Intercomparison study of six HTDMAs: results and recommendations
1Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
2International Laboratory for Air Quality and Health, Queensland University of Technology, QLD 4000, Brisbane, Australia
3Centre for Atmospheric Sciences, University of Manchester, M13 9PL, Manchester, UK
4Laboratoire de Météorologie Physique, Blaise Pascal Univ., 63000, Clermont-Ferrand, France
5Climate Change Unit, Joint Research Center, 21027, Ispra, Italy
*now at: Laboratory for Energy Analysis, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
Abstract. We report on an intercomparison of six different hygroscopicity tandem differential mobility analysers HTDMAs). These HTDMAs are used worldwide in laboratory experiments and field campaigns to measure the water uptake of aerosol particles and have never been intercompared. After an investigation of the different design of the instruments with their advantages and inconveniencies, the methods for calibration, validation and data analysis are presented. Measurements of nebulised ammonium sulphate as well as of secondary organic aerosol generated from a smog chamber were performed. Agreement and discrepancies between the instruments and to the theory are discussed, and final recommendations for a standard instrument are given, as a benchmark for laboratory or field experiments to ensure a high quality of HTDMA data.