Open AccessDipole Structure of Interannual Variations in Summertime Tropical Cyclone Activity over East Asia
Author(s) -
Joo Hong Kim,
Chin Siong Ho,
ChungHsiung Sui,
Sojung Park
Publication year - 2005
Publication title -
journal of climate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.315
H-Index - 287
eISSN - 1520-0442
pISSN - 0894-8755
DOI - 10.1175/jcli3601.1
Subject(s) - climatology , empirical orthogonal functions , jet stream , troposphere , middle latitudes , rossby wave , anticyclone , cyclone (programming language) , tropical cyclone , anomaly (physics) , geopotential height , tropical cyclone rainfall forecasting , east asia , latitude , atmospheric sciences , environmental science , atmospheric circulation , longitude , geology , jet (fluid) , geography , meteorology , precipitation , physics , archaeology , geodesy , condensed matter physics , field programmable gate array , computer science , computer hardware , china , thermodynamics
The present study examines variations in summertime (July–September) tropical cyclone (TC) activity over East Asia during the period 1951–2003. To represent TC activity, a total of 853 TC best tracks for the period were converted to TC passage frequencies (TPFs) within 5° × 5° latitude–longitude grids; TPFs are defined as the percentage values obtained by dividing the number of TC appearances in each grid box by the total number of TCs each year. Empirical orthogonal function analysis of the TPF showed three leading modes: two tropical modes that represent the long-term trend and the relationship with ENSO and one midlatitude mode that oscillates between south of Korea and southeast of Japan with an interannual time scale. The latter proved to be the most remarkable climatic fluctuation of summertime TC activity in the midlatitudes and is referred to as the East Asian dipole pattern (EADP) in this paper. Anomalous atmospheric flows directly connected to the EADP are an enhanced anticyclonic (cyclonic) circulation centering around Japan when the TPF is high south of Korea (southeast of Japan), thereby showing an equivalent barotropic structure in the entire troposphere. This regional circulation anomaly varies in conjunction with the zonally oriented quasi-stationary Rossby wave train in the upper troposphere. This wave train is meridionally trapped in the vicinity of the summer-mean jet stream; therefore, the mean jet stream alters its internal meandering structure according to the phase of the wave train.