下半年Nino3区海表升温对东亚春季大气环流及山东春季降水的影响

INFLUENCES OF NINO3 SST RISING IN THE SECOND HALF YEAR ON EAST ASIA SPRING GENERAL CIRCULATION AND SHANDONG SPRING PRECIPITATION

通过分析下半年Nino3区(150°~90°W,5°S^5°N)海表温度(SST)升高引起的次年春季500 hPa高度、850 hPa及200 hPa经向风的异常特征,发现下半年Nino3区显著升温,可导致次年春季热带和西北太平洋副热带地区的500 hPa高度场升高,即西太平洋副热带高压偏强、偏西、偏北,东亚大槽偏弱、偏东;巴尔喀什湖至贝加尔湖的高度场降低,即该地区经常有低槽维持;亚洲至西太平洋地区盛行纬向环流。我国东部沿海地区及邻近海域的偏南风加强,而我国东北和华北地区的偏北风偏弱。这种高度场与风场的异常恰与山东4月降水偏多年所对应的异常特征相吻合,即下半年Nino3区显著升温通过影响次年春季大气环流异常,进而影响山东春季降水。资料统计表明,下半年Nino3区显著升温,次年山东及我国中纬度东部地区春季尤其4月的降水往往偏多。

By analyzing next-spring abnormal features of 500 hPa height and 850 hPa,200 hPa meridional wind due to Nino3 SST rising, it is found that Nino3 SST rising abnormally in the second half year leads to 500 hPa height field rising in the tropic and Northwest Pacific subtropical region, namely the Northwest Pacific subtropical high is stronger and shifts westwards and northwards compared with the mean, and the trough over East Asia is weaker with its location shifts eastwards; the height field fails from the area around Balkhash to Baikal Lake, i.e., trough often maintains; zonal circulation prevails over Asia and the Western Pacific; Southerly winds intensifies over east part of China and neighboring sea area, while northerly winds weaken over north China and the Northeast of China. The abnormal features of the height and meridional wind fields are uniform with that of much more April precipitation in Shandong. Result suggests that spring precipitation in Shandong and eastem China are often richer after Nino3 SST unusually increasing in the last second half year.