Moored observations of turbulent mixing events in deep Lake Garda, Italy

https://doi.org/10.4081/jlimnol.2020.1983

Authors

Abstract

Deep water circulation and mixing processes are responsible for the transport of matter, nutrients and pollutants in deep lakes. Nevertheless, detailed continuous observations are rarely available. To overcome some of these deficiencies and with the aim of improving our understanding of deep mixing processes, a dedicated yearlong mooring comprising 100 high-resolution temperature sensors and a single current meter were located in the deeper half of the 344 m deepest point of the subalpine Lake Garda, Italy. The observations show peaks and calms of turbulent exchange, besides ubiquitous internal wave activity. In late winter, northerly winds activate episodic deep convective overturning, the dense water being subsequently advected along the lake-floor. Besides deep convection, such winds also set-up seiches and inertial waves that are associated with about 100 times larger turbulence dissipation rates than that by semidiurnal internal wave breaking observed in summer. In the lower 60 m above the lake-floor, however, the average turbulence dissipation rate is approximately constant in value year-around, being about 10 times larger than open-ocean values, except during deep convection episodes.

Dimensions

Altmetric

PlumX Metrics

Downloads

Download data is not yet available.

References

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

Ambrosetti W, Barbanti L, 1999. Deep water warming in lakes: an indicator of climatic change. J. Limnol. 58:1. DOI: https://doi.org/10.4081/jlimnol.1999.1

Antenucci J, Imberger J, 2003. The Seasonal Evolution of Wind/Internal Wave Resonance in Lake Kineret. Limnol. Oceanogr. 48:2055-2061. DOI: https://doi.org/10.4319/lo.2003.48.5.2055

Berger SA, Diehl S, Stibor H, Trommer G, Ruhenstroth M, Wild A, Weigert A, Gerald Jäger C, Striebel M, 2007. Water temperature and mixing depth affect timing and magnitude of events during spring succession of the plankton. Oecologia 150:643-654. DOI: https://doi.org/10.1007/s00442-006-0550-9

Boegman L, Imberger J, Ivey GN, Antenucci JP, 2003. High-frequency internal waves in large stratified lakes. Limnol. Oceanogr. 46:895-919. DOI: https://doi.org/10.4319/lo.2003.48.2.0895

Boehrer B, Fukuyama R, Chikita K, 2008. Stratification of very deep, thermally stratified lakes. Geophys. Res. Lett. 35:L16405. DOI: https://doi.org/10.1029/2008GL034519

Chalamalla VK, Sarkar S, 2015. Mixing, dissipation rate, and their overturn-based estimates in a near-bottom turbulent flow driven by internal tides. J. Phys. Oceanogr. 45:1969-1983. DOI: https://doi.org/10.1175/JPO-D-14-0057.1

Copetti D, Guyennon N, Buzzi F, 2020. Generation and dispersion of chemical and biological gradients in a large-deep multi-basin lake (Lake Como, north Italy): The joint effect of external drivers and internal wave motions. Sci. Tot. Env. 749:141587. DOI: https://doi.org/10.1016/j.scitotenv.2020.141587

Dauxois T, Didier A, Falcon E, 2004. Observations of near-critical reflection of internal waves in a stably stratified fluid. Phys. Fluids 16:1936-1941. DOI: https://doi.org/10.1063/1.1711814

Dillon TM, 1982. Vertical overturns: a comparison of Thorpe and Ozmidov length scales. J. Geophys. Res. 87:9601-9613. DOI: https://doi.org/10.1029/JC087iC12p09601

Dokulil MT, 2014. Impact of climate warming on European inland waters. Inland Wat. 4:27-40. DOI: https://doi.org/10.5268/IW-4.1.705

Ekman VW, 1905. On the influence of the Earth’s rotation on ocean-currents. Ark Math Astron Fys 2:1-52.

