5C.8
Numerical simulation of the interaction from an ocean/land/atmosphere coupled model. Part I: results from the ocean/atmosphere coupled model
Yihong Duan, Shanghai Typhoon Institute, Shanghai, China; and X. Liang and R. Yu
An air-sea coupled model for tropical cyclone study is proposed with MM5V3 the atmospheric part and multi-level POM the oceanic part. Using the air-sea coupled model, a series of experiments are carried out to study the effect of changes in the ocean on tropical cyclone intensity and track by varying the sea surface temperature, the oceanic stratification structure and the oceanic horizontal temperature gradient. The results reconfirm the control of sea surface temperature on tropical cyclone formation and development, and show the non-linear response of tropical cyclone to changes in sea surface temperature with increase in tropical cyclone intensity becoming smaller as the temperature overpasses a critic value. It is found that the oceanic stratification exhibits a great influence on the intensity of tropical cyclone with larger decrease in intensity as the stratification becomes larger, and vice versa. Calculations indicate that the heat content of the ocean with small (large) stratification is large (small) as the surface temperature remains the same, which demonstrates the influence of ocean on tropical cyclone intensity relating to not only surface temperature but also stratification. Oceanic horizontal temperature gradient also has some impacts on the intensity and track of initially quiescent tropical cyclone, which can not be explained by the latent and sensible heat transportation while may be a result of the asymmetric structure of tropical cyclone due to inhomogeneous heating imposed by the ocean. The more inhomogeneous the ocean is horizontally, the larger changes in intensity and track of tropical cyclone is observed.
Session 5C, Air-Sea Interaction II
Tuesday, 25 April 2006, 8:00 AM-9:45 AM, Big Sur
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