The wave-CISK (cumulus convection heating feedback), the air-sea interaction and the evaporation-wind feedback are together introduced into a simple theoretical model, in order to understand their effect on driving tr...The wave-CISK (cumulus convection heating feedback), the air-sea interaction and the evaporation-wind feedback are together introduced into a simple theoretical model, in order to understand their effect on driving tropical atmospheric intraseasonal oscillation (ISO). The results showed that among the introduced dynamical processes the wave-CISK plays a major role in reducing phase speed of the wave to be closer to the observed tropical ISO. While the evaporation-wind feedback plays a major role in unstabilizing the wave. The air-sea interaction has certain effect on slowing down the phase speed of the wave. Therefore, the wave-CISK and evaporation-wind feedback can be regarded as fundamental dynamical mechanism of the tropical ISO. This study also shows that since the effects of the evaporation-wind feedback and the air-sea interaction were introduced, the excited wave is zonally dispersive, which can dynamically explain the activity feature of the observed ISO in the tropical atmosphere very well.展开更多
The results from simple dynamic studies on the evaporation-wind feedback show that the effect cannot change the nature of tropical atmospheric waves (by retarding the speed), so that the evaporation-wind feedback alon...The results from simple dynamic studies on the evaporation-wind feedback show that the effect cannot change the nature of tropical atmospheric waves (by retarding the speed), so that the evaporation-wind feedback alone cannot be an exciting mechanism of intraseasonal oscillation in the tropical atmosphere. This is different from that of the wave-CISK mechanism. With combined effect of the cumulus convection heating and evaporation-wind feedback, the CISK-Kelvin waves and CISK-Rossby waves will develop unstably, explaining the dynamic mechanism of tropical intraseasonal oscillation in a more complete and reasonable way than the convection heating alone. Therefore, the evaporation-wind feedback is also important to the intraseasonal oscillation in the tropical atmosphere.展开更多
A baroclinic semi-geostrophic model with evaporation-wind feedback mechanism(EWFM) and CISK is established,two non-dimensional parameters a and η are introduced to represent EWFM and CISK,respectively.Analytic soluti...A baroclinic semi-geostrophic model with evaporation-wind feedback mechanism(EWFM) and CISK is established,two non-dimensional parameters a and η are introduced to represent EWFM and CISK,respectively.Analytic solutions of the model system are obtained,dynamics analyses and the model atmosphere calculations further confirm that EWFM and CISK are very important physical processes in leading to the low-frequency oscillations in the tropics.展开更多
基金This study is partly supported by National Key Programme for Developing Basic Sciences(G1998040903)
文摘The wave-CISK (cumulus convection heating feedback), the air-sea interaction and the evaporation-wind feedback are together introduced into a simple theoretical model, in order to understand their effect on driving tropical atmospheric intraseasonal oscillation (ISO). The results showed that among the introduced dynamical processes the wave-CISK plays a major role in reducing phase speed of the wave to be closer to the observed tropical ISO. While the evaporation-wind feedback plays a major role in unstabilizing the wave. The air-sea interaction has certain effect on slowing down the phase speed of the wave. Therefore, the wave-CISK and evaporation-wind feedback can be regarded as fundamental dynamical mechanism of the tropical ISO. This study also shows that since the effects of the evaporation-wind feedback and the air-sea interaction were introduced, the excited wave is zonally dispersive, which can dynamically explain the activity feature of the observed ISO in the tropical atmosphere very well.
文摘The results from simple dynamic studies on the evaporation-wind feedback show that the effect cannot change the nature of tropical atmospheric waves (by retarding the speed), so that the evaporation-wind feedback alone cannot be an exciting mechanism of intraseasonal oscillation in the tropical atmosphere. This is different from that of the wave-CISK mechanism. With combined effect of the cumulus convection heating and evaporation-wind feedback, the CISK-Kelvin waves and CISK-Rossby waves will develop unstably, explaining the dynamic mechanism of tropical intraseasonal oscillation in a more complete and reasonable way than the convection heating alone. Therefore, the evaporation-wind feedback is also important to the intraseasonal oscillation in the tropical atmosphere.
基金This work is supported by the National Natural Science Foundation of China.
文摘A baroclinic semi-geostrophic model with evaporation-wind feedback mechanism(EWFM) and CISK is established,two non-dimensional parameters a and η are introduced to represent EWFM and CISK,respectively.Analytic solutions of the model system are obtained,dynamics analyses and the model atmosphere calculations further confirm that EWFM and CISK are very important physical processes in leading to the low-frequency oscillations in the tropics.
