气候变化背景下舟山沿岸上升流区夏季水动力演变机制  

Summer hydrodynamics evolution mechanism in upwelling zone along Zhoushan coast under climate change

作　　者：刘建时 林军[1,2,3] 钟威 徐泽宇 LIU Jianshi;LIN Jun;ZHONG Wei;XU Zeyu(College of Oceanography and Ecological Science,Shanghai Ocean University,Shanghai 201306,China;Engineering Technology Research Center of Marine Ranching,Shanghai Ocean University,Shanghai 201306,China;Key Laboratory of Marine Ecological Monitoring and Restoration Technologies,Shanghai 200137,China)

机构地区：[1]上海海洋大学海洋科学与生态环境学院,上海201306 [2]上海海洋大学海洋牧场工程技术研究中心,上海201306 [3]自然资源部海洋生态监测与修复技术重点实验室,上海200137

出　　处：《上海海洋大学学报》2024年第2期464-479,共16页Journal of Shanghai Ocean University

基　　金：上海市科学技术委员会地方院校能力建设项目(23010502500)。

摘　　要：全球变暖会对舟山沿岸上升流的驱动机制产生深远影响,继而作用于海域内的生态环境及渔业资源发生的变迁。使用三维海洋数值模型FVCOM,模拟研究了热通量、风场等气候环境因子变化下舟山沿岸上升流区夏季水动力及环境因子的分布特征。通过引入跃变检验方法来评估全球变暖对过去三十多年来舟山及其邻近海域的夏季海表温度的影响,发现在2016年前后发生了明显的跃变,跃变后海表温度相对于跃变前升高了约1℃;热通量分析结果显示:春季云量减小短波辐射增加,导致的海水热含量增加是夏季海水升温的重要原因;风速的时空变化表明舟山海域7月风速在近几十年有减弱的趋势。通过构建气候环境因子变化的敏感性数值模型实验探究了舟山沿岸上升流水动力的演变机制,结果表明:海气热通量增加导致的表层海水吸热及平流热输运增加引起的海水层化加强会使得底层海水不易抬升;夏季风应力的减弱削弱了长江冲淡水低盐水舌的离岸扩展,导致上升流区上层海水的层化减弱,从而加强中下层海水向岸爬升,增加沿岸上升流的强度。Global warming is expected to have a profound impact on the driving mechanism of the Zhoushan coastal upwelling,and then affect the changes in the ecological environment and fishery resources in the sea.Using the three-dimensional numerical ocean model FVCOM,we simulated and studied the distribution characteristics of summer hydrodynamics and environmental factors in the upwelling zone of Zhoushan coast under the changes of heat flux,wind field and other climatic and environmental factors.The effect of global warming on the summer sea surface temperature in Zhoushan and its neighboring waters over the past three decades was assessed by introducing a transition test,and it was found that a significant leapfrog occurred around 2016,and the sea surface temperature increased by about 1℃after the transition compared with that before the transition;the results of heat flux analysis showed that the increase of seawater heat content due to the decrease of cloudiness and the increase of short-wave radiation in spring was an important reason for the warming of seawater in summer;the spatial and temporal variations of wind speed show that the wind speed in Zhoushan sea area in July had a tendency to weaken in recent decades.The results show that the enhanced stratification of seawater caused by the increased heat absorption of surface seawater and increased advective heat transport caused by the increased heat flux of sea air makes the bottom seawater difficult to uplift;the reduced wind stress in summer weakens the offshore expansion of the low-salinity tongue of the Changjiang Diluted Water,resulting in a weakening of the stratification of seawater upper layer in the upwelling zone,thereby strengthening the ascent of the middle and lower layers of seawater towards the shore and increasing the intensity of coastal upwelling.

关 键 词：上升流 气候变化 变化机制 数值模拟 舟山海域 

分 类 号：P731.2[天文地球—海洋科学]