The importance of ocean dynamical feedback for understanding the impact of mid-high-latitude warming on tropical precipitation change

Masakazu Yoshimori, Ayako Abe-Ouchi, Hiroaki Tatebe, Toru Nozawa, Akira Oka

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

It has been shown that asymmetric warming between the Northern and Southern Hemisphere extratropics induces a meridional displacement of tropical precipitation. This shift is believed to be due to the extra energy transported from the differentially heated hemisphere through changes in the Hadley circulation. Generally, the column-integrated energy flux in the mean meridional overturning circulation follows the direction of the upper, relatively dry branch, and tropical precipitation tends to be intensified in the hemisphere with greater warming. This framework was originally applied to simulations that did not include ocean dynamical feedback, but was recently extended to take the ocean heat transport change into account. In the current study, an atmosphere-ocean general circulation model applied with a regional nudging technique is used to investigate the impact of extratropical warming on tropical precipitation change under realistic future climate projections. It is shown that warming at latitudes poleward of 40° causes the northward displacement of tropical precipitation from October to January. Warming at latitudes poleward of 60° alone has a much smaller effect. This change in the tropical precipitation is largely explained by the atmospheric moisture transport caused by changes in the atmospheric circulation. The larger change in ocean heat transport near the equator, relative to the atmosphere, is consistent with the extended energy framework. The current study provides a complementary dynamical framework that highlights the importance of midlatitude atmospheric eddies and equatorial ocean upwelling, where the atmospheric eddy feedback modifies the Hadley circulation resulting in the northward migration of precipitation and the ocean dynamical feedback damps the northward migration from the equator.

Original languageEnglish
Pages (from-to)2417-2434
Number of pages18
JournalJournal of Climate
Volume31
Issue number6
DOIs
Publication statusPublished - Mar 1 2018

Keywords

  • Climate change
  • Climate models
  • Hadley circulation
  • Hydrologic cycle

ASJC Scopus subject areas

  • Atmospheric Science

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