Atmospheric Chemistry and Physics Discussions
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10.5194/acpd-7-16071-2007
http://www.atmos-chem-phys-discuss.net/7/16071/2007/
http://www.atmos-chem-phys-discuss.net/7/16071/2007/acpd-7-16071-2007.html
http://www.atmos-chem-phys-discuss.net/7/16071/2007/acpd-7-16071-2007.pdf
16071
16118
2007-11-15
Advection patterns and aerosol optical and microphysical properties by AERONET over south-east Italy in the central Mediterranean
M. Santese
monica.santese@le.infn.it
F. De Tomasi
M. R. Perrone
CNISM, Physics Department, University of Salento, Via per Arnesano, 73100, Lecce, Italy
Aerosol products by AERONET sun-sky radiometer measurements combined with
air-mass backtrajectories were analyzed to identify source regions and
pathways of air masses carrying aerosols to south-east Italy, and to
determine the dependence of aerosol mean optical properties on advection
patterns. Aerosol optical depth (AOD), fine mode fraction (<i>η</i>), single
scattering albedo (SSA), asymmetry factor (<i>g</i>), and lidar ratio (<i>Lr</i>) at 440 nm
were used to characterize aerosol properties. The analysis of
5-day-backtrajectories ending in Lecce on south-east Italy and referring to
240 measurement days of the 2003–2004 years revealed that 32% of the
measurement days were characterized by air masses coming from Sector A,
which includes all continental European sources with the exception of Spain.
3% of the measurement days were characterized by air masses coming from
both the Sector B, which includes the Southern Mediterranean Sea and the
Africa continent, and the Sector C, which includes the Western
Mediterranean, the Iberian Peninsula, and the Atlantic Ocean. 62% of the
measurement days were characterized by mixed advection patterns (Sector M).
We found that AOD, SSA and <i>g</i> average values were not significantly dependent
on air mass source Sector. In contrast, <i>η</i> and <i>Lr</i> average values were
quite affected by the air mass source Sector. AOD, <i>η</i>, SSA, <i>g</i>, and <i>Lr</i>
average values, which were equal to 0.29±0.15, 0.93±0.03, 0.93±0.03, 0.67±0.03, and 72±20 sr, respectively indicated that the
Sector A aerosol could be considered representative of "continental average
aerosol", mostly made of water soluble and a small amount of soot and
insoluble components. Polluted-desert dust particles characterized by
AOD=0.29±0.05, <i>η</i>=0.72±0.05, SSA=0.94±0.03,
<i>g</i>=0.69±0.02, <i>Lr</i>=56±13 sr, were advected over south-east Italy from
Sector B. Sector C was instead responsible for the advection of
maritime-polluted particles, which were characterized by AOD=0.3±0.2,
<i>η</i>=0.8±0.1, SSA=0.94±0.03, <i>g</i>=0.67±0.03, <i>Lr</i>=60±20 sr. Hence, we found that the aerosol load over south-east Italy was dominated by moderately-absorbing, fine-mode particles even if it was also
affected by the minor contribution of desert and maritime type aerosol. The
application of an aerosol mask to the Sector M data points supported last
comment
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