1961-2012年盛夏持续性旱涝异常分析及预测  

Analysis and prediction on abnormal persistent drought and flood and prediction in midsummer in southeast of Northwest China from 1961 to 2012

作　　者：杨金虎[1,2] 孙兰东[3] 林婧婧[1] 杨建玲 

机构地区：[1]中国气象局兰州干旱气象研究所甘肃省干旱气候变化与减灾重点实验室中国气象局干旱气候变化与减灾重点开放实验室,兰州730020 [2]宁夏气象科学研究所,银川750002 [3]上海区域气候中心,上海200030

出　　处：《资源科学》2015年第10期2078-2085,共8页Resources Science

基　　金：国家重点基础研究发展计划项目(2013CB430206);公益性行业(气象)科研专项(GYHY201306027)

摘　　要：利用国家气象信息中心提供的中国西北东部地区1961-2012年盛夏(7-8月)156个台站逐月降水量、国家气候中心提供的74个环流指数以及NCAR/NCEP月平均再分析资料,通过定义盛夏持续性旱涝指数,对中国西北东南部地区盛夏持续性旱涝异常的环流特征进行分析,并建立预测模型,结果表明:近半个世纪来西北东南部盛夏持续性干旱事件发生略多于持续性洪涝事件,但持续性洪涝事件的强度明显强于持续性干旱事件。在持续性涝年乌拉尔山脊明显偏强,西太平洋副热带高压偏西偏强,南亚高压偏东偏强,而且表现为双峰型,低层风场表现为辐合,高层表现为辐散,垂直场上表现为上升运动,且来自印度洋和太平洋的异常水汽能够输送到西北东南部,水汽散度场表现为辐合,因此降水偏多。而持续性旱年正好相反,因此降水偏少。利用前期大气环流指数对持续性旱涝指数建立的集合预报模型具有一定的预测能力,从而为西北东南部盛夏持续性旱涝现象的短期气候预测提供参考依据。Here,we used midsummer（July to August）month by month precipitation data from 156 stations from 1961 to 2012 in eastern northwest China,74 Circulation Index from CMA and NCAR/NCEP monthly mean reanalysis data,and the midsummer persistent drought and flood index to map circulation characteristics of persistent drought and flood abnormality over southeast northwest China. The results show that persistent drought events occurred slightly more than persistent flood events in the last 50 years. The strength of persistent flood events was stronger than persistent drought events. In persistent flood years,the Ural ridge is stronger,West Pacific subtropical high pressure is westerly and stronger,and the South Asian high pressure is easterly and stronger than that in persistent drought years. South Asian high pressure was bimodal,from the divergence field to see,low-level wind field performance convergence,and high-level wind field performance divergence,so vertical movement field display upward motion. Abnormal water vapor from the Indian Ocean and Pacific can be transported to southeast northwest China,moisture divergence field performance convergence,and therefore,sufficient water vapor conditions and upward movement result in more precipitation in midsummer. In persistent drought years the opposite is true：no exception of water vapor sources,vertical field show abnormal sinking movement,and precipitation is less. An ensemble forecasting model of persistent drought and flood events was established by the pre-atmospheric circulation index. By taking advantage of the forecast results of nearly 10 a to test prediction ability we found that the model has predictive ability for midsummer persistent drought and flood phenomenon in this region and provides a reference for short-term climate prediction of midsummer persistent drought and flood.

关 键 词：盛夏 持续性旱涝 旱涝异常 预测 西北东南部 

分 类 号：P426.616[天文地球—大气科学及气象学]