In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 22 ( 2018-11-22), p. 16601-16618
Abstract:
Abstract. The vertical profile of new particle formation (NPF) events
was studied by comparing the aerosol size number distributions measured aloft
and at surface level in a suburban environment in Madrid, Spain, using
airborne instruments. The horizontal distribution and regional impact of the
NPF events was investigated with data from three urban, urban background, and
suburban stations in the Madrid metropolitan area. Intensive regional NPF
episodes followed by particle growth were simultaneously recorded at three
stations in and around Madrid during a field campaign in July 2016. The urban
stations presented larger formation rates compared to the suburban station.
Condensation and coagulation sinks followed a similar evolution at all
stations, with higher values at urban stations. However, the total number
concentration of particles larger than 2.5 nm was lower at the urban station
and peaked around noon, when black carbon (BC) levels are at a minimum. The
vertical soundings demonstrated that ultrafine particles (UFPs) are formed
exclusively inside the mixed layer. As convection becomes more effective and
the mixed layer grows, UFPs are detected at higher levels. The morning
soundings revealed the presence of a residual layer in the upper levels in
which aged particles (nucleated and grown on previous days) prevail. The
particles in this layer also grow in size, with growth rates significantly
smaller than those inside the mixed layer. Under conditions with strong
enough convection, the soundings revealed homogeneous number size
distributions and growth rates at all altitudes, which follow the same
evolution at the other stations considered in this study. This indicates that
UFPs are detected quasi-homogenously in an area spanning at least 17 km
horizontally. The NPF events extend over the full vertical extension of the
mixed layer, which can reach as high as 3000 m in the area, according to
previous studies. On some days a marked decline in particle size (shrinkage)
was observed in the afternoon, associated with a change in air masses.
Additionally, a few nocturnal nucleation-mode bursts were observed at the
urban stations, for which further research is needed to elucidate their
origin.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-18-16601-2018
DOI:
10.5194/acp-18-16601-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
Bookmarklink