A GCM Study on the Tropical Intraseasonal Oscillation

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  • Funds:

    Supported by the National Natural Science Foundation of China under Grant No. 40233033 and the project of Chinese Academy of Sciences (ZKCX3-SW-226).

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  • The ability of AGCM to simulate the tropical intraseasonal oscillation (ISO) has been studied using the output of global spectral model (ALGCM (R42L9)) of the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the outoput is compared with the results from NCEP/NCAR reanalysis for the year 1978-1989. The model displays an evident periodic signal of the tropical ISO. Basic propagating characters of the tropical ISO are captured, and changes in phase speed between Eastern and Western Hemispheres are also well presented, and the simulation of eastward propagation is better than that of westward propagation.This model has increased the ability to simulate the strength of the tropical ISO, especially at 200 hPa,and basically simulates the horizontal structure of wind characterized by the convergence in low-level and divergence in upper-level. The vertical structure of the zonal wind is also well reproduced. Moreover,observed results show that the representing of seasonal preference to form strong ISO in winter and spring is related to ISO's interannual variability, but it is shown in this model with strong ISO in winter and summer and weak ISO in spring and autumn. Structures of some physical elements such as vertical velocity,divergence, speci c humidity, etc., and the special distribution of ISO have also di erences with these from NCEP reanalysis data, which make it clear to develop this model to simulate the structure and spatial distribution of the ISO.
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    沈阳化工大学材料科学与工程学院 沈阳 110142

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A GCM Study on the Tropical Intraseasonal Oscillation

  • 1. State Key Laboratory of Numerical Modeling for Atmospheric Science and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029 Graduate School of the Chinese Academy of Sciences,Beijing 100039;
    State Key Laboratory of Numerical Modeling for Atmospheric Science and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029 Institute of Meteorology,PLA University of Science and Technology,Nanjing 211101;
    Department of Atmospheric Sciences,Nanjing University,Nanjing 210093
Funds: Supported by the National Natural Science Foundation of China under Grant No. 40233033 and the project of Chinese Academy of Sciences (ZKCX3-SW-226).

Abstract: The ability of AGCM to simulate the tropical intraseasonal oscillation (ISO) has been studied using the output of global spectral model (ALGCM (R42L9)) of the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the outoput is compared with the results from NCEP/NCAR reanalysis for the year 1978-1989. The model displays an evident periodic signal of the tropical ISO. Basic propagating characters of the tropical ISO are captured, and changes in phase speed between Eastern and Western Hemispheres are also well presented, and the simulation of eastward propagation is better than that of westward propagation.This model has increased the ability to simulate the strength of the tropical ISO, especially at 200 hPa,and basically simulates the horizontal structure of wind characterized by the convergence in low-level and divergence in upper-level. The vertical structure of the zonal wind is also well reproduced. Moreover,observed results show that the representing of seasonal preference to form strong ISO in winter and spring is related to ISO's interannual variability, but it is shown in this model with strong ISO in winter and summer and weak ISO in spring and autumn. Structures of some physical elements such as vertical velocity,divergence, speci c humidity, etc., and the special distribution of ISO have also di erences with these from NCEP reanalysis data, which make it clear to develop this model to simulate the structure and spatial distribution of the ISO.

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