The aqua-planet experiment (APE)

Response to changed meridional SST profile

David L. Williamson, Michael Blackburn, Kensuke Nakajima, Wataru Ohfuchi, Yoshiyuki O. Takahashi, Yoshi Yuki Hayashi, Hisashi Nakamura, Masaki Ishiwatari, John L. McGregor, Hartmut Borth, Volkmar Wirth, Helmut Frank, Peter Bechtold, Nils P. Wedi, Hirofumi Tomita, Masaki Satoh, Ming Zhao, Isaac M. Held, Max J. Suarez, Myong In Lee & 8 others Masahiro Watanabe, Masahide Kimoto, Yimin Liu, Zaizhi Wang, Andrea Molod, Kavirajan Rajendran, Akio Kitoh, Rachel Stratton

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)57-89
Number of pages33
JournalJournal of the Meteorological Society of Japan
Volume91
Issue number1 A
DOIs
Publication statusPublished - Nov 6 2013

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temperature profile
sea surface temperature
planet
experiment
intertropical convergence zone
atmospheric general circulation model
temperature gradient
simulation
Hadley cell
orography

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

Williamson, D. L., Blackburn, M., Nakajima, K., Ohfuchi, W., Takahashi, Y. O., Hayashi, Y. Y., ... Stratton, R. (2013). The aqua-planet experiment (APE): Response to changed meridional SST profile. Journal of the Meteorological Society of Japan, 91(1 A), 57-89. https://doi.org/10.2151/jmsj.2013-A03

The aqua-planet experiment (APE) : Response to changed meridional SST profile. / Williamson, David L.; Blackburn, Michael; Nakajima, Kensuke; Ohfuchi, Wataru; Takahashi, Yoshiyuki O.; Hayashi, Yoshi Yuki; Nakamura, Hisashi; Ishiwatari, Masaki; McGregor, John L.; Borth, Hartmut; Wirth, Volkmar; Frank, Helmut; Bechtold, Peter; Wedi, Nils P.; Tomita, Hirofumi; Satoh, Masaki; Zhao, Ming; Held, Isaac M.; Suarez, Max J.; Lee, Myong In; Watanabe, Masahiro; Kimoto, Masahide; Liu, Yimin; Wang, Zaizhi; Molod, Andrea; Rajendran, Kavirajan; Kitoh, Akio; Stratton, Rachel.

In: Journal of the Meteorological Society of Japan, Vol. 91, No. 1 A, 06.11.2013, p. 57-89.

Research output: Contribution to journalArticle

Williamson, DL, Blackburn, M, Nakajima, K, Ohfuchi, W, Takahashi, YO, Hayashi, YY, Nakamura, H, Ishiwatari, M, McGregor, JL, Borth, H, Wirth, V, Frank, H, Bechtold, P, Wedi, NP, Tomita, H, Satoh, M, Zhao, M, Held, IM, Suarez, MJ, Lee, MI, Watanabe, M, Kimoto, M, Liu, Y, Wang, Z, Molod, A, Rajendran, K, Kitoh, A & Stratton, R 2013, 'The aqua-planet experiment (APE): Response to changed meridional SST profile', Journal of the Meteorological Society of Japan, vol. 91, no. 1 A, pp. 57-89. https://doi.org/10.2151/jmsj.2013-A03
Williamson, David L. ; Blackburn, Michael ; Nakajima, Kensuke ; Ohfuchi, Wataru ; Takahashi, Yoshiyuki O. ; Hayashi, Yoshi Yuki ; Nakamura, Hisashi ; Ishiwatari, Masaki ; McGregor, John L. ; Borth, Hartmut ; Wirth, Volkmar ; Frank, Helmut ; Bechtold, Peter ; Wedi, Nils P. ; Tomita, Hirofumi ; Satoh, Masaki ; Zhao, Ming ; Held, Isaac M. ; Suarez, Max J. ; Lee, Myong In ; Watanabe, Masahiro ; Kimoto, Masahide ; Liu, Yimin ; Wang, Zaizhi ; Molod, Andrea ; Rajendran, Kavirajan ; Kitoh, Akio ; Stratton, Rachel. / The aqua-planet experiment (APE) : Response to changed meridional SST profile. In: Journal of the Meteorological Society of Japan. 2013 ; Vol. 91, No. 1 A. pp. 57-89.
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AU - Williamson, David L.

AU - Blackburn, Michael

AU - Nakajima, Kensuke

AU - Ohfuchi, Wataru

AU - Takahashi, Yoshiyuki O.

AU - Hayashi, Yoshi Yuki

AU - Nakamura, Hisashi

AU - Ishiwatari, Masaki

AU - McGregor, John L.

AU - Borth, Hartmut

AU - Wirth, Volkmar

AU - Frank, Helmut

AU - Bechtold, Peter

AU - Wedi, Nils P.

AU - Tomita, Hirofumi

AU - Satoh, Masaki

AU - Zhao, Ming

AU - Held, Isaac M.

AU - Suarez, Max J.

AU - Lee, Myong In

AU - Watanabe, Masahiro

AU - Kimoto, Masahide

AU - Liu, Yimin

AU - Wang, Zaizhi

AU - Molod, Andrea

AU - Rajendran, Kavirajan

AU - Kitoh, Akio

AU - Stratton, Rachel

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N2 - 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.

AB - 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.

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