On the change of the tropical cyclone structure during its passage over islands |
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Authors: | A E Pokhil E S Glebova |
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Institution: | 1.Hydrometeorological Research Center of the Russian Federation,Moscow,Russia |
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Abstract: | The impact is studied of small land areas on the configuration and structure of the tropical cyclone as well as on the variations
of different characteristics of hurricanes (wind field, kinetic energy, and vorticity) during their passage over islands.
The results of computations based on the regional numerical atmospheric ETA model for the hurricanes of the Caribbean Sea
and typhoons of the Northwestern Pacific revealed that the disturbance of the symmetric circulation in the vortex accompanied
by significant kinetic energy losses takes place when crossing the archipelagos or separate islands. It is demonstrated that
the vortex intensity depends not on the energy loss due to the underlying surface roughness only but on the heat flux from
it as well. The kinetic energy generation in the hurricane sharply decreases as a result of the decrease in the pressure gradient
over the land that is caused, in turn, by the tropical cyclone moving away from the oceanic heat source. At the recurring
appearance of the cyclone over the warm ocean waters, its deepening and intensification recommence. |
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