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| Titel |
Observations of rapid aerosol optical depth enhancements in the vicinity of polluted cumulus clouds |
| VerfasserIn |
T. F. Eck, B. N. Holben, J. S. Reid, A. Arola, R. A. Ferrare, C. A. Hostetler, S. N. Crumeyrolle, T. A. Berkoff, E. J. Welton, S. Lolli, A. Lyapustin, Y. Wang, J. S. Schafer, D. M. Giles, B. E. Anderson, K. L. Thornhill, P. Minnis, K. E. Pickering, C. P. Loughner, A. Smirnov, A. Sinyuk |
| 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. 21 ; Nr. 14, no. 21 (2014-11-06), S.11633-11656 |
| Datensatznummer |
250119140
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| Publikation (Nr.) |
 copernicus.org/acp-14-11633-2014.pdf |
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| Zusammenfassung |
| During the July 2011 Deriving Information on Surface conditions from
Column and Vertically Resolved Observations Relevant to Air Quality
(DISCOVER-AQ) field experiment in Maryland, significant
enhancements in Aerosol Robotic Network (AERONET) sun–sky radiometer
measured aerosol optical depth (AOD) were observed in the immediate vicinity
of non-precipitating cumulus clouds on some days. Both measured Ångström
exponents and aerosol size distribution retrievals made before, during and
after cumulus development often suggest little change in fine mode particle
size; therefore, implying possible new particle formation in addition to
cloud processing and humidification of existing particles. In addition to
sun–sky radiometer measurements of large enhancements of fine mode AOD,
lidar measurements made from both ground-based and aircraft-based
instruments during the experiment also measured large increases in aerosol
signal at altitudes associated with the presence of fair weather cumulus
clouds. These data show modifications of the aerosol vertical profile as a
result of the aerosol enhancements at and below cloud altitudes. The
airborne lidar data were utilized to estimate the spatial extent of these
aerosol enhancements, finding increased AOD, backscatter and extinction out
to 2.5 km distance from the cloud edge. Furthermore, in situ measurements
made from aircraft vertical profiles over an AERONET site during the
experiment also showed large increases in aerosol scattering and aerosol
volume after cloud formation as compared to before. The 15-year AERONET
database of AOD measurements at the Goddard Space Flight Center (GSFC),
Maryland site, was investigated in order to obtain a climatological
perspective of this phenomenon of AOD enhancement. Analysis of the diurnal
cycle of AOD in summer showed significant increases in AOD from morning
to late afternoon, corresponding to the diurnal cycle of cumulus
development. |
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