Effects of two different biogenic emission models on modelled ozone and aerosol concentrations in Europe

Abstract

<p><strong>Abstract.</strong> Biogenic volatile organic compound (BVOC) emissions are one of the essential inputs for chemical transport models (CTMs), but their estimates are associated with large uncertainties leading to significant influences on air quality modelling. This study aims at investigating the effects of using different BVOC emission models on the performance of a CTM in simulating secondary pollutants, i.e. ozone, organic and inorganic aerosols. The European air quality was simulated for the year 2011 by the regional air quality model Comprehensive Air Quality Model with Extensions (CAMx) version 6.3, using BVOC emissions calculated by two emission models: the Paul Scherrer Institute (PSI) model and the Model of Emissions of Gases and Aerosol from Nature (MEGAN) v2.1. Comparison of isoprene and monoterpene emissions from both models showed large differences in their general amounts as well as their spatial distribution both in summer and winter. MEGAN produced more isoprene emissions by a factor of 3 while the PSI model generated three times of monoterpene emissions in summer, while there was negligible difference (~ 4 %) in sesquiterpene emissions associated with the two models. Despite the large differences in isoprene emissions (i.e. 3-fold), the resulting impact in predicted summer-time ozone proved to be minor (< 10 %, O<sub>3</sub>-MEGAN was higher than O<sub>3</sub>-PSI by ~ 7 ppb). Comparisons with measurements from the European air quality database (AirBase) indicated that PSI emissions might improve the model performance at low ozone concentrations, but worsen it at high ozone levels (> 60 ppb). A much larger effect of the different BVOC emissions was found for the secondary organic aerosol (SOA) concentrations. The higher monoterpene emissions (a factor of ~ 3) by the PSI model led to higher SOA by ~ 110 % on average in summer, compared to MEGAN, improving substantially the model performance for organic aerosol (OA): the mean bias between modelled and measured OA at 8 Aerodyne aerosol chemical speciation monitor (ACSM)/Aerodyne aerosol mass spectrometer (AMS) measurement stations was reduced by 21 %–83 % in rural/remote stations. Effects on inorganic aerosols (particulate nitrate, sulphate, and ammonia) were relatively smaller (< 15 %).</p>

Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland

“…Emissions models have been shown to perform well in both the unstressed and severe drought phases (e.g. Emmerson et al, ; Guenther et al, ; Jiang et al, ) but underestimate observed concentrations during the mild‐to‐moderate drought phase (Potosnak et al, ; Seco et al, ). Conceptual models (Niinemets, ; Potosnak et al, ) have been developed to explain the impacts of mild droughts on isoprene emissions but these have not been tested until now.…”

Isoprene is more affected by climate drivers than monoterpenes: A meta‐analytic review on plant isoprenoid emissions

“…Under the current rate of CO 2 increase, such high concentration is predicted for the year 2065 according to the most pessimistic RCP8.5 scenario (Meinshausen et al, ), whereas 400 ppm were reached in the year 2015 (Blunden & Arndt, ). Such a dramatic CO 2 ‐driven reduction of isoprene emission from plants might have relevant effects on tropospheric chemistry because isoprene has been shown to significantly affect the concentration of tropospheric ozone and other oxidants (Jiang et al, ), and perhaps also the capacity to adapt to climate change (Lerdau, ; Loreto et al, ). However, it was shown that most of the negative effect of elevated CO 2 on isoprene is lost under a simultaneous increase of temperature (Sharkey & Monson, ).…”

Continuous Isoprene Measurements in a UK Temperate Forest for a Whole Growing Season: Effects of Drought Stress During the 2018 Heatwave

“…A number of isoprene emission models have been developed (Andreani‐Aksoyoglu & Keller, 1995; Arneth et al, 2011; Grote & Niinemets, 2008; Guenther et al, 2012, 2006; Müller et al, 2008; Pierce & Waldruff, 1991), with the resulting emission estimates varying by up to a factor of 3 for the same region and season (Guenther et al, 2006; Jiang et al, 2019; Lathière et al, 2010). As isoprene emissions are concurrently influenced by many environmental variables, field measurements as well as studies in controlled environments are necessary to validate emission models.…”