热带季节内振荡时空特征的诊断研究

A DIAGNOSTIC STUDY ON THE TEMPORAL AND SPATIAL CHARACTERISTICS OF THE TROPICAL INTRASEASONAL OSCILLATION

  • 摘要: 文中应用谱分析、小波分析等方法及较长时段的资料进一步总结了热带季节内振荡的一些基本气候特征。热带季节内振荡主要活跃在3个地区,最强的是西太平洋地区,其次是印度洋地区,第三是东太平洋沿岸的赤道以北地区。热带季节内振荡有明显的季节变化,西太平洋地区和印度洋地区的季节内振荡1a中有两次极大值,冬季主要活跃在南半球(10°S附近),而夏季则活跃在北半球(10°N附近),春、秋季热带季节内振荡则明显减弱。东赤道太平洋北侧的季节内振荡只在夏季活跃,而冬季则很弱,且不随季节而南北移动。对于大气的大尺度要素,例如u风场,热带季节内振荡的能量主要集中在1波。而对于像降水这样尺度较小的要素,热带季节内振荡的能量则相对较分散,尽管它仍然在1波有最大的能量,但2~4波也具有较接近的能量。热带季节内振荡以东移的波动为主。热带季节内振荡存在着年际甚至更长时间的变化。20世纪70年代末期季节内振荡的幅度有一明显的突变。

     

    Abstract: The climatic charact eristics of the tropical intraseasonal oscillation (TIO) were summarized by using the spectral analysis,wavelets analysis with some long term data sets.It is found that there are three regions where the TIO are veryactive.The first is the Western Pacific region where the tropical intraseasonal oscillation is most active.The second is the tropical Indian Ocean,the third is the region north to equator in the Eastern Pacific.The TIO has obvious seasonal transition.In western pacific and Indian oceans the TIO has two maximums during oneyear.In winter it is active in southern hemisphere (the Maximum is near 10°S),while in summer the maximum TIO center moves to northern hemisphere (near 10°N).However,it is weakened during spring and autumn.The TIO in eastern pacific north to the equator is active only in summer.It is very weak during winter and it does not shift to southern hemisphere atany time.For the large spatial scale meteorolog ical element,such as U wind field,the energy of the TIO mainly concent rates in the wave number 1.While for the relative small spatial scale elements such as precipitation,the energy of TIO is spread around wave 1 through wave 4.Though the TIO energy of wave 1 is the largest,the energy of wave 2-4 has similar order.The TIO is mainly eastward moving wave.And the TIO also has interannual and evenlonger variabilities,It is closely related to ENSO and the amplitude of the TIO had anabrupt increase in the end of 1970's.

     

/

返回文章
返回