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 8.5 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 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 annual 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.

本数据集为南非区域在典型浓度路径8.5（RCP 8.5）情景下，相对于当前基准期（1976-2005年），2036-2065年预估中值对应的年总降雨量（单位：毫米/年）变化的均方根差（Root Mean Square Difference）。为生成该可视化图像，研究采用罗斯比中心区域模式（Rossby Centre regional model，RCA4）作为侧边界强迫场，对9个粗分辨率大气环流模式（General Circulation Models，GCM）的结果进行降尺度处理，将其空间分辨率提升至0.44°×0.44°。该区域模式模拟的日降雨量平均值被用于计算年降雨量变化的预估结果。本次预估基于高排放典型浓度路径8.5（RCP8.5）情景，该情景下至2100年大气二氧化碳浓度将达到约950ppm。本次研究计算得到的对应均方根差（RMSD）可反映模式模拟预估残差的不确定性范围，并能直观展现不同空间区域预估不确定性的高低分布特征。