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134

Vol. 66 · No. 3

At Zugspitze, PDDS were calculated for the periods

between geodetic surveys and correlated with glacier

mass balances. Surprisingly, the correlation did not

improve compared to monthly air temperatures.

A better climate-glacier correlation could prob-

ably only be achieved using daily information.

Summer snow falls are crucial for glacier mass bal-

ance. Fresh snow has a very high reectivity (80–

97%), whereas typical albedos of glacier ice range

between 20 and 40% (paterson 1994). Due to the

high air content, snow is an effective isolator and

prevents the conduction of sensible heat towards the

underlying ice. Summer snowfalls therefore immedi-

ately reduce ice melt and, depending on the thickness

of the snow pack, a considerable amount of energy

and time is required to reach pre-snowfall condi-

tions. Therefore, it is essential if precipitation occurs

on warmer or colder days and such weather patterns

can only be described with daily meteorological data.

On Nördlicher Schneeferner, a 6 years series of di-

rect mass balance observations using the glaciologi-

cal method (1962/63–1967/68) exists. We applied a

method after Hoinkes and steinaCker (1975) to re-

duce positive degree day sums after snowfall events,

according to the amount of precipitation that falls

below freezing point. Additionally, the snow height

on 1 May is included as an index for the beginning

of the ablation period. It could be shown that the so

modied PDDS are more closely related to glacier

mass balance than the traditional ones (Fig. 11).

5 Conclusions

The Bavarian glaciers are at a critical stage.

Three glaciers have mean ice thicknesses of few me-

ters only. If current melt rates continue in the future,

these ice patches are likely to disappear within a few

years, while the two larger ones have a somewhat

longer life expectancy. The analysis of meteorologi-

cal data revealed that the glacier degradation can be

attributed to increased summer temperatures. The

long-term mass balances show no correlation with

mean winter precipitation from nearby stations, but

fairly good correlations with snow heights in the

case of the glaciers at Zugspitze. A sound estimate

of accumulation conditions requires labour-inten-

sive eld campaigns over several years using a spa-

tially dense net of observation and ideally ground-

penetrating radar. This is particularly true for small

glaciers below the regional snow line, because here,

redistributed snow often remarkably contributes to

total accumulation.

The glaciers in Bavaria owe their existence to

very special, local conditions and thus show a very

individual response to climate change. The larger the

area of a glacier, the closer its link to regional cli-

mate conditions. Short-term variations of the snow

line and consecutive albedo effects complicate the

climate-glacier relation. Therefore, a proper repro-

duction of glacier mass balances requires modelling

approaches on a daily time-step.

Acknowledgements

The work was funded by the DFG (project HA

5061/1-1) and supported by the Bavarian State Min-

istry of the Environment and Public Health. The

laserscanner was kindly provided by the Chair of

Physical Geography of the KU Eichstätt (M. Becht),

C. Breitung supported the eld work. The Bayer-

Tab. 7: Geodetically derived glacier mass balances on the Berchtesgaden glaciers (cm w.e. per year) and mean anoma-

lies to 1961-1990 of summer (5-9) temperatures and winter (10-4) precipitation at Salzburg airport in the corresponding

periods

Blaueis Watzmanngletscher

Period

Summer

temperature

anomalies

(°C)

Winter

precipitation

anomalies

(%)

Glacier

mass

balance

(cm w.e./a)

Period

Summer

temperature

anomalies

(°C)

Winter

precipitation

anomalies

(%)

Glacier

mass

balance

(cm w.e./a)

1889-1924 -0.5 -9 2 – – – –

1924-1949 -0.1 -7 -68 – – – –

1949-1959 0.0 -3 -38 1897-1959 -0.3 -7 -23

1959-1970 -0.2 -5 -26 1959-1970 -0.2 -5 29

1970-1980 -0.2 -3 34 1970-1980 -0.2 -3 47

1980-1989 0.3 8 -68 1980-1989 0.3 8 -31

1989-1999 1.0 11 -36 1989-1999 1.0 11 -38

1999-2009 1.7 0 -21 1999-2009 1.7 0 -51

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 20 21 22

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