Modeling sea ice and melt ponds at SHEBA with the CCSM ice model

The Community Climate System Model (CCSM) sea ice component is used to simulate the annual cycle of ice growth at the SHEBA ice station. The CCSM ice model is used here as a single-grid cell representation of the SHEBA field camp area, approximately 100 km by 100 km in size. The model includes an ice-thickness distribution that represents the distribution of ice floes. The meteorological data from SHEBA are used as hourly forcing, including air temperature, wind speed, humidity, precipitation, solar and longwave radiation. Ice thickness data from ablation stakes are used to initialize and validate the simulation through the year. The standard CCSM-2 model does not have explicitly-modeled melt ponds, so the albedo makes transitions in and out of the summer melt stage too suddenly, contrary to the observations. The impact of including evolving melt ponds on the simulation and the albedo transitions will be shown, including their effect on solar radiation into the ice and transmission through the ice to the upper ocean. The net effect of the transmitted radiation on the upper ocean will be compared to estimates from the field observations.