热带大气10～20天振荡的大气环流模式数值模拟

Numerical Simulation of the Tropical Atmospheric 10～20 Day Oscillation with a General Circulation Model

利用大气环流模式对热带大气１０～２０天振荡进行了数值模拟研究，其结果同观测资料分析基本一致。模式资料的功率谱及动能的分析表明，１０～２０天振荡确实比３０～６０天振荡更突出地存在于热带大气中。同热带大气３０～６０天振荡的结构有些不同，对于在热带１０～２０天振荡，除纬向１波外，纬向２波也很明显；流动的斜压结构特征欠佳；系统以较快速度沿赤道西移。暖ＳＳＴ事件对热带大气１０～２０天振荡的影响也进行了模拟，对结果的比较分析表明，暖ＳＴＴ将使１０～２０天大气振荡减弱，使其结构更趋正压性。

An atmospheric general circulation model is used to simulate the tropical 10～20 day atmospheric oscillation.The results are consistent with observations in several respects indicating that numerical experimentation may be a productive way to study this type of low frequency oscillation.Analyses of the power spectra and kinetic energy show that in the tropical atmosphere,the simulated 10～20 day oscillation is markedly distinct from the simulated 30～60 day oscillation.There are,however,differences in the structure between both oscillations in the tropical atmoshpere.The 10～20 day oscillation exhibits zonal wavenumber 2 features in addition to wavenumber 1.The flow field is less baroclinic and it tends to propagate westward at a faster rate along the equator.The influence of warm sea surface temperatures on the tropical 10～20 day oscillation is also simulated by prescribing global SSTs as observed during 1983 and comparing the results with those from an integration using observed, climatological SSTs.The simulated oscillation is found to be weaker,with a more barotropic vertical structure.