| THE ROLES OF BOUNDARY-LAYER DYNAMICS ON THE DEVELOPMENT OF MADDEN-JULIAN OSCILLATION |
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| 作者姓名： | 巢纪平 林永辉 王斌 |
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| 作者单位： | National Research Center for Marine Environment Forecasts Beijing 100081，Institute of Atmospheric Physics，Chinese Academy of Sciences，Beijing 100029，Department of Meteorology，University of Hawaii，Hawaii，USA |
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| 基金项目： | This work is supported by the National Natural Science Foundation of China. |
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| 摘 要： | In this paper,a tropical atmospheric model of relevance to shorts-term climate variations(Wang and Li 1993)is util-ized for study of the development of Madden-Julian oscillation.The model contains an interactive process ofboundary-layer Ekman convergence and precipitation heating.The model is solved by expanding dependent variables interms of parabolic cylindrical functions in the meridional direction and truncating three meridional modes n=0,2,4 forequatorial symmetric solutions.The free wave solutions obtained under long-wave approximation are induced as aKelvin wave and two Rossby waves.After considering the effect of boundary-layer dynamic process,the modifiedKelvin wave becomes unstable in long-wave bands with a typical growth rate on an order of 10~(-6) s~(-1)and an eastwardphase speed of 10 m s~(-1);the most unstable mode is wavenumber one.These theoretical results are consistent with the ob-served Madden-Julian oscillation in equatorial area.For the two modified Rossby waves,one with a smaller meridionalscale(n=4)decays except for extra long-waves;the other with a larger meridional scale(n=2)grows in short-wavebands.This may be relevant to explaining the westward propagation of super cloud clusters in the Madden-Julianoscillation.The theory suggests that the boundary-layer dynamic process is an important mechanism in the develop-ment of the Madden-Julian oscillation.
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THE ROLES OF BOUNDARY-LAYER DYNAMICS ON THE DEVELOPMENT OF MADDEN-JULIAN OSCILLATION |
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| Chao Jiping National Research Center for Marine Environment Forecasts,Beijing
Lin Yonghui Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing
Wang Bin.THE ROLES OF BOUNDARY-LAYER DYNAMICS ON THE DEVELOPMENT OF MADDEN-JULIAN OSCILLATION[J].Acta Meteorologica Sinica,1995(2). |
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| Authors: | Chao Jiping National Research Center for Marine Environment Forecasts Beijing
Lin Yonghui Institute of Atmospheric Physics Chinese Academy of Sciences Beijing
Wang Bin |
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| Affiliation: | Chao Jiping National Research Center for Marine Environment Forecasts,Beijing 100081
Lin Yonghui Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029
Wang Bin Department of Meteorology,University of Hawaii,Hawaii,USA |
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| Abstract: | In this paper,a tropical atmospheric model of relevance to shorts-term climate variations(Wang and Li 1993)is util- ized for study of the development of Madden-Julian oscillation.The model contains an interactive process of boundary-layer Ekman convergence and precipitation heating.The model is solved by expanding dependent variables in terms of parabolic cylindrical functions in the meridional direction and truncating three meridional modes n=0,2,4 for equatorial symmetric solutions.The free wave solutions obtained under long-wave approximation are induced as a Kelvin wave and two Rossby waves.After considering the effect of boundary-layer dynamic process,the modified Kelvin wave becomes unstable in long-wave bands with a typical growth rate on an order of 10~(-6) s~(-1)and an eastward phase speed of 10 m s~(-1);the most unstable mode is wavenumber one.These theoretical results are consistent with the ob- served Madden-Julian oscillation in equatorial area.For the two modified Rossby waves,one with a smaller meridional scale(n=4)decays except for extra long-waves;the other with a larger meridional scale(n=2)grows in short-wave bands.This may be relevant to explaining the westward propagation of super cloud clusters in the Madden-Julian oscillation.The theory suggests that the boundary-layer dynamic process is an important mechanism in the develop- ment of the Madden-Julian oscillation. |
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| Keywords: | Madden-Julian oscillation intraseasonal oscillation boundary-layer convergence |
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