海南岛9—10月暴雨日数与ENSO的关系研究

Study on The Relationship between Rainstorm Days from September to October and ENSO Event in Hainan Province

利用海南岛18个市县国家气象观测站日降水资料,NCEP/NCAR逐月资料和美国NOAA中心ERSSTV4的逐月海温资料,研究了海南岛秋季暴雨日数与前期海温的关系,结果表明:当前期(7—8月)出现拉尼娜(厄尔尼诺)事件时,西太平洋副高偏北(偏南),南海副高偏弱(偏强),沃克环流偏强(偏弱),印缅槽偏强(偏弱),热带印度洋、孟加拉湾进入南海偏西风偏强(偏弱),有利于(不利于)海南岛秋季暴雨形成。拉尼娜年时,当海南岛上空低值系统偏强(偏弱),赤道印度洋、孟加拉湾进入南海气流偏强明显(不明显),贝湖附近高压脊偏强(偏弱),则暴雨日数偏多(正常)。厄尔尼诺年时,(1)当海南岛上空高压系统控制,贝湖附近高压脊偏弱,则暴雨日数偏少;(2)当西南地区到中南半岛北部为短波槽影响,海南岛处于槽前,东亚大槽偏强,有短波槽配合,则暴雨日数正常;(3)当沃克环流偏弱不明显,巴士海峡、南海北部对流活动活跃,受低值系统和偏东气流影响,暴雨日数偏多。

Based on the daily precipitation data of 18 meteorological stations in Hainan Island,the monthly data of NCEP/NCAR and ocean temperature data of oisst4 in NOAA center of the United States,The relationship between the number of rainstorm days in autumn in Hainan Island and the SST is studied,The results showed that:When there was a La Nina(El Niño)event in the July and August,the subtropical high was northerly(southerly),the South China Sea subtropical high was weak(strong),the Walker circulation was stronger(weaker),India Myanmar trough was strong(weak),the westerly wind from the tropical Indian Ocean and bay of Bengal into the South China Sea was strong(weak),which was favorable(unfavorable)to the formation of Rainstorm in Hainan Island from september to october..In the year of La Nina,when the low value system over Hainan Island was stronger(weaker),the air flow from the equatorial Indian Ocean and Bay of Bengal into the South China Sea was stronger(not obvious),and the high pressure ridge near Lake Baikal was stronger(weaker),the number of rainstorm days was more(normal).In the year of El Niño,(1)When the high pressure system over Hainan Island was Controlled and the ridge of high pressure near Lake Baikal was weak,the number of rainstorm days was less;(2)When the southwest area to the north of Indochina Peninsula was affected by the short wave trough,Hainan Island was in front of the trough,and the East Asia trough was strong,with the cooperation of the short wave trough,the number of rainstorm days was normal.(3)When the Walker circulation was weak and not obvious,the convective activities in Bashi Strait and the northern South China Sea were active,the number of rainstorm days was more by the low value system and easterly airflow.