Institut für Ostseeforschung Warnemünde
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Publications

Journal articles (peer-reviewed):

Beier, S., P. Holtermann, D. Numberger, T. Schott, L. Umlauf, and K. Jürgens. A metatranscriptomics-based assessment of small-scale mixing of sulfidic and oxic waters on redoxcline prokaryotic communities. Environ. Microbiol., in press.

Umlauf, L., P. Holtermann, C. A. Gillner, R. Prien, L. Merckelbach, J. R. Carpenter. Diffusive convection under rapidly varying conditions. J. Phys. Oceanogr., 48, 1731–1747, doi: 10.1175/JPO-D-18-0018.1, 2018.

Bartl⁠, I., I. Liskow, K. Schulz⁠, L. Umlauf, and M. Voss. River plume and bottom boundary layer – Hotspots for nitrification in a coastal bay? Estuar. Coast. Shelf Sci., 208, 70-82, doi: 10.1016/j.ecss.2018.04.023, 2018.

Burchard, H., K. Bolding, R. Feistel, U. Grawe, K.Klingbeil , P. MacCready, V. Mohrholz, L. Umlauf, E. M.van der Lee. The Knudsen theorem and the Total Exchange Flow analysis framework applied to the Baltic Sea, Progr. Oceanogr., 165, 168-186, doi: 10.1016/j.pocean.2018.04.004, 2018.

Holtermann, P., R. Prien, M. Naumann, V. Mohrholz, and L. Umlauf. Deep-water dynamics and mixing processes during a major inflow event in the central Baltic Sea, J. Geophys. Res., 122, 66486667, doi:10.1002/2017JC013050, 2017.

Schulz, K., T. Endoh, and L. Umlauf. Slope-induced tidal straining: Analysis of rotational effects, J. Geophys. Res., 122, 2069-2089, doi: 10.1002/2016JC012448, 2017.

Lappe, C., and L. Umlauf. Efficient boundary mixing due to near-inertial waves in a non-tidal basin: Observations from the Baltic Sea. J. Geophys. Res., 121, 8287-8304, doi: 10.1002/2016JC011985, 2016.

Becherer, J., G. Flöser, L. Umlauf, and H. Burchard. Esturatine circulation vs tidal pumping: Sediment transport in a well-mixed tidal inlet. J. Geophys. Res., 121, 6251-6270, doi: 10.1002/2016JC011640, 2016.

Schulz, K., and L. Umlauf. Residual transport of suspended material by tidal straining near sloping topography. J. Phys. Oceanogr., 46, 2083-2102, doi:10.1175/JPO-D-15-0218.1, 2016.

Schmale, O., S. Krause, P. Holtermann, N. C. Power Guerra, and L. Umlauf. Dense bottom gravity currents and their impact on pelagic methanotrophy at oxic/anoxic transition zones. Geophys. Res. Lett., doi:10.1002/2016GL069032, 2016.

Endoh, T., Y. Yoshikawa, T. Matsuno, Y. Wakata, K.-J. Lee, and L. Umlauf. Observational evidence for tidal straining over a sloping continental shelf, Cont. Shelf. Res., 117, 12–19, doi:10.1016/j.csr.2016.01.018, 2016.

Moghimi, S., J. Thompson, T. Ozkan-Haller, L. Umlauf, S. Zippel. On the modeling of wave-enhanced turbulence nearshore. Ocean Model., doi:10.1016/j.ocemod.2015.11.004, 2016.

Umlauf, L., J. N. Moum, and W. D. Smyth. Energetics of bottom Ekman layers during buoyancy arrest. J. Phys. Oceanogr., 45, 3099–3117, doi:10.1175/JPO-D-15-0041.1, 2015.

Becherer, J., M. T. Stacey, L. Umlauf, and H. Burchard. Lateral Circulation Generates Flood Tide Stratification and Estuarine Exchange Flow in a Curved Tidal Inlet. J. Phys.Oceanogr., 45, 638-656, 2015.

Holtermann, P. L., H. Burchard, U. Gräwe, K. Klingbeil, L. Umlauf. Deep-water dynamics and boundary mixing in a non-tidal stratified basin: A modeling study of the Baltic Sea. J. Geophys. Res.,119, 1465–1487, doi:10.1002/2013JC009483, 2014.

