两种强迫热源对夏季北半球大气低频环流影响的数值试验

NUMERICAL EXPERIMENT IN EFFECTS OF HEAT FORCING ON SUMMER NORTHERN LOWFREQUENCY CIRCULATIONS

利用ＩＡＰ２－ＬＡＧＣＭ模式，做了热带西北太平洋对流层中上层两种（恒定和双周振荡）强迫热源，对北半球夏季大气低频环流影响的数值试验。结果表明，不同热源可激发出明显不同的遥相关型，与之相联系的低频系统也不同。恒定热源激发出的低频波列类似ＥＮＳＯ事件发生发展阶段（１９７２年）的ＰＮＡ型，伴随的低频气旋和反气旋在热带西北太平洋生成，沿波列路径传播，在北美东南部消亡。双周振荡热源产生最显著的遥相关型位于热带西北太平洋－亚洲中纬度地区，呈经向一波型。低频系统生成于北半球，以１°·ｄ－１的速度向北传播，在副热带地区达到最强。

In the context of the IAP 2-level AGCM, numerical study was performed of effects on summer Northern atmospheric lowfrequency circulations of two kinds of heat source forcing (constant and quasibiweekly) in the midupper troposphere. Evidence suggests that either of the sources is responsible for a particular teleconnection pattern associated with a characteristic system; the constant source excites a lowfrequency wavetrain analogous to PNA pattern associated with 1972 ENSO at a development phase and the related lowfrequency cyclone and anticyclone are produced in the tropical NW Pacific, travelling along the wavetrain and disappearing in SE North America; the quasibiweekly one generates a very strong teleconnection, showing meridional wavenumber 1 over the tropical NW Pacificmidlatitude Asia; the lowfrequency system forms in the Northern Hemisphere, moving northward at 1 degree per day and reaching its maximum strength at subtropics.