摘要
基于EFDC(Environmental Fluid Dynamics Code)数值模式建立了长江口及其邻近海域的三维水动力学模型,用于研究风对夏季长江冲淡水扩展的影响。基于实测资料的验证结果表明,模型能够比较真实的反映潮汐、海流、温度和盐度的变化过程。敏感性试验的结果显示,风对夏季长江冲淡水的扩展有着非常显著的影响。在Ekman输送的作用下,长江冲淡水将向风向的右侧扩展。5m/s风速下,东风、东南风、南风和西南风4个风向下的冲淡水明显向外海扩展,而西风、西北风、北风和东北风下的冲淡水都被限制在近岸水域。Ekman输送的强度随风速增强而增强,冲淡水向风向右侧的扩展也越来越明显。舌轴区因为层结明显,湍流活动相对较弱,对风能量的耗散相对较小,所以相同的风速增量对舌轴区表层水的加速作用最强,这导致更多的淡水经由舌轴区输送,使得淡水舌宽度随风速的增加而变窄。对长江口海域表面风的气候统计分析表明,上述数值试验结果能够很好的解释气候态下长江冲淡水扩展方向与表面风变化的关系。
A three-dimensional hydrodynamic model for Yangtze Estuary and the adjacent sea was developed within the framework of Environmental Fluid Dynamics Code （EFDC）. This model was used to study the relationship be- tween winds and Changjiang （Yangtze） River diluted water （CRDW） in summer. Simulated elevations, currents, temperatures and salinities are fairly consistent with observed data. Numerical experiments show that wind plays an important role in the expansion of CRDW. Wind induced Ekman transport would push CRDW to the right of wind direction. At a speed of 5 m/s, easterly, southeasterly, southerly and southwesterly wind push CRDW sea- ward significantly, while westerly, northwesterly, northerly and northeasterly wind confine CRDW to the coastal ar- ea. The Ekman transport is intensified with intensified wind, resulting that more CRDW will be transported to the right of wind direction. Due to stratified water, the turbulence is relatively weak in the axis of the low-salinity tongue. Weak turbulence consumes less wind energy. So the water in the axis of the tongue is accelerated more than water in other areas. Then,more diluted water is transported through the axis area of the low-salinity tongue. Eventually, the width of the tongue becomes smaller with stronger winds. Statistical analysis of observed data also verifies the numerical conclusions.
出处
《海洋学报》
CAS
CSCD
北大核心
2013年第1期25-37,共13页
基金
国家自然科学重点基金"基于非均匀基流的行星波传播新理论与亚澳季风相互作用"(41030961)
