UPWARD FLUSHING OF SEA-WATER THROUGH FIRST YEAR ICE

Observations in both the ice and slush layers suggest that sea water i ntrudes into the snow layer following a snow storm. Ice temperature va lues recorded at I cm below the snow-ice interface show that the upwar d flux of sea water is of short duration. This is followed by a period of intense brine drainage characterized by the migration of a salty b rine layer with salinities up to 42 psu. These results suggest that a snow storm induces a complete (upward) flushing of the brine channel n etwork and major modifications of snow and ice characteristics. Melt r ates and downward brine fluxes were calculated using salinity measured in a 40 cm deep box placed on the ice-water interface, which isolated a 50 x 50 cm area of sea ice from ocean mixing processes. In this sem i-isolated environment, observed salinity changes allowed us to determ ine melt water fluxes and brine drainage or flushing even though ice t hickness measurements did not show any significant change. Melt rates up to 21 cm/month and equivalent growth rates up to 32 cm/month were m easured.