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| Titel |
Aerosol loading in the Southeastern United States: reconciling surface and satellite observations |
| VerfasserIn |
B. Ford, C. L. Heald |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 18 ; Nr. 13, no. 18 (2013-09-16), S.9269-9283 |
| Datensatznummer |
250085699
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| Publikation (Nr.) |
 copernicus.org/acp-13-9269-2013.pdf |
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| Zusammenfassung |
| We investigate the seasonality in aerosols over the Southeastern United
States using observations from several satellite instruments (MODIS, MISR,
CALIOP) and surface network sites (IMPROVE, SEARCH, AERONET). We find that
the strong summertime enhancement in satellite-observed aerosol optical depth
(AOD) (factor 2–3 enhancement over wintertime AOD) is not present in surface
mass concentrations (25–55% summertime enhancement). Goldstein et
al. (2009) previously attributed this seasonality in AOD to biogenic organic
aerosol; however, surface observations show that organic aerosol only
accounts for ∼35% of fine particulate matter (smaller than
2.5 μm in aerodynamic diameter, PM2.5) and exhibits similar
seasonality to total surface PM2.5. The GEOS-Chem model generally
reproduces these surface aerosol measurements, but underrepresents the AOD
seasonality observed by satellites. We show that seasonal differences in
water uptake cannot sufficiently explain the magnitude of AOD increase. As
CALIOP profiles indicate the presence of additional aerosol in the lower
troposphere (below 700 hPa), which cannot be explained by vertical mixing,
we conclude that the discrepancy is due to a missing source of aerosols above
the surface layer in summer. |
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