Wind and tidal mixing controls on stratification and dense water outflows in a large hypersaline bay
Wind and tidal mixing controls on stratification and dense water outflows in a large hypersaline bay
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风和潮汐混合控制大型高盐海湾的分层和浓水流出
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
R. Hofmeister
中科院分区：
文献类型：
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作者：
Y. Hetzel;C. Pattiaratchi;Ryan J. Lowe;R. Hofmeister
在鲨鱼湾（西澳大利亚州的一个大型逆河口），纵向密度梯度建立了重力环流，这对于湾-海洋交换和幼虫等生物物质的运输非常重要。使用三维斜压海洋环流模型（通用河口输运模型，GETM）研究了风和潮汐混合能量对垂直分层和重力环流控制的相对贡献。在这个大型逆河口，风和潮汐对垂直混合的影响被发现具有相似的程度。确定了〜15 m的临界深度，确定是否需要风或潮汐或两者的组合来创造垂直混合条件。在比临界深度浅的地方，风或潮汐都可以充分混合水柱。相比之下，需要风和潮汐的结合才能混合更深的河道。密度驱动的环流在最大分层期后 0-3 天达到峰值，导致潮汐阶段后每两周对沿海底的浓水流出进行调节。盐通量计算为通过较深的北部入口航道的流出量占主导地位提供了新的证据，该流出量在潮汐的所有阶段都持续存在。相比之下，通过西部航道的流出量更加间歇性，潮汐成分更强。入口之间的风力驱动的侧向环流也很重要，并且可以在北风事件期间暂时逆转环流。
In Shark Bay, a large inverse estuary in Western Australia, longitudinal density gradients establish a gravitational circulation that is important for Bay-ocean exchange and transport of biological material such as larvae. The relative contributions of energy from wind and tidal mixing on the control of vertical stratification and gravitational circulation were investigated using the three-dimensional baroclinic ocean circulation model (General Estuarine Transport Model, GETM). In this large inverse estuary, the effects of the winds and tides on vertical mixing were found to be of similar magnitude. A critical depth of ∼15 m was identified that determined whether winds or tides or a combination of the two was required to create vertically mixed conditions. Where it was shallower than the critical depth, either the wind or tide could fully mix the water column. In contrast, a combination of both winds and tides was required to mix the deeper channels. Density-driven circulation peaked 0–3 days after periods of maximum stratification, resulting in a fortnightly modulation of dense water outflows along the seabed following the tidal stage. Salt flux calculations provided new evidence for the predominance of outflow through the deeper northern entrance channel where outflows persisted through all stages of the tide. In contrast, outflows through the western channel were more intermittent with a stronger tidal component. Wind driven lateral circulation between the entrances was also important and could temporarily reverse the circulation during northerly wind events.