三类ENSO相位下中国暖季降水时空变化特征

Spatial and Temporal Characteristics of Warm-Season Precipitation in China and Its Relationship with ENSO

基于全国2048个站点1961—2019年逐日降水观测数据,采用10个降水指标刻画暖季降水时空特征,分析了东部厄尔尼诺(EP)、中部厄尔尼诺(CP)和拉尼娜(LN)事件对中国暖季降水时空特征的影响。研究结果表明:(1)过去59年,我国暖季降水总量、降水强度和极端降水等特征总体上均呈增加趋势,主要表现在东南和西北地区,而华北地区呈减少趋势。(2)东南和西北地区暖季可降水量的增加和增强的水汽通量为降水的形成提供了有利的水汽条件;而华北地区暖季可降水量趋于减少和水汽通量减弱均不利于降水的形成。(3)ENSO事件对我国暖季降水时空特征有显著调节作用。位于中国东北的气旋带来干冷空气和水汽通量减少使得在EP起始年份华北地区暖季降水总量、降水强度和极端降水等均趋于减少。东南地区对LN事件较为敏感,在LN起始年份,位于东南地区的反气旋源源不断的将暖湿气流输送到该区域,为降水增加提供了充沛的水汽条件。

Based on daily observation data over 1961-2019 from 2048 stations across China,10 precipitation indexes were used to characterize the warm-season precipitation structure characteristics.We analyzed the influence of Eastern El Nino(EP),Central El Nino(CP)and La Nina(LN)events on the spatiotemporal characteristics of warm season precipitation in China.The results show that over the past 59 years,the total amount,intensity and extreme precipitation of China's warm season have all shown an increasing trend on the whole,mainly in the southeast and northwest regions,while those in north China show a decreasing trend.What's more,the increase of the warm season precipitation and the enhanced water vapor transport in the southeast and northwest regions provide favorable water vapor conditions for the formation of precipitation.However,in North China,the trend of decreasing precipitation in the warm season and the weakening of water vapor transport are not conducive to the formation of precipitation.In addition,ENSO event has a significant regulating effect on the spatiotemporal characteristics of warm season precipitation in China.Due to the decrease of dry cold air and water vapor transport brought by the cyclone in northeast China,the total amount of warm season precipitation,precipitation intensity and extreme precipitation in North China tend to decrease in the initial year of EP.In the year when EP disappeared,the warm and humid airflow from southeast China provided abundant water vapor for the increase of warm season precipitation in southeast and North China.In the beginning year of LN,anticyclone located in the southeast region continuously transported warm and moist air to this region,providing abundant moisture conditions for precipitation increase.