Root Mean Square Difference between the nine ensemble member change anomalies of the annual mean near-surface (2m) temperature for the 90% percentile for 2066-2095 relative to 1976-2005, under the RCP 8.5 pathway

Root Mean Square Difference for annual mean near-surface (2m) temperature (°C) change from the 90th percentile projected for 2066-2095, 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 temperature 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.

本数据集表征南非地区在典型浓度路径8.5（Representative Concentration Pathway 8.5, RCP8.5）情景下，相较于当前基准期（1976-2005年），2066-2095年预测的第90百分位近地表（2米高度）年平均气温（℃）变化的均方根差（Root Mean Square Difference, RMSD）。为生成该可视化图像，研究采用罗斯比中心区域模式（RCA4）对9个粗分辨率大气环流模式（General Circulation Models, GCM）进行降尺度处理，将其空间分辨率提升至0.44°×0.44°，并以该区域模式作为侧边界强迫场。该模式模拟得到的日平均气温数据，被用于生成年际气温变化的预测结果。本次预测基于高排放情景（RCP8.5），该情景预计到2100年大气二氧化碳浓度将达到约950ppm。本研究计算得到的对应均方根差，可表征模式模拟预测残差的不确定性范围，并能从相对视角展示出预测不确定性高低不同的空间区域分布特征。