Open AccessExtratropical Transition of Tropical Cyclones in the Western North Pacific: Their Frontal Evolution
Author(s) -
Naoko Kitabatake
Publication year - 2008
Publication title -
monthly weather review
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.862
H-Index - 179
eISSN - 1520-0493
pISSN - 0027-0644
DOI - 10.1175/2007mwr1958.1
Subject(s) - extratropical cyclone , middle latitudes , climatology , advection , tropical cyclone , trough (economics) , typhoon , geology , troposphere , jet stream , baroclinity , warm front , cyclogenesis , cyclone (programming language) , environmental science , atmospheric sciences , oceanography , jet (fluid) , economics , macroeconomics , physics , field programmable gate array , computer science , computer hardware , thermodynamics
Extratropical transition (ET) in the western North Pacific during 2001–02 is examined in terms of frontal evolution and its environment using a gridded global analysis dataset produced by the Japan Meteorological Agency. According to the best-track data created by the Regional Specialized Meteorological Center (RSMC) Tokyo-Typhoon Center, 23 out of 52 (44%) tropical cyclones (TCs) completed ET during these two years. These ET cases are classified into three categories in terms of the lower-tropospheric equivalent potential temperature distributions, characteristics of the TCs, and their environments. Eight TCs (35% of all ET cases) had temporary warm secluded frontal patterns and then occluded patterns at the completion of ET, which is defined as a seclusion–occlusion (SO) type. This occurs downstream of an intense upper-tropospheric trough interacting with a TC, which is then likely to move northward while keeping its tropical characteristics and have a large impact on relatively high latitudes including all the Japan islands. Three TCs (13%) were apparently absorbed into vigorous preexisting fronts in the southwest of midlatitude cyclones; this situation is defined as a cold advection (CA) type. A TC of the CA type is likely to lose its tropical characteristics rapidly in strong cold advection that is equatorward of a relatively straight upper-tropospheric jet stream. The other 12 TCs (52%) were organized into an open-wave frontal cyclone, which is defined as an open-wave (OW) type. This has characteristics of both SO and CA and is more related to the midlatitude baroclinic zone compared with the SO type.