Predicting Present and Future Drought
Abstract

Abstract Author: Hyun-Suk Kang, Johan Lee, Won-Tae Kown, Won-Tae Yun

Abstract Title: A Regional Climate Model Simulation of the 1994 East Asian Summer Drought: Present Climate and a Possible Response to Increased SST from the A1B Scenario

Abstract: The climate over East Asia is strongly governed by the monsoon system and most countries in East Asia usually suffer from severe flood and/or drought due to the interannual and intraseasonal variability of the monsoon system. One of the outstanding features of the East Asian summer monsoon (EASM) system is the nonlinear interaction between multi-scale atmospheric motions from planetary to meso-scale, which leads to difficulty in accurate prediction of summer precipitation. During the several decades since late 1970s, the 1994 summer experienced a record-breaking heat and drought event in mid-latitudes between 30-40N over East Asia. Particularly, in summer of 1994, large negative anomalous precipitation areas extend from the southeastern flank of the Tibetan Plateau to the Korean Peninsula and the Japan along the zonal direction with a minimum value of about -4 mm/day centered near the Kyushu Island. Meanwhile, there are large positive anomalous precipitation areas over southern China as well as the northwestern Pacific Ocean south of 30N.

The influence on the 1994 EASM of an increased sea surface temperature, which is obtained from the ECHO-G AR4 simulation for A1B stabilization scenario, is investigated using a regional climate model based on the MM5. Compared to the standard version of MM5, a modified treatment of the lateral boundary condition, and a spectral nudging technique were implemented for long-term integration. The two-step nested domains consist of 54 and 18 km resolution and they comprise large parts of East Asia east to the Tibetan Plateau and the adjacent northwestern Pacific Ocean. Two ensemble experiments are designed: one is for the present climate simulation with the realistic SST and the other one is for the plausible future climate with the increased SST. Detail analyses for the precipitation, temperature, and corresponding atmospheric circulation will be discussed at the workshop.