The Brechtel Scanning Electrical Mobility Sizer (SEMS, see Lopez-Yglesias et al. (2014) Aer. Sci. & Tech.; Leaitch et al. (2013) Elementa: Science of the Anthropocene) was used over a two year period at the Alert, Alaska Global Aerosol Watch station to generate monodisperse calibration aerosols. The generated particles were used to challenge and test a competitor’s scanning mobility particle sizer system as well as to calibrate an Aerosol Chemical Speciation Monitor (ACSM) using monodisperse nitrate particles. A major focus of the measurements was to determine the conditions under which new particles were formed at the site. The SEMS played a key role in validating the sizing performance of other instruments and worked very well over the entire period.