the winter hemisphere. The use of model predictors is a change in philosophy away from correction of the observations to correction of the computed forward radiances. This leads to a natural extension where the gradient of the bias correction can be taken into account in variational retrieval schemes. |
format |
Article in Journal/Newspaper |
author |
Harris, B. A. Kelly, G. |
spellingShingle |
Harris, B. A. Kelly, G. A satellite radiance‐bias correction scheme for data assimilation |
author_facet |
Harris, B. A. Kelly, G. |
author_sort |
Harris, B. A. |
title |
A satellite radiance‐bias correction scheme for data assimilation |
title_short |
A satellite radiance‐bias correction scheme for data assimilation |
title_full |
A satellite radiance‐bias correction scheme for data assimilation |
title_fullStr |
A satellite radiance‐bias correction scheme for data assimilation |
title_full_unstemmed |
A satellite radiance‐bias correction scheme for data assimilation |
title_sort |
satellite radiance‐bias correction scheme for data assimilation |
publisher |
Wiley |
publishDate |
2001 |
url |
http://dx.doi.org/10.1002/qj.49712757418 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.49712757418 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.49712757418 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 127, issue 574, page 1453-1468 ISSN 0035-9009 1477-870X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/qj.49712757418 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
127 |
container_issue |
574 |
container_start_page |
1453 |
op_container_end_page |
1468 |
_version_ |
1802650022308741120 |