Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study
A set of experiments utilizing different implementations of the global ORCA-LIM model with horizontal resolutions of 2°, 0.5° and 0.25° is used to investigate tropical and extra-tropical influences on equatorial Pacific SST variability at interannual to decadal time scales. The model experiments use...
Main Authors: | , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2008
|
Subjects: | |
Online Access: | https://doaj.org/article/a759db825daa472cbb89a476164b1cfd |
id |
ftdoajarticles:oai:doaj.org/article:a759db825daa472cbb89a476164b1cfd |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:a759db825daa472cbb89a476164b1cfd 2023-05-15T17:54:01+02:00 Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study J. F. Lübbecke C. W. Böning A. Biastoch 2008-02-01T00:00:00Z https://doaj.org/article/a759db825daa472cbb89a476164b1cfd EN eng Copernicus Publications http://www.ocean-sci.net/4/73/2008/os-4-73-2008.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/a759db825daa472cbb89a476164b1cfd Ocean Science, Vol 4, Iss 1, Pp 73-88 (2008) Geography. Anthropology. Recreation G Environmental sciences GE1-350 article 2008 ftdoajarticles 2022-12-30T23:49:59Z A set of experiments utilizing different implementations of the global ORCA-LIM model with horizontal resolutions of 2°, 0.5° and 0.25° is used to investigate tropical and extra-tropical influences on equatorial Pacific SST variability at interannual to decadal time scales. The model experiments use a bulk forcing methodology building on the global forcing data set for 1958 to 2000 developed by Large and Yeager (2004) that is based on a blend of atmospheric reanalysis data and satellite products. Whereas representation of the mean structure and transports of the (sub-) tropical Pacific current fields is much improved with the enhanced horizontal resolution, there is only little difference in the simulation of the interannual variability in the equatorial regime between the 0.5° and 0.25° model versions, with both solutions capturing the observed SST variability in the Niño3-region. The question of remotely forced oceanic contributions to the equatorial variability, in particular, the role of low-frequency changes in the transports of the Subtropical Cells (STCs), is addressed by a sequence of perturbation experiments using different combinations of fluxes. The solutions show the near-surface temperature variability to be governed by wind-driven changes in the Equatorial Undercurrent. The relative contributions of equatorial and off-equatorial atmospheric forcing differ between interannual and longer, (multi-) decadal timescales: for the latter there is a significant impact of changes in the equatorward transport of subtropical thermocline water associated with the lower branches of the STCs, related to variations in the off-equatorial trade winds. A conspicuous feature of the STC variability is that the equatorward transports in the interior and along the western boundary partially compensate each other at both decadal and interannual time scales, with the strongest transport extrema occurring during El Niño episodes. The behaviour is rationalized in terms of a wobbling in the poleward extents of the tropical ... Article in Journal/Newspaper Orca Directory of Open Access Journals: DOAJ Articles Pacific |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
spellingShingle |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 J. F. Lübbecke C. W. Böning A. Biastoch Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study |
topic_facet |
Geography. Anthropology. Recreation G Environmental sciences GE1-350 |
description |
A set of experiments utilizing different implementations of the global ORCA-LIM model with horizontal resolutions of 2°, 0.5° and 0.25° is used to investigate tropical and extra-tropical influences on equatorial Pacific SST variability at interannual to decadal time scales. The model experiments use a bulk forcing methodology building on the global forcing data set for 1958 to 2000 developed by Large and Yeager (2004) that is based on a blend of atmospheric reanalysis data and satellite products. Whereas representation of the mean structure and transports of the (sub-) tropical Pacific current fields is much improved with the enhanced horizontal resolution, there is only little difference in the simulation of the interannual variability in the equatorial regime between the 0.5° and 0.25° model versions, with both solutions capturing the observed SST variability in the Niño3-region. The question of remotely forced oceanic contributions to the equatorial variability, in particular, the role of low-frequency changes in the transports of the Subtropical Cells (STCs), is addressed by a sequence of perturbation experiments using different combinations of fluxes. The solutions show the near-surface temperature variability to be governed by wind-driven changes in the Equatorial Undercurrent. The relative contributions of equatorial and off-equatorial atmospheric forcing differ between interannual and longer, (multi-) decadal timescales: for the latter there is a significant impact of changes in the equatorward transport of subtropical thermocline water associated with the lower branches of the STCs, related to variations in the off-equatorial trade winds. A conspicuous feature of the STC variability is that the equatorward transports in the interior and along the western boundary partially compensate each other at both decadal and interannual time scales, with the strongest transport extrema occurring during El Niño episodes. The behaviour is rationalized in terms of a wobbling in the poleward extents of the tropical ... |
format |
Article in Journal/Newspaper |
author |
J. F. Lübbecke C. W. Böning A. Biastoch |
author_facet |
J. F. Lübbecke C. W. Böning A. Biastoch |
author_sort |
J. F. Lübbecke |
title |
Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study |
title_short |
Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study |
title_full |
Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study |
title_fullStr |
Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study |
title_full_unstemmed |
Variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial Pacific: a model study |
title_sort |
variability in the subtropical-tropical cells and its effect on near-surface temperature of the equatorial pacific: a model study |
publisher |
Copernicus Publications |
publishDate |
2008 |
url |
https://doaj.org/article/a759db825daa472cbb89a476164b1cfd |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Orca |
genre_facet |
Orca |
op_source |
Ocean Science, Vol 4, Iss 1, Pp 73-88 (2008) |
op_relation |
http://www.ocean-sci.net/4/73/2008/os-4-73-2008.pdf https://doaj.org/toc/1812-0784 https://doaj.org/toc/1812-0792 1812-0784 1812-0792 https://doaj.org/article/a759db825daa472cbb89a476164b1cfd |
_version_ |
1766161736477442048 |