Sulfuric acid and OH concentrations in a boreal forest site

Petäj̈ä, Tuukka; Mauldin, R. L.; Kosciuch, E.; McGrath, J.; Nieminen, Tuomo; Paasonen, Pauli; Boy, Michael; Adamov, Alexey; Kotiaho, Tapio; Kulmala, Markku

doi:10.5194/acp-9-7435-2009

Cited by 360 publications

(373 citation statements)

References 57 publications

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“…freshly formed particles are mainly formed photochemically (Petäjä et al, 2009;Ehn et al, 2014). The fraction of undefined days, however, remained constant regardless of cloudiness conditions.…”

Section: Effect Of Cloudiness On Npfmentioning

confidence: 99%

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Long-term analysis of clear-sky new particle formation events and nonevents in Hyytiälä

et al. 2017

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Abstract. New particle formation (NPF) events have been observed all around the world and are known to be a major source of atmospheric aerosol particles. Here we combine 20 years of observations in a boreal forest at the SMEAR II station (Station for Measuring Ecosystem-Atmosphere Relations) in Hyytiälä, Finland, by building on previously accumulated knowledge and by focusing on clear-sky (noncloudy) conditions. We first investigated the effect of cloudiness on NPF and then compared the NPF event and nonevent days during clear-sky conditions. In this comparison we considered, for example, the effects of calculated particle formation rates, condensation sink, trace gas concentrations and various meteorological quantities in discriminating NPF events from nonevents. The formation rate of 1.5 nm particles was calculated by using proxies for gaseous sulfuric acid and oxidized products of low volatile organic compounds, together with an empirical nucleation rate coefficient. As expected, our results indicate an increase in the frequency of NPF events under clear-sky conditions in comparison to cloudy ones. Also, focusing on clear-sky conditions enabled us to find a clear separation of many variables related to NPF. For instance, oxidized organic vapors showed a higher concentration during the clear-sky NPF event days, whereas the condensation sink (CS) and some trace gases had higher concentrations during the nonevent days. The calculated formation rate of 3 nm particles showed a notable difference between the NPF event and nonevent days during clear-sky conditions, especially in winter and spring. For springtime, we are able to find a threshold equation for the combined values of ambient temperature and CS, (CS (s −1 ) > −3.091 × 10 −5 × T (in Kelvin) + 0.0120), above which practically no clear-sky NPF event could be observed. Finally, we present a probability distribution for the frequency of NPF events at a specific CS and temperature.

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Section: Effect Of Cloudiness On Npfmentioning

confidence: 99%

“…The gaseous sulfuric acid concentration is estimated from a pseudo-steady-state-approximation proxy developed by Petäjä et al (2009). This proxy takes into consideration the sulfuric acid source and sink terms as…”

Section: Sulfuric Acid and Oxidized Organics Proxiesmentioning

confidence: 99%

Long-term analysis of clear-sky new particle formation events and nonevents in Hyytiälä

et al. 2017

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“…To have longer time series of also the oxidation rates of monoterpenes, simple model calculations for the oxidation rates were made using the UVB radiation intensity, concentration of O 3 and the modelled monoterpene concentration. For the first approximation the concentration of OH-radicals depends on UVB radiation intensity (Rohrer and Berresheim, 2006;Petäjä et al, 2009) and, therefore, the oxidation rates of monoterpenes can be approximated as…”

Section: Concentrations ([Mt] [Oh] and [O 3 ]) Withmentioning

confidence: 99%

Growth rates of nucleation mode particles in Hyytiälä during 2003−2009: variation with particle size, season, data analysis method and ambient conditions

