The recognition of glaciers as important indicators of climate
and the lack of direct measurements in New Zealand highlights
the need for a glacier mass balance program in the Southern
Alps. This thesis addresses this gap by measuring mass balance
directly at the Brewster Glacier. Through direct measurements
using snow pits and ablation stakes, volume and surface change
across the entire glacier were calculated and the mass balance
gradient and equilibrium line altitude (ELA) was determined.
A climate station recorded local climate variables and a Sonic
Ranger 50 (SR50) was installed to measure ablation hourly.
Historic fluctuations were investigated using photographs
of the EOSS taken since 1978 and the EOSS values were compared
to the calculated ELA.
During this study a positive mass balance was measured at
the Brewster Glacier in 2004/5. The calculated volume gain
measured from 1630 km³ to 1780 km³ with a surface
rise of 0.64-0.70 m w.e. averaged over the entire glacier.
Accumulation was measured as 6540 km³ volume gain
or 2.57 m w.e. surface gain and ablation was measured as -4910
km³ volume loss or -1.98 m w.e. surface loss. A linear
mass balance gradient from the lowest to the highest stake
was calculated as 10 mm w.e./m, though it was better represented
by two slopes with a shift in slope at the approx height of
the ELA. The ELA calculated from the mass balance gradient
was 1784 m, which was very similar to the value derived from
the EOSS which was 1780 m. A complex relationship was found
between climate variables and ablation and the combination
of climate variables explained the most melt at 36%.
Through direct measurements, this study established a mass
balance monitoring program at Brewster Glacier and initiated
a long-term study. With this data, New Zealand will be able
to make contributions to the World Glacier Monitoring Service,
proving a better understanding of global fluctuations in mass
George, L. (2005): Mass balance and climate interactions
at Brewster Glacier 2004-5. Unpublished MSc thesis, in Geography,
University of Otago, Dunedin, New Zealand.