Open AccessQuasi-Periodic Behavior of the Pacific–Japan Pattern Affecting Propagation Routes of Summertime Wave Patterns and the Associated Tropical Cyclone Tracks over the Western North Pacific
Author(s) -
Ken-Chung Ko,
Jyun-Hong Liu
Publication year - 2016
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/mwr-d-15-0080.1
Subject(s) - tropical cyclone , climatology , geology , cyclone (programming language) , tropical cyclone rainfall forecasting , low pressure area , tropical wave , latitude , circulation (fluid dynamics) , east asia , monsoon , tropics , oceanography , china , geography , atmospheric pressure , physics , geodesy , archaeology , field programmable gate array , fishery , biology , computer science , computer hardware , thermodynamics
This study introduces a modified Pacific–Japan (PJ) index that exhibits a substantial periodicity of 5–16 days in the East Asian summer monsoon region. The quasi-periodic fluctuations of the PJ index can indicate changes in the large-scale circulation systems. In the PJ high phase, the wave pattern propagates northwestward from the western North Pacific tropics to an area near northern Luzon and is then forced to move westward because of a stationary, anomalous high pressure system over southern Japan. The tropical cyclones (TCs) associated with the anomalous low pressure systems tend to follow a straight-moving propagation route through the northern South China Sea. The anomalous cyclonic flow causes heavy rainfall in eastern Taiwan. However, in the PJ low phase, the wave pattern and TCs follow a recurving propagation route toward higher latitudes. The circulation pattern typically brings heavy rainfall to northern Taiwan in the PJ low phase. Therefore, wave patterns under the influence of the quasi-periodic fluctuations of the PJ pattern affect rainfall because of the changing propagation routes of the wave patterns, as well as the TC tracks.