近60年华北春季干旱特征及其与北大西洋海表温度的关系

利用观测资料统计分析和CAM5.3数值模拟相结合的方法,基于标准化降水蒸散指数(Standardized Precipitation Evapotranspiration Index,SPEI),分析了1955-2018年华北地区春季干旱特征,并重点探讨了对北大西洋产生的影响.华北春季干旱的主要空间分布型为全区一致型,...

Characteristics of spring drought in North China over the past 60 years and its relationship with sea surface temperature in the North Atlantic

Based on the standardized precipitation evapotranspiration index (SPEI),this study applied statistical observational analysis and numerical simulations (CAM 5.3),so as to analyze the characteristics of spring drought in North China (NC) from 1955 to 2018,as well as the impacts of the North Atlantic (NA).The results showed that the main spatial distribution pattern of spring drought in NC was uniform throughout the entire region,and,in the past 60 years,there were 22 drought years and 14 flood years.The main atmospheric circulations of the NC spring drought years were the enhanced continental high,weakened upper westerly jet,and downward movement in NC.Aside from these,both observational analysis and numerical simulation results showed that the warm sea surface temperature (SST) in the NA could cause spring drought in NC.The mechanism is as follows:warm SST in NA can lead to a "+-+" wave train such as the "Silk Road Pattern" with its center above the NA,Europe-western Asia and NC;this wave train would then enhance the continental high over NC,which could cause the downward movements;these downward movements are not conducive to precipitation,and will lead to the air undergoing adiabatic heating;in addition,NC lies to the south of the upper anticyclone circulation,which leads to NC being controlled by the northeast airflow,thus signifying that the warm and humid airflow from the Southwest is weakened.In summary,the wave train causes the high temperature and reduced rain in NC,which is conducive to drought.When the SST in the NA grows cold,the center of the wave train would be reversed,which in turn would cause the continental high over NC to weaken.