The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile
This paper explores the sensitivity of Atmospheric General Circulation Model (AGCM) simulations to changes in the meridional distribution of sea surface temperature (SST). The simulations are for an aqua-planet, a water covered Earth with no land, orography or sea- ice and with specified zonally sym...
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ftnasantrs:oai:casi.ntrs.nasa.gov:20140005686 2023-05-15T18:18:59+02:00 The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile Borth, Hartmut Suarez, Max J. Wedi, Nils P. Frank, Helmut Nakamura, Hisashi Blackburn, Michael Ishiwatari, Masaki Williamson, David L. Lee, Myong-In Satoh, Masaki Kimoto, Masahide Hayashi, Yoshi-Yuki Takahashi, Yoshiyuki O. Mcgregor, John L. Molod, Andrew Stratton, Rachel Nakajima, Kensuke Watanabe, Masahiro RajenDran, Kavirajan Bechtold, Peter Wang, Zaizhi Liu, Yimin Wirth, Volkmar Tomita, Hirofumi Ohfuchi, Wataru Kitoh, Akio Held, Isaac M. Zhao, Ming Unclassified, Unlimited, Publicly available 2013 application/pdf http://hdl.handle.net/2060/20140005686 unknown Document ID: 20140005686 http://hdl.handle.net/2060/20140005686 Copyright, Distribution under U.S. Government purpose rights CASI Geosciences (General) GSFC-E-DAA-TN12736 Journal of the Meteorological Society of Japan: Special Issue on the Aqua-Planet Experiment; 91A; 57-89 2013 ftnasantrs 2019-07-21T00:31:33Z This paper explores the sensitivity of Atmospheric General Circulation Model (AGCM) simulations to changes in the meridional distribution of sea surface temperature (SST). The simulations are for an aqua-planet, a water covered Earth with no land, orography or sea- ice and with specified zonally symmetric SST. Simulations from 14 AGCMs developed for Numerical Weather Prediction and climate applications are compared. Four experiments are performed to study the sensitivity to the meridional SST profile. These profiles range from one in which the SST gradient continues to the equator to one which is flat approaching the equator, all with the same maximum SST at the equator. The zonal mean circulation of all models shows strong sensitivity to latitudinal distribution of SST. The Hadley circulation weakens and shifts poleward as the SST profile flattens in the tropics. One question of interest is the formation of a double versus a single ITCZ. There is a large variation between models of the strength of the ITCZ and where in the SST experiment sequence they transition from a single to double ITCZ. The SST profiles are defined such that as the equatorial SST gradient flattens, the maximum gradient increases and moves poleward. This leads to a weakening of the mid-latitude jet accompanied by a poleward shift of the jet core. Also considered are tropical wave activity and tropical precipitation frequency distributions. The details of each vary greatly between models, both with a given SST and in the response to the change in SST. One additional experiment is included to examine the sensitivity to an off-equatorial SST maximum. The upward branch of the Hadley circulation follows the SST maximum off the equator. The models that form a single precipitation maximum when the maximum SST is on the equator shift the precipitation maximum off equator and keep it centered over the SST maximum. Those that form a double with minimum on the equatorial maximum SST shift the double structure off the equator, keeping the minimum over the maximum SST. In both situations only modest changes appear in the shifted profile of zonal average precipitation. When the upward branch of the Hadley circulation moves into the hemisphere with SST maximum, the zonal average zonal, meridional and vertical winds all indicate that the Hadley cell in the other hemisphere dominates. Other/Unknown Material Sea ice NASA Technical Reports Server (NTRS) |
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NASA Technical Reports Server (NTRS) |
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ftnasantrs |
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Geosciences (General) |
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Geosciences (General) Borth, Hartmut Suarez, Max J. Wedi, Nils P. Frank, Helmut Nakamura, Hisashi Blackburn, Michael Ishiwatari, Masaki Williamson, David L. Lee, Myong-In Satoh, Masaki Kimoto, Masahide Hayashi, Yoshi-Yuki Takahashi, Yoshiyuki O. Mcgregor, John L. Molod, Andrew Stratton, Rachel Nakajima, Kensuke Watanabe, Masahiro RajenDran, Kavirajan Bechtold, Peter Wang, Zaizhi Liu, Yimin Wirth, Volkmar Tomita, Hirofumi Ohfuchi, Wataru Kitoh, Akio Held, Isaac M. Zhao, Ming The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile |
