Seasonal variation of temperature and salinity fields and water masses in the Bien Dong (South China) sea

Seasonal and bimonthly analyses of the CTD and STD data in the Bien Dong Sea have been performed using a variational inverse method (VIM). The results, materialized as gridded data sets (horizontal resolution at 1/4 of a degree at 26 depth levels from 5m to 4500m), show the basic features of the hydrology of the Bien Dong Sea and its trend of seasonal variabilities affecting the properties of the water masses. The seasonally reversing monsoon wind and the variation of net air-sea fluxes play an important role in determining the transformation and spreading of the water masses. The present work is conceived as a basic support to more advanced studies, including diagnostic calculations and assimilation of hydrological data in 3D primitive equation models for the Bien Dong Sea.