A DETAILED ASSESSMENT OF SNOW ACCUMULATION IN KATABATIC WIND AREAS ONTHE ROSS ICE SHELF, ANTARCTICA

An investigation of time dependent snow accumulation and erosion dynam ics in a wind-swept environment was undertaken at two automatic weathe r stations sites on the Ross Ice Shelf between January 1994 and Novemb er 1995 using newly developed instrumentation employing a technique wh ich automatically disperses inert, colored (high albedo) glass microsp heres onto the snow surface at fixed intervals throughout the year. Th e microspheres act as a time marker and tracer to allow the accumulati on rate and wind erosion processes to be quantified with a high tempor al resolution. Snow core and snow pit sampling was conducted twice dur ing the study period to identify microsphere horizons in the annual sn ow accumulation profile, allowing the snow accumulation/erosion events to be reconstructed. The two sites chosen for this investigation have characteristically different mean wind speeds and therefore allow a c omparative examination on the role of wind on ice sheet growth. Mass a ccumulation rate at the two sites for the 14-day integration periods a vailable ranged from 0.0 to >2.0 kg m(-2) d(-1) The mean mass accumula tion rate during the study period was greater at the site with stronge r winds (0.69 kg m(-2) d(-1)) than the site with lower mean wind speed s (0.61 kg m(-2) d(-1)); however, the difference between the two means is not statistically significant. Accumulation rates derived from an ultrasonic snow depth gauge operated at one of the sites are compared to the actual tracer-derived accumulation rates and show the limitatio ns of only having a measure of snow surface height with no instantaneo us measurements of the snow density profile. Snow depth gauge derived accumulation rates were found to be greatly overestimated during high- accumulation periods and were greatly underestimated during low-accumu lation periods.