The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A
The characterization of systematic forecast errors in lower-tropospheric winds is an essential component of model improvement. This paper is motivated by a global, long-standing surface bias in the operational medium-range weather forecasts produced with the Integrated Forecasting System (IFS) of th...
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2022
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Online Access: | http://resolver.tudelft.nl/uuid:88d41b4f-a9fa-424c-a296-ccfac83f2b3b https://doi.org/10.5194/acp-22-13049-2022 |
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fttudelft:oai:tudelft.nl:uuid:88d41b4f-a9fa-424c-a296-ccfac83f2b3b 2024-02-11T10:06:37+01:00 The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A Savazzi, A.C.M. (author) Nuijens, Louise (author) Sandu, Irina (author) Georg, Geet (author) 2022 http://resolver.tudelft.nl/uuid:88d41b4f-a9fa-424c-a296-ccfac83f2b3b https://doi.org/10.5194/acp-22-13049-2022 en eng http://www.scopus.com/inward/record.url?scp=85140608316&partnerID=8YFLogxK Atmospheric Chemistry and Physics (online)--1680-7324--16832d90-3dae-4c5d-be35-cd0bb822e241 http://resolver.tudelft.nl/uuid:88d41b4f-a9fa-424c-a296-ccfac83f2b3b https://doi.org/10.5194/acp-22-13049-2022 © 2022 A.C.M. Savazzi, Louise Nuijens, Irina Sandu, Geet Georg journal article 2022 fttudelft https://doi.org/10.5194/acp-22-13049-2022 2024-01-24T23:33:24Z The characterization of systematic forecast errors in lower-tropospheric winds is an essential component of model improvement. This paper is motivated by a global, long-standing surface bias in the operational medium-range weather forecasts produced with the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). Over the tropical oceans, excessive easterly flow is found. A similar bias is found in the western North Atlantic trades, where the EUREC4A field campaign provides an unprecedented wealth of measurements. We analyze the wind bias in the IFS and ERA5 reanalysis throughout the entire lower troposphere during EUREC4A. The wind bias varies greatly from day to day, resulting in root mean square errors (RMSEs) up to 2.5 m s−1, with a mean wind speed bias up to −1 m s−1 near and above the trade inversion in the forecasts and up to −0.5 m s−1 in reanalyses. These biases are insensitive to the assimilation of sondes. The modeled zonal and meridional winds exhibit a diurnal cycle that is too strong, leading to a weak wind speed bias everywhere up to 5 km during daytime but a wind speed bias below 2 km at nighttime that is too strong. Removing momentum transport by shallow convection reduces the wind bias near the surface but leads to stronger easterly near cloud base. The update in moist physics in the newest IFS cycle (cycle 47r3) reduces the meridional wind bias, especially during daytime. Below 1 km, modeled friction due to unresolved physical processes appears to be too strong but is (partially) compensated for by the dynamics, making this a challenging coupled problem. Atmospheric Remote Sensing Article in Journal/Newspaper North Atlantic Delft University of Technology: Institutional Repository Atmospheric Chemistry and Physics 22 19 13049 13066 |
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Open Polar |
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Delft University of Technology: Institutional Repository |
op_collection_id |
fttudelft |
language |
English |
description |
The characterization of systematic forecast errors in lower-tropospheric winds is an essential component of model improvement. This paper is motivated by a global, long-standing surface bias in the operational medium-range weather forecasts produced with the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). Over the tropical oceans, excessive easterly flow is found. A similar bias is found in the western North Atlantic trades, where the EUREC4A field campaign provides an unprecedented wealth of measurements. We analyze the wind bias in the IFS and ERA5 reanalysis throughout the entire lower troposphere during EUREC4A. The wind bias varies greatly from day to day, resulting in root mean square errors (RMSEs) up to 2.5 m s−1, with a mean wind speed bias up to −1 m s−1 near and above the trade inversion in the forecasts and up to −0.5 m s−1 in reanalyses. These biases are insensitive to the assimilation of sondes. The modeled zonal and meridional winds exhibit a diurnal cycle that is too strong, leading to a weak wind speed bias everywhere up to 5 km during daytime but a wind speed bias below 2 km at nighttime that is too strong. Removing momentum transport by shallow convection reduces the wind bias near the surface but leads to stronger easterly near cloud base. The update in moist physics in the newest IFS cycle (cycle 47r3) reduces the meridional wind bias, especially during daytime. Below 1 km, modeled friction due to unresolved physical processes appears to be too strong but is (partially) compensated for by the dynamics, making this a challenging coupled problem. Atmospheric Remote Sensing |
format |
Article in Journal/Newspaper |
author |
Savazzi, A.C.M. (author) Nuijens, Louise (author) Sandu, Irina (author) Georg, Geet (author) |
spellingShingle |
Savazzi, A.C.M. (author) Nuijens, Louise (author) Sandu, Irina (author) Georg, Geet (author) The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A |
author_facet |
Savazzi, A.C.M. (author) Nuijens, Louise (author) Sandu, Irina (author) Georg, Geet (author) |
author_sort |
Savazzi, A.C.M. (author) |
title |
The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A |
title_short |
The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A |
title_full |
The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A |
title_fullStr |
The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A |
title_full_unstemmed |
The representation of the trade winds in ECMWF forecasts and reanalyses during EUREC4A |
title_sort |
representation of the trade winds in ecmwf forecasts and reanalyses during eurec4a |
publishDate |
2022 |
url |
http://resolver.tudelft.nl/uuid:88d41b4f-a9fa-424c-a296-ccfac83f2b3b https://doi.org/10.5194/acp-22-13049-2022 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://www.scopus.com/inward/record.url?scp=85140608316&partnerID=8YFLogxK Atmospheric Chemistry and Physics (online)--1680-7324--16832d90-3dae-4c5d-be35-cd0bb822e241 http://resolver.tudelft.nl/uuid:88d41b4f-a9fa-424c-a296-ccfac83f2b3b https://doi.org/10.5194/acp-22-13049-2022 |
op_rights |
© 2022 A.C.M. Savazzi, Louise Nuijens, Irina Sandu, Geet Georg |
op_doi |
https://doi.org/10.5194/acp-22-13049-2022 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
22 |
container_issue |
19 |
container_start_page |
13049 |
op_container_end_page |
13066 |
_version_ |
1790604438237347840 |