Future projections of heat waves around Japan simulated by CMIP3 and high-resolution Meteorological Research Institute atmospheric climate models

Abstract

Future changes in heat wave characteristics around Japan are investigated using Coupled Model Intercomparison Project Phase 3 (CMIP3) model outputs, and high-resolution present-day (1979-2003) and future (2075-2099) climate simulations under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B emission scenario. The high-resolution simulations are conducted using 20, 60, and 180 km mesh atmospheric general circulation models (AGCMs), as well as a 5 km mesh regional climate model (RCM) nested within the 20 km mesh AGCM. The CMIP3 models project that the frequency of heat wave days (HWF) will increase 22.8, 22.3, and 26.5 d yr -1 in northern, eastern, and western Japan, respectively. The multimodel ensemble spread of future changes in HWF averaged around Japan is large (4-58 d yr -1). The spread is affected by the climate sensitivity of the models and the simulated magnitude of the interannual variation of the daily maximum temperature in present-day climate. In the atmospheric model simulations, the 5 and 20 km mesh models can qualitatively simulate observed HWF distributions, which are affected by steep backbone mountain ranges in Japan. The 5 and 20 km mesh models project large (>30 d yr -1) increases in HWF in the coastal areas of Japan. The duration of heat wave days is projected to increase in areas with increasing HWF. ©2013. American Geophysical Union. All Rights Reserved.