1. Introduction
The Yellow Sea (YS) is a semi-enclosed marginal sea with depths
ranging from 20 to 90 m in the western Pacific Ocean, bounded by
China and Korea. It is famous for its high productivity and abundant
fishery resources. Recently, environmental problems in the YS became
the center of interest of oceanographers both in China and Korea and
much related research work (e.g. the China GLOBEC-IMBER program
and China Jellyfish Program) is in progress (Sun et al., 2011; Tang
et al., 2007, 2010).
In the past fewdecades, a number of studies have been carried out in
the YS both to investigate the circulation features and for water mass