海陆气协同作用对华北地区夏季高温热浪的影响

Effect of Land–Ocean–Atmosphere Interaction on Summer Heat Waves in North China

通过统计分析并利用WRF(Weather Research and Forecasting)模式进行多组敏感性试验研究发现,华北地区前期土壤湿度异常与夏季高温热浪的关系受到西太平洋副热带高压(西太副高)强度的影响。当西太副高异常偏强时,其西侧南风携带来自热带海洋的大量水汽至华北地区南部并增加该区域降水,不利于前期土壤湿度干异常的维持,从而限制了前期土壤湿度异常对高温热浪的贡献。相反,当西太副高偏弱时,华北地区前期土壤湿度干异常持续能力较强,有利于局地高温热浪的发展。西太副高强度与热带中东太平洋地区海温有关。当夏季热带太平洋海温异常处于暖位相时,西太副高强度相对较弱且华北地区南部降水偏少,有利于前期较干土壤条件的维持。此类情况下前期土壤湿度异常可以作为高温热浪的预测信号。

Based on statistical analysis and multiple sensitivity experiments using the Weather Research and Forecasting model,it is found that the relationship between preceding soil moisture anomalies and summer heat waves in North China is affected by the strength of the West Pacific Subtropical High(WPSH).When the WPSH is strong,the southerly winds on its west side carry a large amount of water vapor from the tropics to the southern parts of North China and increase the precipitation in the region,which is not conducive to maintain the preceding soil moisture dry anomaly,thereby restricting the contribution of the preceding soil moisture anomaly to the summer heat waves.In contrast,when the WPSH is weak,the soil moisture dry anomalies in North China can last for a longer duration and lead to heat waves.The WPSH intensity is associated with the Sea Surface Temperature(SST)in the tropical central−eastern Pacific.When the tropical Pacific SST exhibits positive anomaly in summer,the WPSH is relatively weak,and the precipitation in North China is low,which is conducive for maintaining dry soil conditions in North China.Under such scenarios,the preceding soil moisture anomaly can be employed as the prediction signal of heat waves in North China.