Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms

Credits: Francesco Lanzillo and Francesco Cassano
Submitted: 1 March 2021
Accepted: 21 April 2021
Published: 21 June 2021
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Supplementary: 102
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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.

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Amadori M, Piccolroaz S, Giovannini L, Zardi D, Toffolon M, 2018. Wind variability and Earth’s rotation as drivers of transport in a deep, elongated subalpine lake: The case of Lake Garda. J. Limnol. 77:1814. DOI: https://doi.org/10.4081/jlimnol.2018.1814
Amadori M, Giovannini L, Toffolon M, Piccolroaz S, Zardi D, Bresciani M, Giardino C, Luciani G, Kliphuis M, van Haren H, Dijkstra HA, 2021. Multi-scale validation of a 3D atmosphere-lake model based on standard monitoring data. Environ. Modell. Softw. 139:1364-8152.
Ambrosetti W, Barbanti L, Carrara E, 2010. Mechanisms of hypolimnion erosion in a deep lake (Lago Maggiore, N. Italy). J. Limnol. 69:3-14.
Bluteau C, Lueck R, Ivey G, Jones N, Book J, Rice A, 2017. Determining mixing rates from concurrent temperature and velocity measurements. J. Atm. Ocean. Technol. 34:2283- 2293.
Burchard H, Baumert, H, 1995. On the performance of a mixedlayer model based on the κ-ε turbulence closure. J. Geophys. Res.-Oceans 100:8523-8540.
Crawford GB, Collier RW, 1997. Observations of a deep-mixing event in Crater Lake, Oregon. Limnol. Oceanogr. 42:299-306.
Deltares, 2014. Delft3D-FLOW user manual. Delft, the Netherlands.
Fenocchi A, Rogora M, Sibilla S, Ciampittiello M, Dresti C, 2018. Forecasting the evolution in the mixing regime of a deep subalpine lake under climate change scenarios through numerical modelling (Lake Maggiore, Northern Italy/Southern Switzerland). Clim. Dynam. 51:3521-3536. DOI: https://doi.org/10.1007/s00382-018-4094-6
Fer I, 2014. Near-inertial mixing in the central arctic ocean. J. Phys. Oceanogr. 44:2031-2049. DOI: https://doi.org/10.1175/JPO-D-13-0133.1
Fer I, Lemmin U, Thorpe SA, 2002. Winter cascading of cold water in Lake Geneva. J. Geophys. Res.-Oceans 107:13–1-13–16. DOI: https://doi.org/10.1029/2001JC000828
Finckh P, 1981. Heat-flow measurements in 17 perialpine lakes: Summary. GSA Bull. 92:108-111. DOI: https://doi.org/10.1130/0016-7606(1981)92<108:HMIPLS>2.0.CO;2
Flaim G, Nishri A, Camin F, Corradini S, Obertegger U, 2019. Shift from nival to pluvial recharge of an aquifer-fed lake increases water temperature. Inland Wat.9:261-274. DOI: https://doi.org/10.1080/20442041.2019.1582958
Flaim G, Andreis D, Piccolroaz S, Obertegger U, 2020. Ice cover and extreme events determine dissolved oxygen in a placid mountain lake. Water Resour. Res. 56:e2020WR027321. DOI: https://doi.org/10.1029/2020WR027321
Giovannini L, Antonacci G, Zardi D, Laiti L, Panziera L, 2014. Sensitivity of simulated wind speed to spatial resolution over complex terrain. Energy Proc 59:323-329. DOI: https://doi.org/10.1016/j.egypro.2014.10.384
