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Gabriela Lakkis S.,Pontificia University Catol ica Argentina | Gabriela Lakkis S.,University of Buenos Aires | Lavorato M.,DEILAP CITEDEF | Lavorato M.,Tama University | And 6 more authors.
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2015

Characterization of cirrus clouds over Buenos Aires (34.6°S, 58.5°W) using a ground based lidar is presented. The study, carried out for the period 2010-2011, reveals that cirrus are usually found in the altitude region 8-11. km, with mid-cloud temperatures values varying between -75. °C and 55. °C. The clouds, whose bases altitudes display significant variability while their tops remains close to the tropopause, show geometrical thickness ranging from 1.2 to 5. km, with on average value 3.0±0.9. km. Most commonly observed cirri can be characterized as optically thin cirrus rather than dense ones, with a mean optical depth value of 0.26±0.11 and an applied multiple scattering factor η of 0.85±0.07. In this region, the optical depth increases with increasing geometrical thickness with a partially linear correlation. Lidar ratios are also analyzed and on average the value is 32±17. sr. © 2015 Elsevier Ltd. Source


Gomez N.D.,DEILAP CITEDEF | D'Accurso V.,DEILAP CITEDEF | Manzano F.A.,DEILAP CITEDEF | Codnia J.,DEILAP CITEDEF | And 2 more authors.
International Journal of Chemical Kinetics | Year: 2014

The rate constant of the reaction between CCl2 radicals and HCl was experimentally determined. The CCl2 radicals were obtained by infrared multiphoton dissociation of CDCl3. The time dependence of the CCl2 radicals' concentration in the presence of HCl was determined by laser-induced fluorescence. The experimental conditions allowed us to associate the decrease in the concentration of radicals to the self-recombination reaction to form C2Cl4 and to the reaction with HCl to form CHCl3. The rate constant for the self-recombination reaction was determined to be in the high-pressure regime. The value obtained at 300 K was (5.7 ± 0.1) × 10-13 cm3 molecule-1 s-1, whereas the value of the rate constant measured for the reaction with HCl was (2.7 ± 0.1) × 10-14 cm3 molecule-1 s-1. © 2014 Wiley Periodicals, Inc. Source


Gomez N.D.,DEILAP CITEDEF | D'Accurso V.,DEILAP CITEDEF | Freytes V.M.,CONICET | Manzano F.A.,DEILAP CITEDEF | And 2 more authors.
International Journal of Chemical Kinetics | Year: 2013

An experimental setup that coupled IR multiple-photon dissociation (IRMPD) and laser-induced fluorescence (LIF) techniques was implemented to study the kinetics of the recombination reaction of dichlorocarbene radicals, CCl 2, in an Ar bath. The CCl2 radicals were generated by IRMPD of CDCl3. The time dependence of the CCl2 radicals' concentration in the presence of Ar was determined by LIF. The experimental conditions achieved allowed us to associate the decrease in the concentration of radicals to the self-recombination reaction to form C2Cl 4. The rate constant for this reaction was determined in both the falloff and the high-pressure regimes at room temperature. The values obtained were k0 = (2.23 ± 0.89) × 10-29 cm 6 molecules-2 s-1 and k∞ = (6.73 ± 0.23) × 10-13 cm3 molecules -1 s-1, respectively. © 2013 Wiley Periodicals, Inc. Source

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