Optica Aplicada

URI permanente para esta comunidad

https://hdl.handle.net/10784/1122

Genera y transfiere conocimiento y apropia métodos y tecnologías en las áreas de procesamiento óptico de información y metrología óptica, relevantes para el avance científico, académico y productivo.

Líneas de investigación: Holografía; Metrología Óptica.
Código Minciencias: COL0011527.
Categoría 2019: A.
Escuela: Ciencias.
Departamento académico: Ciencias Físicas.
Coordinador: Elena Montilla; Carlos Andrés Trujillo.
Correo electrónico: emontill@eafit.edu.co; catrujilla@eafit.edu.co

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Mostrando 1 - 5 de 5

Detection of saharan mineral dust aerosol transport over brazilian northeast through a depolarization lidar
(EDP Sciences, 2018-01-01) Guedes A.G.; Landulfo E.; Montilla-Rosero E.; Lopes F.J.S.; Hoelzemann J.J.; Fernandez J.H.; Silva M.P.A.; Santos R.S.S.; Guerrero-Rascado J.L.; Alados-Arboledas L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
In this study we present results of linear volume depolarization ratio profiles obtained by a depolarization lidar in operation in Natal, Brazil. The DUSTER system has 4 channels, namely: 1064, 532 s/p and 355 nm. This system is calibrated with a half-wave plate using the 90° methodology. The data obtained from this system is correlated with AERONET sunphotometer data, and, when available, CALIPSO satellite data. In addition a trajectory model (HYSPLIT) is used to calculate backward trajectories to assess the origin of the dust polluted air parcels. The objective is to create a transport database of Saharan dust. © The Authors, published by EDP Sciences, 2018.
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.
Lalinet status - Station expansion and lidar ratio systematic measurements
(EDP Sciences, 2018-01-01) Landulfo E.; Lopes F.; Moreira G.A.; Da Silva J.; Ristori P.; Quel E.; Otero L.; Pallota J.V.; Herrera M.; Salvador J.; Bali J.L.; Wolfram E.; Etala P.; Barbero A.; Forno R.; Sanchez M.F.; Barbosa H.; Gouveia D.; Santos A.V.; Hoelzemann J.; Fernandez J.H.; Guedes A.; Silva A.; Barja B.; Zamorano F.; Legue R.P.; Bastidas A.; Zabala M.V.; Velez J.; Nisperuza D.; Montilla E.; Arredondo R.E.; Marrero J.C.A.; Vega A.R.; Alados-Arboledas L.; Guerrero-Rascado J.L.; Sugimoto N.; Yoshitaka J.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
LALINET is expanding regionally to guarantee spatial coverage over South and Central Americas. One of the network goals is to obtain a set of regional representative aerosol optical properties such as particle backscatter, extinction and lidar ratio. Given the North-South extension and influence of distinct airmass circulation patterns it is paramount to distinguish these optical parameters in order to gain better perfomance in radiation transfer models. A set of lidar ratio data is presented. © The Authors, published by EDP Sciences, 2018.
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.
Seasonal analysis of the atmosphere during five years by using microwave radiometry over a mid-latitude site
(Elsevier Ltd, 2019-01-01) Bedoya-Velásquez A.E.; Navas-Guzmán F.; de Arruda Moreira G.; Román R.; Cazorla A.; Ortiz-Amezcua P.; Benavent-Oltra J.A.; Alados-Arboledas L.; Olmo-Reyes F.J.; Foyo-Moreno I.; Montilla-Rosero E.; Hoyos C.D.; Guerrero-Rascado J.L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
This work focuses on the analysis of the seasonal cycle of temperature and relative humidity (RH) profiles and integrated water vapor (IWV) obtained from microwave radiometer (MWR) measurements over the mid-latitude city of Granada, southern Spain. For completeness the study, the maximum atmospheric boundary layer height (ABLHmax) is also included. To this end, we have firstly characterized the HATPRO-RPG MWR errors using 55 co-located radiosondes (RS) by means of the mean-bias (bias¯) profile and the standard deviation (SDbias) profile classified under all-weather conditions and cloud-free conditions. This characterization pointed out that temperature from HATPRO-MWR presents a very low bias¯ respects RS mostly below 2.0 km agl, ranging from positive to negative values under all-weather conditions (from 1.7 to -0.4 K with SDbias up to 3.0 K). Under cloud-free conditions, the bias was very similar to that found under all-weather conditions (1.8 to -0.4 K) but with smaller SDbias (up to 1.1 K). The same behavior is also seen in this lower part (ground to 2.0 km agl) for RH. Under all-weather conditions, the mean RH bias ranged from 3.0 to -4.0% with SDbias between 10 and 16.3% while under cloud-free conditions the bias ranged from 2.0 to -0.4% with SDbias from 0.5 to 13.3%. Above 2.0 km agl, the SDbias error increases considerably up to 4 km agl (up to -20%), and then decreases slightly above 7.0 km agl (up to -5%). In addition, IWV values from MWR were also compared with the values obtained from the integration of RS profiles, showing a better linear fit under cloud-free conditions (R2 = 0.96) than under all-weather conditions (R2 = 0.82). The mean bias under cloud-free conditions was -0.80 kg/m2 while for all-weather conditions it was -1.25 kg/m2. Thus, the SDbiasfor all the statistics (temperature, RH and IWV) of the comparison between MWR and RS presented higher values for all-weather conditions than for cloud-free conditions ones. It points out that the presence of clouds is a key factor to take into account when MWR products are used. The second part of this work is devoted to a seasonal variability analysis over five years, leading us to characterize thermodynamically the troposphere over our site. This city atmosphere presents a clear seasonal cycle where temperature, ABLHmax and IWV increase from winter to summer and decrease in autumn, meanwhile RH decreases along the warmer seasons. This city presents cold winters (mean daily maximum temperature: 10.6 ± 1.1 °C) and dry/hot summers (mean daily maximum temperature of 28.8 ± 0.9 °C and mean daily maximum of surface RH up to 55.0 ± 6.0%) at surface (680 m asl). Moreover, considering temporal trends, our study pointed out that only temperature and RH showed a linear increase in winters with a mean-rate of (0.5 ± 0.1) °C/year and (3.4 ± 1.7) %/year, respectively, from ground to 2.0 km agl, meanwhile IWV presented a linear increase of 1.0 kg·m-2/year in winters, 0.78 kg·m-2/year in summers and a linear decrease in autumns of -0.75 kg·m-2/year. © 2018 Elsevier B.V.

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Examinando Optica Aplicada por Autor "Alados-Arboledas L."

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