%0 Journal Article
%T A Simulation Study of the Influence of External Forcing on the Tropical Intraseasonal Oscillation<br>外强迫对热带季节内振荡影响的模拟研究
%A DONG Min
%A Chidong Zhang
%A HE Jin-Hai
%A <br>董敏
%A Chidong Zhang
%A 何金海
%J 大气科学
%D 2006
%I 
%X Using the model experiment results from modified NCAR CCM3,modified NCAR CAM2 and NCEP GFS models,the influences of external forcing of SST and solar radiation(SR) on the tropical intraseasonal oscillation(TIO) are discussed.These models are run under various SST conditions and solar radiation conditions.The output variables such as U wind at 850 hPa and precipitation are undergone spatial-temporal spectral analysis by two-dimensional Fast Fourier Transform(FFT).The spatial-temporal spectral power is compared between the model results and observation and between different model cases.When running under the perpetual external SST and radiation the NCAR CCM3.6 model with McRAS convection scheme can simulate pretty well the tropical intraseasonal oscillation which is similar to the observation.This indicates that the TIO is an internal variability of the atmosphere.In other words,the intraseasonal oscillation in the tropical atmosphere is determined by the internal physical processes of the atmosphere.When the same model is driven by the 12 month climate SST and solar radiation with annual cycle the tropical intraseasonal oscillation produced by the model is substantially weakened.In this case the external forcing have only the annual oscillation,it will force the model to have the annual oscillations which have longer periods than the intraseasnal oscillation.When the SST data of the low boundary condition are changed from 12 month climate value to the observed monthly mean SST,the external forcing has both annual cycle and interannual variability.Driven by this low boundary condition the model will be forced to generate longer period oscillation and the TIO is further weakened.The experiments also show that the external forcing with long period variation will also weaken the eastward propagating components of the TIO and increase the standing part of the TIO.Run the NCAR CAM2 model with RAS convection scheme under 12 month climate SST and run it coupled with a slab ocean model and compare the results from the two cases.The results show the simple air-sea coupling run can produce much stronger tropical intraseasonal oscillation than that produced by the run under the climate SST external forcing.Another comparison with NCEP GFS model run under the observed monthly SST forcing(AMIP II type run) and run coupled with a GCM ocean model also show that the coupling model can produce the most strongest TIO and the external forcing with interannual and annual variability will weaken the TIO substantially.
%K external forcing
%K tropical intraseasonal oscillation
%K influence
%K numerical simulation<br>外强迫
%K 季节内振荡
%K 影响
%K 数值模拟
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=28A2F569B2458C17&jid=46874A5A102033D774D00D819E91CD68&aid=FEA6585F9828FAF5&yid=37904DC365DD7266&vid=340AC2BF8E7AB4FD&iid=38B194292C032A66&sid=09AA1448D1EAF9C1&eid=B941678158018439&journal_id=1006-9895&journal_name=大气科学&referenced_num=5&reference_num=30