台风期间厦门湾潮流边界层特征研究

Characteristics of tide-induced bottom boundary layers in Xiamen Bay under the tropical cyclone conditions

本文基于2007年8月圣帕台风影响台湾海峡期间的厦门湾垂向海流流速剖面观测资料,运用Karman-Prandtl模型统计和分析了流速对数剖面的出现频率和边界层参数(摩阻流速与粗糙长度).结果表明流速剖面满足对数分布出现频率都超过50%,但进行内部一致性原则分析后,流速剖面满足对数分布情况均不足30%.造成流速剖面偏离对数分布的因素主要有:台风、径流、流速加减速、水体分层、底床结构、海底悬沙浓度等等.台风期间的摩阻流速和粗糙长度都大于非台风期间的数值.

A mooring system was used to measure the high-resolution current velocities of different layers above the seabed in Xiamen Bay under the condition of Sepat tropical cyclone conditions in Aug. 2007. Using Karman-Prandfl equation, the characteristics of tide-induced bottom boundary layers were analyzed. It indicates that over 50% of the velocity profiles are logarithmic in a tidal cycle and the ratio drops lower than 30% when the internal consistency analysis was adopted. It is showed that tropical cyclone, runoff, acceleration and deceleration of current velocities, stratification, bed structure and suspended sediment concentrations played important roles to the occurrence of logarithmic profile. The shear velocity and roughness length during tropical cyclone conditions were higher than that of normal time.