Modification of a commercial condensation particle counter for boundary layer balloon-borne aerosol studies

A commercial battery-driven condensation particle counter (TSI-8020) was mo dified for use in a lightweight payload for tethered balloons to study new particle formation in the planetary boundary layer. After modifications, th e instrument was characterized and calibrated over the particle size range 5 less than or equal to D-p less than or equal to 1000 nm and an air pressu re range down to 600 hPa. In 1996, the single-channel instrument was deploy ed in its first held campaign at a rural research station in eastern German y, where the instrument clearly indicated new particle formation near the t op of a low stratus deck. A first field rest with the double-CPC (condensat ion particle counter) payload demonstrated the feasibility of jointly measu ring number concentrations for D-p greater than or equal to 6 nm and D-p gr eater than or equal to 12 nm on the same balloon payload. The difference of the two count signals provides a good measure of new particle formation.