A long-term volume transport time series estimated by combining in situ observation and satellite altimeter data in the northern South China Sea

摘要

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 = 10(6) m(3) 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.