Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Oral

A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG39] Multi-scale ocean-atmosphere interaction in the tropical Indo-Pacific region

Mon. May 21, 2018 10:45 AM - 12:15 PM 201B (2F International Conference Hall, Makuhari Messe)

convener:Yukiko Imada(Meteorological Research Institute, Japan Meteorological Agency), Tomoki Tozuka(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Hiroki Tokinaga(京都大学防災研究所, 共同), Yu Kosaka(Research Center for Advanced Science and Technology, University of Tokyo), Chairperson:Imada Yukiko(Meteorological Research Institute), Tokinaga Hiroki(京都大学白眉センター)

11:45 AM - 12:00 PM

[ACG39-11] Global temperature fluctuations due to tropical Pacific decadal variability and their uncertainty

*Yu Kosaka1, Shang-Ping Xie2, Chuan-Yang Wang3, Yukiko Imada4 (1.Research Center for Advanced Science and Technology, University of Tokyo, 2.Scripps Institution of Oceanography, University of California San Diego, 3.Ocean University of China, 4.Meteorological Research Institute)

Keywords:Global warming, ENSO, IPO

Marked slowdown of global mean surface temperature (GMST) increase from the late 1990s to mid-2010s highlights importance of internal climate variability in the tropical Pacific and its global influence. Evaluation of this tropical Pacific influence is therefore critical for global warming attribution. The present study assesses the global temperature variability associated with the tropical Pacific sea surface temperature (SST) variability based on pre-industrial control experiments by 25 CMIP5 climate models and the tropical Pacific pacemaker experiments by 3 models.

All the models commonly present larger GMST anomalies in decadal than interannual variability associated with 1ºC increase of tropical Pacific SST. This time-scale dependence arises from wider meridional extent of SST anomalies in the tropical and subtropical Pacific and larger sensitivity in the mid- and high latitudes. The former has been recognized as the structural difference between El Niño-Southern Oscillation and the Interdecadal Pacific Oscillation. The latter is due to the longer intrinsic time scales of the extratropical oceans and sea ice. Furthermore, decadal GMST sensitivity is strikingly diverse among models, in contrast to the interannual variability. This diversity is pronounced in the Northern high latitudes and the Southern Ocean. Our analysis on Arctic sea ice variations demonstrates the time-scale dependence and multi-model diversity. The model uncertainty could lead to inconclusive attribution results on the recent global warming slowdown.