skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Scanning Mobility Particle Sizer-Portable Optical Particle Spectrometer Intercomparison Field Campaign Report

Abstract

A portable optical particle spectrometer (POPS) has recently been acquired by the United Kingdom Meteorological (UK Met) Office with the intention of mounting it on an unmanned aerial vehicle (UAV) for atmospheric aerosol research. Before conducting research with the new instrument, an intercomparison has been conducted to test the performance of the POPS against a scanning mobility particle sizer (SMPS) — a veteran and well-characterized particle sizer. As part of the Cloud-Aerosol-Radiation Interactions and Forcing (CLARIFY) campaign, the POPS was installed at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility mobile site on Ascension Island in the South Atlantic Ocean, alongside an ARM-operated SMPS. Both instruments sampled continuously from 20 August to 9 September, 2017. The SMPS and the POPS were connected to a common aerosol inlet; however, in the case of the SMPS, the sample air was dried before it entered the instrument. The POPS is a miniaturized optical particle counter designed specifically for use in balloon and UAV applications. The instrument is fully described in Goa et al. (2016) and so is only briefly described here. The POPS samples particles by drawing air through an inlet tube into an optical chamber, where itmore » is illuminated by a 405nm laser. A sheath air flow is used to focus the sample air into the center of the laser beam, and the sample flow is maintained at a near-constant rate by an onboard pump. Side-scattered laser light is reflected into a photomultiplier tube by a hemispherical mirror, and the signal amplitude recorded by a data logger. Individual particle sizes are then inferred by comparing the recorded signal amplitudes to scattering amplitudes calculated using Mie theory. In common with other optical particle counters, the POPS size distributions are influenced by the refractive index used in the Mie calculations. The POPS is calibrated by the manufacturers (Handix Scientific) using latex spheres, with a refractive index (RI) of 1.615+0.001i. Sampling aerosols with a different refractive index, particularly if they are strongly absorbing, will result in significant uncertainties/errors in the particle size distributions (PSDs). We have therefore used scattering amplitude curves (calculated by Handix) for more absorbing aerosols, with an RI of 1.54+0.027i, which is expected to be more representative of the biomass-burning aerosol particles sampled at the ARM site during the CLARIFY campaign. In contrast to the POPS, the SMPS measures particle size using the differential mobility technique after applying an electrical charge to aerosol particles. The method is independent of the refractive index (Ruzer 2013).« less

Authors:
 [1];  [1];  [1];  [2]
  1. UK Met Office
  2. University of Exeter
Publication Date:
Research Org.:
DOE Office of Science Atmospheric Radiation Measurement (ARM) Program (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Contributing Org.:
UK Met Office, University of Exeter
OSTI Identifier:
1427742
Report Number(s):
DOE/SC-ARM-18-013
DOE Contract Number:  
DE-ACO5-7601830
Resource Type:
Program Document
Country of Publication:
United States
Language:
English
Subject:
CLARIFY, portable optical particle spectrometer, scanning mobility particle sizer, Ascension Island, LASIC, unmanned aerial vehicles, biomass burning aerosols

Citation Formats

Osborne, Martin, Fox, Cathryn, Langridge, Justin, and Haywood, Jim. Scanning Mobility Particle Sizer-Portable Optical Particle Spectrometer Intercomparison Field Campaign Report. United States: N. p., 2018. Web.
Osborne, Martin, Fox, Cathryn, Langridge, Justin, & Haywood, Jim. Scanning Mobility Particle Sizer-Portable Optical Particle Spectrometer Intercomparison Field Campaign Report. United States.
Osborne, Martin, Fox, Cathryn, Langridge, Justin, and Haywood, Jim. Thu . "Scanning Mobility Particle Sizer-Portable Optical Particle Spectrometer Intercomparison Field Campaign Report". United States. https://www.osti.gov/servlets/purl/1427742.
@article{osti_1427742,
title = {Scanning Mobility Particle Sizer-Portable Optical Particle Spectrometer Intercomparison Field Campaign Report},
author = {Osborne, Martin and Fox, Cathryn and Langridge, Justin and Haywood, Jim},
abstractNote = {A portable optical particle spectrometer (POPS) has recently been acquired by the United Kingdom Meteorological (UK Met) Office with the intention of mounting it on an unmanned aerial vehicle (UAV) for atmospheric aerosol research. Before conducting research with the new instrument, an intercomparison has been conducted to test the performance of the POPS against a scanning mobility particle sizer (SMPS) — a veteran and well-characterized particle sizer. As part of the Cloud-Aerosol-Radiation Interactions and Forcing (CLARIFY) campaign, the POPS was installed at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility mobile site on Ascension Island in the South Atlantic Ocean, alongside an ARM-operated SMPS. Both instruments sampled continuously from 20 August to 9 September, 2017. The SMPS and the POPS were connected to a common aerosol inlet; however, in the case of the SMPS, the sample air was dried before it entered the instrument. The POPS is a miniaturized optical particle counter designed specifically for use in balloon and UAV applications. The instrument is fully described in Goa et al. (2016) and so is only briefly described here. The POPS samples particles by drawing air through an inlet tube into an optical chamber, where it is illuminated by a 405nm laser. A sheath air flow is used to focus the sample air into the center of the laser beam, and the sample flow is maintained at a near-constant rate by an onboard pump. Side-scattered laser light is reflected into a photomultiplier tube by a hemispherical mirror, and the signal amplitude recorded by a data logger. Individual particle sizes are then inferred by comparing the recorded signal amplitudes to scattering amplitudes calculated using Mie theory. In common with other optical particle counters, the POPS size distributions are influenced by the refractive index used in the Mie calculations. The POPS is calibrated by the manufacturers (Handix Scientific) using latex spheres, with a refractive index (RI) of 1.615+0.001i. Sampling aerosols with a different refractive index, particularly if they are strongly absorbing, will result in significant uncertainties/errors in the particle size distributions (PSDs). We have therefore used scattering amplitude curves (calculated by Handix) for more absorbing aerosols, with an RI of 1.54+0.027i, which is expected to be more representative of the biomass-burning aerosol particles sampled at the ARM site during the CLARIFY campaign. In contrast to the POPS, the SMPS measures particle size using the differential mobility technique after applying an electrical charge to aerosol particles. The method is independent of the refractive index (Ruzer 2013).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {3}
}

Program Document:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that may hold this item.

Save / Share: