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| Titel |
Factors that influence surface PM2.5 values inferred from satellite observations: perspective gained for the US Baltimore–Washington metropolitan area during DISCOVER-AQ |
| VerfasserIn |
S. Crumeyrolle, G. Chen, L. Ziemba, A. Beyersdorf, L. Thornhill, E. Winstead, R. H. Moore, M. A. Shook, C. Hudgins, B. E. Anderson |
| 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 ; 14, no. 4 ; Nr. 14, no. 4 (2014-02-26), S.2139-2153 |
| Datensatznummer |
250118426
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| Publikation (Nr.) |
 copernicus.org/acp-14-2139-2014.pdf |
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| Zusammenfassung |
| During the NASA DISCOVER-AQ campaign over the US Baltimore, MD–Washington, D.C.,
metropolitan area in July 2011, the NASA P-3B aircraft performed extensive
profiling of aerosol optical, chemical, and microphysical properties. These
in situ profiles were coincident with ground-based remote sensing (AERONET)
and in situ (PM2.5) measurements. Here, we use this data set to study
the correlation between the PM2.5 observations at the surface and the
column integrated measurements. Aerosol optical depth
(AOD550 nm) calculated with the extinction (550 nm) measured
during the in situ profiles was found to be strongly correlated with the
volume of aerosols present in the boundary layer (BL). Despite the strong
correlation, some variability remains, and we find that the presence of
aerosol layers above the BL (in the buffer layer – BuL) introduces
significant uncertainties in PM2.5 estimates based on column-integrated
measurements (overestimation of PM2.5 by a factor of 5). This suggests
that the use of active remote sensing techniques would dramatically improve
air quality retrievals. Indeed, the relationship between the
AOD550 nm and the PM2.5 is strongly improved by
accounting for the aerosol present in and above the BL (i.e., integrating the
aerosol loading from the surface to the top of the BuL). Since more than
15% of the AOD values observed during DISCOVER-AQ are dominated by aerosol
water uptake, the f(RH)amb (ratio of scattering coefficient at
ambient relative humidity (RH) to scattering coefficient at low RH; see
Sect. 3.2) is used to study the impact of the aerosol hygroscopicity on the
PM2.5 retrievals. The
results indicate that PM2.5 can be predicted within a factor up to 2
even when the vertical variability of the f(RH)amb is assumed
to be negligible. Moreover, f(RH = 80%) and RH measurements performed
at the ground may be used to estimate the f(RH)amb during dry
conditions (RHBL < 55%). |
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