On the vertical distribution of pollution particles during the MINOS campaign
Zev Levin1, Amit Teller1, Eliezer Ganor1,
Johannes Schneider2 and Andreas Minikin3
1Department of Geophysics and Planetary Science, Tel Aviv University, Ramat Aviv 69978, Israel
2 Max Planck Institute for Chemistry, Mainz, Germany
3 Institute of Atmospheric Physics, DLR, Germany
Measurements of aerosol properties as a function of height were
carried out in a region north of Crete during the MINOS campaign.
In situ size spectra were measured and aerosol samples were collected
on a number of different surfaces for subsequent chemical analysis.
Two airplanes were used during this campaign, the DLR Falcon and the
Israeli King Air. The Falcon carried out measurements during most of
the campaign period (1-22 August, 2001). In addition to many other
instruments for gas measurements, the instruments relevant to this
report consist of CN instrument and aerosol absorption measurements.
The King Air was used only during the 6, 7, 9 of August 2001. It carried
a variety of instruments for aerosol size measurements (FSSP-100 and
PCASP-100) as well as a aerosol sampling system, a GPS and an albedometer.
During the 9th of August the two airplanes carried out a coordinated flight
from about 150 m to about 6000 m. The lower elevation was chosen for the
purpose of comparing the airborne with the ground measurements carried out
at Finokalia.
The results show that the pollution coming from Europe, passing over Greece
and into the Mediterranean was often found to be distributed in thin layers
extending from about 100 m to 6 km. Chemical analysis of individual particles
revealed that at the lower elevations (150 m) most particles contained sulfate
and nitrate. At higher elevations (3000 m) more particles containing sulfate
were observed.
At the lower levels, the measured high absorption coefficient by the aerosols
suggests that many of them were carbonaceous particles from vehicle pollution
(diesel). The electron micrographic photos of the aerosol samples confirm this.
A surprising result was the relatively low concentrations of the very small
particles (between 5 and 14 nm) that were found at lower elevations.
It is believed that the high concentrations of the particles in the accumulation
mode are responsible for the rapid aggregation of the smaller aerosols onto them.
These results will be presented and discussed.