Time-mean and seasonal variability of the temperature and salinity derived from hydrographic surveys for recent 20 years (1995 to 2014) around Korean Peninsula

Abstract

Coastal ocean seasonal variability of temperature and salinity around Korean Peninsula [East/Japan Sea (EJS), Yellow Sea (YS), and South Sea (SS)] are investigated with conductivity-temperature-depth (CTD) profiles collected from historical hydrographic surveys for recent 20 years (1995 to 2014). In the EJS, seasonal amplitudes of temperature are discontinuously reduced ($<1.5^\circ C$) in concave form, which may indicate the non-seasonal movement of the Ulleung Warm Eddy. Particularly, the the temperature along the EJS coast exhibits clear semiseasonal cycle ($1.5-2.4^\circ C$), which may result from the two subductions having different origins. The seasonal cycle of temperature at the YS is divided into (1) coast and offshore due to tidal mixing and (2) upper and lower layer due to thermocline. The semiseasonal cycle amplitudes of temperature at the YS subsurface (below 40 m depth) become enhanced toward offshore by $0.4^\circ C$, which may be associated with the southward extension of the YS Bottom Cold Water in summer. Additionally, the uncertainty of observations and seasonal amplitudes are extensively examined.