Testing the area–altitude balance ratio (AABR) and accumulation–area ratio (AAR) methods of calculating glacier equilibrium-line altitudes

Abstract In this study, we compare equilibrium-line altitudes (ELAs) calculated using the area–altitude balance ratio (AABR) and accumulation–area (AAR) methods, with measured ELAs derived from direct field observations. We utilise a GIS toolbox to calculate ELA for 64 extant glaciers by applying AABR AAR methods DEMs polygons of their geometry. The (c-ELAs) are then compared zero-net (znb-ELAs) obtained mass-balance time series held WGMS same glaciers. correlation between znb-ELAs (1.56)/AAR (0.58) c-ELAs is very strong, an r 2 = 0.99. smallest median difference (i.e. 65.5 m) when globally representative 1.56 used. When applied palaeoglacier-climate applications, translates ~0.42°C, well within uncertainty palaeotemperature proxies used determine mean summer temperature at ELA. more widely 1.75 shown be statistically invalid due skewness dataset. On basis, calculating glacier ELAs, recommend use global value 1.56.