Root Mean Square Difference between the nine ensemble member change anomalies of the seasonal total rainfall for the median 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 median 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.

本数据集表征南非区域在典型浓度路径8.5（RCP 8.5）情景下，相对于基准期（1976-2005年）的2036-2065年季节（JJA）降水（月均毫米）预估中值的均方根差（Root Mean Square Difference, RMSD）。本图像的生成流程为：选取9个粗分辨率全球环流模式（General Circulation Models, GCM），通过罗斯比中心区域模式（RCA4）对其侧边界进行强迫，将其降尺度至0.44°×0.44°的更高空间分辨率。基于该模式模拟的日降水均值，可生成季节尺度降水变化的预估结果。本次预估采用的高排放情景（RCP 8.5），预计至2100年时大气二氧化碳浓度将达到约950ppm。本次计算得到的对应均方根差，可表征模式模拟预估残差的不确定性范围，并直观展现空间区域内预估不确定性的高低分布特征。