RegCM4模式对雄安及周边区域气候变化的集合预估

基于CSIRO-Mk3-6-0、EC-EARTH、HadGEM2-ES和MPI-ESM-MR共4个全球气候模式，分别驱动区域气候模式RegCM4，所进行的RCP4.5（典型浓度路径）中等排放情景下25 km较高水平分辨率东亚区域21世纪气候变化模拟结果，针对雄安新区及周边区域，在对当代（1986~2005）气候进行检验的基础上，进行了该区域未来气候变化的多模拟集合预估，并给出了模拟间的差别。结果表明:RegCM4可以较好地模拟出分析区域当代平均气温和降水的分布及年内月循环变化特征；对与气温相关的极端气候事件指数，日最高气温最高值（TXx）和日最低气温最低值（TNn），以及和降水相关的指数日最大降水量（RX1day）也有较好的模拟能力。雄安及周边区域未来平均气温、TXx和TNn将不断上升，高温热浪事件在增加的同时，低温事件将减少。未来分析区域平均降水量有所增加；而RX1day的增加更明显，且模拟间的一致性较好，不确定性相对较低，暴雨和洪涝事件的频率和强度均将增大。同时由于气温升高导致的潜在蒸发量相对于降水更大的增加，将使得区域水资源相对不足的现象加重。

Climate Change Projection over Xiong'an District and Its Adjacent Areas: An Ensemble of RegCM4 Simulations

We investigate the future climate changes in the 21st century in the Xiong''an District, recently established by the Chinese government, and its surrounding areas in North China based on 4 sets of RegCM4 climate change simulations over East Asia under the mid-range RCP4.5 (Representative Concentration Pathway) scenario. The model is run at a grid spacing of 25 km, and driven by the global model simulations of CSIRO-Mk3-6-0, EC-EARTH, HadGEM2-ES and MPI-ESM-MR, respectively. Validation of the present day (1986-2005) climate simulations is conducted first, followed by the ensemble projection of future changes along with the inter-simulation spread. Results show that the model can well capture both the spatial distributions of mean temperature and precipitation and their annual cycles. The model also shows a good performance in reproducing the temperature extreme indices of annual maximum value of daily maximum temperature (TXx) and annual minimum value of daily minimum temperature (TNn), and the precipitation extreme index of annual maximum 1-day precipitation (RX1day). Continuous warming and increases of TXx and TNn are found over Xiong''an District and its adjacent areas in the 21st century, indicating a warmer climate condition and more frequent hot spells in the future. With slight increases in mean precipitation, significant increases in RX1day with small inter-simulation spread are projected, indicating the intensification of precipitation extremes and more floods over the region. In the meantime, the greater increase in potential evapotranspiration compared to precipitation following the warming will lead to increases in water stress.