topic_facet |
Geosciences (General) |
description |
This paper explores the sensitivity of Atmospheric General Circulation Model (AGCM) simulations to changes in the meridional distribution of sea surface temperature (SST). The simulations are for an aqua-planet, a water covered Earth with no land, orography or sea- ice and with specified zonally symmetric SST. Simulations from 14 AGCMs developed for Numerical Weather Prediction and climate applications are compared. Four experiments are performed to study the sensitivity to the meridional SST profile. These profiles range from one in which the SST gradient continues to the equator to one which is flat approaching the equator, all with the same maximum SST at the equator. The zonal mean circulation of all models shows strong sensitivity to latitudinal distribution of SST. The Hadley circulation weakens and shifts poleward as the SST profile flattens in the tropics. One question of interest is the formation of a double versus a single ITCZ. There is a large variation between models of the strength of the ITCZ and where in the SST experiment sequence they transition from a single to double ITCZ. The SST profiles are defined such that as the equatorial SST gradient flattens, the maximum gradient increases and moves poleward. This leads to a weakening of the mid-latitude jet accompanied by a poleward shift of the jet core. Also considered are tropical wave activity and tropical precipitation frequency distributions. The details of each vary greatly between models, both with a given SST and in the response to the change in SST. One additional experiment is included to examine the sensitivity to an off-equatorial SST maximum. The upward branch of the Hadley circulation follows the SST maximum off the equator. The models that form a single precipitation maximum when the maximum SST is on the equator shift the precipitation maximum off equator and keep it centered over the SST maximum. Those that form a double with minimum on the equatorial maximum SST shift the double structure off the equator, keeping the minimum over the maximum SST. In both situations only modest changes appear in the shifted profile of zonal average precipitation. When the upward branch of the Hadley circulation moves into the hemisphere with SST maximum, the zonal average zonal, meridional and vertical winds all indicate that the Hadley cell in the other hemisphere dominates. |
format |
Other/Unknown Material |
author |
Borth, Hartmut Suarez, Max J. Wedi, Nils P. Frank, Helmut Nakamura, Hisashi Blackburn, Michael Ishiwatari, Masaki Williamson, David L. Lee, Myong-In Satoh, Masaki Kimoto, Masahide Hayashi, Yoshi-Yuki Takahashi, Yoshiyuki O. Mcgregor, John L. Molod, Andrew Stratton, Rachel Nakajima, Kensuke Watanabe, Masahiro RajenDran, Kavirajan Bechtold, Peter Wang, Zaizhi Liu, Yimin Wirth, Volkmar Tomita, Hirofumi Ohfuchi, Wataru Kitoh, Akio Held, Isaac M. Zhao, Ming |
author_facet |
Borth, Hartmut Suarez, Max J. Wedi, Nils P. Frank, Helmut Nakamura, Hisashi Blackburn, Michael Ishiwatari, Masaki Williamson, David L. Lee, Myong-In Satoh, Masaki Kimoto, Masahide Hayashi, Yoshi-Yuki Takahashi, Yoshiyuki O. Mcgregor, John L. Molod, Andrew Stratton, Rachel Nakajima, Kensuke Watanabe, Masahiro RajenDran, Kavirajan Bechtold, Peter Wang, Zaizhi Liu, Yimin Wirth, Volkmar Tomita, Hirofumi Ohfuchi, Wataru Kitoh, Akio Held, Isaac M. Zhao, Ming |
author_sort |
Borth, Hartmut |
title |
The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile |
title_short |
The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile |
title_full |
The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile |
title_fullStr |
The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile |
title_full_unstemmed |
The Aqua-planet Experiment (APE): Response to Changed Meridional SST Profile |
title_sort |
aqua-planet experiment (ape): response to changed meridional sst profile |
publishDate |
2013 |
url |
http://hdl.handle.net/2060/20140005686 |
op_coverage |
Unclassified, Unlimited, Publicly available |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
CASI |
op_relation |
Document ID: 20140005686 http://hdl.handle.net/2060/20140005686 |
op_rights |
Copyright, Distribution under U.S. Government purpose rights |
_version_ |
1766195794150424576 |