Synoptic distributions of thermal surface mixed layer and thermocline were identified using four airborne expendable bathythermograph (AXBT) surveys (September 1992 and February, May, and September 1993) in the southern Yellow and East China Seas. Seasonality and a dominant driving mechanism of the surface mixed layer were examined. The dominant driving mechanisms differ between seasons and between on-shelf and off-shelf regimes. Currents, eddies, and migration of bottom cold waters (on the shelf) also affect the surface mixed layer. Thermocline thickness, temperature difference from thermocline top to bottom, and thermocline intensity in warm seasons were measured, and their synoptic features were also discussed.is unsuitable to represent mesoscale (10-100 km) features revealed by Furey and Bower (2005) because of its low spatial resolution (e.g. 2° × 2° (de Boyer Montégut et al., 2004)).For these reasons, we have studied synoptic characteristics of vertical layers in YES in extension to the work of Furey and Bower (2005). First, we identify the vertical layers from these AXBT data (Section 2) and examine a dominant mechanism for developing SML with supplementary descriptions of seasonality of SML, which are not mentioned by Furey and Bower (2005) (Sections 3 and 4). Second, we explore the characteristics of the thermocline (Section 5). The distributions of the vertical layers in a given year would be a complement to the climatological version of these distributions (e.g. Chu et al. (1997a) for YS) or any global datasets (e.g. Kara et al. (2003) and de Boyer Montégut et al. (2004)) and would be useful for studies such as heat budget, ocean model validation, and primary production dynamics.
Vertical Layer IdentificationSML is a layer of vertically-uniform temperature, salinity, and density, where active air-sea fluxes generate turbulence to mix the water downward to the SML depth (SMLD), which is the depth of transition from a homogeneous upper layer (i.e. SML) to a stratified layer of the pycnocline (Sprintall and Cronin, 2001). SMLD determined from a temperature profile is not always the same