Root Mean Square Difference between the nine ensemble member change anomalies of the annual total rainfall for the median for 2036-2065 relative to 1976-2005, under the RCP 4.5 pathway

Root Mean Square Difference for annual total rainfall (mm per year) change from the median projected for 2036-2065, relative to present (1976 - 2005), under the RCP 4.5 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 annual change. The projections are generated using the medium to low (RCP4.5) pathway which associates CO2 concentrations of approximately 560ppm 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.本数据集为南部非洲区域在典型浓度路径4.5（RCP 4.5）情景下，相对于基准时段（1976-2005年），2036-2065年降水投影中值对应的年总降水量（单位：毫米/年）变化的均方根差（Root Mean Square Difference，RMSD）。为生成该可视化图像，研究采用罗斯比中心区域模式（RCA4）对9台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°，并以该模式作为侧边界强迫场。该模式模拟的日降水量平均值被用于构建年际降水变化的投影序列。本次投影基于中低排放强度的RCP4.5情景生成，该情景预计到2100年大气二氧化碳浓度将达到约560ppm。所计算得到的对应均方根差可展示模式模拟投影残差的不确定性范围，并能相对直观地呈现不同空间区域投影不确定性的高低分布特征。