European ozone in a future climate: Importance of changes in dry deposition and isoprene emissions

Abstract

[1] Projections of future surface ozone over Europe conducted utilizing chemistry transport models (CTMs) coupled to climate models differ greatly, even in sign. CTM sensitivity studies were conducted in order to investigate the importance of changes in natural isoprene emissions and dry deposition to vegetation, both coupled to meteorology. This knowledge can be used to improve surface ozone projections. Our simulations suggest climate change over Europe would cause changes in surface ozone between À4.0 to +13 ppb(v) on average (April-September) and À3.5 to +25 ppb(v) on average (April-September) daily maximum from 1961-1990 to 2071-2100. The change is positive in the southwest and negative in the north. The isoprene emissions increased by a factor of about 1.8 from 1961-1990 to 2071-2100. A rescaling of isoprene emissions shows that the large increase in isoprene emission is of importance (0-30% of the change in surface ozone) in central, southern, and western Europe. The use of a formulation for ozone dry deposition to vegetation, dependent on meteorology, and changes in snow cover, affecting the dry deposition, are more important processes. The changes in dry deposition to vegetation (not including changes in aerodynamic resistance) explain up to 80% of the surface ozone change in Spain. Therefore it is vital to include meteorological dependence for dry deposition of ozone to vegetation in surface ozone projections. Isoprene emissions are of less importance, but they are nonnegligible and should definitely be emitted online in climate ozone projection studies.Citation: Andersson, C., and M. Engardt (2010), European ozone in a future climate: Importance of changes in dry deposition and isoprene emissions,

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

“…Several other studies have focused only on the regional impact of climate change (Langner et al, 2012a, b;Andersson and Engardt, 2010;Manders et al, 2012;Hedegaard et al, 2008Hedegaard et al, , 2013Katragkou et al, 2011). They found a general increase in ozone concentrations owing to increasing biogenic emissions and favourable conditions for the build-up of ozone pollution as a result of increased temperature, more frequent summer blocking and heat waves and increased short-wave radiation.…”

“…Bloomer et al (2009) estimated the magnitude of these effects from surface ozone observations over the US at about 2.2 ppb per degree Celcius and Pfister et al (2014) showed increasing summertime ozone levels under various climate scenarios. These effects have been quantified over Europe in several model studies Meleux et al, 2007;Langner et al, 2012a, b;Andersson and Engardt, 2010;Manders et al, 2012;Hedegaard et al, 2008Hedegaard et al, , 2013bKatragkou et al, 2011). The general order of magnitude of the climate penalty over Europe is a few ppb by the middle of the century.…”

“…Langer et al (2012b) point out a larger increase at the 95th percentile of hourly ozone, suggesting that the effects of climate change may be particularly important during high-ozone events. The effects of changes in isoprene emissions and dry deposition have been quantified separately by Andersson and Engardt (Andersson and Engardt, 2010), who find increases in mean ozone of up to 5 ppb by 2050 in some parts of western Europe, with as much as 60 % of this change attributed to decreased dry deposition, and with increased isoprene emissions contributing up to 1 ppb. As noted above large uncertainties remain regarding the impact of climate change on biogenic emissions, with up to a factor of 5 difference in isoprene change reported in a multi-model ensemble (Langner et al, 2012b).…”

“…Andersson and Engardt, 2010;Wiedinmyer et al, 2006) with up to a factor of 5 difference between different models for Europe (Langner et al, 2012b). It has been recently shown that the choice of isoprene chemical schemes in climate models can be important (Squire et al, 2015).…”

The effects of global change upon United States air quality

“…1). Although, it has been suggested that periods of 10 to 30 years are required to fully determine climatological conditions (Andersson and Engardt, 2010), the fact that emission inventories can substantially change from one decade to the next suggests that using 5 to 10 year periods for air quality assessment is more appropriate. Thus, five representative summers (June-July-August; with May as a spin-up period) for the present (1995 to 2004) and the future (2045 to 2054) decades were selected.…”