A long-term volume transport time series estimated by combining in situ observation and satellite altimeter data in the northern South China Sea
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We deployed five pressure-recording inverted echo sounders (PIES) along a satellite altimeter track across the continental slope of the northern South China Sea (NSCS) from October 2012 to July 2014, and obtained a time series of volume transport (VTPIES) across the section from their records. Applying the empirical relationship between VTPIES and the satellite altimeter sea surface height anomaly difference across the section, we obtained a time series of volume transport (VTNSCS) over 22 years from 1992 to 2014. The VTNSCS shows a small mean value of −1.6 Sv (1 Sv = 106 m3 s−1) (i.e., toward the southwest), but a significant seasonal reversal and mesoscale eddy induced fluctuations (−11.8 to 19.7 Sv). The monthly mean of VTNSCS over 22 years shows a maximum (3.6 Sv) in July and a minimum (−7.3 Sv) in December. This is the first long time series of volume transport for the NSCS based on in situ data.
KeywordsLong-term time series of volume transport Pressure-recording inverted echo sounder Gravest empirical mode Satellite altimeter Seasonal variability South China sea
This study is supported by the National Basic Research Program of China (2011CB403503), the National Natural Science Foundation of China (41276095, 41476020, 41276028, and 41321004), the Scientific Research Fund of SIO under grants JT1402 and JT1207, and the projects of State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography (SOEDZZ1403), and Global Change and Air-Sea Interaction (GASI-03-01-01-02). The Argo data are provided by China Argo Real-time Data Center (http://www.argo.gov.cn/argo-eng/index.asp). The HYCOM data are downloaded from http://hycom.org/. We thank the crew and participants of the R/V Shiyan-3 for their support during deployment cruise.
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