水体下行漫射衰减系数(Kd)不仅反映了水质的信息,而且是生物-光学模型中的关键参数,因而受到了广泛的关注.本文基于太湖梅梁湾水下光场的数据,分析了不同波长Kd的波动性随水深的变化特征,结果表明:由于水体表面波的作用,在60cm以上,Kd随深度呈现较强烈的震荡现象,而到60cm以下,随着光子的行程增大,介质散射对光场的改变趋于明显,造成该震荡幅度减弱,趋于稳定状态,甚至呈现出光场的渐进态特征.且在0-60cm的区域,下行漫射衰减系数的波动程度与水体的吸收特性呈现明显的线性相关,即水体的吸收作用突显了表面波的效应.该水体中非藻类颗粒物和黄质具有对短波光强烈吸收的特性,减弱了介质散射使光场漫射比例提高的作用,加强了表面波对水下光场的扰动作用,使得相对长波而言,短波的Kd随水深呈现出相对较大的震荡现象.

The downwelling diffuse attenuation coefficient(Kd) indicates the information ofwater quality. It is also key parameter ofbio-opticalmodel and attractingmore and more attentions. Based on the data of light field underwater in Meiliang bay of Taihu lake, the changes ofKdwithwaterdepth is analyzed. The results show that,Kdtakes on significant fluctuationwith the depth above 60cm, which is caused by the surface waves ofwater. But the fluctuation with depth weakens, and approxmi ately levels of,f even showing the characteristic ofasymptotic light fields below 60cm, because the effectof scattering is gradually significant. In the region of0—60cm, there is significant linear correlation between the degree of fluctuation ofdownwelling diffuse attenuation coefficient and the absorption ofwater, namely, the absorption of water strengthens the effectof surfacewave on the light fields in water. TheKdof shortwave takes on evident fluctuation with the depth comparedwith thatof longwave, becauseThe detritus and CDOM inwatersignificantly absorbs the radiation of shortwave, lowers diffuse light, and intensifies the effectof focusing or defocusing of surfacewaves.