Root Mean Square Difference between the nine ensemble member change anomalies of the seasonal mean near-surface (2m) temperature for the 10% percentile for 2036 - 2065 relative to 1976-2005, for the MAM season, under the RCP 8.5 pathway

Root Mean Square Difference for seasonal (MAM) mean near-surface (2m) temperature (°C) change from the 10% percentile 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 temperature 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.

本数据集表征南非地区在典型浓度路径8.5（Representative Concentration Pathway 8.5, RCP8.5）情景下，季节（MAM）近地表（2米）温度变化的均方根差（Root Mean Square Difference, RMSD）；该温度变化为2036-2065年预测气温的10%分位数相较于1976-2005年基准时段的差值。为生成对应图像，研究采用罗斯比中心区域模式（Rossby Centre regional model, RCA4）对9个粗分辨率全球环流模式（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°，并以该模式的侧向边界场作为强迫驱动条件。该模式模拟逐日平均气温，并以此生成季节尺度的气候变化预测结果。本次预测采用高排放情景RCP8.5，该情景预计至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预测残差的不确定性范围，并能直观展现不同空间区域的投影不确定性高低分布特征。