摘要
根据中国国家气象信息中心提供的1961—2016年2400多站的逐日降水观测数据,分析了厄尔尼诺对长江中下游地区夏季持续性降水结构的影响。发现长江中下游地区的降水主要以5d及以内的降水事件为主,其强度主要分布在4—24mm/d;5d以上降水所占比例相对较小,而其强度主要分布在12—24mm/d。其中,长江中下游地区夏季大于5d的降水事件(长持续性降水事件)所占比例和强度在长江以南地区要大于长江以北地区。同时,在厄尔尼诺的影响下,长江以南地区的降水结构从2—5d持续性降水事件(短持续性降水事件)和1d的降水事件(非持续性降水事件)向长持续性降水事件转变,且其强度增加。而长江以北地区,以湖北为主,降水结构存在从非持续性向短持续性降水事件转变的现象,短持续性降水事件的强度也略有增强。因此,厄尔尼诺使得长江中下游地区的降水事件更多地以持续性降水为主,不同持续性降水事件的强度加强。进一步分析发现厄尔尼诺次年西太平洋副热带高压西伸加强,与其相关的东南季风所输送的水汽也有所加强。同时,中高纬度阻塞高压环流形势稳定维持。受这些因子的共同作用,最终导致长江中下游地区夏季降水持续性延长和降水强度加强。而这将给长江中下游地区的农作物种植和经济发展等带来较严重的影响,使防洪、防涝工作面临严峻的挑战。
The impacts of El Nio on summer persistent precipitation structure in the middle and lower reaches of the Yangtze River（MLRYZR）are analysised based on daily gauge precipitation data collected at more than 2400 stations from 1961 to 2016.Precipitation events are found to mainly persist for 1 to 5 days with intensity ranging from 4 to 24 mm/d,while the precipitation events persisting beyond 5 days are relatively less with intensity ranging from 12 to 24 mm/d.The frequency and intensity of long persistent events（LPE：〉5 days）are larger to the south of the Yangtze River than to the north.Furthermore,the structure of persistent precipitation is found to change under the impact of El Nio.To the south of the MLRYZR,precipitation events have changed from short（SPE：2 to 5 days）and non-persistent events（NPE：1 day）to LPE,and the intensity of LPE enhences.To the north of the MLRYZR,precipitation events have changed from NPE to SPE,especially in Hubei province,and the intensity of SPE slightly increases.Hence,El Nio can enhence the persistence and intensity of precipitation events.Further analysis shows that El Nio can promote the westward extension of the western Pacific subtropical high,resulting in abundant water vapor transport from the northwest of the subtropical high to MLRYZR.Meanwhile,the block high remains stable in the middle and high latitudes.These mechanisms finally lead to enhancements in persistence and intensity of precipitation events,bringing serious influences on agriculture and economy in MLRYZR.
作者
余荣
翟盘茂
YU Rong;ZHAI Panmao(Key Laboratory of Meteorological Disaster of Ministry of Education, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China;State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China)
出处
《气象学报》
CAS
CSCD
北大核心
2018年第3期408-419,共12页
Acta Meteorologica Sinica
基金
国家自然科学基金面上项目(41575094)
江苏省研究生科研与实践创新计划项目(KYLX16_0941)
关键词
厄尔尼诺
长江中下游地区
持续性降水结构
El Nino
The middle and lower reaches of the Yangtze River
Persistent precipitation structure
