Seasonal mean near-surface (2m) temperature (°C) change from the 10% percentile projected for 2066 - 2095, relative to present (1976 - 2005), for JJA season under the RCP 4.5 pathway

Seasonal (JJA) mean near-surface (2m) temperature (°C) change from the 10% 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.

本数据集表征南非区域在典型浓度路径（Representative Concentration Pathway, RCP）4.5情景下，相对于基准期（1976-2005年），2066-2095年投影的近地面（2米）季平均（夏季JJA，即6-8月）气温（单位：℃）相较于该时段10%分位值的变化量。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）对9套粗分辨率全球环流模式（General Circulation Models, GCM）的结果进行降尺度处理，将其空间分辨率提升至0.44°×0.44°，并以RCA4作为侧边界强迫场。该模式模拟的日平均气温数据被用于生成季尺度气温变化的投影结果。本投影基于中低排放情景（RCP4.5）生成，该情景预计到2100年大气二氧化碳浓度约为560ppm。研究计算了对应的均方根偏差（Root Mean Square Deviation, RMSD），该指标可表征模式模拟残差投影结果的不确定性范围，并能相对直观地展示空间上投影不确定性高低的区域分布。