| The Conservation of Helicity in Hurricane Andrew （1992） and the Formation of the Spiral Rainband |
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| 作者姓名： | XU Yamei WU Rongsheng |
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| 作者单位： | DepartmentofAtmosphereScience,NanjingUniversity,Nanjing210093KeyLaboratoryofMesoscaleSevereWeatherofMinistryofEducation,China |
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| 摘 要： | The characteristics of helicity in a hurricane are presented by calculating the MM5 model output in addition to theoretical analysis. It is found that helicity in a hurricane mainly depends on its horizontal component, whose magnitude is about 100 to 1000 times larger than its vertical component. It is also found that helicity is approximately conserved in the hurricane. Since the fluid has the intention to adjust the wind shear to satisfy the conservation of helicity, the horizontal vorticity is even larger than the vertical vorticity, and the three-dimensional vortices slant to the horizontal plane except in the inner eye. There are significant horizontal vortices and inhomogeneous helical flows in the hurricane. The formation of the spiral rainband is discussed by using the law of horizontal helical flows. It is closely related to the horizontal strong vortices and inhomogeneous helical flows.
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| 关 键 词： | 安德鲁旋风暴 风暴分析 螺旋雨带形成过程 螺旋密度 速度分析 |
The conservation of helicity in hurricane Andrew (1992) and the formation of the spiral rainband |
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| XU Yamei,WU Rongsheng.The conservation of helicity in hurricane Andrew (1992) and the formation of the spiral rainband[J].Advances in Atmospheric Sciences,2003,20(6):940-950. |
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| Authors: | Xu Yamei Wu Rongsheng |
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| Institution: | Department of Atmosphere Science, Nanjing University, Nanjing 210093;Key Laboratory of Mesoscale Severe Weather of Ministry of Education, China;Department of Geoscience, Zhejiang University, Hangzhou 310028,Department of Geoscience, Zhejiang University, Hangzhou 310028 |
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| Abstract: | The characteristics of helicity in a hurricane are presented by calculating the MM5 model output in addition to theoretical analysis. It is found that helicity in a hurricane mainly depends on its horizontal component, whose magnitude is about 100 to 1000 times larger than its vertical component. It is also found that helicity is approximately conserved in the hurricane. Since the fluid has the intention to adjust the wind shear to satisfy the conservation of helicity, the horizontal vorticity is even larger than the vertical vorticity, and the three-dimensional vortices slant to the horizontal plane except in the inner eye. There are significant horizontal vortices and inhomogeneous helical flows in the hurricane. The formation of the spiral rainband is discussed by using the law of horizontal helical flows. It is closely related to the horizontal strong vortices and inhomogeneous helical flows. |
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| Keywords: | helicity conservation helical flow spiral rainband |
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