Affiliation:
1. Atmosphere and Ocean Research Institute University of Tokyo Kashiwa Japan
2. Meteorological Research Institute Tsukuba Japan
3. Lamont‐Doherty Earth Observatory Columbia University Palisades NY USA
4. Max Planck Institute for Meteorology Hamburg Germany
Abstract
AbstractThe Pacific Walker circulation (PWC) weakens under global warming in climate change projections, supported by a global hydrological constraint. However, the PWC has strengthened over the past decades despite ongoing global warming, and the cause has been a puzzle. Because PWC is coupled with the pattern of sea surface temperature (SST) in the tropical Pacific, quantifying the relative impact of SST pattern change and global warming on the past PWC trend is important. We show, using an atmosphere model driven by observed boundary conditions for 1979–2013 and a hypothetical uniform surface warming trend with varying magnitude, that the PWC scales with warming and weakens by 8% per °C, but this effect cannot overcome the SST pattern effect that intensifies the circulation. Further attribution experiments show that the past strengthening of PWC is explained directly by the SST warming pattern in the narrow equatorial band, about 30% of which is induced by the Indian Ocean.
Funder
Ministry of Education, Culture, Sports, Science and Technology
National Research Foundation of Korea
Publisher
American Geophysical Union (AGU)
Subject
General Earth and Planetary Sciences,Geophysics
Cited by
1 articles.
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