Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms
A calibrated three-dimensional numerical model (Delft3D) and in-situ observations are used to study the relation between deep-water temperature and deep mixing in Lake Garda (Italy). A model-observation comparison indicates that the model is able to adequately capture turbulent kinetic energy produc...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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PAGEPress Publications
2021-06-01
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| Series: | Journal of Limnology |
| Subjects: | |
| Online Access: | https://jlimnol.it/index.php/jlimnol/article/view/2010 |
| _version_ | 1819293902855733248 |
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| author | Bouke Biemond Marina Amadori Marco Toffolon Sebastiano Piccolroaz Hans van Haren Henk A. Dijkstra |
| author_facet | Bouke Biemond Marina Amadori Marco Toffolon Sebastiano Piccolroaz Hans van Haren Henk A. Dijkstra |
| author_sort | Bouke Biemond |
| collection | DOAJ |
| description | A calibrated three-dimensional numerical model (Delft3D) and in-situ observations are used to study the relation between deep-water temperature and deep mixing in Lake Garda (Italy). A model-observation comparison indicates that the model is able to adequately capture turbulent kinetic energy production in the surface layer and its vertical propagation during unstratified conditions. From the modeling results several processes are identified to affect the deep-water temperature in Lake Garda. The first process is thermocline tilting due to strong and persistent winds, leading to a temporary disappearance of stratification followed by vertical mixing. The second process is turbulent cooling, which acts when vertical temperature gradients are nearly absent over the whole depth and arises as a combination of buoyancy-induced turbulence production due to surface cooling and turbulence production by strong winds. A third process is differential cooling, which causes cold water to move from the shallow parts of the lake to deeper parts along the sloping bottom. Two of these processes (thermocline tilting and turbulent cooling) cause deep-mixing events, while deep-cooling events are mainly caused by turbulent cooling and differential cooling. Detailed observations of turbulence quantities and lake temperature, available at the deepest point of Lake Garda for the year 2018, indicate that differential cooling was responsible for the deep-water cooling at that location. Long-term simulations of deep-water temperature and deep mixing appear to be very sensitive to the applied wind forcing. This sensitivity is one of the main challenges in making projections of future occurrences of episodic deep mixing and deep cooling under climate change. |
| first_indexed | 2024-12-24T04:17:49Z |
| format | Article |
| id | doaj.art-dd2c0a57354a47cb9be653b89a08dfa6 |
| institution | Directory Open Access Journal |
| issn | 1129-5767 1723-8633 |
| language | English |
| last_indexed | 2024-12-24T04:17:49Z |
| publishDate | 2021-06-01 |
| publisher | PAGEPress Publications |
| record_format | Article |
| series | Journal of Limnology |
| spelling | doaj.art-dd2c0a57354a47cb9be653b89a08dfa62022-12-21T17:15:54ZengPAGEPress PublicationsJournal of Limnology1129-57671723-86332021-06-0180210.4081/jlimnol.2021.2010Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanismsBouke Biemond0Marina Amadori1Marco Toffolon2Sebastiano Piccolroaz3Hans van Haren4Henk A. Dijkstra5Institute for Marine and Atmospheric research Utrecht, Department of Physics, Utrecht UniversityDepartment of Civil, Environmental and Mechanical Engineering, University of Trento; Institute for Electromagnetic Sensing of the Environment, National Research Council, MilanDepartment of Civil, Environmental and Mechanical Engineering, University of TrentoPhysics of Aquatic Systems Laboratory (APHYS) - Margaretha Kamprad Chair, École Polytechnique Fédérale de LausanneRoyal Netherlands Institute for Sea Research (NIOZ)Institute for Marine and Atmospheric research Utrecht, Department of Physics, Utrecht UniversityA calibrated three-dimensional numerical model (Delft3D) and in-situ observations are used to study the relation between deep-water temperature and deep mixing in Lake Garda (Italy). A model-observation comparison indicates that the model is able to adequately capture turbulent kinetic energy production in the surface layer and its vertical propagation during unstratified conditions. From the modeling results several processes are identified to affect the deep-water temperature in Lake Garda. The first process is thermocline tilting due to strong and persistent winds, leading to a temporary disappearance of stratification followed by vertical mixing. The second process is turbulent cooling, which acts when vertical temperature gradients are nearly absent over the whole depth and arises as a combination of buoyancy-induced turbulence production due to surface cooling and turbulence production by strong winds. A third process is differential cooling, which causes cold water to move from the shallow parts of the lake to deeper parts along the sloping bottom. Two of these processes (thermocline tilting and turbulent cooling) cause deep-mixing events, while deep-cooling events are mainly caused by turbulent cooling and differential cooling. Detailed observations of turbulence quantities and lake temperature, available at the deepest point of Lake Garda for the year 2018, indicate that differential cooling was responsible for the deep-water cooling at that location. Long-term simulations of deep-water temperature and deep mixing appear to be very sensitive to the applied wind forcing. This sensitivity is one of the main challenges in making projections of future occurrences of episodic deep mixing and deep cooling under climate change.https://jlimnol.it/index.php/jlimnol/article/view/2010turbulence modelling in lakesdeep mixingclimate change |
| spellingShingle | Bouke Biemond Marina Amadori Marco Toffolon Sebastiano Piccolroaz Hans van Haren Henk A. Dijkstra Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms Journal of Limnology turbulence modelling in lakes deep mixing climate change |
| title | Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms |
| title_full | Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms |
| title_fullStr | Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms |
| title_full_unstemmed | Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms |
| title_short | Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms |
| title_sort | deep mixing and deep cooling events in lake garda simulation and mechanisms |
| topic | turbulence modelling in lakes deep mixing climate change |
| url | https://jlimnol.it/index.php/jlimnol/article/view/2010 |
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