东北地区夏季风强度的年际变化分析

The Interannual Analysis of the Intensity of East Asian Summer Monsoon in Northeast China

利用1961～2004年的NCEP/NCAR逐日再分析资料以及全国的降水实况资料,计算了东北地区夏季风强度指数,详细分析了东北地区夏季风强度指数与海平面气压场(SLP)、850 hPa环流场、500 hPa位势高度场、海表温度以及NINO3、AO、NPI和NPO指数的关系。结果表明,当中纬度中、西太平洋海平面气压(SLP)升高时,500 hPa位势高度升高,副热带高压加强并偏北,850 hPa环流场反气旋环流加强,华北、东北地区的南风分量加强,东北地区夏季风强;反之,东北地区夏季风弱。海表温度与东北地区夏季风强度指数的相关,在1976/1977年以前在前冬季表现的更明显,在1976/1977年以后则是在夏季表现更明显。东北地区夏季风强度指数与NINO3、AO、NPI、NPO指数的相关性在20世纪70年代均产生了转折性的变化;海平面气压的南北向的跷跷板式的变化对东北地区夏季风强度的影响更明显,而单一的阿留申低压的强弱变化对东北地区夏季风强度影响不大。

The intensity index of East Asian summer monsoon in Northeast China was calculated by using NCEP/NCAR reanalysls dmly date and daily precipitation form 1961 to 2004 station of Northeast China for past 44 years. The relationships between sea-level pressure field ,850 hPa flow field,500 hPa geopotential height field,sea surface temperature and NINO3, AO, NPI and NPO index and intensity index of E^st Asian summer monsoon in Northeast China were analyzed. We found that the Western Pacific sea level pressure （SLP） increased ,500 hPa geopotential height in- creased,and subtropical north strengthened, anti-cyclonic circulation at 850 hPa strengthened, southerly component strengthened in North and Northeast region and East Asian summer monsoon in Northeast China became stronger in Northeast. On the contrary, a weak East Asian summer monsoon was in Northeast China. It is more obvious in winter before 1976/1977 ,and in summer 1976/1977 years later for the relation of sea sur- face temperature and East Asian summer monsoon in Northeast China intensity index. The correlation between intensity index of East Asian sum- mer monsoon in Northeast China and NINO3, AO, NPI, NPO Index in the 1970s has produced a turning point of change; analysis showed that the impact of the see-saw-style changes （NPO） at sea level pressure on the East Asian summer monsoon in Northeast China intensity is more obvi- ous,while single strength of the Aleutian low pressure change （NPI） has little effect on the East Asian summer monsoon in Northeast China.