 |
| Titel |
Comparison of surface and column measurements of aerosol scattering properties over the western North Atlantic Ocean at Bermuda |
| VerfasserIn |
R. P. Aryal, K. J. Voss, P. A. Terman, W. C. Keene, J. L. Moody, E. J. Welton, B. N. Holben |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 14 ; Nr. 14, no. 14 (2014-07-30), S.7617-7629 |
| Datensatznummer |
250118911
|
| Publikation (Nr.) |
 copernicus.org/acp-14-7617-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Light scattering by size-resolved aerosols in near-surface air at Tudor
Hill, Bermuda, was measured between January and June 2009. Vertical
distributions of aerosol backscattering and column-averaged aerosol optical
properties were characterized in parallel with a micro-pulse lidar (MPL) and
an automated sun–sky radiometer. Comparisons were made between extensive
aerosol parameters in the column, such as the lidar-retrieved extinction at
400 m and the aerosol optical depth (AOD), and scattering was measured with a
surface nephelometer. Comparisons were also made for intensive parameters
such as the Ångström exponent and calculations using
AERONET(Aerosol Robotic Network)-derived
aerosol physical parameters (size distribution, index of refraction) and Mie
theory, and the ratio of submicron scattering to total scattering for size-segregated
nephelometer measurements. In these comparisons the r2 was
generally around 0.50. Data were also evaluated based on back trajectories.
The correlation between surface scattering and lidar extinction was highest
for flows when the surface scattering was dominated by smaller particles and
the flow had a longer footprint over land then over the ocean. The
correlation of AOD with surface scatter was similar for all flow regimes.
There was also no clear dependence of the atmospheric lapse rate, as
determined from a nearby radiosonde station, on flow regime. The
Ångström exponent for most flow regimes was 0.9–1.0, but for the
case of air originating from North America, but with significant time over
the ocean, the Ångström exponent was 0.57 ± 0.18. The submicron
fraction of aerosol near the surface (Rsub-surf) was significantly
greater for the flows from land (0.66 ± 0.11) than for the flows which
spent more time over the ocean (0.40 ± 0.05). When comparing
Rsub-surf and the column-integrated submicron scattering fraction,
Rsub-col, the correlation was similar, r2 = 0.50, but
Rsub-surf was generally less than Rsub-col, indicating more large
particles contributing to light scattering at the surface, contrary to
conditions over continents and for polluted continental transport over the
ocean. In general, though, the marginal correlations indicate that the column
optical properties are weakly correlated with the surface optical
measurements. Thus, if it is desired to associate aerosol chemical/physical
properties with their optical properties, it is best to use optical and
chemical/physical measurements with both collected at the surface or both
collected in the column. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|