In order to identify or shed light on dominant long‐term processes of the deep hypolimnion of Lake Geneva (309 m depth), time series of temperature and horizontal currents and profiles of temperature and oxygen, taken for over a decade in the deepest part of the lake, were analyzed. The focus was on the summer stratification period (May to October). During that period, temperatures near the bottom always increased quasi‐linearly with the same gradient and small amplitude variability. Vertical mean temperature gradients in the lowest 60 m of the water column remained nearly constant over the years and were comparable to those of the deep ocean. Mean current velocity at the deepest point was 3.0 ± 0.5 cm s⁻¹ and ever‐present inertial motions clearly dominated currents. Oxygen decreased quasi‐linearly and eutrophication appeared not to affect this rate of decrease. It is suggested that as in the deep ocean, breaking internal waves and friction from decaying inertial motion occurring in the deep hypolimnion strongly contribute to turbulent mixing in that layer. The climate change‐induced long‐term warming trend seen in the upper layers of the lake was not detected in the deep hypolimnion. Instead, year‐to‐year climate change‐induced variability strongly affected the deep hypolimnion. During cooling in cold winters, lateral advection contributed more to temperature decrease and oxygen renewal in the deep hypolimnion than vertical convection. The present analysis has shown that the dynamics of this layer are highly three‐dimensional and that the processes occurring therein cannot be correctly described by traditional one‐dimensional concepts.

中文翻译：

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长期温度，氧气和电流测量揭示了对日内瓦湖深层水体动力学的洞察力

为了确定或阐明日内瓦湖深层水体（深度309 m）的主要长期过程，对温度和水平电流的时间序列以及温度和氧气的分布进行了研究，该过程是在日内瓦最深处进行了十多年的研究湖，进行了分析。重点是夏季分层期（5月至10月）。在此期间，底部附近的温度始终以相同的梯度和较小的幅度变化准线性增加。多年来，水柱最低60 m处的垂直平均温度梯度几乎保持恒定，可与深海相媲美。最深处的平均速度为3.0±0.5 cm s ^-1惯性运动明显地主导着电流。氧气近似线性下降，富营养化似乎不影响这种下降速度。建议像在深海中那样，深层俯冲中发生的内部波的破裂和惯性运动的衰减会强烈地促进该层的湍流混合。在深层水lim中未发现由气候变化引起的在湖上层的长期变暖趋势。取而代之的是，逐年的气候变化引起的变化强烈影响了深层的俯冲。在寒冷的冬季降温期间，横向对流比竖直对流对深层水体温度下降和氧气更新的贡献更大。