Size specific steady-state accumulation-area ratio: an improvement for equilibrium-line estimation of small palaeoglaciers

Characteristic distribution of the steady-state accumulation-area ratio (AAR0) of valley and corrie glaciers was investigated in a global dataset comprised of 46 glaciers. There is a positive relationship between AAR0 and glacier area with smaller glaciers having lower values of AAR0 compared with larger glaciers. The relationship between glacier area (S) and steady-state AAR of studied glaciers can be optimally described by a logarithmic regression equation. This relationship is thought to be a globally valid approximation if the size of the glacier is not smaller than 10−1 km2. In the case of palaeoglaciers an AAR0 value of 0.44 ± 0.07 is best applied on glaciers with areas in the range 0.1-1 km2, 0.54 ± 0.07 for glaciers covering areas between 1 and 4 km2 and 0.64 ± 0.04 for glaciers larger than 4 km2. This assumes insignificant debris cover for the investigated palaeoglaciers. The proposed size-specific AAR0 values take into account the geometric/hypsometric properties of (palaeo)glaciers. The results have major importance for palaeoglaciological reconstructions in many regions of former marginal/niche glaciation characterized by small former glaciers.