Root Mean Square Difference between the nine ensemble member change anomalies of the seasonal total rainfall for the median for 2066-2095 relative to 1976-2005, for the DJF season, under the RCP 8.5 pathway

Root Mean Square Difference for seasonal (DJF) rainfall (mm per month) change from the median projected for 2066-2095, relative to present (1976 - 2005), under the RCP 8.5 pathway for the southern African region. To generate the image, nine coarse General Circulation Models (GCM) are downscaled to a finer spatial resolution (0.44°x 0.44°) using the Rossby Centre regional model (RCA4) forcing its lateral boundaries. The model simulated daily rainfall averages, which are used to generate projections of seasonal change. The projections are generated using the high (RCP8.5) pathway which associates CO2 concentrations of approximately 950ppm by the year 2100. The associated RMSD it calculated and shows the uncertainty range of the projected model simulated residual values, and gives a relative perspective of spatial areas associated with higher and lower projection uncertainties.

本数据集聚焦南部非洲区域，针对典型浓度路径8.5（RCP 8.5）情景下，2066-2095年季节（DJF，即12月、1月、2月）降雨（单位：毫米/月）变化相对于基准期（1976-2005年）投影中位数的均方根差（Root Mean Square Difference, RMSD）。为生成该可视化成果，研究团队采用罗斯比中心区域模式（RCA4）对9个粗分辨率大气环流模式（General Circulation Models, GCM）进行降尺度处理，将其空间分辨率提升至0.44°×0.44°，并以该模式的侧边界作为强迫条件。该模式模拟的日降雨均值被用于生成季节尺度降雨变化的未来投影。本次投影基于高排放情景RCP8.5路径生成，该情景预计至2100年大气二氧化碳浓度将达到约950ppm。本研究计算得到的对应均方根差（RMSD）可展示投影模型模拟残差的不确定性范围，并能直观呈现不同空间区域投影不确定性的高低分布差异。