Root Mean Square Difference between the nine ensemble member change anomalies of the seasonal mean near-surface (2m) temperature for the 90% percentile for 2066 - 2095 relative to 1976-2005, for the JJA season, under the RCP 4.5 pathway

Root Mean Square Difference for seasonal (JJA) mean near-surface (2m) temperature (°C) change from the 90% percentile projected for 2066-2095, relative to present (1976 - 2005), 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 temperature 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.

本数据集为南部非洲区域在典型浓度路径4.5（Representative Concentration Pathway 4.5，RCP4.5）情景下，相对于基准期（1976-2005年），2066-2095年季节（JJA，即6、7、8月）近地面（2米）气温变化的90%分位数对应的均方根差（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（Rossby Centre regional model, RCA4），通过强迫其侧边界条件，将9套粗分辨率全球环流模式（General Circulation Models, GCM）的结果降尺度至0.44°×0.44°的精细空间分辨率。该模式模拟的日平均气温数据被用于生成季节尺度气温变化的预估结果。本次预估基于中低强度的典型浓度路径（RCP4.5）情景，该情景预计到2100年大气二氧化碳浓度约为560ppm。所计算得到的对应均方根差可表征模式模拟预估残差的不确定性范围，并能相对直观地展现不同空间区域预估不确定性的高低分布特征。