NORTHEAST WATER POLYNYA - SATELLITE-OBSERVATIONS SUMMER 1992 AND 1993

Polynyas in the Arctic have recently attracted much attention with studies of their geophysics (including water movements, heat flux and carbon dioxide flux) and their biology (including all phases from plankton over benthos to marine mammals and polar birds). A programme of remote sensing was undertaken in connection with two cruises by research vessels in the North-East Water polynya at the north-east corner of Greenland. Data from the Advanced Very High Resolution Radiometer (AVHRR) instrument on the NOAA satellites and Synthetic Aperture Radar (SAR) on ERS-1 was used supported by ground information collected by the research vessel, USCGC Polar Sea. The observations made are reported with examples of special events that control the state of the polynya. Based on repeated observations of flees the motion pattern is determined, for 1992 by means of AVHRR and for 1993 by ERS-1 SAR. They confirm the anti-cyclonic movement around the Belgica Bank supported by a system of troughs surrounding the Bank. The influence of a storm is studied as well as that of the break-off of major parts of the shorefast ice that limit the polynya in the north and the south. On this basis the maintenance of the polynya during the summer is discussed and the possible influence of these barriers. They are probably very important for the existence and the extent of the polynya. The periods studied are considered too short to reveal conclusive results and they give only a hint of what happens during the winters preceding the opening of the polynya in spring.