Goldman CR, Jassby A, 1990. Spring mixing depth as a determinant of annual primary production in lakes, p. 125–132.In: M.M. Tilzer and C. Serruya (eds.), Large Lakes. Brock/Springer Series in Contemporary Bioscience. Springer, Berlin. DOI: https://doi.org/10.1007/978-3-642-84077-7_6
Goto Y, Yasuda I, Nagasawa M, 2016. Turbulence estimation using fast-response thermistors attached to a free-fall vertical microstructure profiler. J. Atm. Ocean. Technol. 33:2065-2078. DOI: https://doi.org/10.1175/JTECH-D-15-0220.1
Holzner CP, Aeschbach-Hertig W, Simona M, Veronesi M, Imboden D, Kipfer R, 2009. Exceptional mixing events in meromictic Lake Lugano (Switzerland/Italy), studied using environmental tracers. Limnol. Oceanogr. 54:1113-1124. DOI: https://doi.org/10.4319/lo.2009.54.4.1113
Hupfer M, Lewandowski J, 2008. Oxygen controls the phosphorus release from lake sediments – a long-lasting paradigm in limnology. Int. Rev. Hydrobiol.93:415-432. DOI: https://doi.org/10.1002/iroh.200711054
Imboden D, Stotz B, Wuest A, 1987. Hypolimnic mixing in a deep alpine lake and the role of a storm event. Int. Ver. Theor. Angew. 1922-2010:67–73. DOI: https://doi.org/10.1080/03680770.1987.11897904
Imboden DM, Lemmin U, Joller T, Schurter M, 1983. Mixing processes in lakes: mechanisms and ecological relevance. Schweiz. Z. Hydrol. 45:11-44. DOI: https://doi.org/10.1007/BF02538150
Krishna S, Ulloa HN, Kerimoglu O, Minaudo C, Anneville O, Wüest A, 2021. Model-based data analysis of the effect of winter mixing on primary production in a lake under reoligotrophication. Ecol. Modell.440:109401. DOI: https://doi.org/10.1016/j.ecolmodel.2020.109401
Laborde S, Antenucci J, Copetti D, Imberger J, 2010. Inflow intrusions at multiple scales in a large temperate lake. Limnol. Oceanogr.55:1301-1312.
Lane A, 1989. The heat balance of the North Sea. Report No. 8. Proudman Oceanographic Laboratory, Liverpool: 46 pp.
Lau M, Valerio G, Pilotti M, Hupfer M, 2020. Intermittent meromixis controls the trophic state of warming deep lakes. Sci. Rep. 10:12928.
Lenstra WK, Hahn-Woernle L, Matta E, Bresciani M, Giardino C, Salmaso N, Musanti M, Fila G, Uittenbogaard R, Genseberger M, van der Woerd HJ, Dijkstra HA, 2014. Diurnal variation of turbulence-related quantities in Lake Garda. Adv. Ocean. Limnol. 5:184-203.
Lepori F, Bartosiewicz M, Simona M, Veronesi M, 2018. Effects of winter weather and mixing regime on the restoration of a deep perialpine lake (Lake Lugano, Switzerland and Italy). Hydrobiologia 824:229-242. DOI: https://doi.org/10.1007/s10750-018-3575-2
Lesser GR, Roelvink J v, Van Kester J, Stelling G, 2004. Development and validation of a three-dimensional morphological model. Coast. Engin. 51:883-915.
Lincoln BJ, Rippeth TP, Lenn YD, Timmermans ML, Williams WJ, Bacon S, 2016. Wind-driven mixing at intermediate depths in an ice-free Arctic Ocean. Geophys. Res. Lett. 43:9749-9756.
Meybeck M, Blanc P, Moulherac AE, Corvi C, 1991. Chemical evidence of water movements in the deepest part of Lake Leman (Lake Geneva). Aquat. Sci. 53:273-289.
Michalski J, Lemmin U, 1995. Dynamics of vertical mixing in the hypolimnion of a deep lake: Lake Geneva. Limnol. Oceanogr. 40:809-816.
Mortimer CH, 1974. Lake hydrodynamics. Int. Verein. Theor. Angew. Limnol. Mitteil. 20:124-197.
