Interannual variability of terpenoid emissions in an alpine city

Kaser, L.; Peron, Arianna; Graus, M.; Striednig, Marcus; Wohlfahrt, Georg; Juráň, Stanislav; Karl, T.

doi:10.5194/acp-22-5603-2022

Cited by 22 publications

(18 citation statements)

References 97 publications

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“…In spring 2021, isoprene enhancements were larger in the more densely populated sector (Figure S23), and this divergence grew from January to April 2021 with more dynamic diurnal patterns resulting in average spring concentrations that were double that of the less densely populated sector (0.57 ± 0.20 vs 0.29 ± 0.14 ppb). Together, these results point to additional, understudied urban sources of isoprene (or other C 5 H 8 H + ions), consistent with other summertime studies that could not fully explain urban isoprene fluxes, and while isoprene is emitted by humans, it is not a common component of VCP formulations.…”

Section: Resultssupporting

confidence: 86%

Policy-Related Gains in Urban Air Quality May Be Offset by Increased Emissions in a Warming Climate

Cao

Gentner

Commane

et al. 2023

Environ. Sci. Technol.

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Air quality policies have made substantial gains by reducing pollutant emissions from the transportation sector. In March 2020, New York City's activities were severely curtailed in response to the COVID-19 pandemic, resulting in 60−90% reductions in human activity. We continuously measured major volatile organic compounds (VOCs) during January−April 2020 and 2021 in Manhattan. Concentrations of many VOCs decreased significantly during the shutdown with variations in daily patterns reflective of human activity perturbations, resulting in a temporary ∼28% reduction in chemical reactivity. However, the limited effect of these dramatic measures was outweighed by larger increases in VOC-related reactivity during the anomalously warm spring 2021. This emphasizes the diminishing returns from transportationfocused policies alone and the risk of increased temperature-dependent emissions undermining policy-related gains in a warming climate.

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Section: Resultssupporting

confidence: 86%

Policy-Related Gains in Urban Air Quality May Be Offset by Increased Emissions in a Warming Climate

Cao

Gentner

Commane

et al. 2023

Environ. Sci. Technol.

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“…However, there are still large uncertainties in simulated BVOC emissions and their trends, such as in the treatment of drought and heat wave stress and the emission factors of certain tree species. Previous observations have shown that isoprene and monoterpene emissions are affected differently by drought severity (Brilli et al, 2007;Kaser et al, 2022;Otu-Larbi et al, 2020;Šimpraga et al, 2011). Isoprene emis-sions remain unchanged under mild drought but increase under moderate drought with increased leaf temperature due to changes in stomatal conductance (Kaser et al, 2022).…”

Section: Discussionmentioning

confidence: 98%

Regional to global distributions, trends, and drivers of biogenic volatile organic compound emission from 2001 to 2020

Wang,

Liu,

et al. 2024

Atmos. Chem. Phys.

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Abstract. Biogenic volatile organic compounds (BVOCs) are important precursors to ozone and secondary organic aerosols in the atmosphere, affecting air quality, clouds, and climate. However, the trend in BVOC emissions and driving factors for the emission changes in different geographic regions over the past 2 decades has remained unclear. Here, regional to global changes in BVOC emissions during 2001–2020 are simulated using the latest Model of Emission of Gases and Aerosols from Nature (MEGANv3.2) with the input of time-varying satellite-retrieved vegetation and reanalysis meteorology data. Comparison of model simulations with the site observations shows that the model can reasonably reproduce the magnitude of isoprene and monoterpene emission fluxes. The spatial distribution of the modeled isoprene emissions is generally comparable to the satellite retrievals. The estimated annual average global BVOC emissions are 835.4 Tg yr−1 with the emissions from isoprene, monoterpenes, sesquiterpenes, and other BVOC comprised of 347.7, 184.8, 23.3, and 279.6 Tg yr−1, respectively. We find that the decrease in global isoprene emissions (−0.07 % per year) caused by the increase in CO2 concentrations (−0.20 % per year) is stronger than that caused by changes in vegetation (−0.03 % per year) and meteorological factors (0.15 % per year). However, regional disparities are large. Isoprene emissions increase significantly in Europe, East Asia, and South Asia (0.37 % per year–0.66 % per year). Half of the increasing trend is contributed by increased leaf area index (LAI) (maximum over 0.02 m2 m−2 yr−1) and tree cover. Changes in meteorological factors contribute to another half, with elevated temperature dominating in Europe and increased soil moisture dominating in East and South Asia. In contrast, in South America and Southeast Asia, shifts in vegetation type associated with the BVOC emission capacity, which partly results from the deforestation and agricultural expansion, decrease the BVOC emission and offset nearly half of the emission increase caused by changes in meteorological factors. Overall, isoprene emission increases by 0.35 % per year and 0.25 % per year in South America and Southeast Asia, respectively. In Central Africa, a decrease in temperature dominates the negative emission trend (−0.74 % per year). Global monoterpene emissions show a significantly increasing trend (0.34 % per year, 0.6 Tg yr−1) compared to that of isoprene (−0.07 % per year, −0.2 Tg yr−1), especially in strong greening hotspots. This is mainly because the monoterpene emissions are more sensitive to changes in LAI and are not subject to the inhibition effect of CO2. The findings highlight the important roles of vegetation cover and biomass, temperature, and soil moisture in modulating the temporal variations of global BVOC emissions in the past 2 decades.

