A new method to retrieve the real part of the equivalent refractive index of atmospheric aerosols

S. Vratolis, P. Fetfatzis, A. Argyrouli, A. Papayannis, D. Müller, I. Veselovskii, A. Bougiatioti, A. Nenes, E. Remoundaki, E. Diapouli, M. Manousakas, M. Mylonaki, K. Eleftheriadis

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)
22 Downloads (Pure)

Abstract

In the context of the international experimental campaign Hygroscopic Aerosols to Cloud Droplets (HygrA-CD, 15 May to 22 June 2014), dry aerosol size distributions were measured at Demokritos station (DEM) using a Scanning Mobility Particle Sizer (SMPS) in the size range from 10 to 550 nm (electrical mobility diameter), and an Optical Particle Counter (OPC model Grimm 107 operating at the laser wavelength of 660 nm) to acquire the particle size distribution in the size range of 250 nm to 2.5 μm optical diameter. This work describes a method that was developed to align size distributions in the overlapping range of the SMPS and the OPC, thus allowing us to retrieve the real part of the aerosol equivalent refractive index (ERI). The objective is to show that size distribution data acquired at in situ measurement stations can provide an insight to the physical and chemical properties of aerosol particles, leading to better understanding of aerosol impact on human health and earth radiative balance. The resulting ERI could be used in radiative transfer models to assess aerosol forcing direct effect, as well as an index of aerosol chemical composition. To validate the method, a series of calibration experiments were performed using compounds with known refractive index (RI). This led to a corrected version of the ERI values, (ERICOR). The ERICOR values were subsequently compared to model estimates of RI values, based on measured PM2.5 chemical composition, and to aerosol RI retrieved values by inverted lidar measurements on selected days.

Original languageEnglish
Pages (from-to)54-62
Number of pages9
JournalJournal of Aerosol Science
Volume117
Early online date29 Dec 2017
DOIs
Publication statusPublished - 1 Mar 2018

Keywords

  • Aerosol refractive index
  • Lidar
  • Optical particle counter
  • Scanning mobility particle sizer

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