长江口细颗粒悬沙浓度垂向分布

Vertical Profiles of Fine Suspension Concentration in the Changjiang Esturary

在长江口利用“声学悬沙观测系统”观测到大潮四种典型的高时空分辨率细颗粒悬沙浓度声学垂向分布图和垂线分布曲线。悬沙浓度垂线分布曲线表明：（１）在涨潮时呈Ｌ形，悬沙浓度的垂向变化梯度小（浓度小于１０ｇ／ｌ）。（２）在涨急时呈射流形，射流顶的悬沙浓度达１０ｇ／ｌ，悬沙浓度的垂向变化梯度大。（３）在落潮时从水面到水底悬沙浓度按指数增加，可能代表恒定均匀流中悬沙处于平衡条件的分布，泥沙垂向扩散系数εＳ在数值上大约是泥沙颗粒沉降速度ωＳ的两倍。（４）在落急时是不连续，并且在水体中部呈射流形，悬沙浓度的垂向变化梯度大。

This paper reports on four patterns of vertical suspension concentration profiles obtained at spring tide in the Changjiang Estuary by using an acoustic suspended sediment monitor.Type I is L shaped at flood tide.Vertical gradients in suspension concentration are small(<1 0 g L -1 ).Type II is jet like at max.flood tide.Suspension concentration at the head of jet reaches or exceeds 10 0 g L -1 ,and vertical gradients in suspension concentration are large.Type III is characterized by an exponential increase from surface to bottom at ebb tide.Type IV is discontinuous and jet like in the mid water depth at max.ebb tide.Vertical gradients in suspension concentration are large.