前期土壤湿度、海表面温度对中国夏季极端气温的预测能力评估

基于中国587站日最高、最低气温观测资料、月平均的ERA_interim土壤湿度（Soil Moisture，SM）再分析资料及扩展重建的海表面温度（Sea Surface Temperature，SST）资料（ERSST），对极端气温指数进行了定义，利用变形的典型相关分析和集合典型相关分析方法（Ensemble Canonical Correlation，ECC），分析了1979-2009年我国夏季极端气温与前期（春、前冬）SM、SST间的线性联系，建立了中国夏季极端气温预测模型，并对独立样本检验的效果进行了评估。结果表明：1）与中国夏季极端气温联系密切的前期SST异常的空间分布为类PDO（Pacific Decadal Oscillation）型，前期土壤湿度异常的区域为华南、青藏高原、东北和西北地区。2）交叉检验结果表明基于前冬预测因子的极端气温预测模型技巧高于春季，基于SM的极端气温预测模型技巧高于SST。3）独立样本检验表明基于前期SM、SST的ECC模型对中国东部夏季极端气温有一定的预测能力。因此，可以在夏季极端气温的预测业务中考虑前期SM、SST的影响。

Assessment of the summer extreme temperature predicting abilities in China for the previous soil moisture and sea surface temperature

In the present study,based on the maximum and minimum surface air temperatures of 587 stations in China,ERA-interim reanalysis soil moisture(SM) data and the extended reconstructed sea surface temperature(ERSST) data,the possible linear connection between the previous(spring and winter) sea surface temperature(SST),soil moisture and summer extreme temperature in China during the period of 1979-2009 is investigated.Statistical summer extreme temperature prediction models were developed using Barnett-Presisendorfer Canonical Correlation Analysis(BP-CCA),the Ensemble Canonical Correlation(ECC) method,and newly defined summer extreme temperature indices.In addition,the scores for the prediction models with predictive skill in the independent sample tests were calculated.The results showed that the summer extreme temperature in China has a close relationship with the previous SST and SM anomaly,while the spatial distribution of the previous SST anomaly was similar to the PDO pattern,and the previous SM anomaly in southern China,the Tibetan Plateau,northeastern China and the western part of northwestern China.The cross-validation tests showed that the BP-CCA models based on the previous winter predictors had higher predictive skill than those based on the previous spring predictors.Meanwhile,the BP-CCA models based on SM had higher predictive skill than those based on SST.Additionally,the independent sample tests showed that the ECC models based on the previous SM and SST had high predictive skill for summer extreme temperature in China.The study results revealed that the previous soil moisture and sea surface temperature contain valuable signals for summer extreme temperature in eastern China,and can be considered for inclusion in summer extreme temperature prediction operations.