Simultaneous HTDMA and HR-ToF-AMS measurements at the HKUST Supersite in Hong Kong in 2011

This paper presents the results of simultaneous aerosol hygroscopicity and composition measurements using a Humidified Tandem Differential Mobility Analyzer (HTDMA) and an Aerodyne High‐Resolution Time‐of‐Flight Aerosol Mass Spectrometer (HR‐ToF‐AMS) at the HKUST Supersite, located at a coastal suburban site in Hong Kong. Growth factors (GFs) at 90% relative humidity and the size‐resolved composition of ambient aerosols at dry electrical mobility diameters of 75, 100, 150, and 200 nm were measured in May, September, and November 2011. Bimodal GF distributions with a dominant more hygroscopic (MH) mode and a small fraction of the nonhygroscopic or less hygroscopic mode (number fraction