Spatial Structure And Temporal Variability Of The Zonal Flow In The Luzon Strait


Title: Spatial Structure And Temporal Variability Of The Zonal Flow In The Luzon Strait

Journal: Journal of Geophysical Research: Oceans, 120(2): 759-776

Authors: ZHANG Z. -W., P. -L. Li, L. -X. Xu, C. Li, W. Zhao, J. -W. Tian*, Q. -X. Yang, and T. -D. Qu

Abstract:One year long, full-depth velocity measurements were used to examine the spatial structure and temporal variability of the zonal flow in the Luzon Strait (LSZF). The observation revealed a renewedmean flow structure: in the upper (<500 m) and deep (>2000 m) layers, the LSZF was mostly westward; inthe intermediate layer (500–2000 m), it was dominated by an eastward flow in the south but a westwardflow in the north. The volume transport across the observed section between 19.8°N and 21.2°N exhibitedstrong seasonal and intraseasonal variability. On the seasonal time scale, the upper-layer transport showeda clear annual cycle, strongest in January and weakest in June; the intermediate-layer transport also showeda semiannual cycle, attaining its peaks (troughs) in January and June (April and October). On the intraseasonaltime scale, both the upper-layer and intermediate-layer transports showed significant energy peaks atabout 60 and 10–30 days. Further analysis indicated that the ~60 day variability might be attributed to theimpinging mesoscale eddies from the Pacific, while the 10–30 day variability appeared to obtain its energyfrom local intraseasonal wind forcing and baroclinic instability of the background current. The 10–100 dayupper-layer and intermediate-layer transport variabilities were highly anticorrelated, suggesting a baroclinicnature of the intraseasonal variabilities of the LSZF.