The asymmetry of air temperature: A new potential method to predict precipitation frequency

There is a significant bias in the precipitation frequency (PF) obtained from numerical model simulations. In this study, the authors use the temperature asymmetry (TA) as an indirect indicator to predict PF. The empirical orthogonal function method is used to analyze the spatiotemporal correlation of TA and PF at interannual and interdecadal time scales. Furthermore, the authors explore using the TA to improve PF prediction in CMIP6 models. Results show that (1) on an interannual time scale, PF and TA show good spatial and temporal correlations; (2) PF and TA exhibit similar modal transitions on interdecadal time scales; and (3) using TA as an indirect indicator can significantly improve the prediction of PF. The TA may be an indirect method for improving precipitation predictions. 摘要 在数值模拟中日降水频率具有明显的偏差. 利用EOF方法, 分析了在年际和年代际尺度上降水频率与气温的非对称性的时空相关特征, 并探索使用非对称性改进模式降水频率预测的方法. 得到以下结论: 1) 在年际尺度上, 降水频率和气温的非对称的前两个模态的空间和时间相关系数良好; 2) 在年代际尺度上两者展现出相似的模态转变; 3) 非对称性作为降水频率的间接指标可以明显的改进降水频率的预测.