New particle formation in the Midwestern USA: Event characteristics, meteorological context and vertical profiles

Pryor, Sara C.; Spaulding, A. M.; Barthelmie, R.J.

doi:10.1016/j.atmosenv.2010.07.045

Cited by 42 publications

(64 citation statements)

References 52 publications

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“…However, uncertainty remains regarding how important BVOC are to particle growth, how BVOC emissions might alter in the future, and what fraction of nucleation mode particles are removed by forest canopies and thus play no role in regional climate forcing. Consistent with prior research (Crippa and Pryor, 2013;Pryor et al, 2010), data collected during 2012-2014 over a deciduous forest in southern Indiana exhibit evidence of frequent NPF events (Fig. 4).…”

Section: Discussionsupporting

confidence: 73%

Forest canopy interactions with nucleation mode particles

2014

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Abstract. Ultrafine particle size distributions through a deciduous forest canopy indicate that nucleation mode particle concentrations decline with depth into the canopy, such that number concentrations at the bottom of the canopy are an average of 16 % lower than those at the top. However, growth rates of nucleation mode particles (diameters 6-30 nm) are invariant with height within the canopy, which implies that the semi-volatile gases contributing to their growth are comparatively well-mixed through the canopy. Growth rates of nucleation mode particles during a meteorological drought year (2012) were substantially lower than during a meteorologically normal year with high soil water potential (2013). This may reflect suppression of actual biogenic volatile organic compound (BVOC) emissions by drought and thus a reduction in the production of condensable products during the drought-affected vegetation season. This hypothesis is supported by evidence that growth rates during the normal year exhibit a positive correlation with emissions of BVOC modeled on observed forest composition, leaf area index, temperature and photosynthetically active radiation (PAR), but particle growth rates during the drought-affected vegetation season are not correlated with modeled BVOC emissions. These data thus provide indirect evidence that drought stress in forests may reduce BVOC emissions and limit growth of nucleation mode particles to climate-relevant sizes.

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Section: Discussionsupporting

confidence: 73%

Forest canopy interactions with nucleation mode particles

2014

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“…Similarly to the formation rate, the growth rate has a clear maximum in spring and autumn, a minimum during the dry winter season and a smaller minimum during the wet mid-summer. This cycle is similar to those observed in various other environments (Dal Maso et al, 2005;Qian et al, 2007;Manninen et al, 2010;Pryor et al, 2010;Cheung et al, 2011;Yli-Juuti et al, 2011) and opposite to the annual cycle of estimated sulphuric acid concentrations in Botsalano (Vakkari et al, 2011).…”

Section: Aerosol Formation and Growth Ratessupporting

confidence: 72%

Boundary layer nucleation as a source of new CCN in savannah environment

et al. 2013

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The South African savannah region is a complex environment of air pollution and natural emissions influenced by a strong seasonal cycle in biomass burning and strong precipitation. However, the scarcity of long-term observations means that the knowledge of controlling aerosol processes in this environment is limited. Here we use a recent dataset of 18 months of aerosol size distribution observations trying to understand the annual cycle of cloud condensation nuclei (CCN). Our observations show that the concentration of CCN-sized particles remains, in line with previous studies, high throughout the year with the highest concentrations during the dry winter and the lowest during the wet summer. During the wet season with reduced anthropogenic and biomass burning primary emissions, this pool of CCN is partly filled by boundary layer nucleation with subsequent growth. The enhanced importance of formation and growth during the wet season is addressed to increased biogenic activity together with enhanced free tropospheric removal decreasing the concentration of pre-existing CCN. During the dry season, while frequent new particle formation takes place, particle growth is reduced due to reduced condensing vapour concentrations. Thus in the dry season particles are not able to grow to sizes where they may act as CCN nearly as efficiently as during the wet season. The observations are compared to simulations by a global aerosol model GLOMAP. To our surprise, the global aerosol model utilized to explain the observations was not capable of re-producing the characteristics of particle formation and the annual CCN cycle, despite earlier good performance in predicting the particle concentrations in a number of diverse environments, including the South African savannah region. While the average yearly CCN concentrations of modelled CCN is close to observed concentrations, the characteristics of nucleation bursts and subsequent growth are not captured satisfactory by the model. Our sensitivity tests using different nucleation parameterizations and condensing organic vapour production rates show that neither of these is likely to explain the differences between observed and modelled nucleation and growth rates. A sensitivity study varying 28 modelling parameters indicates that the main uncertainties in the result are due to uncertainties in biomass burning emissions during the dry season, and anthropogenic sulphur emissions during the wet season, both in terms or emitted mass and particle sizes. The uncertainties appear to be mostly related to uncertainties in primary particle emissions, including the emissions variability not captured by monthly emission inventories. The results of this paper also highlights the fact that deficiencies in emissions estimates may result in deficiencies in particle production fluxes, while the end product such as modelled CCN concentration may be in line with observations

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“…A high seasonal event frequency in spring in the northern hemisphere is shared by other statistical descriptions of NPF events across the globe (e.g., Birmili and Wiedensohler, 2000;Hõrrak et al, 2000;Mäkelä et al, 2000;Birmili et al, 2003;Dal Maso et al, 2005;Pryor et al, 2010). There are a few exceptions to this seasonal trend found in the literature, including the high elevations studies discussed in the introduction.…”

Section: Discussionmentioning

confidence: 60%

Climatology of New Particle Formation and Corresponding Precursors at Storm Peak Laboratory

Hallar

Petersen

McCubbin

et al. 2016

Aerosol Air Qual. Res.

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Thirteen years of measurements of ultrafine (3-10 nm diameter) aerosols are presented from a remote high elevation (3210 m a.s.l.) site in Colorado, Storm Peak Laboratory. Previous work has shown that frequent new particle formation (NPF) occurs regularly at the site (52% of days). This long-term climatology of ultrafine aerosols clearly shows a seasonal dependence on new particle formation at Storm Peak Laboratory, reaching a maximum during the spring season and a minimum in summer. Recent sulfur dioxide data indicates a strong source region west of Storm Peak Laboratory, and this wind direction corresponds to the predominant wind direction observed during NPF events.

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New particle formation in the Midwestern USA: Event characteristics, meteorological context and vertical profiles

Cited by 42 publications

References 52 publications

Forest canopy interactions with nucleation mode particles

Forest canopy interactions with nucleation mode particles

Boundary layer nucleation as a source of new CCN in savannah environment

Climatology of New Particle Formation and Corresponding Precursors at Storm Peak Laboratory

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