This study aims to investigate variability of the deep South China Sea(SCS)circulation using the Hybrid Coordinate Ocean Model(HYCOM)global reanalysis product.The results reveal that annual cycle is a dominant compone...This study aims to investigate variability of the deep South China Sea(SCS)circulation using the Hybrid Coordinate Ocean Model(HYCOM)global reanalysis product.The results reveal that annual cycle is a dominant component in the deep SCS circulation.Meanwhile,the boundary circulation strength is the weakest in January and peaks between June and September.The eastern and southern boundary currents strengthen/weaken one to three months earlier than that in the western and northern boundaries.Vector Empirical Orthogonal Functions(VEOF)analysis results reveal that semiannual and intraseasonal fluctuations are significant components,of which the spatial patterns are mainly confined in the northern and western boundary areas as well as the southwestern sub-basin.Wavelet analysis results show the strength of significant fluctuation varies year to year.Trend analysis results indicate a decadal weakening in the deep SCS circulation.An anomalous anticyclonic circulation,50–70 km apart from the slope break,tends to weaken the cyclonic boundary circulation in the western and northern boundaries as well as the southwestern sub-basin.This trend is similar to the observed decadal weakening in the North Atlantic deep circulation.Thus,the findings of this study reveal that the variation of the deep SCS circulation has a remarkable response to the climate change.The mechanisms responsible for the variation are worth pursuing if more observations are available.展开更多
基金The National Key Research and Development Program of China under contract No.2019YFC1408400the National Natural Science Foundation of China under contract Nos 41876029 and 41821004.
文摘This study aims to investigate variability of the deep South China Sea(SCS)circulation using the Hybrid Coordinate Ocean Model(HYCOM)global reanalysis product.The results reveal that annual cycle is a dominant component in the deep SCS circulation.Meanwhile,the boundary circulation strength is the weakest in January and peaks between June and September.The eastern and southern boundary currents strengthen/weaken one to three months earlier than that in the western and northern boundaries.Vector Empirical Orthogonal Functions(VEOF)analysis results reveal that semiannual and intraseasonal fluctuations are significant components,of which the spatial patterns are mainly confined in the northern and western boundary areas as well as the southwestern sub-basin.Wavelet analysis results show the strength of significant fluctuation varies year to year.Trend analysis results indicate a decadal weakening in the deep SCS circulation.An anomalous anticyclonic circulation,50–70 km apart from the slope break,tends to weaken the cyclonic boundary circulation in the western and northern boundaries as well as the southwestern sub-basin.This trend is similar to the observed decadal weakening in the North Atlantic deep circulation.Thus,the findings of this study reveal that the variation of the deep SCS circulation has a remarkable response to the climate change.The mechanisms responsible for the variation are worth pursuing if more observations are available.
