Incorporation of a physically based melt pond scheme into the sea ice component of a climate model

Abstract

The extent and thickness of the Arctic sea ice cover has decreased dramatically in the past few decades with minima in sea ice extent in September 2005 and 2007. These minima have not been predicted in the IPCC AR4 report, suggesting that the sea ice component of climate models should more realistically represent the processes controlling the sea ice mass balance. One of the processes poorly represented in sea ice models is the formation and evolution of melt ponds. Melt ponds accumulate on the surface of sea ice from snow and sea ice melt and their presence reduces the albedo of the ice cover, leading to further melt. Toward the end of the melt season, melt ponds cover up to 50% of the sea ice surface. We have developed a melt pond evolution theory. Here, we have incorporated this melt pond theory into the Los Alamos CICE sea ice model, which has required us to include the refreezing of melt ponds. We present results showing that the presence, or otherwise, of a representation of melt ponds has a significant effect on the predicted sea ice thickness and extent. We also present a sensitivity study to uncertainty in the sea ice permeability, number of thickness categories in the model representation, meltwater redistribution scheme, and pond albedo. We conclude with a recommendation that our melt pond scheme is included in sea ice models, and the number of thickness categories should be increased and concentrated at lower thicknesses.

First-year sea ice melt pond fraction estimation from dual-polarisation C-band SAR – Part 2: Scaling in situ to Radarsat-2

“…Improvements to parameterisations of f p have led to more comprehensive, physically based sea ice albedo schemes used in climate model simulations (Taylor and Feltham, 2004;Lüthje et al, 2006;Køltzow, 2007;Skyllingstad et al, 2009;Flocco et al, 2010) and greater understanding of ice-albedo feedbacks (Holland et al, 2012). However, parameterisations are based on limited field observations that do not account for the horizontal heterogeneity of ice types and f p .…”

New insight from CryoSat-2 sea ice thickness for sea ice modelling

“…Our reference simulation includes a prognostic melt pond model (Flocco et al, 2010(Flocco et al, & 2012 and the elastic anisotropic plastic rheology (Wilchinski and Feltham, 2006;Tsamados et al, 2013;Heorton et al, 2018). Otherwise, default CICE settings are chosen: 7 vertical ice layers, 1 snow layer, linear remapping ITD approximation (Libscomp and Hunke, 2004), Bitz and Libscomp (1999) thermodynamics, Maykut and Untersteiner (1971) conductivity, Rothrock (1975) ridging scheme with a Cf value of 12 (empirical parameter that accounts for frictional energy dissipation) and the Delta-Eddington radiation scheme 35 (Briegleb and Light, 2007 Comparing the CICE simulation with CS2 reveals that CICE default underestimates the mean monthly sea ice thickness by about 0.8 m (see Fig.…”

The refreezing of melt ponds on Arctic sea ice

“…A first attempt at modeling the refreezing of melt ponds was described in Taylor and Feltham [2004], although this ignored the role of pond salinity. A simpler version of this approach, essentially treating the ice lid growth as a classic Stefan phase change problem, was incorporated into a climate sea ice model by Flocco et al [2010Flocco et al [ , 2012. Based on these works, Hunke et al [2010] developed another melt pond routine based on similar principles.…”

“…Previous modeling studies of melt ponds have focused on their formation and summertime evolution [Taylor and Feltham, 2004;Flocco et al, 2010Flocco et al, , 2012L€ uthje et al, 2006;Skylingstad, 2009]. In autumn, the ponds refreeze at their upper surface to form an ice lid, which insulates them from the atmosphere and traps pond water between the sea ice and the ice lid.…”

“…Based on these works, Hunke et al [2010] developed another melt pond routine based on similar principles. The model presented by Flocco et al [2010Flocco et al [ , 2012 distinguishes between active (no ice lid) and nonactive ponds that are covered by an ice lid.…”