Nowcasting Sea Ice Movement Through the Bering Strait

Geostrophic wind velocities were calculated using atmospheric pressure data from Bering Strait stations at Uelen (Siberia), Bukhta Provideniya (Siberia) and Nome (Alaska). These velocities were matched to Strait sea ice displacements derived from satellite imagery (1974–1984), resulting in an all-weather ice movement and now-casting model. Also, five ice displacement modes were identified. The first mode is Chukchi to Bering Sea movement when northeasterly winds exceed 11.5 m/s. The second and third modes are Bering to Chukchi Sea movement. Mode two is driven by a pre-existing north-flowing ocean current during weak opposing winds. Mode three is due to winds and currents acting in concert. The first immobilization mode (maximum duration one week) is an apparent balance between northerly wind stress, water stress from the south, and internal ice stresses. The second immobilization mode is due to large, double, solid ice arches jamming the Strait up to four weeks.