Aerosol particles during the Innsbruck Air Quality Study (INNAQS): The impact of transient fluxes on total aerosol number exchange

Sporadic gust-like motions of vertical wind and concurrently measured large changes in particle number concentration (termed particle gusts) significantly biased total particle fluxes, reflecting, however, rather local fluxes at the measurement height. The particle gust events were identified by applying the median absolute deviation (MAD) method to particle fluxes. The particle flux was reconstructed by means of a continuous wavelet transform (CWT) to confirm the validity of the EC calculations during particle gusts. Their origin could not clearly be identified, but they indicate the presence of poorly mixed air parcels which are strongly enriched with particles. Due to the episodic yet large contribution to particle fluxes in Innsbruck, the potential impact of particle gusts on turbulent particle exchange should also be evaluated at other urban and non-urban sites.