FY 1985

Sea ice prediction modelling

Nelson, C., and C.H. Pease

In Oceans 84 Conference Proceedings, Marine Technology Society, Washington, D.C., 7 pp (1984)

An experimental ice forecasting model for the Bering Sea is undergoing operational evaluation at the National Meteorological Center. Sea ice extent, ice floe velocities, and changes in ice thickness along three transects are predicted by a wind-driven, free drift sea ice model and a linear, one-dimensional balance of the thermodynamic terms at the air, sea, and ice interfaces. Ice edge positions for model initialization and forecast verification are manually digitized from the Navy/NOAA Joint Ice Center regional ice analysis chart. Dynamic and thermodynamic forcing fields are derived from the NMC operational analyses and forecasts of sea level pressure and 1000 mb temperatures and a regional objective sea surface temperature analysis. The ice forecast model runs daily and a 6-day forecast chart is disseminated as experimental guidance for field office evaluation to the JIC and to the Anchorage Weather Service Forecast Office. Preliminary subjective verification of the 6-day forecasts indicates reasonable success in predicting ice movement. However, the model shows sensitivity to input parameters describing ice extent, thickness, and concentration and forecast accuracy clearly depends on the skill of the atmospheric forecasts in the 3-5 day range. Results from model predictions during February 1983 and throughout the 1983-84 ice season will be discussed.