收稿日期: 2001-06-14
修回日期: 2001-10-29
网络出版日期: 2002-01-10
基金资助
国家重点基础研究发展规划资助项目(G1998040900(I))
Impact of Position and Horizontal-Scale of Strong Convection Area on the Low-Frequency Oscillation in the Tropical Atmosphere
Received date: 2001-06-14
Revised date: 2001-10-29
Online published: 2002-01-10
利用包括CISK机制的简单三维热带大气模式研究强对流活动的位置和水平尺度对热带大气低频振荡的影响.结果表明强对流活动的经向位置对低频振荡有重要影响.当对流活动在赤道印度洋和赤道西太平洋加强时, 在赤道印度洋地区激发出低频振荡并向东传播, 周期为28d左右, 扰动为KelvinRossby波型, 具有明显斜压结构, 低层辐合, 高层辐散;然而, 当对流活动在热带印度洋和热带西太平洋, 即菲律宾附近地区加强时, 在热带西太平洋地区激发出向西传播的低频振荡, 周期为30d左右, 扰动为弱Rossby波型, 斜压结构, 且与南亚季风有紧密关系.研究结果还表明, 强对流活动的纬向位置对振荡周期和结构没有直接影响, 但强对流区域的尺度大小对热带大气低频振荡的周期有明显影响:强对流活动区域的纬向尺度越小, 所激发的低频振荡的周期就越短.热带大气中的10～20d振荡, 可能是由较小区域的对流活动激发出来的.
关键词： 低频振荡; 对流活动; Rossby波(罗斯贝波); Kelvin波(开尔文波)
崔雪锋 , 黄荣辉 . 热带强对流区域的位置和水平尺度对大气低频振荡的影响[J]. 中国科学院大学学报, 2002 , 19(1) : 49 -58 . DOI: 10.7523/j.issn.2095-6134.2002.1.007
The influence of position and horizontal scale of strong convective activities on the low frequency oscillation in the tropical atmosphere is discussed by using a simple three-dimensional numerical model of the tropical atmospheric motion including the wave CISK mechanism.The results show that the meridional position of strong convective activities has an important impact on the low frequency oscillation in the tropical atmosphere.When convctive activities are intensified over the equatorial Indian Ocean and the equatorial westerm Pacific,the oscillation excited by the intemal heating propagates eastward form the equatorial Indian Ocean and has a period of about 28 days, and its disturbance exhibits the combined Kelvin Rossby wave pattern and has an obvious baroclinic structure with the convergence in the lower atmosphere and the divergence in the upper atmosphere.However,when convective activities are intensfied over the tropical Indian Ocean and the tropical western Pacific around the Philippines,the oscillation excited by the internal heating propagates westward from the tropical western Pacific and has a period of about 30 days,and its distrubance has weaker baroclinic structure than that excited by the heating in the equatorial atmosphere,and it exhibits the Rossby wave pattern,which is closely associated with the South Asian summer monsoon.Moreover,the results show that a period and structure of oscillation is not dependent upon the zonal position of strong convective activities.The results also show that the horizontal scale of strong convection area has an obvious influence on the period of the low frequency oscillation in the tropical atmosphere.The strong convective activities over a smaller convection area can excite the low frequency oscillation with a smaller period.This can explain that the 10～20 days oscillation in the tropical atmosphere may be excited by the convective activities over a smaller convection area.
Key words： low frequency oscillation; convective activities; Rossby wave; Kelvin wave
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