A 500 year palaeo record of sulphate and mineral dust from an Alpine ice core (Colle Gnifetti, Swiss Alps)

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A 500 year palaeo record of sulphate and mineral
dust from an Alpine ice core (Colle Gnifetti,
Swiss Alps)
M. Schwikowski 1, H.W. Gäggeler 1,2, U.
Schotterer2 1 Paul Scherrer Institute,
Switzerland 2 Department of Chemistry and
Biochemistry, University of Berne, Switzerland
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Motivation

• Reconstruction of local and regional climate and
  atmospheric parameters
• Documentation of the effects of anthropogenic
  emissions

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The ice core

• Drilling site Colle Gnifetti glacier saddle at
  4450 m asl in the Monte Rosa area
• Length 124 m (bedrock)
• Accumulation rate 0.3 m water equiv. y-1
• Cold glacier firn temperatures ltlt 0C

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Location
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Time period accessible by this ice core
Dating error 2 years
Dating error 20 years
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Mineral dust tracer Ca21977 Saharan dust event
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Mineral dust recordExtrem events Saharan dust
2529 samples (5 per year)
1937
1901
1977
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Mineral dust record long term trendIncreased
Ca2 from 1450 to 1620 (LIA?)
5-year averages
Little Ice Age in NH cold, dry, increased
atmospheric circulation
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Sea salt record (Strength of Westerlies) No trend
5-year averages
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nssSulphate recordAnthropogenic emissions,
Saharan dust
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nssSulphate trendincreased concentrations from
1870-1970
5-year averages
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Trend in nssSO42-/Ca2 ratioChange in mineral
dust source or SO2 emissions?
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Source contribution to SO42- (?eq L-1)
Period Total Sea salt Mineral dust exSO42- exSO42-
Natural Anthrop.
Industrial1963-1981 14.7 0.23(2) 1.92(13) 0.98(6) 11.6(79)
Pre-industrial 1750-1870 2.71 0.19(7) 1.54(57) 0.98(36) -
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Oldest ice
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Conclusion

• No change in frequency of major Saharan dust
  transports
• From 1450 to 1620 A.D. increased input of mineral
  dust and lower nssSO42-/Ca2 ratios (probably
  related to LIA)
• No change in strength of Westerlies
• Change in area of mineral dust source (and
  probably in pre-industrial SO2 emissions)