A 22 month record of surface meteorology and energy balance from the ablation zone of Brewster Glacier, New Zealand

Multi-annual records of glacier surface meteorology and energy balance are necessary to resolve glacier-climate interactions but remain sparse, especially in the Southern Hemisphere. To address this, we present a record from the ablation zone of Brewster Glacier, New Zealand, between October 2010 and September 2012. The mean air temperature was 1.2 degrees C at 1760 m a.s.l., with only a moderate temperature difference between the warmest and coldest months (similar to 8 degrees C). Long-term annual precipitation was estimated to exceed 6000 mm a(-1), with the majority of precipitation falling within a few degrees of the freezing level. The main melt season was between November and March (83% of annual ablation), but melt events occurred during all months. Annually, net radiation was positive (a source of energy) and supplied 64% of the melt energy, driven primarily by net shortwave radiation. Net longwave radiation was often positive during cloudy conditions in summer, demonstrating the radiative importance of clouds during melt. Turbulent sensible and latent heat fluxes were directed towards the surface in the summer months, accounting for just over a third of the energy for melt (34%). The energy gain associated with rainfall was small except during heavy events in summer.