Numerical simulation of wind-driven circulation in Lake Tanganyika
Keywords:
Hydrodynamic model, Currents, Particle trackingAbstract
A three-dimensional numerical circulation model of Lake Tanganyika, developed within the Lake Tanganyika Research Project (LTR-FAO/FINNIDA) is described. The model is based on full non-linear hydrodynamics equations, modified according to hydrostatic and Boussinesq approximations. A space-splitting scheme is used for numerical approximation of governing equations. Numerical experiments with different wind loading revealed the rather complicated flow structure in Lake Tanganyika.
Data for model validation have been collected since May 1993. Main hydrological and meteorological parameters such as water level, wind speed and direction, air temperature, humidity and water temperature are recorded with automatic devices. A simple Lagrangian approach with floating buoys and GPS system is used for current measurements.
The obtained surface velocities in different locations lake-wide were compared with the calculated surface currents. Agreement between measured and simulated velocities was satisfactory. Accuracy of the simulations depends on the accuracy of the wind forcing reconstruction. Regular strong winds are observed over Lake Tanganyika during the dry season, a period of trade winds that starts at the end of May and lasts until late August or early September. Numerical experiments with a mesoscale meteorological model (Savijärvi, H., 1995. Sea breeze effects on large–scale atmospheric flow. Contr. Atmos. Phys. 68 335–344) showed that the lake-land breeze system is intensified during this period.
The collected data and the numerical experiments with the circulation model provide a solid base for understanding the main hydrophysical processes on a lake-wide scale. Important knowledge has also been obtained on the spatial and temporal dynamics of currents.
References
Asnani, G.C. 1993. Tropical Meteorology, India: Indian Institute of Tropical Meteorology.
Benqué, J.-P., Haugel, A. and Violet, P.-L. 1982. Numerical Models in Environmental Fluid Mechanics, Engineering Applications of Computational Hydraulics, Vol. II, Boston, MA: Pitman.
Coulter, G.W. and Spigel, R.H. 1991. “Hydrodynamics”. In Lake Tanganyika and its Life, Oxford: British Museum (Natural History) and Oxford University Press. chap. 3.
Gill, A.E. 1982. Atmosphere-Ocean Dynamics, New York: Academic Press.
Kotilainen, P., Huttula, T. and Peltonen, A. 1995. “Lake Tanganyika Hydrodynamics (Results of March 1993–December 1994)”. In FAO/FINNIDA Research for the Management of the Fisheries on Lake Tanganyika GCP/RAF/271/FIN-TD/42 (En).
Patankar, S. 1980. Numerical Heat Transfer and Fluid Flow, New York: Hemisphere Publishing Corporation.
Peyret, R. and Taylor, D.T. 1983. Computational Methods for Fluid Flow, Berlin: Springer.
Podsetchine, V. and Huttula, T. 1994. “Hydrological Modelling on Lake Tanganyika”. In FAO/FINNIDA Research for the Management of the Fisheries on Lake Tanganyika GCP/RAF/271/FIN-TD/29 (En).
Savijärvi, H. 1995. Sea breeze effects on large-scale atmospheric flow. Contr. Atmos. Phys., 68: 335–344.
Tabata, M. 1977. A finite element approximation corresponding to the upwind finite differencing. Mem. Numer. Math., 4: 46–63.
Published
Issue
Section
License
Manuscripts must be original. They must not be published or be under consideration for publication elsewhere, in whole or in part. It is required that the lead author of accepted papers complete and sign the MSU Press AEHM Author Publishing Agreement and provide it to the publisher upon acceptance.
