http://www.cnr.it/ontology/cnr/individuo/prodotto/ID276931
Midlatitude cirrus classification at Rome Tor Vergata through a multichannel Raman-Mie-Rayleigh lidar (Articolo in rivista)
- Type
- Label
- Midlatitude cirrus classification at Rome Tor Vergata through a multichannel Raman-Mie-Rayleigh lidar (Articolo in rivista) (literal)
- Anno
- 2013-01-01T00:00:00+01:00 (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
- 10.5194/acp-13-11853-2013 (literal)
- Alternative label
D. Dionisi1,2, P. Keckhut1, G. L. Liberti2, F. Cardillo2, and F. Congeduti2 (2013)
Midlatitude cirrus classification at Rome Tor Vergata through a multichannel Raman-Mie-Rayleigh lidar
in Atmospheric chemistry and physics (Online)
(literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- D. Dionisi1,2, P. Keckhut1, G. L. Liberti2, F. Cardillo2, and F. Congeduti2 (literal)
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- 1 Laboratoire Atmosphères, Milieux, Observations Spatiales-IPSL, UMR8190, CNRS/INSU, UVSQ-UPMC, UniverSud Paris, Guyancourt, France
2 Istituto di Scienze dell'Atmosfera e del Clima, Consiglio Nazionale delle Ricerche, Rome, Italy (literal)
- Titolo
- Midlatitude cirrus classification at Rome Tor Vergata through a multichannel Raman-Mie-Rayleigh lidar (literal)
- Abstract
- A methodology to identify and characterize cirrus
clouds has been developed and applied to the multichannelmultiwavelength
Rayleigh-Mie-Raman (RMR) lidar in
Rome Tor Vergata (RTV). A set of 167 cirrus cases, defined
on the basis of quasi-stationary temporal period conditions,
has been selected in a data set consisting of about 500 h of
nighttime lidar sessions acquired between February 2007 and
April 2010. The derived lidar parameters (effective height,
geometrical and optical thickness and mean back-scattering
ratio) and the cirrus mid-height temperature (estimated from
the radiosonde data of Pratica di Mare, WMO, World Meteorological
Organization, site no. 16245) of this sample have
been analyzed by the means of a clustering multivariate analysis.
This approach identified four cirrus classes above the
RTV site: two thin cirrus clusters in mid- and upper troposphere
and two thick cirrus clusters in mid-upper troposphere.
These results, which are very similar to those derived
through the same approach at the lidar site of the Observatoire
de Haute-Provence (OHP), allows characterization of
cirrus clouds over the RTV site and attests to the robustness
of such classification.
To acquire some indications about the cirrus generation
methods for the different classes, analyses of the extinctionto-
backscatter ratio (lidar ratio, LReff), in terms of frequency
distribution functions and dependencies on the mid-height
cirrus temperature, have been performed. A preliminary
study relating some meteorological parameters (e.g., relative
humidity, wind components) to cirrus clusters has also been
conducted.
The RTV cirrus results, recomputed through the cirrus
classification by Sassen and Cho (1992), show good agreement
with other midlatitude lidar cirrus observations for the
relative occurrence of subvisible (SVC), thin and opaque cirrus
classes (10 %, 49% and 41 %, respectively). The overall
mean value of cirrus optical depth is 0.37±0.18, while most
retrieved LReff values range between 10-60 sr, and the estimated
mean value is 31±15 sr, similar to LR values of lower
latitude cirrus measurements.
The obtained results are consistent with previous studies
conducted with different systems and confirm that cirrus
classification based on a statistical approach seems to be a
good tool both to validate the height-resolved cirrus fields
calculated by models and to investigate the key processes
governing cirrus formation and evolution. However, the lidar
ratio and optical depth analyses are affected by some uncertainties
(e.g., lidar error noise, multiple scattering effects,
supercooled water clouds) that reduce the confidence of the
results. Future studies are needed to improve the characterization
of the cirrus optical properties and, thus, the determination
of their radiative impact. (literal)
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