Glacier mass balance: the first 50 years of international monitoring (Braithwaite, 2002)

Flashcards based on lecture notes about glacier mass balance monitoring from 1946-1995.

Glacier mass balance

Changes in glacier mass, especially changes from year to year.

Accumulation

Gaining mass as snow.

Ablation

Losing mass by melting and iceberg calving.

H.W. Ahlmann's glaciological work

Measurements of accumulation and ablation on glaciers in Nordic countries, pioneered in the 1920s and 1930s.

Storglaciären, Northern Sweden

Continuous mass-balance measurements started in 1946.

The International Hydrological Decade (IHD)

1965–74, provided further stimulation to new mass-balance measurements, especially in Canada.

Measuring winter and summer balances

Visiting the glacier twice yearly (spring and autumn) to measure when the mass balance is at a maximum (end of winter accumulation season) and minimum (end of summer melt season), respectively.

Winter balance

Snow accumulation during the winter season.

Summer balance

The net result of melting, offset by greater or smaller snowfalls during the summer.

Ablation area

The area where glacier ice is exposed at the end of the summer.

Accumulation area

The glacier surface layer generally consists of snow of varying density.

Internal accumulation

Meltwater from the snow surface can penetrate a few metres into the snow cover and refreeze when it encounters cold snow.

Mean specific balance

The average of specific balances measured at many sites on the glacier.

The fluctuations of glaciers series

Published by the World Glacier Monitoring Service (WGMS), sponsored by UNESCO.

MNAM

The mean mass-balance amplitude

SDBA

The standard deviation of its net balance

Mass-balance amplitude

Characterized by large mass-balance amplitude (maritime) and high mass- balance variability as expressed by the standard deviation.

The hydrological method

Uses a water-balance approach to compute glacier mass balance.

The geodetic method

Involved photogrammetric mapping of the whole glacier area at two points in time, and calculating the volume change in the intervening period.

Laser profiling

Accurate volume deter- minations can also be made with airborne laser profiling