Hygroscopic growth study in the framework of EARLINET during the SLOPE I campaign: synergy of remote sensing and in situ instrumentation
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AuthorBedoya-Velásquez, Andrés Esteban; Navas-Guzmán, Francisco; Granados-Muñoz, María José; Titos, Gloria; Román, Roberto; Casquero-Vera, Juan Andrés; Ortiz-Amezcua, Pablo; Benavent Oltra, José Antonio; Arruda-Moreira, G.; Montilla-Rosero, Elena; David Hoyos, Carlos; Artiñano, Begoña; Coz, Esther; Olmo Reyes, Francisco José; Alados Arboledas, Lucas; Guerrero-Rascado, Juan Luis
Copernicus Publications on behalf of the European Geosciences Union.
Bedoya-Velásquez, A.E. [et al.]. Hygroscopic growth study in the framework of EARLINET during the SLOPE I campaign: synergy of remote sensing and in situ instrumentation. Atmos. Chem. Phys., 18, 7001–7017, 2018. [https://doi.org/10.5194/acp-18-7001-2018].
SponsorshipThis work was supported by the Andalusia Regional Government through project P12-RNM-2409; by the Spanish Ministry of Economy and Competitiveness through projects CGL2013-45410-R and CGL2016-81092-R, the excelence network CGL2017-90884-REDT, the FPI grant (BES-2014- 068893), and the Juan de la Cierva grants FJCI-2014-22052 and FJCI-2014-20819; by the University of Granada trough the Plan Propio Program P9 Call-2013 contract. Andrés Bedoya has been supported by a grant for PhD studies in Colombia, COLCIENCIAS (Doctorado Nacional – 647), associated with the Physics Sciences program at the Universidad Nacional de Colombia, Sede Medellín and Asociación Universitaria Iberoamericana de Postgrado (AUIP). The study has also been supported by the Swiss National Science Foundation trough project PZ00P2_168114. Financial support for EARLINET was through the ACTRIS Research Infrastructure Project EU H2020 (Grant agreement no. 654109), particularly trough the TNA GRA-3 HYGROLIRA. We thank the AERO group from ESRL-GMD at NOAA for providing the CPD software used for routine measurements at the SNS, and for their technical support. The authors gratefully acknowledge the FEDER program for the instrumentation used in this work.
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 (γ) 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 532 nm 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 γ measured with remote sensing (γ532=0.48±0.01 and γ355=0.40±0.01) with respect to the values calculated using Mie theory (γ532=0.53±0.02 and γ355=0.45±0.02), with relative differences between measurements and simulations lower than 9 % at 532 nm and 11 % at 355 nm.