et al. 2011

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Abstract. The condensational growth rate of aerosol particles formed in atmospheric new particle formation events is one of the most important factors influencing the lifetime of these particles and their ability to become climatically relevant. Diameter growth rates (GR) of nucleation mode particles were studied based on almost 7 yr of data measured during the years 2003-2009 at a boreal forest measurement station SMEAR II in Hyytiälä, Finland. The particle growth rates were estimated using particle size distributions measured with a Differential Mobility Particle Sizer (DMPS), a Balanced Scanning Mobility Analyzer (BSMA) and an Air Ion Spectrometer (AIS). Two GR analysis methods were tested. The particle growth rates were also compared to an extensive set of ambient meteorological parameters and trace gas concentrations to investigate the processes/constituents limiting the aerosol growth. The median growth rates of particles in the nucleation mode size ranges with diameters of 1.5-3 nm, 3-7 nm and 7-20 nm were 1.9 nm h −1 , 3.8 nm h −1 , and 4.3 nm h −1 , respectively. The median relative uncertainties in the growth rates due to the size distribution instrumentation in these size ranges were 25 %, 19 %, and 8 %, respectively. For the smallest particles (1.5-3 nm) the AIS data yielded on average higher growth rate values than the BSMA data, and higher growth rates were obtained from positively charged size distributions as compared with negatively charged particles. For particles larger than 3 nm in diameter no such systematic differences were found. For these particles the uncertainty in the growth rate related to Correspondence to: T. Yli-Juuti (taina.yli-juuti@helsinki.fi) the analysis method, with relative uncertainty of 16 %, was similar to that related to the instruments. The growth rates of 7-20 nm particles showed positive correlation with monoterpene concentrations and their oxidation rate by ozone. The oxidation rate by OH did not show a connection with GR. Our results indicate that the growth of nucleation mode particles in Hyytiälä is mainly limited by the concentrations of organic precursors.

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“…The sulfuric acid diffusion coefficients were estimated as a function of relative humidity from the H 2 SO 4 loss measured by CIMS along the flow tube. The detailed information regarding the operational principles and calibration of CIMS is given in [25][26][27] and therefore will not be given here again. The charging and detection efficiency of CIMS in the presence of trace concentrations of base impurities is discussed thoroughly theoretically (e.g., [13,28]) and also in recent experimental reports (e.g., [9,10]).…”

Section: Methodsmentioning

confidence: 99%

Temperature-Dependent Diffusion of H2SO4 in Air at Atmospherically Relevant Conditions: Laboratory Measurements Using Laminar Flow Technique

et al. 2017

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Abstract:We report flow tube measurements of the effective sulfuric acid diffusion coefficient at ranges of different relative humidities (from ∼4 to 70%), temperatures (278, 288 and 298 K) and initial H 2 SO 4 concentrations (from 1 × 10 6 to 1 × 10 8 molecules·cm −3 ). The measurements were carried out under laminar flow of humidified air containing trace amounts of impurities such as amines (few ppt), thus representing typical conditions met in Earth's continental boundary layer. The diffusion coefficients were calculated from the sulfuric acid wall loss rate coefficients that were obtained by measuring H 2 SO 4 concentration continuously at seven different positions along the flow tube with a chemical ionization mass spectrometer (CIMS). The wall loss rate coefficients and laminar flow conditions were verified with additional computational fluid dynamics (CFD) model FLUENT simulations. The determined effective sulfuric acid diffusion coefficients decreased with increasing relative humidity, as also seen in previous experiments, and had a rather strong power dependence with respect to temperature, around ∝ T 5.6 , which is in disagreement with the expected temperature dependence of ∼T 1.75 for pure vapours. Further clustering kinetics simulations using quantum chemical data showed that the effective diffusion coefficient is lowered by the increased diffusion volume of H 2 SO 4 molecules via a temperature-dependent attachment of base impurities like amines. Thus, the measurements and simulations suggest that in the atmosphere the attachment of sulfuric acid molecules with base molecules can lead to a lower than expected effective sulfuric acid diffusion coefficient with a higher than expected temperature dependence.

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Sulfuric acid and OH concentrations in a boreal forest site

Cited by 360 publications

References 57 publications

Long-term analysis of clear-sky new particle formation events and nonevents in Hyytiälä

Long-term analysis of clear-sky new particle formation events and nonevents in Hyytiälä

Growth rates of nucleation mode particles in Hyytiälä during 2003−2009: variation with particle size, season, data analysis method and ambient conditions

Temperature-Dependent Diffusion of H2SO4 in Air at Atmospherically Relevant Conditions: Laboratory Measurements Using Laminar Flow Technique

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