Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean
We present a new method for assimilating observations of sea surface height (SSH) into a high‐resolution primitive equation model. The method is based on the concept of reinitialization. First, the surface velocity increments necessary to adjust the model forecast to the observed geostrophic surface...
Published in: | Journal of Geophysical Research: Oceans |
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Language: | English |
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AGU (American Geophysical Union)
1996
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ftoceanrep:oai:oceanrep.geomar.de:2235 2023-05-15T17:31:03+02:00 Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean Oschlies, Andreas Willebrand, Jürgen 1996 text https://oceanrep.geomar.de/id/eprint/2235/ https://oceanrep.geomar.de/id/eprint/2235/1/Oschlies_et_al-1996-Journal_of_Geophysical_Research__Oceans_%281978-2012%29.pdf https://doi.org/10.1029/95JC03801 en eng AGU (American Geophysical Union) https://oceanrep.geomar.de/id/eprint/2235/1/Oschlies_et_al-1996-Journal_of_Geophysical_Research__Oceans_%281978-2012%29.pdf Oschlies, A. and Willebrand, J. (1996) Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean. Open Access Journal of Geophysical Research: Oceans, 101 (C6). pp. 14175-14190. DOI 10.1029/95JC03801 <https://doi.org/10.1029/95JC03801>. doi:10.1029/95JC03801 info:eu-repo/semantics/openAccess Article PeerReviewed 1996 ftoceanrep https://doi.org/10.1029/95JC03801 2023-04-07T14:45:26Z We present a new method for assimilating observations of sea surface height (SSH) into a high‐resolution primitive equation model. The method is based on the concept of reinitialization. First, the surface velocity increments necessary to adjust the model forecast to the observed geostrophic surface currents are projected onto deep velocity increments by a linear regression method. Second, changes in the density field required to balance the changes in the velocity field geostrophically are obtained from an inversion of the thermal wind equation. A unique partition of the density increments into corresponding temperature and salinity changes is realized by conserving the local θ‐S relation of the model forecast. In contrast to pure statistical methods that infer temperature and salinity changes from correlations with SSH anomalies, our approach explicitly conserves water mass properties on isopycnals. For the assimilation experiment we use optimally interpolated maps of Geosat SSH anomalies (the mean topography is taken from the model), which are assimilated into the World Ocean Circulation Experiment (WOCE) Community Modeling Effort (CME) model of the North Atlantic Ocean at 5‐day intervals covering the year 1987. It is shown that the assimilation significantly improves the model's representation of eddy activity, with the hydrographic structure of individual eddies agreeing well with independent hydrographic observations. The importance of a careful treatment of water mass properties in the assimilation process is discussed and further illustrated by comparing different assimilation schemes. Article in Journal/Newspaper North Atlantic OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Journal of Geophysical Research: Oceans 101 C6 14175 14190 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
We present a new method for assimilating observations of sea surface height (SSH) into a high‐resolution primitive equation model. The method is based on the concept of reinitialization. First, the surface velocity increments necessary to adjust the model forecast to the observed geostrophic surface currents are projected onto deep velocity increments by a linear regression method. Second, changes in the density field required to balance the changes in the velocity field geostrophically are obtained from an inversion of the thermal wind equation. A unique partition of the density increments into corresponding temperature and salinity changes is realized by conserving the local θ‐S relation of the model forecast. In contrast to pure statistical methods that infer temperature and salinity changes from correlations with SSH anomalies, our approach explicitly conserves water mass properties on isopycnals. For the assimilation experiment we use optimally interpolated maps of Geosat SSH anomalies (the mean topography is taken from the model), which are assimilated into the World Ocean Circulation Experiment (WOCE) Community Modeling Effort (CME) model of the North Atlantic Ocean at 5‐day intervals covering the year 1987. It is shown that the assimilation significantly improves the model's representation of eddy activity, with the hydrographic structure of individual eddies agreeing well with independent hydrographic observations. The importance of a careful treatment of water mass properties in the assimilation process is discussed and further illustrated by comparing different assimilation schemes. |
format |
Article in Journal/Newspaper |
author |
Oschlies, Andreas Willebrand, Jürgen |
spellingShingle |
Oschlies, Andreas Willebrand, Jürgen Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean |
author_facet |
Oschlies, Andreas Willebrand, Jürgen |
author_sort |
Oschlies, Andreas |
title |
Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean |
title_short |
Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean |
title_full |
Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean |
title_fullStr |
Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean |
title_full_unstemmed |
Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean |
title_sort |
assimilation of geosat altimeter data into an eddy-resolving primitive equation model of the north atlantic ocean |
publisher |
AGU (American Geophysical Union) |
publishDate |
1996 |
url |
https://oceanrep.geomar.de/id/eprint/2235/ https://oceanrep.geomar.de/id/eprint/2235/1/Oschlies_et_al-1996-Journal_of_Geophysical_Research__Oceans_%281978-2012%29.pdf https://doi.org/10.1029/95JC03801 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://oceanrep.geomar.de/id/eprint/2235/1/Oschlies_et_al-1996-Journal_of_Geophysical_Research__Oceans_%281978-2012%29.pdf Oschlies, A. and Willebrand, J. (1996) Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean. Open Access Journal of Geophysical Research: Oceans, 101 (C6). pp. 14175-14190. DOI 10.1029/95JC03801 <https://doi.org/10.1029/95JC03801>. doi:10.1029/95JC03801 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1029/95JC03801 |
container_title |
Journal of Geophysical Research: Oceans |
container_volume |
101 |
container_issue |
C6 |
container_start_page |
14175 |
op_container_end_page |
14190 |
_version_ |
1766128366787756032 |