Snow and ice on Bear Lake (Alaska) – sensitivity experiments with two lake ice models

ABSTRACT

Snow and ice thermodynamics of Bear Lake (Alaska) are investigated with a simple freshwater lake model (FLake) and a more complex snow and ice thermodynamic model (HIGHTSI). A number of sensitivity experiments have been carried out to investigate the influence of snow and ice parameters and of different complexity on the results. Simulation results are compared with observations from the Alaska Lake Ice and Snow Observatory Network. Adaptations of snow thermal and optical properties in FLake can largely improve accuracy of the results. Snow-to-ice transformation is important for HIGHTSI to calculate the total ice mass balance. The seasonal maximum ice depth is simulated in FLake with a bias of −0.04 m and in HIGHTSI with no bias. Correlation coefficients between ice depth measurements and simulations are high (0.74 for FLake and 0.9 for HIGHTSI). The snow depth simulation can be improved by taking into account a variable snow density. Correlation coefficients for surface temperature are 0.72 for FLake and 0.81 for HIGHTSI. Overall, HIGHTSI gives slightly more accurate surface temperature than FLake probably due to the consideration of multiple snow and ice layers and the expensive iteration calculation procedure.

• snow on lake ice
• thermodynamic ice model
• heat conductivity of snow
• albedo
• snow to ice transformation

7. Acknowledgements

The third author (YY) was supported in early 2011 by a CIMO scholarship from Ministry of Education in Finland. The HIGHTSI modelling was supported by the National Natural Science Foundation of China (grant no. 51079021, 40930848) and the Norwegian Research Council (grant no. 193592/S30). The field data are courtesy of the ALISON (http://www2.gi.alaska.edu/alison/ALISON_pubs.html).The authors thank Dr. Ekaterina Kurzeneva for valuable discussions during the preparation of this manuscript. The suggestions by two anonymous reviewers led to significant improvements of the manuscript.