Restricted horizontal exchange and vertical stratification restrict ventilation of bottom waters in many coastal systems, leading to stagnant basin water conditions. Dense inflows from oceanic sources can lead to dramatic changes in basin‐scale properties over very short timescales. Here, we used a semi‐enclosed coastal basin with deep‐anoxia (Lough Furnace) as a test bed, in order to discern estuary‐ocean exchange dynamics that lead to irregular and ephemeral deep‐water ventilations. Measured densities and current profiler‐based estimates of volume fluxes were used to compute typical renewal times of individual water masses in the stratified inner basin. Renewal timescales were primarily determined by freshwater flux and the spring‐neap tidal cycle. The deployment period culminated with observations of a ventilation of the basin water which had been stagnant for over 2.5 yr. Entrainment of ambient resident water doubled the volume of the dense plume and diluted its oxygen content. Following ventilation, the volumetric extent of anoxia expanded by 20% within several months, owing to uplifting of old basin water and oxygen consumption in the new basin water. Founded on these observations, a predictive model was constructed relying only on freshwater, atmospheric pressure, and wind data and successfully recreated ventilation events over the past decade. Hindcasting the model back multiple decades implied contrasting periods of higher and lower frequency variability in ventilation occurrence. This model offers a diagnostic tool for assessing how climatic change may influence the oxygen climate in systems that experience contrasting regimes of suboxia and ventilation.

中文翻译：

---

表征缺氧沿海盆地的通风事件：观察到的动力学和气候驱动因素的作用

受限制的水平交换和垂直分层限制了许多沿海系统底部水的通风，导致流域水状况停滞。来自海洋的大量流入会在很短的时间内导致流域尺度特性的剧烈变化。在这里，我们使用具有深层缺氧的半封闭沿海盆地（熔炉）作为试验床，以识别导致不规则和短暂的深水通风的河口-海洋交换动力学。测得的密度和基于流量分布的电流剖面仪的估计值用于计算分层内盆地中各个水团的典型更新时间。更新时间尺度主要由淡水通量和春季潮汐周期决定。部署期的最后结果是流域水的通风停滞了2.5年以上。夹带周围的居民水使浓烟羽的体积增加了一倍，并稀释了其氧气含量。通风后，由于旧盆地水的增加和新盆地水中的氧气消耗，缺氧的体积范围在几个月内扩大了20％。基于这些观察结果，仅依靠淡水，大气压力和风的数据构建了预测模型，并成功地重建了过去十年的通风事件。对模型进行多时后隐式隐含暗示了通风发生频率上下波动的对比时期。