Multi-RCM near-term projections of summer climate extremes over East Asia

Abstract

A first systematic analysis was conducted to assess near-term future changes in climate extremes over East Asia during the summer season (June–August) using five regional climate model (RCM) simulations participating in the CORDEX-East Asia project (HadGEM3-RA, RegCM4, SNU-MM5, SNU-WRF, and YSU-RSM). The 20-year return values of extreme temperature and precipitation were compared between the present (1979–2005) and near-term future (2024–2049) periods, which were estimated using the generalized extreme value (GEV) analysis. Multi-RCM mean results show that temperature and precipitation will increase in both means and extremes and that the increase in precipitation extreme will follow the enhanced moisture availability with warming (~ 7% °C−1, Clausius–Clapeyron relation). It was found that the increases in GEV location parameter (mean intensity) and scale parameter (inter-annual variability) contribute dominantly to the increase in extremes of temperature and precipitation, respectively. Robust inter-RCM relations were observed between mean and extreme projections over East Asia and even on grid scales, more strongly for temperature. Model biases and future projections exhibit a significant relationship for temperature such that RCMs with warmer biases tend to predict stronger warming and vice versa. Results from three sub-regions (South Korea, Southern China, and Mongolia and northern China) consistently indicate that temperature increase involves an overall shift of the daily temperature distribution toward warmer conditions while precipitation increases are due to dominant increases in moderate-heavy rainfall events. Our multi-RCM assessment provides new insights to the uncertainty in future climate extremes over East Asia.