The Boreal Summer Intraseasonal Oscillation Simulated by Four Chinese AGCMs Participating in the CMIP5 Project

The performances of four Chinese AGCMs participating in the Coupled Model Intercomparison Project Phase 5 （CMIP5） in the simulation of the boreal summer intraseasonal oscillation （BSISO） are assessed. The authors focus on the major characteristics of BSISO： the intensity, significant period, and pro...

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Bibliographic Details
Published in:Advances in atmospheric sciences 2014-09, Vol.31 (5), p.1167-1180
Main Authors: Zhao, Chongbo, Zhou, Tianjun, Song, Lianchun, Ren, Hongli
Format: Article
Language:English
Subjects:
Atmospheric Sciences
Climate prediction
Earth and Environmental Science
Earth Sciences
Geophysics/Geodesy
Meteorology
Ocean circulation
Ocean-atmosphere interaction
Propagation
Seasons
中国
北半球
夏季季节
大气环流模式
季节内振荡
平均降水量
模拟
降水分析
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Summary:The performances of four Chinese AGCMs participating in the Coupled Model Intercomparison Project Phase 5 （CMIP5） in the simulation of the boreal summer intraseasonal oscillation （BSISO） are assessed. The authors focus on the major characteristics of BSISO： the intensity, significant period, and propagation. The results show that the four AGCMs can reproduce boreal summer intraseasonal signals of precipitation; however their limitations are also evident. Compared with the Climate Prediction Center Merged Analysis of Precipitation （CMAP） data, the models underestimate the strength of the intraseasonal oscillation （ISO） over the eastern equatorial Indian Ocean （IO） during the boreal summer （May to October）, but overestimate the intraseasonal variability over the western Pacific （WP）. In the model results, the westward propagation dominates, whereas the eastward propagation dominates in the CMAP data. The northward propagation in these models is tilted southwest-northeast, which is also different from the CMAP result. Thus, there is not a northeast-southwest tilted rain belt revolution off the equator during the BSISO＇s eastward journey in the models. The biases of the BSISO are consistent with the summer mean state, especially the vertical shear. Analysis also shows that there is a positive feedback between the intraseasonal precipitation and the summer mean precipitation. The positive feedback processes may amplify the models＇ biases in the BSISO simulation.
ISSN:0256-1530
1861-9533
DOI:10.1007/s00376-014-3211-7