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Further Study of Typhoon Tracks and the Low-Frequency (30-60 Days) Wind-Field Pattern at 850 hPa |
TIAN Hua,LI Chong-Yin |
1.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;2.Editorial Board of the Institute of Atmospheric Physics, Beijing 100029, China,1.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China;3.Institute of Meteorology, the People's Liberation Army (PLA) University of Science and Technology, Nanjing 211101, China |
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Abstract The association of typhoon tracks over the western Pacific with the low-frequency wind-field pattern of atmospheric intraseasonal (30-60 days) oscillation at 850 hPa is further studied by using observational data analyses. Comparative analyses of the composite wind fields at 850 hPa, contrasting the atmospheric intraseasonal oscillation (ISO) with the original circulation, show that the typhoon tracks are closely related to the wind pattern of the ISO but are not obviously related to the original wind fields. Case studies of two typhoons in 2006 also show that the low-frequency wind-field pattern, particularly the maximum-value line (belt) of low-frequency cyclonic vorticity at 850 hPa, is closely related to the typhoon track. Therefore, the low-frequency circulation pattern and the maximum-value line (belt) of low-frequency cyclonic vorticity at 850hPa can be used to predict typhoon tracks over the northwestern Pacific.
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Received: 15 October 2010
Revised: 06 November 2010
Accepted: 06 November 2010
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