Global Change Abstracts The Swiss Contribution - SCNAT

Global Change Abstracts – The Swiss Contribution | Atmosphere 53
timate selected OVOC and NMHC emissions of the
current vehicle fleet under highway conditions.
For the measured OVOCs the highest EFs were
found for ethanol (9.7 mg/km), isopropanol (3.2
mg/km), and acetaldehyde (2.5 mg/km), followed
by acetone, benzaldehyde, and acrolein. Formaldehyde,
the most abundant OVOC measured in
other studies, was not measured by the method applied.
Relative emissions of the measured OVOCs
were estimated to contribute approximately 6 and
4% to the total road traffic VOC emissions from
Switzerland and Europe, respectively. Results are
compared with those from previous studies from
the same tunnel performed in 1993 and 2002, and
from campaigns in other tunnels. A continuous
reduction in the emission factors (EFs) was determined
for all measured compounds from 1993 until
2004. The relative contributions of light-duty
vehicles (LDV) and heavy-duty vehicles (HDV) to the
total emissions indicated that OVOCs were mainly
produced by the HDVs, whereas LDVs dominated
the production of the NMHCs.
Environmental Science Technology, 2007, V41,
N20, OCT 15, pp 7060-7066.
08.1-44
A photochemical modeling study of ozone and
formaldehyde generation and budget in the
Po basin
Liu L, Andreani Aksoyoglu S, Keller J, Ordonez C,
Junkermann W, Hak C, Braathen G O, Reimann S,
Astorga Llorens C, Schultz M, Prevot A S H, Isaksen I S A
Norway, Switzerland, France, Germany, Sweden,
Italy
Modelling , Meteorology & Atmospheric Sciences
In this work, a photochemical dispersion model,
CAMx (Comprehensive Air quality Model with
eXtensions) was used to simulate a high ozone
episode observed in the Po basin during the 2003
FORMAT (Formaldehyde as a Tracer of Oxidation
in the Troposphere) campaign. The study focuses
on formaldehyde and ozone, and a budget analysis
was set up for interpreting the importance
of different processes, namely emission, chemistry,
transport and deposition, for three different
areas (urban, downwind, suburban) around the
Milan metropolitan region. In addition, a sensitivity
study was carried out based on 11 different
VOC emission scenarios. The results of the budget
study show that the strongest O-3 production
rate (4 ppbv/hour) occurs in the downwind area
of the city of Milan, and that accumulated O 3 is
transported back to Milan city during nighttime.
More than 80% of the HCHO concentration over
the Milan metropolitan region is secondary, i.
e., photochemically produced from other VOCs.
The sensitivity study shows that the emissions
of isoprene are not, on average, a controlling factor
for the peak concentrations of O 3 and HCHO
over the model domain because of very few oak
trees in this region. Although the paraffinic (PAR)
emissions are fairly large, a 20% reduction of PAR
yields only 1.7% of HCHO reduction and 2.7% reduction
of the O 3 peak. The largest reduction of
O 3 levels can be obtained by reduced xylene (XYL)
emissions. A 20% reduction of the total anthropogenic
VOC emissions leads to 15.5% (20.3 ppbv)
reduction of O 3 peak levels over the Milan metropolitan
region.
Journal of Geophysical Research Atmospheres,
2007, V112, ND22, NOV 20 ARTN: D22303.
08.1-45
Cloud microphysics and aerosol indirect effects
in the global climate model ECHAM5-HAM
Lohmann U, Stier P, Hoose C, Ferrachat S, Kloster S,
Röckner E, Zhang J
Switzerland, USA, Italy, Germany, Canada
Meteorology & Atmospheric Sciences , Modelling
The double-moment cloud microphysics scheme
from ECHAM4 that predicts both the mass mixing
ratios and number concentrations of cloud
droplets and ice crystals has been coupled to
the size-resolved aerosol scheme ECHAM5-HAM.
ECHAM5-HAM predicts the aerosol mass, number
concentrations and mixing state. The simulated
liquid, ice and total water content and the cloud
droplet and ice crystal number concentrations as
a function of temperature in stratiform mixedphase
clouds between 0 and -35 degrees C agree
much better with aircraft observations in the
ECHAM5 simulations. ECHAM5 performs better
because more realistic aerosol concentrations are
available for cloud droplet nucleation and because
the Bergeron-Findeisen process is parameterized
as being more efficient. The total anthropogenic
aerosol effect includes the direct, semi- direct
and indirect effects and is defined as the difference
in the top-of-the-atmosphere net radiation
between present-day and pre- industrial times.
It amounts to & minus; 1.9 W m(-2) in ECHAM5,
when a relative humidity dependent cloud cover
scheme and aerosol emissions representative for
the years 1750 and 2000 from the AeroCom emission
inventory are used. The contribution of the
cloud albedo effect amounts to -0.7 W m(-2). The
total anthropogenic aerosol effect is larger when
either a statistical cloud cover scheme or a different
aerosol emission inventory are employed because
the cloud lifetime effect increases.
Atmospheric Chemistry and Physics, 2007, V7,
N13, pp 3425-3446.