Thermobaricity: Pressure effects on temperature stratification and circulation in lakes - PONTEM

社会意义：在不久的将来，为人民提供足够的优质水将是一项重大挑战。土地利用和气候变化加剧了这一问题。我们只有有限的可能性来创造新的水或季节性地将水库中的水转移到短缺时期。明智地利用和管理水资源似乎是缓解这一状况的最有希望的工具。因此，对湖泊采用了数值模型：然而，水性质的实施仍然依赖于海洋假设。因此，在接近最大密度温度(即接近4°C)的湖泊深水中模拟的流动是有缺陷的，或者与现实完全脱节。我们假设，在数值模式中包含热压性解决了这个问题，并且适当地反映了热压性效应。我们对湖水的物理性质有了更好的了解。湖泊数值模型可能会有实质性的改进。科学挑战：在温带和亚极地气候带，热压性控制着深湖的再循环。尽管这个话题最近在海洋学中引起了兴趣，但深水湖泊的特征还没有得到妥善的处理。根据定义，当热压效应占主导地位时，势密度的方便性质就会丧失。这使得稳定性考虑因素很难显示。然而，我们相信，对温压效应的描述可以显著改进。我们建议从热力学方法的基础开始，从稳定性考虑到简约模拟，并将通过在数值模式中适当地包含热压性来完成这一研究计划，以在一些突出的情况下展示影响。我们相信，有了我们的共同能力，我们就能找到理解和交流温压效应的新方法。根据我们的经验，我们找到了有效的数值方法来恰当地处理这个问题，以便在一些深水湖泊中实现和演示温压效应。我们将使用Deltares的DELFT3D模型进行数值模拟。我们期待这一项目为未来富有成效的合作开辟新的前景。

Societal Relevance: Providing the population with sufficient good quality water will be one of the great challenges in near future. Land use and climate change exacerbate this problem. We have only limited possibilities to create new water or transfer water in reservoirs seasonally to periods of shortage. Wise use and management of water resources appear as the most promising tools to alleviate the situation. Hence, numerical models have been adopted for lakes: the implementation of water properties however is still tied to ocean assumptions. As a consequence, simulated flows in the deep water of lakes close to temperature of maximum density (i.e. near 4°C) are flawed or entirely disconnected from reality. We hypothesize that an inclusion of thermobaricity in numerical models solves this issue and thermobaric effects are properly reflected. We have much better knowledge of the physical properties of lake waters. Numerical lake models could be substantially improved. Scientific Challenge: Thermobaricity is controlling recirculation in deep lakes in the temperate and subpolar climate zone. Though the topic has gained interest recently in oceanography, the features in deep lakes have not been properly dealt with. By definition, the convenient property of potential density is lost, when thermobaric effects are dominant. This makes stability considerations difficult to display. However, we are convinced that the description of thermobaric effects can significantly be improved. We propose to start from basics of thermodynamic approaches to stability considerations to parsimonious modelling and will complete this research programme by the implementation of a proper inclusion of thermobaricity in numerical models to demonstrate the effects in some prominent cases. We are convinced that with our joined competences we find new approaches to understand and communicate thermobaric effects. From our experience we find effective numerical approaches to properly deal with the topic to implement and demonstrate thermobaric effects in some deep lakes. We will use the model DELFT3D by DELTARES for numerical simulations. We expect that this project opens the perspective of future fruitful collaboration.