Eriksen CC, 1982. Observations of internal wave reflection off sloping bottoms. J. Geophys. Res. 87:525-538. DOI: https://doi.org/10.1029/JC087iC01p00525

Farmer DM, 1978. Observations of long nonlinear internal waves in a lake. J. Phys. Oceanogr. 8:63-73. DOI: https://doi.org/10.1175/1520-0485(1978)008<0063:OOLNIW>2.0.CO;2

Fer I, Lemmin U, Thorpe SA, 2002. Winter cascading of cold water in Lake Geneva. J. Geophys. Res. 107:C6. DOI: https://doi.org/10.1029/2001JC000828

Galbraith PS, Kelley DE, 1996. Identifying overturns in CTD profiles. J. Atmos. Ocean. Tech. 13:688-702. DOI: https://doi.org/10.1175/1520-0426(1996)013<0688:IOICP>2.0.CO;2

Garanaik A, Venayagamoorthy SK, 2019. On the inference of the state of turbulence and mixing efficiency in stably stratified flows. J. Fluid Mech. 867:323-333. DOI: https://doi.org/10.1017/jfm.2019.142

Garrett CJR, Munk WH, 1972. Space-time scales of internal waves. Geophys. Fluid Dyn. 3:225-264. DOI: https://doi.org/10.1080/03091927208236082

Gill AE, 1982. Atmosphere-ocean dynamics. Academic Press: 682 pp.

Giovannini L, Laiti L, Zardi D, de Franceschi M, 2015. Climatological characteristics of the Ora del Garda wind in the Alps. Int. J. Clim. 35:4103-4115. DOI: https://doi.org/10.1002/joc.4270

Gloor M, Wüest A, Münnich M, 1994. Benthic boundary mixing and resuspension induced by internal seiches. Hydrobiol. 284:59-68. DOI: https://doi.org/10.1007/BF00005731

Goudsmit G-H, Peeters F, Gloor M, Wüest A, 1997. Boundary versus internal diapycnal mixing in stratified natural waters. J. Geophys. Res. 102:27903-27914. DOI: https://doi.org/10.1029/97JC01861

Goudsmit G‐H, Burchard H, Peeters F, Wüest A, 2002. Application of k‐ϵ turbulence models to enclosed basins: The role of internal seiches. J. Geophys. Res. 107:3230. DOI: https://doi.org/10.1029/2001JC000954

Gregg MC, 1989. Scaling turbulent dissipation in the thermocline. J. Geophys. Res. 94:9686-9698. DOI: https://doi.org/10.1029/JC094iC07p09686

Gregg MC, D’Asaro EA, Riley JJ, Kunze E, 2018. Mixing efficiency in the ocean. Annu. Rev. Mar. Sci. 10:443-473. DOI: https://doi.org/10.1146/annurev-marine-121916-063643

Guyennon N, Valerio G, Salerno F, Pilotti M, Tartari G, Copetti D, 2014. Internal wave weather heterogeneity in a deep multi-basin subalpine lake resulting from wavelet transform and numerical analysis. Adv. Water Res. 71:149-161. DOI: https://doi.org/10.1016/j.advwatres.2014.06.013

Imboden DM, Wüest A, 1995. Mixing mechanisms in lakes, p. 83-138. In: A. Lerman, D.M. Imboden and J.R. Gat (eds.), Physics and chemistry of lakes. Cham, Springer. DOI: https://doi.org/10.1007/978-3-642-85132-2_4

IOC, SCOR, IAPSO, 2010. The international thermodynamic equation of seawater – 2010: Calculation and use of thermodynamic properties. Intergovernmental Oceanographic Commission, Manuals and Guides No. 56, UNESCO.

LeBlond PH, Mysak LA, 1978. Waves in the ocean. Elsevier: 602 pp.

Lemmin U, Mortimer CH, Bäuerle E, 2005. Internal seiche dynamics in Lake Geneva. Limnol. Oceanogr. 50:207-216. DOI: https://doi.org/10.4319/lo.2005.50.1.0207

Leoni B, Garibaldi L, Gulati R, 2014. How does interannual trophic variability caused by vertical water mixing affect reproduction and population density of the Daphnia longispina group in Lake Iseo, a deep stratified lake in Italy. Inland Wat. 4:193-203. DOI: https://doi.org/10.5268/IW-4.2.663

Li S, Li H, 2006. Parallel AMR code for compressible MHD and HD equations. T-7, MS B284, Theoretical division, Los Alamos National Laboratory. Available from: http://math.lanl.gov/Research/Highlights/amrmhd.shtml

Lorke A, Peeters F, Bäuerle E, 2006. High-frequency internal waves in the littoral zone of a large lake. Limnol. Oceanogr. 51: 1935-1939. DOI: https://doi.org/10.4319/lo.2006.51.4.1935