Yamazaki, H., C. Locke, L. Umlauf, H. Burchard, T. Ishimaru, and D. Kamykowski. A Lagrangian model for phototaxis-induced thin layer formation. Deep Sea Res. II, 101, 193-206, doi: 10.1016/j.dsr2.2012.12.010, 2014.

Burchard, H., U. Gräwe, P. Holtermann, K. Klingbeil, and L. Umlauf. Turbulence closure modeling in coastal waters. Die Küste, 81, 69-87, 2014.

Smyth, W. D., H. Burchard and L. Umlauf. Baroclinic interleaving instability: second-moment closure approach. J. Phys. Oceanogr., 42, 764–784, doi: 10.1175/JPO-D-11-066.1, 2012.

Holtermann, P., L. Umlauf, T. Tanhua, O. Schmale, G. Rehder, and J. Waniek. The Baltic Sea Tracer Release Experiment. 1. Mixing rates. J. Geophys. Res., 117, C01021, doi:10.1029/2011JC007439, 2012.

Holtermann, P., and L. Umlauf. The Baltic Sea Tracer Release Experiment. 2. Mixing processes. J. Geophys. Res., 117, C01022, doi:10.1029/2011JC007445, 2012.

Dellwig, O., B. Schnetger, H.-J. Brumsack, H.-P. Grossart, and L. Umlauf. Dissolved reactive manganese at pelagic redoxclines (Part II): Hydrodynamic conditions for accumulation. J. Mar. Sys., 90, 31-41, doi:10.1016/j.jmarsys.2011.08.007, 2012.

Becherer, J. , H. Burchard, G. Flöser, V.Mohrholz, and L.Umlauf. Evidence of tidal straining in well-mixed channel flow from micro-structure observations. Geophys. Res. Lett., 38, L17611, doi:10.1029/2011GL049005, 2011.

Becherer, J., and L. Umlauf. Boundary mixing in lakes. 1. Modeling the effect of shear-induced convection. J. Geophys. Res., 116, C10017, doi:10.1029/2011JC007119, 2011.

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

van der Lee, E. M., and L. Umlauf. Internal-wave mixing in the Baltic Sea: Near-inertial waves in the absence of tides. J. Geophys. Res., 116, C10016, doi:10.1029/2011JC007072, 2011.

Umlauf, L., and H. Burchard. Diapycnal transport and mixing efficiency in stratified boundary layers near sloping topography. J. Phys. Oceanogr., 41, 329-345, 2011.

Umlauf, L., L. Arneborg, R. Hofmeister, and H. Burchard. Entrainment in shallow rotating gravity currents: A modeling study. J. Phys. Oceanogr., 40, 1819–1834, 2010.

Umlauf, L., The description of mixing in stratified layers without shear in large-scale ocean models, J. Phys. Oceanogr., 39, 3032-3039, 2009.

Umlauf, L., and L. Arneborg. Dynamics of rotating shallow gravity currents passing through a channel. Part I: Observation of transverse structure, J. Phys. Oceanogr., 39, 2385-2401, 2009.

Umlauf, L., and L. Arneborg. Dynamics of rotating shallow gravity currents passing through a channel. Part II: Analysis, J. Phys. Oceanogr., 39, 2402-2416, 2009.

Reissmann, J., H. Burchard, R. Feistel, E. Hagen, H.U. Lass, V. Mohrholz, G. Nausch, L. Umlauf, and G. Wieczorek, State-of-the-art review on vertical mixing in the Baltic Sea and consequences for eutrophication, Progr. Oceanogr., 82, 47-80, 2009.

Burchard, H., F. Janssen, K. Bolding, L. Umlauf, and H. Rennau, Model simulations of dense bottom currents in the Western Baltic Sea, Cont. Shelf Res., 29, 205-220, 2009.

Wieczorek, G., E. Hagen, and L. Umlauf, Eastern Gotland Basin case study of thermal variability in the wake of deep water intrusions, J. Mar. Sys., 74, S65-S79, 2008.

Umlauf, L, T. Tanhua, J. Waniek, O. Schmale, P. Holtermann, and G. Rehder, Hunting a new oceanic tracer, Eos, 89(43), 419-420, 2008.

