 |
| Titel |
Vertically resolved aerosol properties by multi-wavelength lidar measurements |
| VerfasserIn |
M. R. Perrone, F. De Tomasi, G. P. Gobbi |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 3 ; Nr. 14, no. 3 (2014-02-03), S.1185-1204 |
| Datensatznummer |
250118347
|
| Publikation (Nr.) |
 copernicus.org/acp-14-1185-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| An approach based on the graphical method of Gobbi and co-authors (2007) is
introduced to estimate the dependence on altitude of the aerosol fine mode
radius (Rf) and of the fine mode contribution (η) to the
aerosol optical thickness (AOT) from three-wavelength lidar measurements. The
graphical method of Gobbi and co-authors (2007) was applied to AERONET
(AErosol RObotic NETwork) spectral extinction observations and relies on the
combined analysis of the Ångstrom exponent (å) and its
spectral curvature Δå. Lidar measurements at 355, 532 and
1064 nm were used in this study to retrieve the vertical profiles of
å and Δå and to estimate the dependence on
altitude of Rf and η(532 nm) from the
å–Δå combined analysis. Lidar measurements
were performed at the Department of Mathematics and Physics of the
Universita' del Salento, in south-eastern Italy. Aerosol from continental
Europe, the Atlantic, northern Africa, and the Mediterranean Sea are often
advected over south-eastern Italy and as a consequence, mixed advection
patterns leading to aerosol properties varying with altitude are dominant.
The proposed approach was applied to ten measurement days to demonstrate its
feasibility in different aerosol load conditions. The selected days were
characterized by AOTs spanning the 0.26–0.67, 0.15–0.39, and 0.04–0.27
range at 355, 532, and 1064 nm, respectively. Mean lidar ratios varied
within the 31–83, 32–84, and 11–47 sr range at 355, 532, and 1064 nm,
respectively, for the high variability of the aerosol optical and
microphysical properties. å values calculated from lidar
extinction profiles at 355 and 1064 nm ranged between 0.1 and 2.5 with a
mean value ± 1 standard deviation equal to 1.3 ± 0.7.
Δå varied within the −0.1–1 range with mean value
equal to 0.25 ± 0.43. Rf and η(532 nm) values
spanning the 0.05–0.3 μm and the 0.3–0.99 range,
respectively, were associated with the å–Δå data points. Rf and η values showed no
dependence on the altitude. 60% of the data points were in the Δå–å space delimited by the η and
Rf curves varying within 0.80–0.99 and 0.05–0.15 μm,
respectively, for the dominance of fine-mode particles in driving the AOT
over south-eastern Italy. Vertical profiles of the linear particle
depolarization ratio retrieved from lidar measurements, aerosol products from
AERONET sun photometer measurements collocated in space and time, analytical
back trajectories, satellite true colour images, and dust concentrations from
the BSC–DREAM (Barcelona Super Computing Center-Dust REgional Atmospheric
Model) model were used to demonstrate the robustness of the proposed method. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|