Abstract
Abstract. In order to obtain the source/sink functions for atmospheric particulates located on the planetary surface or elevated in the atmosphere; direct aerosol emission measurements are required. For this purpose, the performance of an airborne aerosol flux measurement system with an improved 3-km spatial resolution is evaluated in this study. Eddy covariance method was used in flux calculations. A footprint for airborne flux sampling with the increased resolution becomes comparable in area to the footprint for tower sampling (with the footprint length being 2 to 10 km). The improvement in spatial resolution allows quantification of emission rates from individual sources located several kilometers apart. Locally measured aerosol flux provides useful information about aerosol sources and sinks located below or aloft of measurement altitude. The advantage is a moving platform that allows scanning of aerosol emissions or depositions over practically unlimited geographic scales. The technique delivers effective emission rates of atmospheric particulates from specific sources such as highway segments, city blocks, and remote and industrial areas. The improved spatial resolution airborne flux measurements were conducted in ambient conditions with low (<500 m) mixed boundary layer heights. Measurement results are reported from clean and partly polluted marine environments, and heavily polluted continental environments. The upward and downward fluxes from the clean marine environment were smaller than 0.5×106 particles m−2 s−1 in absolute value. The effective emissions measured from a ship plume ranged from 2×108 to 3×108 m−2 s−1, and effective fluxes measured crossing cities plumes with populations of 10 000 to 12 000 inhabitants were in the range of 2×108 to 3×108 m−2 s−1. Correlations between heat and aerosol fluxes are evaluated.