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Tropical cyclone energy dispersion under vertical shears
Author(s) -
Ge Xuyang,
Li Tim,
Zhou Xiaqiong
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl031867
Subject(s) - baroclinity , rossby wave , anticyclone , cyclogenesis , geology , tropical cyclogenesis , barotropic fluid , climatology , cyclone (programming language) , westerlies , tropical wave , troposphere , middle latitudes , atmospheric sciences , tropical cyclone , field programmable gate array , computer science , computer hardware
Tropical cyclone Rossby wave energy dispersion under easterly and westerly vertical shears is investigated in a baroclinic model. In a resting environment, the model simulates a Rossby wave train that has a baroclinic structure with alternating cyclonic‐anticyclonic‐cyclonic (anticyclonic‐cyclonic‐anticyclonic) circulations in the lower (upper) troposphere. A significant asymmetry appears in the wave train development under easterly and westerly vertical shears, that is, an easterly (westerly) shear confines the maximum amplitude of the wave train primarily to the lower (upper) level. It is proposed that the vertical wind shear may impact the Rossby wave train development through both the barotropic‐baroclinic mode coupling and the modulation of the group velocity by the mean flow through a “Doppler shift effect”. Additional experiments with uniform westerly and easterly mean flows confirm the hypothesis. The enhancement of the Rossby wave train in the lower level by the easterly shear may have an important implication for understanding the tropical cyclogenesis and the origin of the synoptic wave trains in the western North Pacific.