The influence of regional circulation patterns on wet and dry mineral dust and sea salt deposition over Greenland

Climate Dynamics, Vol. 28, No. 6 doi:10.1007/s00382-006-0211-z, 2007

M.A. Hutterli, C.C. Raible and T.F. Stocker

Physics Institute, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland.
T. Crueger
Max-Planck-Institute for Meteorology, Hamburg, Bundesstrasse 53, 20146 Hamburg, Germany.
H. Fischer
Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Columbusstrasse, 27568 Bremerhaven, Germany.
K.K. Andersen and M.L. Siggaard-Andersen
Ice and Climate, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
J.R. McConnell
Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, USA.
R.C. Bales and J.F. Burkhart
University of California, Merced, 4225 N. Hospital Road, Atwater, CA 95301, USA.

Annually resolved ice core records from different regions over the Greenland ice sheet (GrIS) are used to investigate the spatial and temporal variability of calcium (Ca2+, mainly from mineral dust) and sodium (Na+, mainly from sea salt) deposition. Cores of high common inter-annual variability are grouped with an EOF analysis, resulting in regionally representative Ca2+ and Na+ records for northeastern and central Greenland. Utilizing a regression and validation method with ERA-40 reanalysis data, these common records are associated with distinct regional atmospheric circulation patterns over the North American Arctic, Greenland, and Central to Northern Europe. These patterns are interpreted in terms of transport and deposition of the impurities. In the northeastern part of the GrIS sea salt records reflect the intrusion of marine air masses from southeasterly flow. A large fraction of the Ca2+ variability in this region is connected to a circulation pattern suggesting transport from the west and dry deposition. This pattern is consistent with the current understanding of a predominantly Asian source of the dust deposited over the GrIS. However, our results also indicate that a significant fraction of the inter-annual dust variability in NE and Central Greenland is determined by the frequency and intensity of wet deposition during the season of high atmospheric dust loading, rather than representing the variability of the Asian dust source and/or long-range transport to Greenland. The variances in the regional proxy records explained by the streamfunction patterns are high enough to permit reconstructions of the corresponding regional deposition regimes and the associated circulation patterns.