Tab. 1+2 Sites and depth of reference level 1963 and mean annual net balance since 1963

Measurements of the gross beta activity of firn samples taken from drillings in the region of the North Water polynya allow us to identify deposits of the radioactive Fall-out of 1963, due to a maximum of gross beta activity in a vertical profile. Drillings were made in the lower region of the accumulation area (Percolation Zone). The reference horizon of 1963 in this area is well marked by a concentration of deposits of radioactive fall out. This method of dating still enables us to determine the mean annual net accumulation since 1963.