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

Abstract

ABSTRACT. 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°C at 1760 m a.s.l., with only a moderate temperature difference between the warmest and coldest months (�8°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.

Intercomparison of different uncertainty sources in hydrological climate change projections for an alpine catchment (upper Clutha River, New Zealand)

“…A potential explanation could be related to the predominant air temperature during mature precipitation events along the main divide. At Brewster Glacier (located along the main divide just west of the Clutha catchment), Cullen and Conway (2015) found air temperature to be frequently around the rain-snow threshold during events with major solid precipitation, which led to the conclusion that the accumulation of snow in areas along the main divide is vulnerable to small variations in air temperature. The relatively large variability during the reference period was therefore seen as a first indicator for a potentially high sensitivity of the modelled snow storage and runoff to projected warming.…”

Cloud effects on surface energy and mass balance in the ablation area of Brewster Glacier, New Zealand

“…1). Table 1 gives details of instrumentation and annual average surface climate variables at AWS glacier , while further details of the locality and AWS instrumentation can be found in Cullen and Conway (2015). Measurements at AWS glacier ran for 22 months from 25 October 2010 to 1 September 2012 (inclusive).…”

“…This paper addresses these issues by resolving the SEB and SMB at a site in the ablation zone of Brewster Glacier over a 22-month period in 2010-2012. High-quality surface climate data presented in Cullen and Conway (2015) are used to force an SMB model (Mölg et al, 2008) to estimate both SEB and SMB terms over this period (measurement period). The cloud metrics presented in Conway et al (2015) are used to identify clear-sky and overcast conditions and thus characterize surface climate, SEB, and melt energy during each condition.…”

An 11-year record of mass balance of Brewster Glacier, New Zealand, determined using a geostatistical approach

“…The Southern Alps are surrounded by vast areas of ocean and are strongly influenced by both subtropical and polar air masses, with the interaction of these contrasting air masses in the prevailing westerly airflow resulting in synoptic scale atmospheric circulation having a strong influence on glacier behaviour others, 1992, 1997;Clare and others, 2002;Gillett and Cullen, 2011). The massbalance programme on Brewster Glacier has provided a platform from which to assess glacier sensitivity to atmospheric forcing in the Southern Alps (Anderson and others, 2010;Gillett and Cullen, 2011;Cullen, 2013, 2016;Conway and others, 2015;Cullen and Conway, 2015).…”