Lorke A, 2007. Boundary mixing in the thermocline of a large lake. J. Geophys. Res. 112:C09019. doi:10.1029/2006JC004008 DOI: https://doi.org/10.1029/2006JC004008

Lorrai C, Umlauf L, Becherer JK, Lorke A, Wüest A, 2011. Boundary mixing in lakes: 2. Combined effects of shear-and convectively induced turbulence on basin-scale mixing. J. Geophys. Res. 116:C10018. DOI: https://doi.org/10.1029/2011JC007121

Mater BD, Venayagamoorthy SK, St. Laurent L, Moum JN, 2015. Biases in Thorpe scale estimation of turbulence dissipation. Part I: Assessments from large-scale overturns in oceanographic data. J. Phys. Oceanogr. 45:2497-2521. DOI: https://doi.org/10.1175/JPO-D-14-0128.1

Matsumoto Y, Hoshino M, 2004. Onset of turbulence by a Kelvin-Helmholtz vortex. Geophys. Res. Lett. 31:L02807. DOI: https://doi.org/10.1029/2003GL018195

Oakey NS, 1982. Determination of the rate of dissipation of turbulent energy from simultaneous temperature and velocity shear microstructure measurements. J. Phys. Oceanogr. 12:256-271. DOI: https://doi.org/10.1175/1520-0485(1982)012<0256:DOTROD>2.0.CO;2

Osborn TR, 1980. Estimates of the local rate of vertical diffusion from dissipation measurements. J. Phys. Oceanogr. 10:83-89. DOI: https://doi.org/10.1175/1520-0485(1980)010<0083:EOTLRO>2.0.CO;2

Perroud M, Goyette S, Martynov A, Beniston M, Anneville O, 2009. Simulation of multiannual thermal profiles in deep Lake Geneva: A comparison of one-dimensional lake models. Limnol. Oceanogr. 54:1574-594. DOI: https://doi.org/10.4319/lo.2009.54.5.1574

Phillips OM, 1971. On spectra measured in an undulating layered medium. J. Phys. Oceanogr. 1:1-6. DOI: https://doi.org/10.1175/1520-0485(1971)001<0001:OSMIAU>2.0.CO;2

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. DOI: https://doi.org/10.1038/s41598-019-44730-1

Polzin K L, Toole JM, Ledwell JR, Schmitt RW, 1997. Spatial variability of turbulent mixing in the abyssal ocean. Science 276:93-96. DOI: https://doi.org/10.1126/science.276.5309.93

Portwood GD, de Bruyn Kops SM, Caulfield CP, 2019. Asymptotic dynamics of high dynamic range stratified turbulence. Phys. Rev. Lett. 122:194504. DOI: https://doi.org/10.1103/PhysRevLett.122.194504

Preusse M, 2012. Properties of internal solitary waves in deep temperate lakes. Ph.D. Thesis University of Konstanz. DOI: https://doi.org/10.1371/journal.pone.0041674

Ravens TM, Kocsis O, Wüest A, Granin N, 2000. Small-scale turbulence and vertical mixing in Lake Baikal. Limnol. Oceanogr. 45:159-173. DOI: https://doi.org/10.4319/lo.2000.45.1.0159

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, Morabito G, Mosello R, Garibaldi L, Simona M, Buzzi F, Ruggiu D, 2003. A synoptic study of phytoplankton in the deep lakes south of the Alps (lakes Garda, Iseo, Como, Lugano, and Maggiore). J. Limnol. 62:207. DOI: https://doi.org/10.4081/jlimnol.2003.207

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

Sarkar S, Scotti A, 2017. From topographic internal gravity waves to turbulence. Ann. Rev. Fluid Mech. 49:195-220. DOI: https://doi.org/10.1146/annurev-fluid-010816-060013

Swann GEA, Panizzo VN, Piccolroaz S, Pashley V, Horstwood MSA, Roberts S, Vologina E, Piotrowska N, Sturm M, Zhdanov A, Granin N, Norman V, McGowan S, Mackay AS, 2020. Changing nutrient cycling in Lake Baikal, the world’s oldest lake. Proc. Natl. Acad. Sci. USA 117:27211-27217. DOI: https://doi.org/10.1073/pnas.2013181117