Lorke, A., L. Umlauf, and V. Mohrholz,  Stratification and mixing on sloping boundaries, Geophy. Res. Lett., 35, L14610, doi:10.1029/2008GL034607, 2008.

Holt, J., and L. Umlauf. Modelling the tidal mixing fronts of the northwest European continental shelf. Cont. Shelf. Res., 28, 887-903, 2008.

Yakushev, E. V., F. Pollehne, G. Jost, I. Kuznetsov, B. Schneider, L. Umlauf, Analysis of the water column oxic/anoxic interface in the Black and Baltic Seas with a numerical model, Marine Chemistry, 388-410, 2007

Umlauf, L., L. Arneborg, H. Burchard, V. Fiekas, H.-U. Lass, V. Mohrholz, H. Prandke. The transverse structure of turbulence in a rotating gravity current, Geophys. Res. Lett., 34, L08601, doi:10.1029/2007GL029521, 2007

Arneborg, L., V. Fiekas, L. Umlauf, and H. Burchard. Gravity current dynamics and entrainment – A process study based on observations in the Arkona Basin, J. Phys. Oceangr., 37, 2094-2113, 2007.

Sellschopp, J., L. Arneborg, M. Knoll, V. Fiekas, F. Gerdes, H. Burchard, H. U. Lass, V. Mohrholz, L. Umlauf. Direct observations of a medium-intensity inflow into the Baltic Sea, Cont. Shelf Res, 26, 2393-2414, 2006

Burchard, H., K. Bolding, W. Kühn, A. Meister, T. Neumann, and L. Umlauf. Description of a flexible and extendable physical-biogeochemical model system for the water column, J. Mar. Sys., 61,180-211, 2006.

Burchard, H.U. Lass, V. Mohrholz, L. Umlauf, J. Sellschopp, V. Fiekas, K. Bolding, and L. Arneborg. Dynamics of medium-intensity dense water plumes in the Arkona Sea, Western Baltic Sea, Ocean Dynamics, 55, 391-402, 2005.

Umlauf, L., and U. Lemmin. Inter-basin exchange and mixing in a large lake. The role of long internal waves. Limnol. Oceanogr., 50(5), 1601-1611, 2005.

Burchard, H., and L. Umlauf. Observations and numerical modelling of mixed layer turbulence: Do they represent the same statistical quantities? Deep-Sea Res. II, 52, 1069-1074, 2005.

Umlauf, L. Modelling the effects of horizontal and vertical shear in stratified turbulent flows. Deep Sea Res. II, 52, 1181-1201, 2005.

Umlauf, L., and H. Burchard. Second-order turbulence closure models for geophysical boundary layers. A review of recent work. Cont. Shelf Res., 25, 795-827, 2005. Invited paper.

Umlauf, L., H. Burchard, and K. Hutter, Extending the k-omega turbulence model towards oceanic applications, Ocean Modelling, 5, 195-218, 2003.

Umlauf, L., and H. Burchard, A generic length-scale equation for geophysical turbulence models, J. Mar. Res., 61, 235-265, 2003.

Umlauf. L., and H. Burchard, Reply to: "Comments on 'A generic length-scale equation for geophysical turbulence models'" by L. Kantha and S. Carniel, J. Mar. Res., 61, 703-706, 2003.

Thorpe, S. A., and L. Umlauf, Internal gravity wave frequencies and wavenumbers from single point measurements over a slope, J. Mar.Res., 60, 699-723, 2002.

Lorke, A., L. Umlauf, T. Jonas, and A. Wüst, Dynamics of turbulence in low-speed oscillating bottom-boundary layers of stratified basins, Environmental Fluid Mech., 2, 291-313, 2002.

Jöhnk, K., and L. Umlauf, Modeling the metalimnectic oxygen minimum in a medium sized alpine lake, Ecological Modeling, 136, 67-80, 1999.

L. Umlauf, Y. Wang, and K. Hutter, Comparing two topography-following primitive equation models for lake circulation, J. Comp. Phys., 153, 638-659, 1999.

 

Books and articles in books:

Umlauf, L., Internal structure and dynamics of stratified flow over sloping topography, Habilitation Thesis, University of Rostock, Germany, 2013.

