Aerosol Distribution in The Planetary Boundary Layer Aloft a Residential Area

World Multidisciplinary Earth Sciences Symposium 2016

Hovorka, Jan^1 ; Leoni, Cecilia^1 ; Doekalová, Veronika^1 ; Ondráek, Jakub^2 ; Zíková, Nadda^1

Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benátská 2, Prague 2

128 01, Czech Republic^1

Laboratory of Aerosol Chemistry and Physics, Institute of Chemical Process Fundamentals of the CAS, V. V. I., Rozvojová 2/135, Prague 6

165 02, Czech Republic^2

关键词: Aerosol distribution;    Aerosol particle concentrations;    Airborne measurements;    Concentration profiles;    Ground measurements;    Number concentration;    Planetary boundary layers;    Temperature inversions;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/44/5/052017/pdf
DOI  :  10.1088/1755-1315/44/5/052017

来源: IOP

【 摘 要 】

Atmospheric aerosol is an omnipresent component of the Earth atmosphere. Aerosol particle of diameters1 μm defines ultrafine or coarse aerosol particles, respectively. Aerosol particle concentrations within the planetary boundary layer-PBL are measured at the ground level while their vertical profiles in the PBL are usually estimated by modelling. The aim of this study was to construct vertical concentration profiles of ultrafine and coarse aerosol particles from airborne and ground measurements conducted in an urban airshed. Airborne measurements were done by an unmanned airship, remotely controlled with GPS 10 Hz position tracking, and electrically powered with propulsion vectoring, which allows average cruising speed of 6 m.s-1. The airship carried three aerosol monitors and a temperature sensor. The monitors acquired 1 Hz data on mass concentration of coarse and number concentration of ultrafine particles. Four flight sequences were conducted on the 2ndof March 2014 above Plesna village, up-wind suburb of Ostrava in the Moravian-Silesian region of the Czech Republic. The region is a European air pollution hot-spot. Repeated flights were carried out in several height levels up to 570 m above ground level-a.g.l. Early morning flight revealed a temperature inversion in the PBL up to 70 m a.g.l. This lead to coarse particle concentrations of 50 μgm-3below the inversion layer and 10 μgm-3above it. Concurrently, air masses at 90-120 m a.g.l. were enriched with ultrafine particles up to 2.5x104cm-3, which may indicate a fanning plume from a distant emission source with high emission height. During the course of the day, concentrations of ultrafine and coarse particle gradually decreased. Nevertheless, a sudden increase of ultrafine particle concentrations up to 3.7x104cm-3was registered at 400 m a.g.l. at noon and also after a lag of 20 min at the ground. This may indicate formation of new aerosol particles at higher altitudes, which are then transported downward by evolved convective mixing. Detailed information acquired by the airship measurements allow us to better understand processes resulting in the increase of aerosol particle concentrations at ground level in urban air.