Nash JD, Caldwell DR, Zelman MJ, Moum JN, 1999. a thermocouple probe for high-speed temperature measurement in the ocean. J. Atm. Ocean. Technol. 16:1474-1482.
North RP, North RL, Livingstone DM, Kster O, Kipfer R, 2014. Long-term changes in hypoxia and soluble reactive phosphorus in the hypolimnion of a large temperate lake: consequences of a climate regime shift. Global Change Biol. 20:811-823.
Peeters F, Finger D, Hofer M, Brennwald M, Livingstone DM, Kipfer R, 2003. Deep-water renewal in Lake Issyk-Kul driven by differential cooling. Limnol. Oceanogr. 48:1419-1431.
Piccolroaz S, Amadori M, Toffolon M, Dijkstra, HA, 2019. Importance of planetary rotation for ventilation processes in deep elongated lakes: Evidence from Lake Garda (Italy). Sci. Rep. 9:8290.
Piccolroaz S, Woolway RI, Merchant CJ, 2020. Global reconstruction of twentieth century lake surface water temperature reveals different warming trends depending on the climatic zone. Climatic Change 160:427-442.
Preusse M, Peeters F, Lorke A, 2010. Internal waves and the generation of turbulence in the thermocline of a large lake. Limnol. Oceanogr. 55:2353-2365. DOI: https://doi.org/10.4319/lo.2010.55.6.2353
Reiss RS, Lemmin U, Cimatoribus AA, Barry DA, 2020. Wintertime coastal upwelling in Lake Geneva: An efficient transport process for deep water renewal in a large, deep lake. J. Geophys. Res.-Oceans 125:e2020JC016095. DOI: https://doi.org/10.1029/2020JC016095
Rogora M, Buzzi F, Dresti C, Leoni B, Lepori F, Mosello R, Patelli M, Salmaso N, 2018. Climatic effects on vertical mixing and deep-water oxygen content in the subalpine lakes in Italy. Hydrobiologia 824:33-50. DOI: https://doi.org/10.1007/s10750-018-3623-y
Sadro S, Melack JM, Sickman JO, Skeen K, 2019. Climate warming response of mountain lakes affected by variations in snow. Limnol. Oceanogr. Lett. 4:9-17. DOI: https://doi.org/10.1002/lol2.10099
Salmaso N, 2005. Effects of climatic fluctuations and vertical mixing on the interannual trophic variability of Lake Garda, Italy. Limnol. Oceanogr. 50:553-565. DOI: https://doi.org/10.4319/lo.2005.50.2.0553
Salmaso N, Decet F, 1998. Interactions of physical, chemical and biological processes affecting the seasonality of mineral composition and nutrient cycling in the water column of a deep subalpine lake (Lake Garda, Northern Italy). Arch. Hydrobiol. 142:385-414. DOI: https://doi.org/10.1127/archiv-hydrobiol/142/1998/385
Salmaso N, Mosello R, Garibaldi L, Decet F, Maria C, Brizzio P, Cordella P, 2002. Vertical mixing as a determinant of trophic status in deep lakes: A case study from two lakes south of the Alps (Lake Garda and Lake Iseo). J. Limnol. 62:33-41. DOI: https://doi.org/10.4081/jlimnol.2003.s1.33
Salmaso N, Boscaini A, Capelli C, Cerasino L, 2018. Ongoing ecological shifts in a large lake are driven by climate change and eutrophication: evidences from a three-decade study in Lake Garda. Hydrobiologia 824:177-195. DOI: https://doi.org/10.1007/s10750-017-3402-1
Schwefel R, Gaudard A, Wüest A, Bouffard, D, 2016. Effects of climate change on deepwater oxygen and winter mixing in a deep lake (Lake Geneva): Comparing observational findings and modeling. Water Resour. Res. 52:8811-8826.