Umlauf, L., and H. Burchard, A generic transport equation for the length scale in turbulent flows. In: Marine Turbulence. Theory, Observations and Models. Edited by: H. Z. Baumert, J. H. Simpson, and J. Sündermann. Cambridge University Press. pp. 188-196, 2005.

Umlauf, L., Turbulence parameterisation in hydrobiological models for natural waters, PhD Thesis, Darmstadt University, Germany, pp 228, 2001. Download Part I  and Part II.

 

Editorial work:

 

Anderson, E., D., C. Troy, L. Umlauf, and J. Wang (Conveners). Comparing physical processes in large lakes, shallow seas, and semi-enclosed basins. Session PO24A at the Ocean Science Meeting 2016, New Orleans, LA, USA, 21-26 February 2016.

Beletsky, D., L. Umlauf, C. Troy, C. Wu, R. Rao, J. Wang (Conveners). Comparing physical processes in large lakes and shallow seas. Session 055 at the Ocean Science Meeting 2014, Honolulu, HI, USA, 23-28 February 2014.

Wirth, A., and L. Umlauf (Conveners). Small-scale Processes and their parameterization. Session OS14 at the EGU General Assembly 2010, Vienna, Austria. 

Burchard, H., L. Umlauf, and F. Peters (eds.), Impact of Small-scale Physics on Marine Biology - Selected papers from the 2nd Warnemünde Turbulence Days, 28-30 September 2005, Rostock, Germany, J. Mar. Sys., 70,  215-308, 2008.

Umlauf, L., and G. Kirillin (eds.), Proceedings of the 11th workshop on physical processes in natural waters, Warnemünde, Germany, 3-6 September 2007, IGB report, 25, Leibniz-Institute for Freshwater Ecology and Inland Fisheries Berlin (IGB), Germany, 2007.

Burchard, H., and L. Umlauf (eds.), WTD 2003 Special Issue, papers presented at the First Warnemünde Turbulence Days, 17-19 September 2003, Warnemünde, Germany, Deep-Sea Res. II, 52, 1069-1357, 2005.

 

(Some) other publications:

 

Nausch, G., R. Feistel, L. Umlauf, K. Nagel and H. Siegel, Hydrographisch-chemische Bedingungen in der deutschen ausschließlichen Wirtschaftszone (AWZ) im Jahr 2008, Technical Report, Leibniz-Institute for Baltic Sea Research, Warnmünde, Germany, 2009.

Nausch, G., R. Feistel, L. Umlauf, K. Nagel and H. Siegel, Hydrographisch-chemische Zustandseinschätzung der Ostsee 2007. No. 72 of Marine Science Reports, Leibniz-Institute for Baltic Sea Research, Warnmünde, Germany, 2008.

 

Umlauf, L., and H. Burchard. Hydrodynamics - Lecture Notes, Baltic Sea Research Institute, Warnemünde, Germany, 2006. 

Yakushev, E.V., F. Pollehne, G. Jost, I. Kuznetsov, B. Schneider and L. Umlauf. Redox Layer Model (ROLM): a tool for analysis of the water column oxic/anoxic interface processes. No. 68 of Marine Science Reports, Leibniz-Institute for Baltic Sea Research, Warnemünde, Germany, 2006.

Umlauf, L., K. Bolding, and H. Burchard. GOTM – Scientific Documentation. Version 3.2. No. 63 of Marine Science Reports, Leibniz-Institute for Baltic Sea Research, Warnemünde, Germany, 2005.(Please check up-to-date version on www.gotm.net).

 

Selected Presentations:

Umlauf, L. Mixing and entrainment in shallow gravity currents on a rotating slope. Oral presentation. Gordon Research Conference on Ocean Mixing, Andover, NH, USA, 05 June 2018. Invited.

Umlauf, L., and C.  Lappe. Boundary mixing in nontidal basins: Observations from the Batlic Sea. Oral presentation. 49th Liège Colloqium on Ocean Dynamics, Liège, Belgium, 25 May 2017.

Umlauf, L., C. Lappe, and P. Holtermann. Turbulence and mixing in a rotating shallow bottom gravity current. Oral presentation. Ocean Science Meeting 2016, New Orleans, LA, USA, 24 February 2016.

