Preprints
https://doi.org/10.5194/gmd-2021-272
https://doi.org/10.5194/gmd-2021-272

Submitted as: model evaluation paper 06 Oct 2021

Submitted as: model evaluation paper | 06 Oct 2021

Review status: this preprint is currently under review for the journal GMD.

Validation of turbulent heat transfer models against eddy covariance flux measurements over a seasonally ice covered lake

Joonatan Ala-Könni, Kukka-Maaria Kohonen, Matti Leppäranta, and Ivan Mammarella Joonatan Ala-Könni et al.
  • Institute for Atmospheric and Earth System Research / Physics, Faculty of Science, University of Helsinki, Helsinki, Finland

Abstract. In this study we analyzed turbulent heat fluxes over a seasonal ice cover on boreal lake located in southern Finland. Eddy covariance (EC) measurements from four ice-on seasons between 2014 and 2019 are compared to three different bulk transfer models: one with a constant transfer coefficient, and two with stability adjusted transfer coefficients: the Lake Heat Flux Analyzer and SEA-ICE. All three models correlate to the EC results well in general, although typically underestimating the magnitude and the variance of the flux in comparison to the EC observations. Differences between the models are small, with the constant transfer coefficient model performing slightly better than the stability adjusted models. Small difference in temperature and humidity between surface and air results in low correlation between models and EC. During melting periods (surface temperature T0 > 0 °C), the model performance for LE decreases when comparing to the freezing periods (T0 < 0 °C), while the opposite is true for H. At low wind speed EC shows relatively high fluxes (±20 W m−2) for H and LE due to non-local effects that the bulk models are not able to reproduce. Finally, the uncertainty in the estimation of the surface temperature and humidity affects the bulk heat fluxes, especially when the difference between surface and air values are small.

Joonatan Ala-Könni et al.

Status: open (until 01 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Joonatan Ala-Könni et al.

Data sets

Lake Kuivajärvi dataset Heikki Laakso, Ivan Mammarella, Janne Levula, Kukka-Maaria Erkkilä, Teemu Matilainen & Turo Salminen https://doi.org/10.23729/9b209b52-2ea0-4d89-b059-062b734142d8

SMEAR II forest meteorology Janne Rinne, Erkki Siivola, Heikki Laakso, Janne Levula, Johanna Patokoski, Juho Aalto, Maija Kajos, Markku Kulmala, Matti Leskinen, Pasi Aalto, Pasi Kolari ,Pekka Rantala, Petri Keronen, Risto Taipale, Taina Ruuskanen & Toivo Pohja https://doi.org/10.23729/2001890a-2f0b-4e37-8c70-4d2cb5f40273

Model code and software

SHEBA Sea-Ice Ed Andreas https://doi.org/10.5281/zenodo.5534911

Lake heat flux analyzer Woolway, R. I., Jones, I. D., Hamilton, D. P., Maberly, S. C.,Muraoka, K., Read, J. S., Smyth, R. L. & Winslow, L. A. https://doi.org/10.5281/zenodo.5534907

Joonatan Ala-Könni et al.

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Short summary
Properties of seasonally ice covered lakes aren't currently sufficiently included in global climate models. To fill this gap, this study evaluates three models that could be used to quantify the amount of heat that moves from and into the lake by the air above it and through evaporation of the ice cover. The results show that difficulties in measuring the surface temperature of ice introduce errors and that a simple model was better at predicting the transport of heat than the complex models.