Examinando por Autor "Titos G."

Mostrando 1 - 2 de 2
  • No hay miniatura disponible
    Ítem
    Hygroscopic growth study in the framework of EARLINET during the SLOPE i campaign: Synergy of remote sensing and in situ instrumentation
    (Copernicus GmbH, 2018-05-18) Bedoya-Velásquez A.E.; Navas-Guzmán F.; Granados-Muñoz M.J.; Titos G.; Román R.; Andrés Casquero-Vera J.; Ortiz-Amezcua P.; Antonio Benavent-Oltra J.; De Arruda Moreira G.; Montilla-Rosero E.; Hoyos C.D.; Artiñano B.; Coz E.; Olmo-Reyes F.J.; Alados-Arboledas L.; Guerrero-Rascado J.L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    This study focuses on the analysis of aerosol hygroscopic growth during the Sierra Nevada Lidar AerOsol Profiling Experiment (SLOPE I) campaign by using the synergy of active and passive remote sensors at the ACTRIS Granada station and in situ instrumentation at a mountain station (Sierra Nevada, SNS). To this end, a methodology based on simultaneous measurements of aerosol profiles from an EARLINET multi-wavelength Raman lidar (RL) and relative humidity (RH) profiles obtained from a multi-instrumental approach is used. This approach is based on the combination of calibrated water vapor mixing ratio (r) profiles from RL and continuous temperature profiles from a microwave radiometer (MWR) for obtaining RH profiles with a reasonable vertical and temporal resolution. This methodology is validated against the traditional one that uses RH from co-located radiosounding (RS) measurements, obtaining differences in the hygroscopic growth parameter (?) lower than 5% between the methodology based on RS and the one presented here. Additionally, during the SLOPE I campaign the remote sensing methodology used for aerosol hygroscopic growth studies has been checked against Mie calculations of aerosol hygroscopic growth using in situ measurements of particle number size distribution and submicron chemical composition measured at SNS. The hygroscopic case observed during SLOPE I showed an increase in the particle backscatter coefficient at 355 and 532nm with relative humidity (RH ranged between 78 and 98%), but also a decrease in the backscatter-related Ångström exponent (AE) and particle linear depolarization ratio (PLDR), indicating that the particles became larger and more spherical due to hygroscopic processes. Vertical and horizontal wind analysis is performed by means of a co-located Doppler lidar system, in order to evaluate the horizontal and vertical dynamics of the air masses. Finally, the Hänel parameterization is applied to experimental data for both stations, and we found good agreement on ? measured with remote sensing (?532 0.48 ± 0.01 and ?355 0.40 ± 0.01) with respect to the values calculated using Mie theory (?532 0.53 ± 0.02 and ?355 0.45 ± 0.02), with relative differences between measurements and simulations lower than 9% at 532nm and 11% at 355nm. © Author(s) 2018.
  • No hay miniatura disponible
    Ítem
    Long-term aerosol optical hygroscopicity study at the ACTRIS SIRTA observatory: Synergy between ceilometer and in situ measurements
    (Copernicus GmbH, 2019-01-01) Bedoya-Velásquez A.E.; Titos G.; Antonio Bravo-Aranda J.; Haeffelin M.; Favez O.; Petit J.-E.; Andrés Casquero-Vera J.; José Olmo-Reyes F.; Montilla-Rosero E.; Hoyos C.D.; Alados-Arboledas L.; Luis Guerrero-Rascado J.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    An experimental setup to study aerosol hygroscopicity is proposed based on the temporal evolution of attenuated backscatter coefficients from a ceilometer colocated with an instrumented tower equipped with meteorological sensors at different heights. This setup is used to analyze a 4.5-year database at the ACTRIS SIRTA observatory in Palaiseau (Paris, France, 2.208E, 48.713N; 160 m above sea level). A strict criterion-based procedure has been established to identify hygroscopic growth cases using ancillary information, such as online chemical composition, resulting in 8 hygroscopic growth cases from a total of 107 potential cases. For these eight cases, hygroscopic growth-related properties, such as the attenuated backscatter enhancement factor (RH) and the hygroscopic growth coefficient I3, are evaluated. This study shows that the hygroscopicity parameter 3 is negatively correlated with the aerosol organic mass fraction but shows a positive correlation with the aerosol inorganic mass fraction. Among inorganic species, nitrate exhibited the highest correlation. This is the first time that hygroscopic enhancement factors are directly retrieved under ambient aerosols using remote-sensing techniques, which are combined with online chemical composition in situ measurements to evaluate the role of the different aerosol species in aerosol hygroscopicity.. © Author(s) 2019.