Effect of melt ponds on first-year sea ice ablation - Integration of RADARSAT-1 and thermodynamic modelling

The arctic spring melt evolution and the associated surface energy, balance (SEB) are critical in determining the eventual break-up date of first year sea ice (FYI). Mechanically weak FYI is linked to a near-isothermal ice temperature profile with relatively, high brine volumes. Melt pond evolution on FYI plays a critical role in the SEB (through albedo influences) which determines the ice's thermodynamic structure. A one-dimensional thermodynamic sea ice model was used to examine the susceptibility of FYI to break up as a function of percent melt pond fraction. An ice surface with 80% pond fraction can produce thermodynamically weak ice more than three weeks earlier than an ice surface with 10% pond fraction. As expected, a non-linear relationship exists between the ice temperature gradient change (ITGC) and pond fraction to illustrate pond fraction effects on FYI break-up potential. Further modelling experiments suggest the sea ice model overestimates FYI melt rates in this case mainly due to inadequate albedo representation during the melt pond season. This suggests that we require either better model parameterizations of surface albedo or the capability to use remote sensing data to directly estimate melt pond fractions and their associated albedo for use in annual FYI simulations. Inversion of surface albedo from RADARSAT-1 imagery over smooth FYI is possible throughout the melt season in this case. Results show that RADARSAT-1 derived surface albedo ingested into the thermodynamic sea ice model improve sea ice simulations to better predict the timing of FYI break-up.