太湖梅梁湾水下光场扰动的特征分析

Characteristic Analysis of the Fluctuation of Light Field under Water in Meiliang Bay of Taihu Lake

在水体表面波的扰动作用下,水下光场随深度呈现较为明显的波动现象,且水中光合作用会对水下光场波动作出响应,因而此现象引起了广泛的关注。基于太湖梅梁湾观测的水下光场数据,计算了水下光场随深度的变化,并分析了其波动特征。结果表明:表面波引起了水下光场较为明显的波动现象,波动振幅最大的深度基本小于20 cm,远小于海洋中对应的深度;水下光场波动的振幅随深度呈e的负指数衰减,漫射消光系数越大,水下光场的波动衰减得也越快;当深度大于30 cm时,水下光场的扰动现象基本消失。还计算了船舶对水下光场观测的影响,发现直射光未被遮挡的情况下,漫射比例越高,其相对误差越大。

There is a significant fluctuation in the light field under water caused by surface wave of water, to which the photosynthesis of phytoplankton in water responses. As a result, the phenomenon is attracting more and more attentions. Based on the data of light field under water in Meiliang Bay of Taihu Lake, the variation of light field under water with depth was calculated and the fluctuant characteristics of light field under water were analyzed. The results show that significant fluctuation in light field under water is resulted from surface wave of water. The maximal fluctuation depth in aptitude is approximately smaller than 20 cm, which is much smaller than that in ocean. The decrease of the fluctuation varies with depth is exponential. The larger is the diffuse attenuation coefficient, the faster is the attenuation of magnitude of the light field under water. The fluctuation will almost disappear when the depth is larger than 30 cm. In addition, the effect of boat on the measured light field under water was investigated. If the direct sunlight isn＇t blocked by the boat the larger proportion of the skylight in the incident light, the more relative errors just beneath the surface of water caused by the shelter of boat will be.