2008年徐州地区严重秋冬连旱成因分析

Analysis on the Reasons for Consecutive Severe Droughts in Autumn and Winter in Xuzhou in 2008

[目的]研究2008年徐州地区严重秋冬连旱的成因。[方法]利用观测站降水资料和NCEP/NCAR再分析资料,分析2008年10月～2009年1月徐州地区秋冬连旱期间的环流背景、垂直运动、气温异常及水汽条件的变化,揭示此次秋冬连旱的成因。[结果]2008年秋、冬季徐州地区长时间受稳定形势控制,处于东部沿海槽后,高空盛行下沉气流;南支槽强度明显偏弱,再加上副高位置偏东,强度偏弱,印度洋和南海的水汽输送条件不利。秋季偏暖,冷空气势力偏弱;入冬以来虽有几次冷空气活动,但影响主体偏北,再加上南方暖湿气流不充足,二者缺少很好的结合,使得冷空气影响时以大风降温天气为主,降水出现较少。[结论]该研究为该地区干旱的预防提供理论依据。

[Objective] The aim was to study the reasons for consecutive severe droughts in autumn and winter.[Method] By dint of precipitation and NCEP/NCAR reanalysis data in observatory station,the circulation background,vertical movement,abnormal temperature and changes of water vapor conditions in Xuzhou from October 2008 to January 2009 were expounded to reveal the causes for consecutive drought in autumn and winter.[Result] Xuzhou was under stable situation for a long time in autumn and winter in 2008,being behind east coastal trough,the downward airstream prevailing;the south trough intensity was weak,and in addition to the east subtropical high and weak intensity,the water vapor transportation condition in Indian Ocean and South Sea was unfavorable.The autumn was warm and the cold air was weak;ever since winter,there were several cold air activities.But the influencing body was in the east,and the south warm and wet airstream was insufficient.Thus,they couldn＇t met,which resulted into gale and lower temperature and less precipitation when under the influence of cold air.[Conclusion] The study provided theoretical basis for the prevention of drought in the area.