珠江口伶仃洋及磨刀门盐淡水混合特征及机制分析

基于2016年1月3日至18日的珠江口盐度分层观测资料，对比分析伶仃洋与磨刀门盐淡水混合特征及其机制，结果表明:（1）伶仃洋及磨刀门水域口门处盐度分层最明显，小潮阶段分层特征最显著；（2）磨刀门分层较伶仃洋更为显著，主要原因在于上游流量的差异；（3）大潮转小潮过程中，伶仃洋上游盐度虽向口门下落，但下落速度较慢，分层逐渐明显，而磨刀门水道中盐淡水却混合充分，这是由于盐度在河道中剧烈震荡并快速退出河口所致；（4）在伶仃洋及磨刀门口门附近，重力环流与潮汐剪切产生的抑制混合作用大于潮流紊动促进混合的作用，因此分层显著，河口上游水深较浅，潮流紊动作用较强，起到促进混合的作用。

Comparative analysis of the characteristics and mechanism of the salt-fresh water mixing in Lingdingyang and Modaomen estuary,Pearl River Estuary

Based on the stratified observation data of the Pearl River Estuary for half a month in the dry season from January 3 to 18, 2016, analysis of the mixing characteristics and mechanism of salt-fresh water in Lingdingyang and Modaomen estuary. The results show that: (1) Salinity stratification is the most obvious at the mouth of Lingdingyang and Modaomen estuary, during the neap tide salinity stratification is the most significant, the mixing strength increases gradually with the increase of the tidal range; (2) Salinity stratification of Modaomen estuary is more significant than Lingdingyang estuary, the reason is the difference of the upstream flow; (3) During the spring tide turns to neap tide, salinity stratification becomes obvious gradually in Lingdingyang estuary, while the salt fresh water in Modaomen estuary is mixed sufficiently, this is because although the salinity fell towards to the mouth but it fell slowly lead to some still stay in the river in Lingdingyang estuary, but in Modaomen estuary the salinity shakes violently and quickly exits the estuary; (4) In the mouth of Lingdingyang and Modaomen estuary, the inhibitory action produced by gravity circulation and tidal shear is greater than the auxo-action of tidal turbulence, so salinity stratification is significant; the water depth in the upstream of the estuary is shallow, so the tidal turbulence is strong that promoting the mixing of salt-fresh water.