Aerosol emissions and dimming/brightening in Europe: Sensitivity studies with ECHAM5-HAM

Abstract

[1] Observational data indicate a decrease of surface solar radiation (SSR) in Europe from about 1950 to the mid-1980s, followed by a renewed increase. Changing aerosol emissions have been suggested as a likely cause for this observed dimming and brightening. (Scandinavia and eastern Europe). All-sky conditions show similar trends in the ensemble mean, but the spread among ensemble members is considerable, emphasizing the importance of clouds. Surface temperatures are found to depend mostly on the prescribed SSTs, with an additional aerosol component in some regions like eastern Europe. For precipitation, internal variability is too large to allow for any firm conclusions.Citation: Folini, D., and M. Wild (2011), Aerosol emissions and dimming/brightening in Europe: Sensitivity studies with

Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

“…This decrease in AAer precursor emissions and the accompanied increase in downward surface solar radiation (solar "brightening") is considered as the likely cause of the rapid warming over Western Europe (Wild 2009(Wild , 2012Folini and Wild 2011;Nabat et al 2014). However, it is still not clear to what extent the rapid warming over Western Europe is a result of a fast land-atmosphere response to the direct impact of changes in GHGs and AAer and to what extent the warming is mediated by the SST changes induced by these forcings.…”

A pathway analysis of global aerosol processes

“…7). In HAM, SO 2 dissolves in clouds into S(IV) products which are subsequently oxidized by O 3 and H 2 O 2 into SO 4 (Feichter et al, 1996). The resulting sulfate aerosol species is allocated to the hydrophilic accumulation and coarse modes (distributed according to available number densities).…”

“…ECHAM-HAM has been used to study non-linearities in aerosol response due to emission changes (Stier et al, 2006a), aerosol effects in a transient climate (Stier et al, 2006b), aerosol activation and cloudprocessing (Roelofs et al, 2006), aerosol indirect effects (Lohmann et al, 2007), the impact of pollution mitigation on climate forcing (Kloster et al, 2008), the impact of volcanic eruptions on climate (Niemeier et al, 2009;Timmreck et al, 2010), the impact of aerosol nucleation on radiative forcing (Makkonen et al, 2009;Kazil et al, 2010) and brightening of surface radiation due to aerosols (Folini and Wild, 2011), climate forcing due to secondary organic aerosols (O'Donnell et al, 2011) and aerosol indirect effects due to shipping emissions (Peters et al, 2012) to name but a few studies. The general circulation model ECHAM was developed at the Max Planck Institute for Meteorology and evolved from the model at the European Centre for Medium-Range Weather Forecasting.…”

“…The processes described in M7 cause redistribution of aerosol mass and numbers among the modes. Part of HAM is a sulfur cycle model (Feichter et al, 1996) that predicts the evolution of dimethyl sulfide (DMS), sulfur dioxide (SO 2 ) and gaseous sulfate (SO − 4 ) using monthly mean fields of the oxidants OH, H 2 O 2 , NO 2 and O 3 , calculated off-line by the MOZART (model for ozone and related chemical tracers) chemical transport model (Horowitz et al, 2003). The aerosol in HAM is affected by the meteorology calculated by ECHAM, and in turn provides feedback to ECHAM as it affects atmospheric radiative transfer and cloud microphysics.…”

“…The early models represented only a single aerosol species such as sulfate or dust (Langner and Rodhe, 1991;Feichter et al, 1996;Tegen and Lacis, 1996;Roelofs et al, 1998;Lohmann et al, 1999;Rasch et al, 2000). Following that, models started to simulate a combination of aerosol species that were externally mixed, (Takemura et al, 2000;Chin et al, 2002).…”