Future climatic drivers and their effect on PM10 components in Europe and the Mediterranean Sea
Authors: Cholakian Arineh , Colette Augustin , Coll Isabelle , Ciarelli Giancarlo , Beekmann Matthias 
Published: April 2019

Abstract. Multiple CMIP5 (Coupled Model Intercomparison Project phase 5) future scenarios run with the CHIMERE
chemistry transport model (CTM) are compared to historic simulations in order
to study some of the drivers governing air pollution. Here, the focus is on
regional climate, anthropogenic emissions and long-range transport. Two major
subdomains are explored – the European region and the Mediterranean Basin –
with both areas showing high sensitivity to climate change. The Mediterranean
area is explored in the context of the ChArMEx (the Chemistry Aerosol
Mediterranean Experiment) project, which examines the current and future
meteorological and chemical conditions of the Mediterranean area. This
climate impact study covers the period from 2031 to 2100 and considers
possible future scenarios in comparison with 1976 to 2005 historic
simulations using three Representative Concentration Pathways (RCPs; RCP2.6,
RCP4.5 and RCP8.5). A detailed analysis of total PM10 (particulate
matter with a diameter smaller that 10 µm) concentrations is
carried out, including the evolution of PM10 and changes to its
composition. The individual effects of meteorological conditions on
PM10 components are explored in these scenarios in an effort to
pinpoint the meteorological parameter(s) governing each component. The
anthropogenic emission impact study covers the period from 2046 to 2055 using
current legislation (CLE) and maximum feasible reduction (MFR) anthropogenic
emissions for the year 2050 compared with historic simulations covering the
period from 1996 to 2005 and utilizing CLE2010 emissions data. Long-range
transport is explored by changing the boundary conditions in the chemistry
transport model over the same period as the emission impact studies. Finally,
a cumulative effect analysis of these drivers is performed, and the impact of
each driver on PM10 and its components is estimated. The results
show that regional climate change causes a decrease in the PM10
concentrations in our scenarios (in both the European and Mediterranean
subdomains), as a result of a decrease in nitrate, sulfate, ammonium and dust
atmospheric concentrations in most scenarios. On the contrary, BSOA (biogenic
secondary organic aerosol) displays an important increase in all scenarios,
showing more pronounced concentrations for the European subdomain compared
with the Mediterranean region. Regarding the relationship of different
meteorological parameters to concentrations of different species, nitrate and
BSOA show a strong temperature dependence, whereas sulfate is most strongly
correlated with relative humidity. The temperature-dependent behavior of BSOA
changes when looking at the Mediterranean subdomain, where it displays more
dependence on wind speed, due to the transported nature of BSOA existing in
this subdomain. A cumulative look at all drivers shows that anthropogenic
emission changes overshadow changes caused by climate and long-range
transport for both of the subdomains explored, with the exception of dust
particles for which long-range transport changes are more influential,
especially in the Mediterranean Basin. For certain species (such as sulfates
and BSOA), in most of the subdomains explored, the changes caused by
anthropogenic emissions are (to a certain extent) reduced by the boundary
conditions and regional climate changes.