Seasonal mean near-surface (2m) temperature (°C) change from the 90% percentile projected for 2036-2065, relative to present (1976 - 2005), for JJA season under the RCP 8.5 pathway

Seasonal (JJA) mean near-surface (2m) temperature (°C) change from the 90% 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.

本数据集聚焦南非区域，针对典型浓度路径8.5（RCP 8.5）情景，计算得到相对于基准时段（1976年-2005年），2036年-2065年预估的90%分位数对应的近地面（2米高度）气温（单位：摄氏度）的季节（JJA，即6、7、8月）平均变化量。为生成对应可视化图像，研究人员使用罗斯比中心区域气候模式（RCA4），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°的空间分辨率，以该模式作为侧边界强迫场。该模式模拟的逐日气温平均值被用于生成季节变化的气候预估结果。本次预估基于高排放情景（RCP8.5），该情景预计到2100年大气二氧化碳浓度约达950ppm。研究同时计算了相关的均方根偏差（Root Mean Square Deviation, RMSD），其结果可表征预估模式模拟残差的不确定性范围，并能从相对视角区分出预估不确定性较高与较低的空间区域。