An Operational View of Sea Ice Prediction: Diagnosing ice free dates using the Navy’s Global Coupled Atmosphere-Ocean-Sea Ice Prediction System

Abstract:

The Naval Research Laboratory is developing a global coupled atmosphere-ocean-sea ice seamless prediction system with the goals of improving of short-term and long-term predictions, as well as an enhanced understanding of environmental interactions. The system utilizes the Navy’s Global Environmental Model (NAVGEM), the Navy’s HYbrid Coordinate Ocean Model (HYCOM), and the Los Alamos National Laboratory’s sea ice (CICE) model for the atmosphere, ocean, and sea ice model respectively. Using this model, we examine lead times needed to predict ice free conditions, and examine the model biases with multiple approaches. For the years 2013 and 2014, we perform hindcast runs starting at intervals of days to weeks before the minimum Arctic ice extent. As expected, shorter lead times lead to a better performance of the prediction of ice free periods, but biases associated with relatively short lead times (i.e., days) differ from biases associated with relatively longer lead (i.e., weeks) times. The representation of synoptic events is important during short lead times, while difficulties in representing surface fluxes are important for longer lead times. This study aids in the understanding of the important processes needed for sea ice prediction at different time-scales.