Open AccessChanges in wave climate off Hiratsuka, Japan, as affected by storm activity over the western North Pacific
Author(s) -
Sasaki W.,
Iwasaki S. I.,
Matsuura T.,
Iizuka S.,
Watabe I.
Publication year - 2005
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jc002730
Subject(s) - extratropical cyclone , climatology , storm track , empirical orthogonal functions , storm , significant wave height , tropical cyclone , environmental science , atmospheric sciences , cyclone (programming language) , wind speed , geology , wind wave , oceanography , field programmable gate array , computer science , computer hardware
Changes in wave climate off Hiratsuka during 1980–2003 are investigated on the basis of hourly observed wave and atmospheric data obtained at a tower 1 km off Hiratsuka in Sagami Bay, Japan. First, the interannual variability of significant wave heights ( H s ) for the summer mean (June–August, SH s ) is analyzed. A large difference between wave spectrum ( E ( f , t )) in high SH s years and that in low SH s years is found at the frequency of 0.09 Hz. It is revealed that the difference is related to the changes in enhanced tropical cyclone (with central air pressure below 980 hPa) activity in the western North Pacific. Second, the interannual variability of H s for the winter mean (December–February, WH s ) is investigated. It is found that there is a large difference between E ( f , t ) in high WH s years and that in low WH s years at the frequency of 0.11 Hz. It is revealed that the difference is related to the changes in southerly wind intensity (integral of southerly wind speed by hours) associated with extratropical cyclones. Third, the interdecadal variability of WH s is described. The time series of anomalies of WH s , smoothed by means of a 7‐year moving average, is divided into three periods: 1980–1985, 1986–1996, and 1997–2003. The first empirical orthogonal function of 10‐m meridional sea surface winds captures the interdecadal variability over the storm track. The smoothed WH s exhibits similar variation to that of the leading principal component of the winds.