Articles | Volume 9, issue 5
Atmos. Meas. Tech., 9, 2179–2194, 2016
Atmos. Meas. Tech., 9, 2179–2194, 2016

Research article 17 May 2016

Research article | 17 May 2016

An optical particle size spectrometer for aircraft-borne measurements in IAGOS-CARIBIC

Markus Hermann1, Andreas Weigelt1,2,a, Denise Assmann1, Sascha Pfeifer1, Thomas Müller1, Thomas Conrath1, Jens Voigtländer1, Jost Heintzenberg1, Alfred Wiedensohler1, Bengt G. Martinsson3, Terry Deshler4, Carl A. M. Brenninkmeijer5, and Andreas Zahn6 Markus Hermann et al.
  • 1Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany
  • 2Environmental Chemistry Department, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany
  • 3Division of Nuclear Physics, Lund University, Professorsgatan 1, 22363 Lund, Sweden
  • 4Department of Atmospheric Science, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
  • 5 Air Chemistry Division, Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany
  • 6Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
  • anow at: Federal Maritime and Hydrographic Agency, Wuestland 2, 22589 Hamburg, Germany

Abstract. The particle number size distribution is an important parameter to characterize the atmospheric aerosol and its influence on the Earth's climate. Here we describe a new optical particle size spectrometer (OPSS) for measurements of the accumulation mode particle number size distribution in the tropopause region on board a passenger aircraft (IAGOS-CARIBIC observatory: In-service Aircraft for a Global Observing System – Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container). A modified KS93 particle sensor from RION Co., Ltd., together with a new airflow system and a dedicated data acquisition system, is the key component of the CARIBIC OPSS. The instrument records individual particle pulse signal curves in the particle size range 130–1110 nm diameter (for a particle refractive index of 1.47-i0.006) together with a time stamp and thus allows the post-flight choice of the time resolution and the size distribution bin width. The CARIBIC OPSS has a 50 % particle detection diameter of 152 nm and a maximum asymptotic counting efficiency of 98 %. The instrument's measurement performance shows no pressure dependency and no particle coincidence for free tropospheric conditions. The size response function of the CARIBIC OPSS was obtained by a polystyrene latex calibration in combination with model calculations. Particle number size distributions measured with the new OPSS in the lowermost stratosphere agreed within a factor of 2 in concentration with balloon-borne measurements over western North America. Since June 2010 the CARIBIC OPSS is deployed once per month in the IAGOS-CARIBIC observatory.

Short summary
Aerosol particles are an important component of the Earth's atmosphere. Here we describe the composition and characterization of a new optical particle size spectrometer (OPSS) for aircraft-borne measurements of the aerosol particle size distribution (how many particles there are with a certain size) in the 140–1050 nm size range. The OPSS was characterized throughout concerning its measurement capabilities (response, pressure dependence, coincidence) and validated versus balloon measurement.