根据2011年春季（4月）夏季（8月）两个航次调查的CTD温盐资料，获得观测期间黄、东海主要水团特征：（1）夏季黄海冷水团10℃等温线在黄海海域中部30m以深，影响范围西至122°E南至34°N，最低温度为6．2℃，比气候态平均冷水团温度低约2℃；（2）夏季冲淡水以长江口为中心，呈半圆形向外扩展，并：无明显NE转向，30．00等盐线在32°N断面上东至124°E，南至29．5°N，扩展范围与往年相比偏西1。左右，而在sE方向较往年有明显延伸扩展。水文结构特征为：（1）春季，温跃层主要在南黄海中部以西，跃层强度仅为0．10—0．40℃／m；密跃层主要在长江口以东，跃层强度0．20—0．30kg／m4；（2）夏季，温跃层强度最高值在长江口东北，跃层强度达到2．41℃／m，上界深度5．5m，厚度2．5m；黄海温跃层强度普遍强于东海，主要是冷水团区域表底显著的温度差异造成；密跃层强度高值区在33°N断面西侧海区，强度达到1．38kg／m2，上界深度5．5m，厚度约为1．5m；沿长江冲淡水舌轴方向的密跃层强度为0_30—0．60kg／m2，自西向东逐渐减弱。%Temperatures and salinities structures and water masses varied significantly with season in the Yellow Sea and East China Sea. The two cruises were carried out in spring （April） and summer （August） of 2011 to investigate the reasons of jelly fish break-out. It was found that （1） 10℃ isotherm which stood for the Yellow Sea Cold Water in summer consisted in the central of the Yellow Sea below the 30m depth, the range extended to 122℃E in the west and to 34°N in the south. The lowest temperature was 6.2℃ which was 2.0℃ lower than the average climatological value; （2） The Changji- ang River Diluted water spread eastward in semicircle centered in the Changjiang River mouth in summer. No obvious northeastward direction-turning was found and the 30.00 isohaline extended to 124°E in the east and to 29.5°N in the south. The Changjiang River Diluted water extension was about l°west along 32°N section but distinctly extended to southeast- ward compared with the averages; （3） Taiwan Warm Current water could reach 28°N and 30°N in the surface and bottom layer in spring, respectively. It was not observed in the 0--30m layer in summer. It extended to 30.5°N in the northward in the bottom. Hydrographic structures were （1） in spring, the thermocline lay in the center of the Yellow Sea. The thermo- cline intensity was 0.10--0.40℃/m. The pycnocline lay in the east of Changjiang River estuary and the intensity was 0.20--0.30kg/m4; （2） in summer, the maximum value of the thermocline intensity （2.41℃/m） lay in the northeast of Changjiang River mouth with upper depth at 5.5m and 2.5m thickness. The thermocline intensity in the Yellow Sea was stronger than that in the East China Sea because of remarkable temperature difference in the surface and bottom affected by the Yellow Sea Cold Water; （3） The distribution of pycnocline intensity was almost the same as the thermocline in summer and the maximum value of the pycnocline intensity （1.38kg/m4） lay in the west of 33°N section. The pycnocline upper depth was 5.5m and thickness was 1.5m. Pycnocline intensity along the tongue axes of the Changjiang River Diluted water was 0.30--0.60kg/m4, weakening from west to east. The intensity of thermocline and pycnocline gradually got weaker while the upper depth and thickness got stronger from offshore to the central shelf sea. Key words Seasonal variation of water mass and hydrographical structure, Thermocline, Pycnocline, Yellow Sea and East China Sea
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