On the nature of the sea ice albedo feedback in simple models

• Main Authors: Moon, Woosok, Wettlaufer, John S.
• Format: Text
• Language: unknown
• Published: arXiv 2013
• Subjects: Atmospheric and Oceanic Physics physics.ao-ph; FOS Physical sciences; 86 Primary, 34 Secondary; Sea ice
• Online Access: https://dx.doi.org/10.48550/arxiv.1305.0629; https://arxiv.org/abs/1305.0629

We examine the nature of the ice-albedo feedback in a long standing approach used in the dynamic-thermodynamic modeling of sea ice. The central issue examined is how the evolution of the ice area is treated when modeling a partial ice cover using a two-category-thickness scheme; thin sea ice and open water in one category and "thick" sea ice in the second. The problem with the scheme is that the area-evolution is handled in a manner that violates the basic rules of calculus, which leads to a neglected area-evolution term that is equivalent to neglecting a leading-order latent heat flux. We demonstrate the consequences by constructing energy balance models with a fractional ice cover and studying them under the influence of increased radiative forcing. It is shown that the neglected flux is particularly important in a decaying ice cover approaching the transitions to seasonal or ice-free conditions. Clearly, a mishandling of the evolution of the ice area has leading-order effects on the ice-albedo feedback. Accordingly, it may be of considerable importance to re-examine the relevant climate model schemes and to begin the process of converting them to fully resolve the sea ice thickness distribution in a manner such as remapping, which does not in principle suffer from the pathology we describe. : 8 pages, 2 figures, one table