Root Mean Square Difference in percentage (%) between the nine ensemble member change anomalies of the seasonal percentage rainfall for the median for 2036 - 2065 relative to 1976-2005, for the SON season, under the RCP 8.5 pathway

Root Mean Square Difference in percentage (%) between the nine ensemble member change anomalies of the seasonal percentage rainfall for the median for 2036 - 2065 relative to 1976-2005, for the SON season, 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.

本数据集针对南非区域，在RCP 8.5排放情景下，计算SON季节（9-11月，南半球春季）中，2036-2065年相较于1976-2005年的季节降水百分率中位数对应的9个集合成员变化距平的百分比形式均方根差（Root Mean Square Difference，RMSD）。为生成对应可视化图像，研究采用罗斯比中心区域模式（Rossby Centre regional model, RCA4）作为侧边界强迫工具，将9个粗分辨率全球环流模式（General Circulation Models, GCM）的模拟结果降尺度至0.44°×0.44°的更高空间分辨率。该模式模拟的日降水平均值被用于生成季节降水变化的投影，本次投影基于高排放情景RCP8.5开展，该情景预计到2100年大气二氧化碳浓度将达到约950ppm。本次计算得到的均方根差可反映模式模拟投影残差的不确定性范围，并可直观呈现投影不确定性较高与较低的空间区域分布特征。