Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM
A new type of EI Nino event has been identified in the last decade. During "warm pool" EI Nino (WPEN) events, sea surface temperatures (SSTs) in the central equatorial Pacific are warmer than average. The EI Nino signal propagates poleward and upward as large-scale atmospheric waves, causi...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20110008490 2023-05-15T13:34:40+02:00 Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM Molod, Andrea M. Nielsen, J. Eric Frith, Stacey M. Hurwitz, Margaret M. Newman, Paul A. Song, In-Sun Oman, Luke D. Unclassified, Unlimited, Publicly available March 2011 application/pdf http://hdl.handle.net/2060/20110008490 unknown Document ID: 20110008490 http://hdl.handle.net/2060/20110008490 Copyright, Distribution as joint owner in the copyright CASI Meteorology and Climatology 2011 ftnasantrs 2018-06-09T22:57:10Z A new type of EI Nino event has been identified in the last decade. During "warm pool" EI Nino (WPEN) events, sea surface temperatures (SSTs) in the central equatorial Pacific are warmer than average. The EI Nino signal propagates poleward and upward as large-scale atmospheric waves, causing unusual weather patterns and warming the polar stratosphere. In austral summer, observations show that the Antarctic lower stratosphere is several degrees (K) warmer during WPEN events than during the neutral phase of EI Nino/Southern Oscillation (ENSO). Furthermore, the stratospheric response to WPEN events depends of the direction of tropical stratospheric winds: the Antarctic warming is largest when WPEN events are coincident with westward winds in the tropical lower and middle stratosphere i.e., the westward phase of the quasi-biennial oscillation (QBO). Westward winds are associated with enhanced convection in the subtropics, and with increased poleward wave activity. In this paper, a new formulation of the Goddard Earth Observing System Chemistry-Climate Model, Version 2 (GEOS V2 CCM) is used to substantiate the observed stratospheric response to WPEN events. One simulation is driven by SSTs typical of a WPEN event, while another simulation is driven by ENSO neutral SSTs; both represent a present-day climate. Differences between the two simulations can be directly attributed to the anomalous WPEN SSTs. During WPEN events, relative to ENSO neutral, the model simulates the observed increase in poleward planetary wave activity in the South Pacific during austral spring, as well as the relative warming of the Antarctic lower stratosphere in austral summer. However, the modeled response to WPEN does not depend on the phase of the QBO. The modeled tropical wind oscillation does not extend far enough into the lower stratosphere and upper troposphere, likely explaining the model's insensitivity to the phase of the QBO during WPEN events. Other/Unknown Material Antarc* Antarctic NASA Technical Reports Server (NTRS) Antarctic The Antarctic Austral Pacific |
institution |
Open Polar |
collection |
NASA Technical Reports Server (NTRS) |
op_collection_id |
ftnasantrs |
language |
unknown |
topic |
Meteorology and Climatology |
spellingShingle |
Meteorology and Climatology Molod, Andrea M. Nielsen, J. Eric Frith, Stacey M. Hurwitz, Margaret M. Newman, Paul A. Song, In-Sun Oman, Luke D. Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM |
topic_facet |
Meteorology and Climatology |
description |
A new type of EI Nino event has been identified in the last decade. During "warm pool" EI Nino (WPEN) events, sea surface temperatures (SSTs) in the central equatorial Pacific are warmer than average. The EI Nino signal propagates poleward and upward as large-scale atmospheric waves, causing unusual weather patterns and warming the polar stratosphere. In austral summer, observations show that the Antarctic lower stratosphere is several degrees (K) warmer during WPEN events than during the neutral phase of EI Nino/Southern Oscillation (ENSO). Furthermore, the stratospheric response to WPEN events depends of the direction of tropical stratospheric winds: the Antarctic warming is largest when WPEN events are coincident with westward winds in the tropical lower and middle stratosphere i.e., the westward phase of the quasi-biennial oscillation (QBO). Westward winds are associated with enhanced convection in the subtropics, and with increased poleward wave activity. In this paper, a new formulation of the Goddard Earth Observing System Chemistry-Climate Model, Version 2 (GEOS V2 CCM) is used to substantiate the observed stratospheric response to WPEN events. One simulation is driven by SSTs typical of a WPEN event, while another simulation is driven by ENSO neutral SSTs; both represent a present-day climate. Differences between the two simulations can be directly attributed to the anomalous WPEN SSTs. During WPEN events, relative to ENSO neutral, the model simulates the observed increase in poleward planetary wave activity in the South Pacific during austral spring, as well as the relative warming of the Antarctic lower stratosphere in austral summer. However, the modeled response to WPEN does not depend on the phase of the QBO. The modeled tropical wind oscillation does not extend far enough into the lower stratosphere and upper troposphere, likely explaining the model's insensitivity to the phase of the QBO during WPEN events. |
author |
Molod, Andrea M. Nielsen, J. Eric Frith, Stacey M. Hurwitz, Margaret M. Newman, Paul A. Song, In-Sun Oman, Luke D. |
author_facet |
Molod, Andrea M. Nielsen, J. Eric Frith, Stacey M. Hurwitz, Margaret M. Newman, Paul A. Song, In-Sun Oman, Luke D. |
author_sort |
Molod, Andrea M. |
title |
Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM |
title_short |
Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM |
title_full |
Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM |
title_fullStr |
Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM |
title_full_unstemmed |
Response of the Antarctic Stratosphere to Warm Pool EI Nino Events in the GEOS CCM |
title_sort |
response of the antarctic stratosphere to warm pool ei nino events in the geos ccm |
publishDate |
2011 |
url |
http://hdl.handle.net/2060/20110008490 |
op_coverage |
Unclassified, Unlimited, Publicly available |
geographic |
Antarctic The Antarctic Austral Pacific |
geographic_facet |
Antarctic The Antarctic Austral Pacific |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_source |
CASI |
op_relation |
Document ID: 20110008490 http://hdl.handle.net/2060/20110008490 |
op_rights |
Copyright, Distribution as joint owner in the copyright |
_version_ |
1766055593623158784 |