Aerosol flux measurements during the Melpitz Column experiment

Janine Lückerath1, Birgit Wehner2, Andreas Held1
1 Atmospheric Chemistry, Universität Bayreuth
2 Leibniz Institute for Tropospheric Research, Leipzig

P 6.4 in Paving the way for research: Databases, instruments, networks
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Turbulent transport determines the vertical distribution of aerosol particles in the atmospheric boundary layer. Thus, measuring vertical aerosol fluxes is essential in order to locate and quantify net particle sources and sinks.

In this study, vertical aerosol fluxes were measured by eddy covariance above the Melpitz grassland site close to the town of Torgau in Saxony (Germany) from May to June 2015. The eddy covariance setup included a sonic anemometer (usonic3, METEK, Germany) and two condensation particle counters (CPC), a commercial CPC (Model 3010, TSI, USA) and a custom-built Fast CPC (FCPC; Wehner et al., 2011) with different response to changes in particle concentration. Here, the differences of the observed CPC and FCPC flux measurements are compared with a theoretically estimated difference due to flux attenuation.

Due to the faster response, the fluxes derived from FCPC data were typically larger than CPC fluxes. A linear regression indicates that the high frequency contribution, which is only covered by the FCPC, yields 28 % higher deposition velocities on average. When applying a simple correction method to estimate the flux attenuation due to a non-perfect time response of the CPC and FCPC, the corrected particle deposition velocities agree within a few percent.

In conclusion, it was possible to explain the differences in particle deposition velocities derived from two co-located condensation particle counters by their characteristic response behavior, and to correct the associated flux attenuation by a simple correction method. 

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