摘要
利用ＮＣＥＰ再分析资料，通过统计相关及合成分析研究了热带大气季节内振荡（ＩＳＯ）的年际变化与ＥＮＳＯ循环之间的关系。结果表明，热带大气季节内振荡（也称３０～６０天低频振荡）的年际变化在热带中西太平洋地区最强。在曰 Ｎｉｎｏ。成熟之前的春夏季，热带西太平洋的 ３０～６０天振荡异常活跃，其动能明显增加且逐渐东移；在曰 Ｎｉｎｏ成熟以后，热带西太平洋大气３０～６０天低频振荡迅速减弱。与这种加强的３０～６０天振荡相伴随，在赤道北侧为异常的气旋式环流，赤道地区出现偏西风异常。相反，在 Ｌａ Ｎｉｎａ成熟之前的春夏季，热带西太平洋大气３０～６０天振荡偏弱。进一步的分析还发现，东亚冬季风的年际变化是引起热带大气３０～６０天振荡的年际变化的主要机制：强东亚冬季风导致热带西太平洋积云对流加强，从而引起热带西太平洋大气３０～６０天振荡加强；相反，对应于弱的东亚冬季风，热带西太平洋地区积云对流偏弱，大气３０～６０天振荡偏弱。作者的资料分析还证实，热带大气 ３０～６０天低频振荡的年际变化，作为一种外强迫，对曰 Ｎｉｎｏ的形成起着十分重要的作用。
Based on the NCEP reanalysis data, the relationship between the interannual variability of tropical atmospheric intraseasonal oscillation (ISO) and ENSO cycle has been studied through statisti- cal and composite analyses. The results suggest that the interannual variability of the tropical atmos- pheric ISO (30~ 60 day low-frequency oscillation) is most obvious in the central and western Pacific. During the spring and summer prior to the mature El Nino, the 30~ 60 day oscillation in the western Pacific is very active, its kinetic energy is clearly increased and the anomalous center of kinetic energy gradually propagates eastward. Along with the strengthened 30~ 60 day oscillation, there is an anoma- lous cyclone to the north of the equator and the westerly prevails in the equator. On the contrary, dur- ing the spring and summer prior to the mature La Nina, the atmospheric 30~ 60 low-frequency oscillation in the western Pacific is weak. Further analyses also suggest that the interannual variability of the winter monsoon over East Asia is reponsible for the interannual variability of tropical atmospher- ic 30~ 60 day oscillation: corresponding to the strong (weak) winter monsoon over East Asia, the cumu- lus convection in the tropical western Pacific is strengthened (weakend), therefore the atmospheric 30~ 60 day oscillation is active (weak). The data analyses further prove that as an external forcing, the interannual variability of tropical atmospheric 30~ 60 day oscillation plays an important role in the formation of E1 Nino.
出处
《大气科学》
CSCD
北大核心
2001年第6期798-808,共11页
Chinese Journal of Atmospheric Sciences
基金
国家重点基础研究发展规划项目G1998040903-2
国家攀登计划A"南海季风试验研究"
中国科学院大气物理研究所创新面
