长江冲淡水扩展区域孤立水团分析

ISOLATED LOW-SALINITY WATER MASS IN EXPANSION AREA OF CHANGJIANG DILUTED WATER

本文利用2017年5月长江口外海域的实测资料,研究了孤立低盐水团的三维结构以及输运过程,并进一步统计了孤立水团发生的历史事件。低盐水团的水文参数在未脱离前于上层呈现同心圆等值区分布。研究发现,大潮引起的强上升流对低盐水团的脱离起到决定性的作用。孤立低盐水团的生消周期为7-10d,其脱离和输运受长江径流、风场等的影响,偏北风和偏南风对水团输运分别起到抑制和促进作用。低盐水团的脱离及输运过程极大加强了冲淡水跨锋面的营养盐和陆源有机物的输运。这些发现进一步丰富了对长江冲淡水输运过程的研究。

Based on in-situ observation in May 2017 and associated satellite-derived data,we analyzed isolated low-salinity water masses in the extension areas of the Changjiang River estuary and investigated the 3-D structure,transport,and detachment of the water masses,and the events of low-salinity water masses in history were also studied.We found that strong upwelling by strong tides movement was responsible for the detachment of low-salinity water mass.The hydrological parameters of the water mass before detachment presented a concentric distribution in the upper layer.The life cycles of the water masses were 7 to 10 days,whose detachment and transport were affected by the Changjiang River runoff,wind field etc.The northerly inhibited while southerly wind promoted the transport of the water masses.The detachment and transport of the water masses greatly promoted the exchanges of nutrients and organic matter with diluted water,which shall enrich our understanding of the low-salinity water masses off the Changjiang River estuary.