东南亚地区未来气候变化的区域气候模式预估

Climate Change Projection over Southeast Asia Based on the Regional Climate Model Simulation

在联合区域气候降尺度试验CORDEX(Coordinated Regional Climate Downscaling Experiment)的框架下,使用全球气候模式MPI-ESM-MR(简称MPI)的模拟结果,驱动区域气候模式RegCM4(Regional Climate Mode version 4),开展了在中等温室气体排放路径RCP4.5下的东南亚区域21世纪气候变化预估试验。试验中模式的水平分辨率为25 km×25 km,积分时间为1981~2099年。模式对东南亚区域当代(1986~2005年)气候的模拟结果表明:MPI与RegCM4对这一区域年平均气温、降水的空间分布特征均具有较好的模拟能力;相比于全球模式,高分辨率的RegCM4提供了空间分布上更为精细的气候信息,但其模拟的气温存在系统性冷偏差,对降水的模拟则普遍偏多。对未来气候变化的预估显示,MPI与RegCM4预估的未来气温均一致表现为增加,至21世纪末期(2081~2099年),预估的区域年平均气温升高幅度分别为1.8℃和1.7℃。二者对降水的预估则存在较大差异,MPI预估的年平均降水有不同程度增加,而RegCM4则出现减少现象,特别是在海洋大陆地区。两者预估的21世纪末期区域年平均降水变化分别5%(90 mm)和−6%(−147 mm)。RegCM4对极端温度指数的预估结果表明:未来东南亚地区高温热浪事件将持续增多,极端冷事件相应减少;在海洋大陆地区,降水强度和连续无雨日数出现同时增加现象,表明该地区洪涝和干旱风险未来均将增大。

We investigated the future climate change over a coordinated regional climate downscaling experiment(CORDEX)in the Southeast Asia region using a regional climate model(RegCM4)in this study.The model is driven by the global model of MPI-ESM-MR(hereinafter referred to as MPI)at a grid spacing of 25 km under the middle range representative concentration pathway of RCP4.5 with the time period of 1981–2099.Results show that MPI and RegCM4 could reproduce the spatial pattern and magnitude of annual mean temperature and precipitation well over the region.Compared to driving MPI,RegCM4 can provide finer spatial details of the climate variables due to its much higher resolution than MPI;however,it has a prevailing cold bias for temperature and wet bias for precipitation during the simulations.The projected future changes using MPI and RegCM4 show an increase in the annual mean temperature.Moreover,the regional average warming toward the end of the 21st century(2081–2099)is predicted to be 1.8℃and 1.7℃using MPI and RegCM4,respectively.Meanwhile large differences are observed in their precipitation projections,more significant over the Maritime Continent compared to other regions.The precipitation projected using MPI shows an increase,whereas that using RegCM4 model show a considerable decrease.By the end of the 21st century,the projected changes in the regional mean precipitation over Southeast Asia using MPI and RegCM4 are 5%(90 mm)and−6%(−147 mm),respectively.An analysis of the extreme indices simulated with the RegCM4 shows a large frequency of heat waves in the future.The projected increases in precipitation intensity and consecutive dry days over the Maritime Continent indicate high risks of flood and drought over the region.