Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations
The region south of South Africa, encompassing the Agulhas Current and Retroflection, and part of the Southern Ocean, is known for its severe meteorological conditions. Because of these conditions, in-situ observations are rare. Consequently, remote-sensing satellite observations and high-resolution...
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2012
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Online Access: | https://doi.org/10.4102/sajs.v108i3/4.735 https://doaj.org/article/48764ae5887648bb944c38df7bd1e72a |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:48764ae5887648bb944c38df7bd1e72a 2023-05-15T16:53:58+02:00 Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations Christophe Messager Vincent Faure 2012-03-01 https://doi.org/10.4102/sajs.v108i3/4.735 https://doaj.org/article/48764ae5887648bb944c38df7bd1e72a en eng Academy of Science of South Africa doi:10.4102/sajs.v108i3/4.735 0038-2353 1996-7489 https://doaj.org/article/48764ae5887648bb944c38df7bd1e72a undefined South African Journal of Science, Vol 108, Iss 3/4 (2012) numerical weather forecast Agulhas Retroflection air–sea fluxes ocean wind remote sensing geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2012 fttriple https://doi.org/10.4102/sajs.v108i3/4.735 2023-01-22T18:11:47Z The region south of South Africa, encompassing the Agulhas Current and Retroflection, and part of the Southern Ocean, is known for its severe meteorological conditions. Because of these conditions, in-situ observations are rare. Consequently, remote-sensing satellite observations and high-resolution regional weather forecasts at the ocean surface are difficult to assess. However, atmospheric data collected in the southern hemisphere summer of 2008 during the International Polar Year-BONUS-GoodHope campaign were used to validate two satellite data sets: the twice daily QuikSCAT winds and the daily OAflux data set of latent and sensible heat fluxes. The surface winds and heat fluxes forecasts produced by a regional atmospheric model were also assessed along the ship track. In this study, we have shown that the two data sets exhibited a very good accordance with daily in-situ observations. During the campaign, the correlation coefficients for wind speed and direction were 0.97 and 0.91, respectively, and those for latent and sensible heat fluxes were 0.92 and 0.90, respectively. The QuikSCAT wind speed was underestimated by 1.37 m/s relative to in-situ data, south of the Subtropical Front. Large differences in heat fluxes in both OAflux and the atmospheric model were observed when crossing the Subtropical Front and a warm eddy, as well as during a storm, when gale force winds reached more than 20 m/s. The two data sets were then used to assess the regional model forecasts over a larger area south of South Africa, not limited to the ship track. Most of the model errors were located in a region north of the Subtropical Front, where the sea surface temperature used by the model was not accurate enough to reproduce the relevant mesoscale oceanic features driving the spatial variability of the surface winds and heat fluxes. Finally, compared to in-situ and remote sensing observations, the numerical modelling weather forecast produced realistic atmospheric conditions over the sea south of the Subtropical Front. Article in Journal/Newspaper International Polar Year Southern Ocean Unknown Southern Ocean South African Journal of Science 108 3/4 |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
fttriple |
language |
English |
topic |
numerical weather forecast Agulhas Retroflection air–sea fluxes ocean wind remote sensing geo envir |
spellingShingle |
numerical weather forecast Agulhas Retroflection air–sea fluxes ocean wind remote sensing geo envir Christophe Messager Vincent Faure Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations |
topic_facet |
numerical weather forecast Agulhas Retroflection air–sea fluxes ocean wind remote sensing geo envir |
description |
The region south of South Africa, encompassing the Agulhas Current and Retroflection, and part of the Southern Ocean, is known for its severe meteorological conditions. Because of these conditions, in-situ observations are rare. Consequently, remote-sensing satellite observations and high-resolution regional weather forecasts at the ocean surface are difficult to assess. However, atmospheric data collected in the southern hemisphere summer of 2008 during the International Polar Year-BONUS-GoodHope campaign were used to validate two satellite data sets: the twice daily QuikSCAT winds and the daily OAflux data set of latent and sensible heat fluxes. The surface winds and heat fluxes forecasts produced by a regional atmospheric model were also assessed along the ship track. In this study, we have shown that the two data sets exhibited a very good accordance with daily in-situ observations. During the campaign, the correlation coefficients for wind speed and direction were 0.97 and 0.91, respectively, and those for latent and sensible heat fluxes were 0.92 and 0.90, respectively. The QuikSCAT wind speed was underestimated by 1.37 m/s relative to in-situ data, south of the Subtropical Front. Large differences in heat fluxes in both OAflux and the atmospheric model were observed when crossing the Subtropical Front and a warm eddy, as well as during a storm, when gale force winds reached more than 20 m/s. The two data sets were then used to assess the regional model forecasts over a larger area south of South Africa, not limited to the ship track. Most of the model errors were located in a region north of the Subtropical Front, where the sea surface temperature used by the model was not accurate enough to reproduce the relevant mesoscale oceanic features driving the spatial variability of the surface winds and heat fluxes. Finally, compared to in-situ and remote sensing observations, the numerical modelling weather forecast produced realistic atmospheric conditions over the sea south of the Subtropical Front. |
format |
Article in Journal/Newspaper |
author |
Christophe Messager Vincent Faure |
author_facet |
Christophe Messager Vincent Faure |
author_sort |
Christophe Messager |
title |
Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations |
title_short |
Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations |
title_full |
Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations |
title_fullStr |
Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations |
title_full_unstemmed |
Validation of remote sensing and weather model forecasts in the Agulhas ocean area to 57°S by ship observations |
title_sort |
validation of remote sensing and weather model forecasts in the agulhas ocean area to 57°s by ship observations |
publisher |
Academy of Science of South Africa |
publishDate |
2012 |
url |
https://doi.org/10.4102/sajs.v108i3/4.735 https://doaj.org/article/48764ae5887648bb944c38df7bd1e72a |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
International Polar Year Southern Ocean |
genre_facet |
International Polar Year Southern Ocean |
op_source |
South African Journal of Science, Vol 108, Iss 3/4 (2012) |
op_relation |
doi:10.4102/sajs.v108i3/4.735 0038-2353 1996-7489 https://doaj.org/article/48764ae5887648bb944c38df7bd1e72a |
op_rights |
undefined |
op_doi |
https://doi.org/10.4102/sajs.v108i3/4.735 |
container_title |
South African Journal of Science |
container_volume |
108 |
container_issue |
3/4 |
_version_ |
1766044573858004992 |