Tennekes H, Lumley JL, 1972. A first in turbulence. MIT Press: 300 pp. DOI: https://doi.org/10.7551/mitpress/3014.001.0001

Thorpe SA, 1977. Turbulence and mixing in a Scottish loch. Phil. Trans. Roy. Soc. Lond. A 286: 25-181. DOI: https://doi.org/10.1098/rsta.1977.0112

Thorpe SA, Keen JM, Jiang R, Lemmin U, 1996. High frequencu internal waves in Lake Geneva. Phil. Trans. R. Soc. Lond. A 354 237-257. DOI: https://doi.org/10.1098/rsta.1996.0008

Toffolon M, Piccolroaz S, Dijkstra HA, 2017. A plunge into the depths of Italy’s Lake Garda. Eos 98. Available from: https://eos.org/meeting-reports/a-plunge-into-the-depths-of-italys-lake-garda DOI: https://doi.org/10.1029/2017EO074499

Valerio G, Pilotti M, Clelia M, Imberger J, 2012. The structure of basin scale internal waves in a stratified lake in response to lake bathymetry and wind spatial and temporal distribution: Lake Iseo, Italy. Limnol. Oceanogr. 57:772-786. DOI: https://doi.org/10.4319/lo.2012.57.3.0772

Valerio G, Pilotti M, Lau M, Hupfer M, 2019. Oxycline oscillations induced by internal waves in deep Lake Iseo. Hydrol. Earth Syst. Sci. 23:1763-1777. DOI: https://doi.org/10.5194/hess-23-1763-2019

van Haren H, 2017. Exploring the vertical extent of breaking internal wave turbulence above deep-sea topography. Dyn. Atmos. Oc. 77:89-99. DOI: https://doi.org/10.1016/j.dynatmoce.2017.01.002

van Haren H, 2018. Philosophy and application of high-resolution temperature sensors for stratified waters. Sensors 18:3184. DOI: https://doi.org/10.3390/s18103184

van Haren H, 2019. Open-ocean interior moored sensor turbulence estimates, below a Meddy. Deep-Sea Res. I 144:75-84. DOI: https://doi.org/10.1016/j.dsr.2019.01.005

van Haren H, Gostiaux L, 2012. Detailed internal wave mixing above a deep-ocean slope. J. Mar. Res. 70:173-197. DOI: https://doi.org/10.1357/002224012800502363

van Haren H, Maas L, Zimmerman JTF, 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, Cimatoribus AA, Gostiaux L, 2015. Where large deep-ocean waves break. Geophys. Res. Lett. 42:2351-2357. DOI: https://doi.org/10.1002/2015GL063329

Wang Y, Hutter C, Bäuerle E, 2000. Wind-induced baroclinic response of Lake Constance. Ann. Geophys. 18:1488-1501. DOI: https://doi.org/10.1007/s00585-000-1488-6

Warhaft Z, 2000. Passive scalars in turbulent flows. Ann. Rev. Fluid Mech. 32:203-240. DOI: https://doi.org/10.1146/annurev.fluid.32.1.203

Wetzel RG, 2001. Limnology: Lake and river ecosystems. Academic Press, San Diego: 1006 pp.

Winters KB, 2015. Tidally driven mixing and dissipation in the boundary layer above steep submarine topography. Geophys. Res. Lett. 42:7123-7130. DOI: https://doi.org/10.1002/2015GL064676

Wüest A, Lorke A, 2003. Small-scale hydrodynamics in lakes. Ann. Rev. Fluid Mech. 35:373-412. DOI: https://doi.org/10.1146/annurev.fluid.35.101101.161220

Downloads

Published
2020-11-03
Info
Issue
Section
Original Articles
Edited by
Aldo Marchetto, CNR-IRSA Verbania, Italy
Keywords:
Yearlong high-resolution moored temperature observations, deep Lake Garda, internal waves, turbulent overturning, convective cooling
Statistics
  • Abstract views: 1889

  • PDF: 239
How to Cite
1.
van Haren H, Piccolroaz S, Amadori M, Toffolon M, Dijkstra HA. Moored observations of turbulent mixing events in deep Lake Garda, Italy. J Limnol [Internet]. 2020 Nov. 3 [cited 2021 Jul. 28];80(1). Available from: https://jlimnol.it/index.php/jlimnol/article/view/jlimnol.2020.1983

Most read articles by the same author(s)