Three debris-free glaciers of various areas have been monitored for the last 5 to 8 years in Everest region (Central Himalaya, Nepal) and their annual glacier-wide mass balances (Ba) obtained from the glaciological method strongly differ. Mera Glacier (5.1 km2 in 2012) is located in the southern part of the region and has been in steady state over the last 5 to 8 years, whereas Pokalde (0.1 km2 in 2011) and Changri Nup glaciers (0.92 km2 in 2013), approximately 30 km farther north in the drier inner part of the range, have been losing mass rapidly with a Ba of -0.69 ± 0.28 m w.e. a-1 (2009-15) and -1.24 ± 0.27 m w.e. a-1 (2010-15), respectively. Changri Nup specific mass balance has been confirmed by the geodetic method using SPOT5 and Pléiades images from 2009, 2013 and 2015, but the validation is still incomplete because part of the avalanche-fed areas are not taken into account, which may result in a slight bias toward negative mass balances. A qualitative comparison between annual glacier-wide mass balances and annual or seasonal meteorological variables acquired at the elevation of glaciers suggests that these glaciers are sensitive to precipitation and to the incoming radiative energy fluxes. Occasional very severe cyclonic storms originating in the Bay of Bengal can reach the highlands of Nepal triggering huge snow falls, like Typhoon Phailin responsible for a +0.33 m w.e. increase in 2012-13 Ba of Mera Glacier in 2 days only (13-15 October 2013). This contrasted mass balance pattern over rather short distances can be explained by two facts. On the one hand, it is related to the low elevation of Pokalde and Changri Nup glaciers, both culminating at 5690 m a.s.l., an altitude frequently almost reached by the ELA. On the other hand, we observe a strong south-north horizontal gradient of precipitation (steeper than -21 mm km-1 corresponding to -2% km-1). We suspect that glaciers located in the inner and leeward part of the range, submitted to arid conditions, are less balanced with the present climate than glaciers located in frontal position relatively to the monsoon influx, on the windward side of the range and in turn receiving large amounts of precipitation.
