Analysis on hydrological characteristics off the Pearl River Estuary in summer and winter of 2006

Based on the data observed during the summer and winter cruises in 2006,the authors analyze the distributions of temperature and salinity off the Pearl River Estuary,the characteristics of thermocline,halocline and pycnocline as well as their relations to upwelling,mesoscale eddies and currents.The results show that:(1) strong thermocline,pycnocline and halocline exist in summer and are strongly affected by the diluted water,upwelling and eddies;in particular,the spreading of the diluted water leads to the formation of double thermocline and barrier layer in some waters;(2) in winter,sea water mixes well in the shallow shelf,while there exists weak thermocline at the shelf slope.