Root Mean Square Difference between the nine ensemble member change anomalies of the seasonal total rainfall for the 10% percentile for 2036 - 2065 relative to 1976-2005, for the JJA season, under the RCP 8.5 pathway

Root Mean Square Difference for Seasonal (JJA) rainfall (mm per month) change from the 10% percentile projected for 2036-2065, 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.

本数据集聚焦南非地区RCP 8.5排放路径下的降雨变化预估不确定性：其核心指标为2036-2065年季节性（6-8月，JJA）降雨量（单位：毫米/月）相较于1976-2005年基准期的变化量的10%分位数所对应的均方根差（Root Mean Square Difference, RMSD）。
本图像的生成流程如下：采用罗斯比中心区域模式（Rossby Centre regional model, RCA4）作为降尺度工具，通过其侧边界强迫场，将9个粗分辨率全球环流模式（General Circulation Models, GCM）的结果降尺度至0.44°×0.44°的更高空间分辨率；基于该模式模拟的日降雨量平均值，可生成季节性降雨变化的预估结果。本次预估采用的高排放路径（RCP8.5）对应至2100年二氧化碳浓度约950ppm的情景。本次计算得到的对应均方根差，可展示模式模拟预估残差的不确定性范围，并直观呈现空间上预估不确定性高低的区域分布特征。