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“…Indeed, the opposite behaviour is seen, and CO 2 emissions decrease with increasing temperature as demand for building heating falls. Although anthropogenic emissions far outweigh any biogenic contributions to the observed CO 2 fluxes, it is possible to identify biogenic signals in other gases at IAO (Karl et al, 2018;Kaser et al, 2022).…”

Section: Carbon Dioxide Exchangementioning

confidence: 99%

Energy and mass exchange at an urban site in mountainous terrain – the Alpine city of Innsbruck

et al. 2022

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Abstract. This study represents the first detailed analysis of multi-year, near-surface turbulence observations for an urban area located in highly complex terrain. Using 4 years of eddy covariance measurements over the Alpine city of Innsbruck, Austria, the effects of the urban surface, orographic setting and mountain weather on energy and mass exchange are investigated. In terms of surface controls, the findings for Innsbruck are in accordance with previous studies at city centre sites. The available energy is partitioned mainly into net storage heat flux and sensible heat flux (each comprising about 40 % of the net radiation, Q*, during the daytime in summer). The latent heat flux is small by comparison (only about 10 % of Q*) due to the small amount of vegetation present but increases for short periods (6–12 h) following rainfall. Additional energy supplied by anthropogenic activities and heat released from the large thermal mass of the urban surface helps to support positive sensible heat fluxes in the city all year round. Annual observed CO2 fluxes (5.1 kg C m−2 yr−1) correspond well to modelled emissions and expectations based on findings at other sites with a similar proportion of vegetation. The net CO2 exchange is dominated by anthropogenic emissions from traffic in summer and building heating in winter. In contrast to previous urban observational studies, the effect of the orography is examined here. Innsbruck's location in a steep-sided valley results in marked diurnal and seasonal patterns in flow conditions. A typical valley wind circulation is observed (in the absence of strong synoptic forcing) with moderate up-valley winds during daytime, weaker down-valley winds at night (and in winter) and near-zero wind speeds around the times of the twice-daily wind reversal. Due to Innsbruck's location north of the main Alpine crest, southerly foehn events frequently have a marked effect on temperature, wind speed, turbulence and pollutant concentration. Warm, dry foehn air advected over the surface can lead to negative sensible heat fluxes both inside and outside the city. Increased wind speeds and intense mixing during foehn (turbulent kinetic energy often exceeds 5 m2 s−2) help to ventilate the city, illustrated here by low CO2 mixing ratios. Radiative exchange is also affected by the orography – incoming shortwave radiation is blocked by the terrain at low solar elevation. The interpretation of the dataset is complicated by distinct temporal patterns in flow conditions and the combined influences of the urban environment, terrain and atmospheric conditions. The analysis presented here reveals how Innsbruck's mountainous setting impacts the near-surface conditions in multiple ways, highlighting the similarities with previous studies in much flatter terrain and examining the differences in order to begin to understand interactions between urban and orographic processes.

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Interannual variability of terpenoid emissions in an alpine city

Cited by 22 publications

References 97 publications

Policy-Related Gains in Urban Air Quality May Be Offset by Increased Emissions in a Warming Climate

Policy-Related Gains in Urban Air Quality May Be Offset by Increased Emissions in a Warming Climate

Regional to global distributions, trends, and drivers of biogenic volatile organic compound emission from 2001 to 2020

Energy and mass exchange at an urban site in mountainous terrain – the Alpine city of Innsbruck

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