LAKE 2.0: a model for temperature, methane, carbon dioxide and oxygen dynamics in lakes
- 1Lomonosov Moscow State University, GSP-1, 119234, Leninskie Gory, 1, bld. 4, Moscow, Russia
- 2Department of Physics, P.O. Box 48, 00014, University of Helsinki, Helsinki, Finland
- 3Department of Forest Sciences, P.O. Box 27, 00014, University of Helsinki, Helsinki, Finland
- 4Department of Environmental Sciences, Niemenkatu 73, 15140 Lahti, University of Helsinki, Helsinki, Finland
- 5Department of Environmental Sciences, P.O. Box 65, 00014, University of Helsinki, Helsinki, Finland
- 6Institute of Numerical Mathematics, Russian Academy of Sciences, 119333, Gubkina, 8, Moscow, Russia
Abstract. A one-dimensional (1-D) model for an enclosed basin (lake) is presented, which reproduces temperature, horizontal velocities, oxygen, carbon dioxide and methane in the basin. All prognostic variables are treated in a unified manner via a generic 1-D transport equation for horizontally averaged property. A water body interacts with underlying sediments. These sediments are represented by a set of vertical columns with heat, moisture and CH4 transport inside. The model is validated vs. a comprehensive observational data set gathered at Kuivajärvi Lake (southern Finland), demonstrating a fair agreement. The value of a key calibration constant, regulating the magnitude of methane production in sediments, corresponded well to that obtained from another two lakes. We demonstrated via surface seiche parameterization that the near-bottom turbulence induced by surface seiches is likely to significantly affect CH4 accumulation there. Furthermore, our results suggest that a gas transfer through thermocline under intense internal seiche motions is a bottleneck in quantifying greenhouse gas dynamics in dimictic lakes, which calls for further research.