中国区域性大气加权平均温度线性模型精度评估

以欧洲中期天气预报中心的再分析资料ERA5为参考数据，评估由探空数据建立的中国区域88个单站大气加权平均温度（T_m）与地表气温（T_s）线性关系模型的精度.各站T_m-T_s线性模型计算的T_m（计算值）与ERA5 气压层数据积分所得的T_m（参考值）间偏差均方根值（RMSE）为1.8~5.5 K.不同站模型计算值与参考值间存在-1.22~4.54 K 的系统性偏差，且绝大多数测站（82个站）系统性偏差为正值，即模型计算值总体上大于参考值.补偿各站系统性偏差后，模型计算值与参考值间RMSE降为1.5~3.5 K.与使用中国区域统一模型相比，使用单站模型平均能提高0.6 K的T_m计算精度，尤其在中国西部、西北和内蒙区域，精度提高可达1~3.9 K.对所有测站模型计算值和参考值间偏差时序进行分析，发现超过半数测站的偏差存在明显季节性变化.

On the accuracy of regional weighted mean temperature linear models over China

We used the ERA5 data from European Centre for Medium-Range Weather Forecasts to evaluate the accuracy of regional weighted mean temperature (T_m) linear models over China.These models were derived from historical radiosonde data of 88 Chinese stations.For these stations,the root mean square errors (RMSEs) between single-station model derived T_m and ERA T_m are 1.8-5.5 K,and -1.22-4.54 K of which are system biases.For 82 out of the total 88 stations,the system biases are positive,indicating that the model derived values are generally larger than ERA T_m.The RMSEs can be reduced to 1.5-3.5 K after removal of the system biases.On average,the RMSE of T_m from single-station model is smaller than that from the unified model by 0.6 K,suggesting that single-station models are generally more accurate than the unified model.In western China,northwestern China and Inner Mongolia,the accuracy can be improved by 1-3.9 K using single station models compared with the unified model.Time series of the biases between model derived T_m and ERA T_m show obvious seasonal cycles for over half of the stations.