Root Mean Square Difference between the nine ensemble member change anomalies of the seasonal total rainfall for the 90% percentile for 2036 - 2065 relative to 1976-2005, for the SON season, under the RCP 4.5 pathway

Root Mean Square Difference for seasonal (SON) rainfall (mm per month) change from the 90% percentile 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 seasonal 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.

本数据集针对南部非洲区域，在典型浓度路径（Representative Concentration Pathway，RCP）4.5情景下，计算以1976-2005年为基准期的当前时段相对的2036-2065年季节（SON，即9月、10月、11月）降雨量（单位：毫米/月）90%分位预测值的均方根差（Root Mean Square Difference，RMSD）。为生成对应图像，采用罗斯比中心区域模式（Rossby Centre regional model, RCA4）对其侧边界进行强迫，将9个粗分辨率全球环流模式（General Circulation Models, GCM）降尺度至0.44°×0.44°的更高空间分辨率；该模式模拟的日降雨量平均值被用于生成季节降雨变化的预测结果。本次预测基于中低强度的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。所计算得到的相关均方根差，可展示模式模拟预测残差的不确定性范围，并能相对呈现出预测不确定性高低各异的空间区域分布特征。