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Seasonal changes in dust size distributions in the EPICA-DML ice core in different climatic stages and implications for the dust transport

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Citation:
Wegner, A. , Fischer, H. and Ruth, U. (2008): Seasonal changes in dust size distributions in the EPICA-DML ice core in different climatic stages and implications for the dust transport , 3rd International Workshop on Mineral Dust, September 15-17, 2008 in Leipzig, Germany. .
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Abstract:

Mineral dust measured in ice cores from Antarctica provides unique information about climate variability in the past more than 800 000 years. Higher dust load in the atmosphere during glacial times is attributed to higher aridity in the source and higher storminess during colder climate. Changes in dust concentration in ice cores emerge from changes in the source and changes of the transport. Dust size distribution data provide the possibility to separate concentration changes in ice cores in those attributed to the source and those attributed to the transport. The low accumulation in almost all ice cores from the Antarctic plateau complicates the measurements of dust concentration and size in seasonal resolution. The EPICA ice core drilled in Dronning Maud Land, an area of relatively high accumulation (recent accumulation rate: 64 kg/(m²year)), provides the unique possibility to obtain dust concentration and size distribution data in subannual resolution even during the last Glacial, when the accumulation was lower by a factor of two. Here we present data from two depth intervals, one during the Glacial and one during the Antarctic cold reversal (ACR). We found dust maxima during winter with dust concentration higher by a factor of 7.5 in winter than in summer during the last Glacial, and by a factor of 3.5 during the ACR. Dust concentration changes on Glacial-Interglacial time scales are in the order of 50-100. Dust size changes are on annual scale in the same order of magnitude as on glacial-interglacial time scales. With a simple one dimensional transport model we attributed subannual changes in the dust concentration during glacial times to 40-70% to the source and the remaining 30-60% to the transport. During the ACR almost all subannual dust concentration changes in DML can be explained by transport.

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