Atmospheric Measurement Techniques (Jun 2009)
Experimental characterization of the COndensation PArticle counting System for high altitude aircraft-borne application
Abstract
A characterization of the ultra-fine aerosol particle counter COPAS (<B>CO</b>ndensation <B>PA</B>rticle counting <B>S</B>ystem) for operation on board the Russian high altitude research aircraft M-55 Geophysika is presented. The COPAS instrument consists of an aerosol inlet and two dual-channel continuous flow Condensation Particle Counters (CPCs) operated with the chlorofluorocarbon FC-43. It operates at pressures between 400 and 50 hPa for aerosol detection in the particle diameter (<I>d<sub>p</sub></I>) range from 6 nm up to 1 μm. The aerosol inlet, designed for the M-55, is characterized with respect to aspiration, transmission, and transport losses. The experimental characterization of counting efficiencies of three CPCs yields <I>d<sub>p</I>50</sub> (50% detection particle diameter) of 6 nm, 11 nm, and 15 nm at temperature differences (Δ<I>T</I>) between saturator and condenser of 17°C, 30°C, and 33°C, respectively. Non-volatile particles are quantified with a fourth CPC, with <I>d<sub>p</I>50</sub>=11 nm. It includes an aerosol heating line (250°C) to evaporate H<sub>2</sub>SO<sub>4</sub>-H<sub>2</sub>O particles of 11 nm<<I>d<sub>p</sub></I><200 nm at pressures between 70 and 300 hPa. An instrumental in-flight inter-comparison of the different COPAS CPCs yields correlation coefficients of 0.996 and 0.985. The particle emission index for the M-55 in the range of 1.4–8.4×10<sup>16</sup> kg<sup>−1</sup> fuel burned has been estimated based on measurements of the Geophysika's own exhaust.
