Cyclone Phase of Tropical Cyclones Landfalling in Japan during 2004-2006

Abstract

Cyclone phases for 15 tropical cyclones (TCs) that made 17 landfalls in Japan during 2004-2006 are examined by using the gridded reanalysis datasets of the Japan Meteorological Agency. TCs with 9 landfalls south of 40°N from late June through early September had the structure of typical tropical cyclones, i.e., a thermally symmetric warm-core structure. TCs of 3 landfallings north of 40°N and one landfalling in western Japan in mid-June had the structure of a frontal cyclone, which suggests that the environmental baroclinicity would have contributed to the structure change of the cyclones. With the other 4 landfalls south of 40°N after mid-September, TCs were transitioning into extratropical cyclones with a thermally asymmetric warm-core structure, and were associated with significant features including frontal heavy rainfall and localized gusts related to the environmental baroclinicity. This suggests that precautions should be taken against a TC approaching Japan in mid- and late autumn associated with features different from those of a typical TC.