Tethered balloon measurements of biogenic volatile organic compounds at a Boreal forest site

Abstract

Abstract. Measurements of biogenic volatile organic compounds (VOCs) were performed at Hyytiälä, a Boreal forest site in Southern Finland as part of the project OSOA (origin and formation of secondary organic aerosol) in August 2001. At this site, frequent formation of new particles has been observed and the role of biogenic VOCs in this process is still unclear. Tethered balloons served as platforms to collect VOC samples within the planetary boundary layer at heights up to 1.2 km above ground during daytime. Mean mixed layer concentrations of total monoterpenes varied between 10 and 170 pptv, with α-pinene, limonene and Δ3-carene as major compounds, isoprene was detected at levels of 2–35 pptv. A mixed layer gradient technique and a budget approach are applied to derive surface fluxes representative for areas of tens to hundreds of square kilometres. Effects of spatial heterogeneity in surface emissions are examined with a footprint analysis. Depending on the source area considered, mean afternoon emissions of the sum of terpenes range between 180 and 300 μg m−2 h−1 for the period of 2 to 12 August 2001. Surface fluxes close to Hyytiälä were higher than the regional average, and agree well with mean emissions predicted by a biogenic VOC emission model. Total rates of monoterpene oxidation were calculated with a photochemical model. The rates did not correlate with the occurrence of new particle formation, but the ozone pathway was of more importance on days with particle formation. Condensable vapour production from the oxidation of monoterpenes throughout the mixed layer can only account for a fraction of the increase in aerosol mass observed at the surface.

New Particle Formation and Growth in an Isoprene-Dominated Ozark Forest: From Sub-5 nm to CCN-Active Sizes

“…The isoprene-to-MT carbon ratio was 15.3 § 7.2 during the campaign period. This ratio was close to those found in Amazonian rain forests (e.g., 15.2; Greenberg et al 2004) where NPF was not observed at the ground level, but much higher than 0.18 observed in the Finland boreal forest (Spirig et al 2004) where frequent NPF was observed.…”

Local Arctic Air Pollution: A Neglected but Serious Problem

“…Other pollutants, especially those that have implications for public health or ecosystems, have received less attention: for example, nitrogen oxides, NO x ; volatile organic compounds, VOCs; sulfur dioxide, SO 2 ; carbon monoxide, CO; and particulate matter, PM. In addition, not all sectors that contribute to local emissions in the Arctic were considered in previous assessments; for example, waste burning is not (Huang et al, 2015), (b) Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants version 5 (ECLIPSEv5; Stohl et al, 2015), and (c) Hemispheric Transport of Air Pollution version 2 (HTAPv2; Janssens-Maenhout et al, 2015) for the year 2010, from Sergent (2017). Note not all inventories cover the entire Arctic, hence the focus on Eurasia.…”

“…In the past years, it has been recognized that flaring linked to oil and gas extraction, particularly in northern Russia, is an important source of BC, suggested to be 66% of the total Arctic BC emissions (Stohl et al, 2013(Stohl et al, , 2015. More recent estimates suggest higher BC emissions from flaring activities in Russia (Huang et al, 2015;Huang & Fu, 2016) although note that estimates are very dependent on the emission factors used in different studies, for example, 1.6 g/m 3 of emitted gas in Stohl et al (2013) and 2.27 g/m 3 in Huang et al (2015).…”

“…However, BVOC emissions have been poorly characterized in the boreal regions and the Arctic. Measurements have generally focused on European boreal forests with a major emphasis on monoterpenes (Bäck et al, 2012;Juráň et al, 2017;Rantala et al, 2015;Spirig et al, 2004;Zhou et al, 2017). Coniferous tree species characteristic of the boreal forests are efficient monoterpene emitters (Rinne, Tuovinen, et al, 2000), which leads to larger monoterpene/isoprene emission ratios in the boreal regions compared with forest ecosystems at lower latitudes (Guenther et al, 2012).…”

Spectral mixture analyses of hyperspectral data acquired using a tethered balloon

“…In addition, because tethered balloons have been used to quantify a variety of trace gas fluxes at the landscape scale [i.e. methane (Beswick et al, 1998;Choularton et al, 1995), non-methane hydrocarbons (Davis et al, 1994;Guenther et al, 1996;Greenberg et al, 1999;Spirig et al, 2004;Zimmerman et al, 1988), and carbon dioxide (Kuck et al, 2000)], employing quantitative radiometric instrumentation on such a platform opens new opportunities for comparing trace gas flux and spectral properties of vegetation at scales comparable to and larger than those measured by standard flux towers. Therefore, data acquired through platforms such as the SWAMI may be used to complement those data acquired through the tower-based Spectral Network (SpecNet) Working Group.…”