Innovations in Dynamic Modelling of Iceberg Drift

Dynamic models of iceberg drift require as input the currents and winds which drive the iceberg, but in the past it has not been possible to obtain adequate data on currents. Two cruises of CSS Dawson have collected data for the testing and development of a dynamic iceberg drift model, with current profiles continuously monitored by a doppler current profiler. Winds were measured by an anemometer on a bow mast. Iceberg tracks were logged by radar ranges and bearings, while the ship was positioned by LORAN C.Sonar profiles and photographs were analyzed to estimate the mass and the cross-sectional areas in air and in water. Twelve drift track segments of seven icebergs have been compiled at 10 min intervals for periods of 12 hours to 3 days. A dynamic model reproduces the tracks with an average rms position error of only 5% of the distance travelled.