气候变化背景下舟山沿岸上升流区夏季水动力演变机制

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 °C；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。

Upwelling zone along the Zhoushan coast in the context of climate change Hydrodynamic evolution mechanism in summer

Global warming will 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 simulate and study 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 °C 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 has 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 will make the bottom seawater difficult to uplift; the weakened wind stress in summer weakens the offshore expansion of the low-salinity tongue of the Changjiang Diluted Water, weakening of the stratification of the upper seawater in the upwelling zone.