A numerical study of melt ponds

Abstract

High-resolution turbulence simulations are used to examine the importance of melt pond geometry in setting pond growth rates and albedo. Modeling the circulation of water in melt ponds using large-eddy simulation shows that both convective and wind-forced conditions generate well-mixed ponds, suggesting that stratification is not a significant factor in pond circulation. Simulations with a variety of pond shapes and sizes indicate that the basic ratio of sidewall area to bottom area, R, can be used to characterize melting rates for ponds with simple shapes. Ponds with large values of R will generally melt more rapidly in the horizontal direction at the expense of bottom melting. Consequently, small and elongated ponds will have a relatively larger lateral growth rate in comparison with large, symmetric ponds, assuming minimal lateral flux of meltwater. Simulations also show that pond shape can affect the sidewall and bottom turbulence transfer rates. Ponds with large R tend to have reduced transfer rates because of weaker circulations. A bulk pond model is developed on the basis of a rectangular geometry and an assumption of uniform mixing as suggested by the turbulence model and pond scaling using R. Comparison of the bulk model with results from the large-eddy simulation cases shows good agreement. Copyright 2007 by the American Geophysical Union.