Abstract
Abstract. 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.
Highlights
Atmospheric aerosol particles play a crucial role in the Earth’s climate, principally by means of the radiative effect due to aerosol–radiation and aerosol–cloud interactions, affecting the Earth–atmosphere energy balance and, the Earth’s climate
This comparison allows us to investigate the feasibility of the use of GDAS temperature information to compute the relative humidity (RH) profiles in combination with Raman lidar (RL) profiles, in order to increase the database for hygroscopicity studies
The methodology proposed for calculating RH profiles by combining calibrated r (z) from RL and temperature profiles from microwave radiometer (MWR) has been used in this work to study aerosol hygroscopicity
Summary
Atmospheric aerosol particles play a crucial role in the Earth’s climate, principally by means of the radiative effect due to aerosol–radiation and aerosol–cloud interactions, affecting the Earth–atmosphere energy balance and, the Earth’s climate. Water vapor plays a major role in the aerosol–radiation interaction due to the ability of some atmospheric aerosol particles to take up water from the environment In this sense, hygroscopic growth is the process by which aerosol particles uptake water and increase their size under high relative humidity (RH) conditions (Hänel, 1976). Hygroscopic growth is the process by which aerosol particles uptake water and increase their size under high relative humidity (RH) conditions (Hänel, 1976) This process is related to changes in the optical and microphysical properties of the aerosol particles and, it becomes a crucial factor that modifies the role of aerosols in atmospheric processes and radiative forcing. There are other in situ instruments such as the white-light humidified optical particle spectrometer (WHOPS) (Rosatti et al, 2015) or the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) (Sorooshian et al, 2008) that have been used to determine the impact of enhanced RH on the aerosol properties from airborne platforms
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
