Związek krótkookresowych zmian miąższości pokrywy śnieżnej na Lodowcu Avatsmarka (NW Spitsbergen) z parametrami meteorologicznymi wiosną 2001 i 2002 roku

The work has been intended to determine relations between short-term changes of the snow cover thickness on the glacier and meteorological parameters recorded on the glacier and in the glacier vicinity. Short-term relations are regarded as connections between variations of the snow depth on the glacier and the course of meteorological factors in a scale of up to 24-hours. Detailed snow and meteorological measurements were carried out on the equilibrium line (364 m a.s.l.) of Aavatsmark Glacier (NW Spitsber-gen) in two periods: 11 - 30th April 2001 and 12th April - 5th May 2002. The thickness of snow was investigated with the use of Sonic Ranging Sensor SR50 Campbell Scientific Ltd. Meteorological data comes from an automatic weather station located on the glacier?s surface and from meteorological sites on Kaffioyra and Ny-Alesund. All measurements were taken in 10-minute step. Short-term changes of the snow thickness on glaciers in winter seasons are influenced by the precipitation and snow transport. The wind power determines the scale of snow transport. In consequence, the increase of wind speed causes higher intensity of changes of the snow level. The intensity of changes of the snow depth within the range from 0 to 8ˇ10-6 m/s is connected with the average wind speed of 4 m/s and changes intensity over 17ˇ10-6 m/s accompanied the average wind speed 8.7 m/s. The appearance of precipitation in daily or longer time-scale causes the increase of snow thickness and the weakness of relations between changes of the snow depth and the wind speed. In a time-scale of several hours the snow supply leads to the increase of both intensity and amplitude of snow level changes. Significant increase of the intensity and amplitude of changes of snow depth took place over the average wind speed 5 m/s in days without precipitation and over 8 m/s in days with snowfall. Short-term changes of the snow thickness are constrained by availability of an unconsolidated, easy-to-transport material. The major part of that material comes from precipitation. As a result short-term changes of the snow depth are more noticeable during days with precipitation. A thin crust layer on the snow surface has been formed as a result of friction of air masses and snow particles. In emergence of the positive tempe-rature and good radiation conditions in the upper snow layer ice crust can be formed. After stabilization of the snow cover even powerful wind gust can?t start transporting the material and short-term changes of the snow thickness are limited.