Pergamon

J. Aemsol Sci. Vol. 29. Suppl. 1. pp. S5133514, 1998 8 1598 Published by Elsevier Science Ltd. All rights reserved

Printed in Great Britain 0021-8502/98 $19.00 + O.CXJ

SOURCE REGIONS FOR ATMOSPHERIC AEROSOL MEASURED IN THE WESTERN ARCTIC

A.V. POLISSAR’.‘, P.K. HOPKE’, J.M. HARRIS’, B.A. BODHAINE’, and E.G. DUTTON’

’ Department of Chemistry, Clarkson University, Potsdam, NY 13699-58 10, U.S.A. * CMDL, NOAA, 325 Broadway, Boulder, CO 80303, U.S.A. l On leave from the Institute of Atmospheric Physics, 109017 Moscow, Russia

KEYWORDS

Arctic aerosol; Receptor modeling; Long-range transport

Aerosol data including condensation nuclei (CN), black carbon (BC), and aerosol light scattering (SC) measurements at Barrow, Alaska for the period from 1977 to 1994 have been analyzed. The description of the monitoring site at Barrow and instrumentation has been presented by Bodhaine (1989). A receptor modeling method called the potential source contribution function (PSCF) (Hopke et al., 1995) that combines the aerosol data with meteorological information in the form of ten-day air parcel backward trajectories was applied to identify possible source areas and the preferred pathways that gives rise to the observed high aerosol concentrations. Ten-day back trajectories arriving twice daily at 500 m above sea level were calculated for the five-year period from 1989 to 1993 by using the isentropic transport model (Harris and Kahl, 1994).

Black carbon and scattering coefficient time series show an annual cycle with the Arctic haze maxima in the winter and spring and minima in the summer. The scattering coefficient time series usually had broad peaks or a combination of the two major peaks, the winter maximum connected with the long-range aerosol transport, and the spring peak associated with the long- range transport plus photochemically-enhanced sulfate production from SO,. The condensation nucleus plot shows maxima in March and in August. After examination of the aerosol seasonal variations the data were segregated into time periods representing the spring, summer, and winter seasons. Then the PSCF analyses for these periods were performed based on criterion values on the averages of the measured parameters. The results for CN and BC are shown in the Figure 1. In winter the high PSCF values for BC are related to anthropogenic source areas in Eurasia (Fig. 1 B) while in spring in addition to these Eurasian sources there are also high PSCF regions in North America (Fig. 1D). The trajectory domain in winter and spring is larger than in summer reflecting weaker transport from midlatitudes to the Arctic during the summertime. In summer no high PSCF areas for BC can be observed (Fig. 1F). The result is related to the poor transport into the Arctic plus the strong removal of BC aerosol by precipitation in summer. In contrast to the BC map the CN plot for summer (Fig. 1E) shows high PSCF areas in the North Pacific Ocean. The winter spring map for CN show that CN could be mostly connected with the long-range transport from Eurasia (Fig, 1 A) while in spring and summer CN could be related to the reduced sulfur compound emission from biogenic activities in the ocean (Fig. 1 C and 1 E).

It is concluded that the PSCF method is effective in identifying possible aerosol source locations. The winter CN peak, as well as the winter and spring peaks in BC concentrations measured in Barrow are related to the long-range aerosol transport from Eurasia and North America. The summer CN peak is connected with emissions from the North Pacific Ocean.

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Abstracts of the 5th International Aerosol Conference 1998

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Figure 1. PSCF plot for condensation nuclei (A, C, and E) and black carbon (B, D, and F) during the months of October to February (A and B), of March to May (C and D), and of June to August (E and F)

Acknowledgements. The work at Clarkson University was supported by the NSF under

Grants OPP 9423252 and ATM 952373 1. We thank the Barrow Observatory staff and

NOAAICMDL base funding.

REFERENCES

Bodhaine, B.A., (1989) Barrow surface aerosol: 1976-l 986, Atmos. Environ., 23,2357-2369.

Harris, J.M. and J.D.W. Kahl, (1994) Analysis of lo-day isentropic flow patterns for Barrow, Alaska: 19851992,J. Geophys. Res., 99,25845-25855.

Hopke, P.K., L.A. Barrie, S.-M. Li, M.-D. Cheng, C. Li, and Y. Xie, (1995) Possible sources

and preferred pathways for biogenic and non-sea-salt sulfur for the high Arctic, J.

Geophys. Res., 100, 16595- 16603.