Development of balloon-borne impactor payload for profiling free tropospheric aerosol

AbstractSize-segregated aerosol vertical profiles in the troposphere are critically important for source attribution, transformation processes, atmospheric stability, and radiative forcing. For the first time, the development of a 6-stage Impactor for real-time balloon-borne measurements of size-segregated (cut-off diameter (Dae): 0.15-5 µm) aerosol mass concentrations in the free troposphere (FT) was tested during spring 2016 over Hyderabad, India, is presented. Total aerosol mass concentrations obtained with the 6-stage Impactor (MTI) and a co-located optical particle counter (OPC) (MTOPC) measurements at the surface under ambient conditions agreed to within 15%. The effect of aerosol particle growth on the MTI data are assessed using an urban aerosol particle model by scaling mass concentration of water-soluble (hydrophilic) aerosol particles at ambient RH to that at RH =50%. An overall uncertainty of the measurement of the MTI was estimated to be about 19%. The altitude variation of size-segregated ma...