Umlauf, L., P. Holtermann, H. Burchard, T. Tanhua, J. Ledwell, O. Schmale. Basin-scale overturning circulation and the role of small-scale processes (Lessons learned from the Baltic Sea). Workshop on Energy transfers in Atmosphere and Ocean, University of Hamburg, Hamburg, Germany, 20-22 April 2015.

A. Oschlies, and L. Umlauf. Geht der Ostsee die Luft aus? Summerschool organized by the "Studienstiftung des Deutschen Volkes". Mariehman, Aland-Islands, 17-23 August 2014. Invited.

Umlauf, L., J. N. Moum, and W. D. Smyth. Convective mixing and mixing efficiency in turbulent bottom boundary layers induced by internal waves. Oral presentation. Ocean Science Meeting 2014, Honolulu, HI, USA, 23-28 February 2014.

Umlauf, L. Turbulence and Mixing in the Baltic Sea. Oral presentation. Applied Physics Laboratory (APL), University of Washington, Seattle, Washington, USA, 07 November 2013. Invited.

Umlauf, L., P. Holtermann, T. Tanhua, O. Schmale, G. Rehder. Internal dynamics and mixing processes
in stratified basins without tides. Oral presentation. What can be learned from the Baltic Sea? CILER-GERL seminar. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, Michigian, USA, 28 October 2013. Invited.

Umlauf, L., L. Arneborg, H. Burchard. Dynamics of and Entrainment into thin, dense Boundary Currents descending from the Shelves into the Deep Basins. Oral presentation. IASC workshop on internal mixing processes in the Artic Ocean, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA, USA, 21 October 2013. Invited.

Umlauf, L. Turbulence and Mixing in the Baltic Sea. Oral presentation. POA seminar. CEOAS (Oregon State Univeristy), Corvallis, Oregon, USA, 15 October 2013. Invited

Umlauf, L. Who mixes the Baltic Sea? About gravity currents, internal waves, and topographic effects. Oral Presentation. Climate Science Seminar, Alfred-Wegener-Institut (AWI), Bremerhaven, Germany, 26 April 2013. Invited.

Umlauf, L., H. Burchard, U. Gräwe, P. Holtermann,A. Lorke. Lecture. Three-dimensional modeling of physical processes in lakes. Block Seminar Physical Limnology, IUP, Heidelberg University, Germany, 21 March 2013. Invited.

Umlauf, L., P. Holtermann, T. Tanhua, O. Schmale, G. Rehder, J. J. Waniek. Internal vs. boundary mixing: Results from a long-term tracer experiment in the Baltic Sea. IUP-AWI Seminar Ocean-Atmosphere-Cryosphere Interactions. Oral presentation. University of Bremen, Bremen, Germany, 04 February 2013. Invited.

Umlauf, L., P. Holtermann, T. Tanhua, O. Schmale, G. Rehder, J. J. Waniek. Oral presentation. The Baltic Sea Tracer Release Experiment. CEEB Seminar, EAWAG, Kastanienbaum, Switzerland, 16 April 2012. Invited.

Umlauf, L. The Baltic Sea Tracer Release Experiment. Poster presentation. Ocean Sciences Meeting 2012, Salt Lake City, USA, 20-24 February 2012.

Umlauf, L. Mixing in the coastal ocean: What can be expected from today's turbulence models? Oral presentation. Helmholtz-Zentrum Geesthacht, Seminar, Geesthacht, Germany, 10. March 2011. Invited.

Umlauf, L., E. M. van der Lee. Internal-wave mixing in the Baltic Sea: Near-inertial waves in the absence of tides. Oral presentation. 7th Baltic Sea Science Congress, Konferenz, St. Petersburg, Russia, 22.-26. August 2011.

E. M. van der Lee, L. Umlauf. Internal-wave mixing in the Baltic Sea: Near-inertial waves in the absence of tides. Warnemünde Turbulence Days, Konferenz, Vilm, Germany, 05-08. September 2011. 

Umlauf, L. The effect of rotation on entrainment in bottom gravity currents. Oral presentation. Workshop on Small-scale variability in the general circulation of the atmosphere and oceans. Tremsbüttel Castle, Germany, 15-17 September 2010. Invited.

Umlauf, L., and H. Burchard. Mixing and secondary circulation in stratified oscillating boundary layers near sloping topography. Oral presentation. PPNW Workshop 2010, Reyjkjavik, Iceland, 28 June - 1 July 2010.

