珠江口以西陆架夏季上升流的研究

A study on the summer upwellings in shelf waters west to Zhujiang River mouth

本文主要依据南海北部珠江口以西陆架区1977～1981年的水温、盐度和溶解氧饱和度等要素的序列历史资料,对该海域的上升流现象进行了分析研宄。

Routine mouthly hydrographic survey has been taken by research vessels of state Oceanic Administration in shelf waters west to Zhujiang River mouth since late 70's. Analysis of these historical data of temperature,salinity and disolved oxygen content indicates that summer upwelling is a common phenomenon in shelf waters west to Zhujiang River mouth——a portion of the northern South China Sea. The seasonal upwelling carries high salinith ,low oxygen content ,cold water from deeper layers toward surface which causes water temperature at mid and lower layers of this area decreases during summer. At the same time the salinity increases and the relative disolved oxygen content decreases. These features are clearly show in the temporal and spatial distribution of these water properties mentioned above. It is found that there is an upwelling center located at Guangzhou Bay to the northeast of Hainan Island. Upwelling is significantly intensified near this upwellig center. Further analysis suggests that except the spatial inhomogensity summer upwelling is also subjected to significant interannual variations.