Latent Heat Flux in the Agulhas Current
In-situ observation, climate reanalyses, and satellite remote sensing are used to study the annual cycle of turbulent latent heat flux (LHF) in the Agulhas Current system. We assess if the datasets do represent the intense exchange of moisture that occurs above the Agulhas Current and the Retroflect...
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| Format: | Article |
| Language: | English |
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MDPI AG
2019-07-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/11/13/1576 |
| _version_ | 1798017111699750912 |
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| author | Arielle Stela Imbol Nkwinkwa N. Mathieu Rouault Johnny A. Johannessen |
| author_facet | Arielle Stela Imbol Nkwinkwa N. Mathieu Rouault Johnny A. Johannessen |
| author_sort | Arielle Stela Imbol Nkwinkwa N. |
| collection | DOAJ |
| description | In-situ observation, climate reanalyses, and satellite remote sensing are used to study the annual cycle of turbulent latent heat flux (LHF) in the Agulhas Current system. We assess if the datasets do represent the intense exchange of moisture that occurs above the Agulhas Current and the Retroflection region, especially the new reanalyses as the former, the National Centers for Environmental Prediction Reanalysis 2 (NCEP2) and the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis second-generation reanalysis (ERA-40) have lower sea and less distinct surface temperature (SST) in the Agulhas Current system due to their low spatial resolution thus do not adequately represent the Agulhas Current LHF. We use monthly fields of LHF, SST, surface wind speed, saturated specific humidity at the sea surface (Qss), and specific humidity at 10 m (Qa). The Climate Forecast System Reanalysis (CFSR), the European Centre for Medium-Range Weather Forecast fifth generation (ERA-5), and the Modern-Era Retrospective analysis for Research and Applications version-2 (MERRA-2) are similar to the air−sea turbulent fluxes (SEAFLUX) and do represent the signature of the Agulhas Current. ERA-Interim underestimates the LHF due to lower surface wind speeds than other datasets. The observation-based National Oceanography Center Southampton (NOCS) dataset is different from all other datasets. The highest LHF of 250 W/m<sup>2</sup> is found in the Retroflection in winter. The lowest LHF (~100 W/m<sup>2</sup>) is off Port Elizabeth in summer. East of the Agulhas Current, Qss-Qa is the main driver of the amplitude of the annual cycle of LHF, while it is the wind speed in the Retroflection and both Qss-Qa and wind speed in between. The difference in LHF between product are due to differences in Qss-Qa wind speed and resolution of datasets. |
| first_indexed | 2024-04-11T16:01:30Z |
| format | Article |
| id | doaj.art-75e1a71db29446aa8ee4385e39d7996a |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-04-11T16:01:30Z |
| publishDate | 2019-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-75e1a71db29446aa8ee4385e39d7996a2022-12-22T04:15:01ZengMDPI AGRemote Sensing2072-42922019-07-011113157610.3390/rs11131576rs11131576Latent Heat Flux in the Agulhas CurrentArielle Stela Imbol Nkwinkwa N.0Mathieu Rouault1Johnny A. Johannessen2Department of Oceanography, Ma-Re Institute, University of Cape Town, Cape Town 7701, South AfricaDepartment of Oceanography, Ma-Re Institute, University of Cape Town, Cape Town 7701, South AfricaNansen Environmental and Remote Sensing Research Center and Geophysical Institute, University of Bergen, N-5006 Bergen, NorwayIn-situ observation, climate reanalyses, and satellite remote sensing are used to study the annual cycle of turbulent latent heat flux (LHF) in the Agulhas Current system. We assess if the datasets do represent the intense exchange of moisture that occurs above the Agulhas Current and the Retroflection region, especially the new reanalyses as the former, the National Centers for Environmental Prediction Reanalysis 2 (NCEP2) and the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis second-generation reanalysis (ERA-40) have lower sea and less distinct surface temperature (SST) in the Agulhas Current system due to their low spatial resolution thus do not adequately represent the Agulhas Current LHF. We use monthly fields of LHF, SST, surface wind speed, saturated specific humidity at the sea surface (Qss), and specific humidity at 10 m (Qa). The Climate Forecast System Reanalysis (CFSR), the European Centre for Medium-Range Weather Forecast fifth generation (ERA-5), and the Modern-Era Retrospective analysis for Research and Applications version-2 (MERRA-2) are similar to the air−sea turbulent fluxes (SEAFLUX) and do represent the signature of the Agulhas Current. ERA-Interim underestimates the LHF due to lower surface wind speeds than other datasets. The observation-based National Oceanography Center Southampton (NOCS) dataset is different from all other datasets. The highest LHF of 250 W/m<sup>2</sup> is found in the Retroflection in winter. The lowest LHF (~100 W/m<sup>2</sup>) is off Port Elizabeth in summer. East of the Agulhas Current, Qss-Qa is the main driver of the amplitude of the annual cycle of LHF, while it is the wind speed in the Retroflection and both Qss-Qa and wind speed in between. The difference in LHF between product are due to differences in Qss-Qa wind speed and resolution of datasets.https://www.mdpi.com/2072-4292/11/13/1576latent heat fluxAgulhas Currentspecific humiditywind speedCFSRMERRA-2ERA-5ERA-Interim |
| spellingShingle | Arielle Stela Imbol Nkwinkwa N. Mathieu Rouault Johnny A. Johannessen Latent Heat Flux in the Agulhas Current Remote Sensing latent heat flux Agulhas Current specific humidity wind speed CFSR MERRA-2 ERA-5 ERA-Interim |
| title | Latent Heat Flux in the Agulhas Current |
| title_full | Latent Heat Flux in the Agulhas Current |
| title_fullStr | Latent Heat Flux in the Agulhas Current |
| title_full_unstemmed | Latent Heat Flux in the Agulhas Current |
| title_short | Latent Heat Flux in the Agulhas Current |
| title_sort | latent heat flux in the agulhas current |
| topic | latent heat flux Agulhas Current specific humidity wind speed CFSR MERRA-2 ERA-5 ERA-Interim |
| url | https://www.mdpi.com/2072-4292/11/13/1576 |
| work_keys_str_mv | AT ariellestelaimbolnkwinkwan latentheatfluxintheagulhascurrent AT mathieurouault latentheatfluxintheagulhascurrent AT johnnyajohannessen latentheatfluxintheagulhascurrent |