Umlauf, L., and H. Burchard. Diapycnal transport and mixing efficiency in stratified oscillating boundary layers near sloping topography. Oral presentation, EGU General Assembly 2010, Vienna, Austria, 02-07 May 2010.

van der Lee, and L. Umlauf. Observation of interior and boundary-layer mixing processes due to near-inertial waves in a stratified basin without tides. Poster Presentation.EGU General Assembly 2010, Vienna, Austria, 02-07 May 2010. Young Scientist Oustanding Poster Award.

Umlauf, L., L. Arneborg, R. Hofmeister, V. Mohrholz, H. Burchard. The effect of rotation on gravity current entrainment. MOCA-09, IAPSO session on Ocean Mixing, Montreal, Canada, 19-24 July 2009. Invited.

Umlauf, L., L. Arneborg, R. Hofmeister, H. Burchard. Does rotation affect entrainment in buoyancy-driven flows? Gordon Research Conference on Coastal Ocean Circulation, Colby-Sawyer College, New London, NH, USA, 07-12 June 2009. Invited.

Umlauf, L., L. Arneborg, V. Mohrholz, H. Burchard. Boundary layer effects in topographically constrained bottom gravity currents. Mini-Symposium "Ocean Bottom and Surface Boundary Layers", WHOI,  Woods Hole, USA, 09-13 July 2007. Invited.

Umlauf, L., L. Arneborg, V. Mohrholz, H. Burchard. Transverse Structure of Turbulence and Dynamics of Rotating Gravity Currents in a Channel. 39th International Liege Colloquium on Ocean Dynamics "Turbulence Re-Revisited". Liege, Belgium, 07-11 May 2007. Invited.

Umlauf, L., V. Mohrholz, F. Janssen, H. Burchard, L. Arneborg. Turbulence and current structure in dense gravity currents. Conference on Coastal and Shelf Seas. Bangor, UK, 10-12 April 2006. Oral presentation.

Umlauf, L., L. Arneborg, H. Burchard. Transverse secondary circulation in dense gravity currents: Implications for entrainment and transport. Ocean Sciences Meeting, Honolulu, USA, 20-24 February 2006. Oral presentation.

Umlauf, L., L. Arneborg, H. Burchard. One-point modeling of turbulence in stable stratified interfaces. Internal waves, Turbulence, and Shelf Seas Workshop, University of Bangor, UK, 9-11 November 2005. Invited.

Umlauf, L., Explicit algebraic second-order modelling of buoyancy-affected entrainment. Interdisciplinary Aspects of Turbulence. Workshop of the Max Plank Society for Astrophysics. Tegernsee, Germany. 18-22 April 2005. Invited.

Umlauf, L., and U. Lemmin. Inter-basin exchange and mixing in a large lake. The role of long internal waves. PECS conference. Merida, Mexico. 19-22 October 2004. Oral presentation.

Umlauf, L. Stably stratified turbulent flow with uniform horizontal shear – physics and modelling. EGS-AGU-EUG  Joint Assembly. Nice, France. 6-11 April 2003. Oral presentation.

Umlauf, L. Inter-basin exchange due to long internal waves. Jour fixe SFB 454, University of Constance, Germany 29. November 2004. Invited.

Umlauf, L., and H. Burchard, A generic length-scale equation for second-order turbulence models of geophysical boundary layers, Geophysical Research Abstracts, 27th General Assembly of the European Geophysical Society, ISSN 1029-7006, 4, 2002. Oral presentation.

Umlauf, L., and K. Jöhnk, Modelling the oxygen stratification of Lake Ammer, Estonian Marine Institute, Report 10, ISSN 1406-023 X, 84-91, Tallin (Estonia), 1999. Oral presentation.

Umlauf, L.,  A comparison of different turbulent closure schemes for mixing processes in lakes, Abstracts of the 3rd Vereshchagin Baikal Conference, Limnological Institute of the Siberian Branch of the Russian Academy of Science, Irkutsk, Russia, 2000. Oral presentation.

Umlauf, L., Comparing two topography-following primitive equation models for lake circulation, UFZ-Berich Nr. 23, 3rd Workshop on Physical Processes in Natural Waters, Magdeburg, Germany, ISSN 0948-9452, 46-50, 1998. Oral presentation.