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 4.5 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 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.

针对南非地区典型浓度路径4.5（Representative Concentration Pathway 4.5, RCP 4.5）情景，计算9-11月（September-October-November, SON）季节中，2036-2065年相较1976-2005年基准期的季节降雨百分率中位数对应的9个集合成员变化距平的百分比均方根差（Root Mean Square Difference, RMSD）。为生成该可视化图像，研究人员借助罗斯比中心区域模式（Rossby Centre regional model, RCA4），将9个粗分辨率通用环流模式（General Circulation Models, GCM）降尺度至0.44°×0.44°的更高空间分辨率，并以该模式作为侧边界强迫场。该模式模拟的日降雨量平均值被用于生成季节变化预估情景。本次预估采用中低辐射强迫（RCP4.5）路径，该路径预计到2100年时大气二氧化碳浓度将达到约560ppm。本次计算得到的均方根差（RMSD）能够表征预估模式模拟残差值的不确定性范围，并可从相对视角揭示具有较高与较低预估不确定性的空间区域分布特征。