Schwefel R, Müller B, Boisgontier A, Wuest A, 2019. Global warming affects nutrient upwelling in deep lakes. Aquat. Sci. 81:50.
Simona M, 2003. Winter and spring mixing depths affect the trophic status and composition of phytoplankton in the northern meromictic basin of Lake Lugano. J. Limnol. 62:190-206.
Skamarock WC, Klemp JB, Dudhia J, Gill DO, Liu Z, Berner J, Wang W, Powers GJ, Duda MG, Barker DM, et al, 2008. A description of the Advanced Research (WRF) model, Version 3. University Corporation for Atmospheric Research, Boulder.
Socolofsky SA, Jirka GH, 1995. Environmental fluid mechanics 1: Mixing and transport in the environment. Texas A&M University: 184 pp.
Sommer T, Carpenter JR, Schmid M, Lueck RG, Wüest A, 2013. Revisiting microstructure sensor responses with implications for double-diffusive fluxes. J. Atm. Ocean. Technol. 30:1907-1923.
Straile D, J hnk K, Henno R, 2003. Complex effects of winter warming on the physicochemical characteristics of a deep lake. Limnol. Oceanogr. 48:1432-1438.
Swann GEA, Panizzo VN, Piccolroaz S, Pashley V, Horstwood MSA, Roberts S, Vologina E, Piotrowska N, Sturm M, Zhdanov A, Granin N, Norman C, McGowan S, Mackay AW, 2020. Changing nutrient cycling in Lake Baikal, the world’s oldest lake. P. Natl. Acad. Sci. USA 117:27211-27217. DOI: https://doi.org/10.1073/pnas.2013181117
Valerio G, Pilotti M, Barontini S, Leoni B, 2015. Sensitivity of the multiannual thermal dynamics of a deep pre-alpine lake to climatic change. Hydrol. Process. 29:767-779. DOI: https://doi.org/10.1002/hyp.10183
van Haren H, Maas L, Zimmerman J, Ridderinkhof H, Malschaert H, 1999. Strong inertial currents and marginal internal wave stability in the central North Sea. Geophys. Res. Lett. 26:2993-2996. DOI: https://doi.org/10.1029/1999GL002352
van Haren H, Piccolroaz S, Amadori M, Toffolon M, Dijkstra HA, 2021. Moored observations of turbulent mixing events in deep Lake Garda, Italy. J. Limnol. 80:1983. DOI: https://doi.org/10.4081/jlimnol.2020.1983
Verburg P, Antenucci JP, Hecky, RE, 2011. Differential cooling drives large-scale convective circulation in Lake Tanganyika. Limnol. Oceanogr. 56:910-926. DOI: https://doi.org/10.4319/lo.2011.56.3.0910
Wolk F, Yamazaki H, Seuront L, Lueck, RG, 2002. A new freefall profiler for measuring biophysical microstructure. J. Atm. Ocean. Technol. 19:780-793. DOI: https://doi.org/10.1175/1520-0426(2002)019<0780:ANFFPF>2.0.CO;2
Woolway R, Merchant C, 2003. Worldwide alteration of lake mixing regimes in response to climate change. Nat. Geosci. 12:271-276. DOI: https://doi.org/10.1038/s41561-019-0322-x
Wüest A, Lorke A, 2003. Small-scale hydrodynamics in lakes. Annu. Rev. Fluid Mech. 35:373-412. DOI: https://doi.org/10.1146/annurev.fluid.35.101101.161220

Edited by

Diego Fontaneto, CNR-IRSA Water Research Institute, Verbania, Italy

Supporting Agencies

EOMORES project

How to Cite

Biemond, Bouke, Marina Amadori, Marco Toffolon, Sebastiano Piccolroaz, Hans van Haren, and Henk A. Dijkstra. 2021. “Deep-Mixing and Deep-Cooling Events in Lake Garda: Simulation and Mechanisms”. Journal of Limnology 80 (2). https://doi.org/10.4081/jlimnol.2021.2010.