Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

Abstract

Abstract. Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors, such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain. We applied the boundary-layer-chemistry-transport model SOSA (model to Simulate the concentrations of Organic vapours and Sulphuric Acid) to investigate Scots pine (Pinus sylvestris) monoterpene emissions in a boreal coniferous forest at the SMEAR (Station for Measuring forest Ecosystem-Atmosphere Relations) II site, southern Finland. SOSA was applied to simulate monoterpene emissions with three different emission modules: the semiempirical G95, MEGAN (Model of Emissions of Gases and Aerosols from Nature) 2.04 with improved descriptions of temperature and light responses and including also carbonyl emissions, and a process-based model SIM-BIM (Seasonal Isoprenoid synthase Model -Biochemical Isoprenoid biosynthesis Model). For the first time, the emission models included seasonal and diurnal variations in both quantity and chemical species of emitted monoterpenes, based on parameterizations obtained from field measurements. Results indicate that modelling and observations agreed reasonably well and that the model can be used for investigating regional air chemistry questions related to monoterpenes. The predominant modelled monoterpene concentrations, α-pinene and 3 -carene, are consistent with observations.

Modeling the role of highly oxidized multifunctional organic molecules for the growth of new particles over the boreal forest region

“…In boreal forests, the growth of the particles is dominated by condensation of organic compounds formed from oxidation of biogenic volatile organic compounds (BVOCs) emitted by the vegetation . Studies have shown that NPF can provide a significant amount of CCN and thereby have a substantial climate impact (e.g., Jokinen et al, 2015;Kerminen et al, 2012;Merikanto et al, 2009;Scott et al, 2014;Spracklen et al, 2008).…”

“…In many studies (e.g., Bergström et al, 2012;Farina et al, 2010;Fountoukis et al, 2014;Hodzic et al, 2009;Lane et al, 2008;Murphy et al, 2012) the vapors are assumed to be semi-volatile and in equilibrium with the (liquid, well-mixed) particles, making it possible to model formation of BSOA by simple gas-particle equilibrium partitioning (Pankow, 1994). In other studies (e.g., Scott et al, 2015;Spracklen et al, 2008;Tunved et al, 2010;Westervelt et al, 2013) the vapors are assumed to be nonvolatile and the irreversible particle growth is only limited by the collision rate between the vapor molecules and the particles. Recently, large-scale model studies (Jokinen et al, 2015;Langmann et al, 2014;Li et al, 2015;Riipinen et al, 2011;Yu, 2011) have included both mechanisms to be able to treat semi-volatile and nonvolatile vapors, which have yielded a better agreement between model results and observations.…”

Annual cycle of volatile organic compound exchange between a boreal pine forest and the atmosphere

“…Longer time series have also consisted of measurements from May to September only (Räisänen et al, 2009;Taipale et al, 2011). This has had a direct effect on the capability of models to predict monoterpene concentrations (Smolander et al, 2014).…”

Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

“…The most abundant volatile monoterpene, emitted mainly by coniferous trees (i.e. Pinus canariensis), is α-pinene (AndreaniAksoyoglu and Keller, 1995;Rinne et al, 2009;Smolander et al, 2014) and the tracers related to its photochemical oxidation (SOA PIN) are cis-pinonic acid, 3-hydroxyglutaric acid (3-HGA) and 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) Szmigielski et al, 2007).…”