North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model
This study examines the mechanisms of the Pacific decadal oscillation (PDO) in the GEOS-5 general circulation model. The model simulates a realistic PDO pattern that is resolved as the first empirical orthogonal function (EOF) of winter sea surface temperature (SST). The simulated PDO is primarily f...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20140013019 2023-05-15T13:14:51+02:00 North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model Vikhliaev, Yury V. Schubert, Siegfried D. Achuthavarier, Deepthi Unclassified, Unlimited, Publicly available October 25, 2013 application/pdf http://hdl.handle.net/2060/20140013019 unknown Document ID: 20140013019 http://hdl.handle.net/2060/20140013019 Copyright, Distribution as joint owner in the copyright CASI Geophysics GSFC-E-DAA-TN11815 2013 ftnasantrs 2019-07-21T06:13:24Z This study examines the mechanisms of the Pacific decadal oscillation (PDO) in the GEOS-5 general circulation model. The model simulates a realistic PDO pattern that is resolved as the first empirical orthogonal function (EOF) of winter sea surface temperature (SST). The simulated PDO is primarily forced by Aleutian low through Ekman transport and surface fluxes, and shows a red spectrum without any preferred periodicity. This differs from the observations, which indicate a greater role of El Nino-Southern Oscillation (ENSO) forcing, and likely reflects the too short time scale of the simulated ENSO. The geostrophic transport in response to the Aleutian low is limited to the Kuroshio-Oyashio Extension, and is unlikely the main controlling factor in this model, although it reinforces the Ekman-induced SST anomalies. The delay between the Aleutian low and the PDO is relatively short (1 year) suggesting that the fast Ekman response (rather than Rossby wave propagation) sets the SST pattern immediately following an Aleutian low fluctuation. The atmospheric feedback (response to the SST) is only about 25 of the forcing and never evolves into an Aleutian low completely, instead projecting onto the North Pacific Oscillation (NPO), a meridional dipole in sea level pressure (SLP). The lack of preferred periodicity and weak atmospheric response bothindicate a coupled oscillation is an unlikely mechanism for the PDO in this model. In agreement with recent studies, the NPO is correlated with the North Pacific Gyre Oscillation (NPGO), which is another leading EOF of the North Pacific SST. A possible connection between the PDO and the NPGO is discussed. Other/Unknown Material aleutian low NASA Technical Reports Server (NTRS) Oyashio ENVELOPE(157.000,157.000,50.000,50.000) Pacific |
institution |
Open Polar |
collection |
NASA Technical Reports Server (NTRS) |
op_collection_id |
ftnasantrs |
language |
unknown |
topic |
Geophysics |
spellingShingle |
Geophysics Vikhliaev, Yury V. Schubert, Siegfried D. Achuthavarier, Deepthi North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model |
topic_facet |
Geophysics |
description |
This study examines the mechanisms of the Pacific decadal oscillation (PDO) in the GEOS-5 general circulation model. The model simulates a realistic PDO pattern that is resolved as the first empirical orthogonal function (EOF) of winter sea surface temperature (SST). The simulated PDO is primarily forced by Aleutian low through Ekman transport and surface fluxes, and shows a red spectrum without any preferred periodicity. This differs from the observations, which indicate a greater role of El Nino-Southern Oscillation (ENSO) forcing, and likely reflects the too short time scale of the simulated ENSO. The geostrophic transport in response to the Aleutian low is limited to the Kuroshio-Oyashio Extension, and is unlikely the main controlling factor in this model, although it reinforces the Ekman-induced SST anomalies. The delay between the Aleutian low and the PDO is relatively short (1 year) suggesting that the fast Ekman response (rather than Rossby wave propagation) sets the SST pattern immediately following an Aleutian low fluctuation. The atmospheric feedback (response to the SST) is only about 25 of the forcing and never evolves into an Aleutian low completely, instead projecting onto the North Pacific Oscillation (NPO), a meridional dipole in sea level pressure (SLP). The lack of preferred periodicity and weak atmospheric response bothindicate a coupled oscillation is an unlikely mechanism for the PDO in this model. In agreement with recent studies, the NPO is correlated with the North Pacific Gyre Oscillation (NPGO), which is another leading EOF of the North Pacific SST. A possible connection between the PDO and the NPGO is discussed. |
format |
Other/Unknown Material |
author |
Vikhliaev, Yury V. Schubert, Siegfried D. Achuthavarier, Deepthi |
author_facet |
Vikhliaev, Yury V. Schubert, Siegfried D. Achuthavarier, Deepthi |
author_sort |
Vikhliaev, Yury V. |
title |
North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model |
title_short |
North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model |
title_full |
North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model |
title_fullStr |
North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model |
title_full_unstemmed |
North Pacific Decadal Variability in the GEOS-5 Atmosphere-Ocean Model |
title_sort |
north pacific decadal variability in the geos-5 atmosphere-ocean model |
publishDate |
2013 |
url |
http://hdl.handle.net/2060/20140013019 |
op_coverage |
Unclassified, Unlimited, Publicly available |
long_lat |
ENVELOPE(157.000,157.000,50.000,50.000) |
geographic |
Oyashio Pacific |
geographic_facet |
Oyashio Pacific |
genre |
aleutian low |
genre_facet |
aleutian low |
op_source |
CASI |
op_relation |
Document ID: 20140013019 http://hdl.handle.net/2060/20140013019 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766265725905797120 |