Total OH reactivity measurement in a BVOC dominated temperate forest during a summer campaign, 2014

Ramasamy, Sathiyamurthi; Ida, Akira; Jones, C. E.; Kato, S.; Tsurumaru, Hiroshi; Kishimoto, Iori; Kawasaki, Shio; Sadanaga, Yasuhiro; Nakashima, Yoshihiro; Nakayama, Tomoki; Matsumi, Yutaka; Mochida, Michihiro; Kagami, Sara; Deng, Yange; Ogawa, Shuichi; Kawana, Kaori; Kajii, Yoshizumi

doi:10.1016/j.atmosenv.2016.01.039

Cited by 29 publications

(32 citation statements)

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“…The contrast of the meteorological conditions is more obvious when NPF and no‐event days are compared (Figure S8). On NPF days, the high solar radiation and air temperature during the daytime promote the emission of BVOCs (Ramasamy et al, ) and the formation of BSOA (Han et al, , ). The relatively low RH values in the daytime might also be favorable for NPF, as suggested elsewhere (Hamed et al, ; Han et al, ).…”

Section: Resultsmentioning

confidence: 99%

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Hygroscopicity of Organic Aerosols and Their Contributions to CCN Concentrations Over a Midlatitude Forest in Japan

et al. 2018

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The formation of biogenic secondary organic aerosols (BSOAs) in forest environments is potentially important to cloud formation via changes of the cloud condensation nuclei (CCN) activity of aerosols. In this study, the CCN activation of submicrometer aerosols and their chemical compositions and size distributions were measured at a midlatitude forest site in Japan during the summer of 2014 to assess the hygroscopicity of the organic aerosols and their contributions to the local CCN concentrations. The mean number concentrations of the condensation nuclei and CCN at supersaturation (SS) conditions of 0.11–0.80% were 1,238 and 166–740 cm−3, respectively. Organic aerosols and sulfate dominated the submicrometer aerosol mass concentrations. The particle hygroscopicity increased with increases in particle diameters. The hygroscopicity parameter for the organics, κorg, was positively correlated with the atomic O to C ratio. The product of κorg and the volume fraction of OA was 0.12, accounting for 38% of the water uptake by aerosol particles. The hygroscopicity parameter of the locally formed fresh BSOA was estimated to be 0.09. The contribution of OA to the CCN number concentration, which was assessed by subtracting the CCN concentration of the hypothetical inorganic aerosols from that of the ambient aerosols, was 50–182 cm−3 for the SS range of 0.11–0.80%. The increase of the CCN number concentrations per 1‐μg/m3 increase of the BSOA was 23–299 cm−3 at 0.11–0.80% SS. The contribution of the BSOA to the CCN number concentration can be enhanced by new particle formation.

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Section: Resultsmentioning

confidence: 99%

“…Broad-leaf trees, such as Quercus serrata and Quercus crispula, are also distributed (Okumura, 2009). The concentrations of VOCs and inorganic gaseous species in the studied forest in a part of the studied period are reported elsewhere (Ramasamy et al, 2016).…”

Section: Atmospheric Observationsmentioning

confidence: 99%

Hygroscopicity of Organic Aerosols and Their Contributions to CCN Concentrations Over a Midlatitude Forest in Japan

et al. 2018

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“…The emissions of isoprene, monoterpenes, and sesquiterpenes from the area with these tree species were extracted from emission studies [ Tani and Kawawata, ; Mochizuki et al, ; Matsunaga et al, ; Matsunaga et al, ]. Ramasamy et al [] reported the presence of these VOCs at the site based on the observation during summer in a different year. They reported similar average mixing ratios of isoprene and the sum of 12 monoterpenes.…”

Section: Methodsmentioning

confidence: 99%

“…Matsunaga et al, 2013]. Ramasamy et al [2016] reported the presence of these VOCs at the site based on the observation during summer in a different year. They reported similar average mixing ratios of isoprene and the sum of 12 monoterpenes.…”

Section: Introductionmentioning

confidence: 99%

Hygroscopicity and cloud condensation nucleus activity of forest aerosol particles during summer in Wakayama, Japan

et al. 2017

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Size‐resolved distributions of the hygroscopic growth factor (g) and the ratios of cloud condensation nuclei (CCN) to condensation nuclei were observed at a forest site during summer in Japan. The g distributions at 85% relative humidity were unimodal. During 0900–2100 Japan Standard Time (JST) on new particle formation (NPF) event days, less hygroscopic particles (g ~ 1.1) were dominant in the Aitken‐mode range and the CCN activation diameters of the aerosols were large. These results are explained by the substantial contribution from newly formed biogenic secondary organic aerosol (BSOA). Hygroscopicity parameter κ for newly formed Aitken particles, calculated from g and CCN activation diameters, were 0.12 and 0.16, respectively, which were estimated to be the κ of organics. The κ values of particles were higher during 2100–0900 JST on NPF event days, in which the aerosols were characterized by the dominance of large and more hygroscopic particles. The number fractions of CCN that were predicted from time‐ and size‐resolved g at 0.23% and 0.41% supersaturations better matched the measured values compared to the cases with the time‐averaged g and/or g for the bulk composition, which suggests that the differences in particle hygroscopicity with time and size are important to CCN activation. A cloud parcel model indicates that the contributions from less hygroscopic particles to the number concentrations of CCN and cloud droplets were potentially large during NPF event days, which suggests a marked contribution from locally formed BSOA particles alongside particles from background air.

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“…The diurnal cycle of OH total reactivity with a maximum around midday in a biogenic environment is well documented in literature from observations of OH reactivity for a Mediterranean forest (Zannoni et al, 2016), for temperate forests (Sinha et al, 2008;Ramasamy et al, 2016) but also for tropical forests Williams et al, 2016). The values of OH reactivity in or outside thermals in the present study are the lower bound of measurements over forests and gathered in Yang et al (2016), between 1 and 76 s −1 .…”

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LES study of the impact of moist thermals on the oxidative capacity of the atmosphere in southern West Africa

Brosse¹,

Leriche²,

Mari³

et al. 2017

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Abstract. The hydroxyl radical (OH) is a highly reactive specie and plays a key role in the oxidative capacity of the atmosphere. The total OH reactivity, corresponding to the inverse of OH lifetime, may have a significant fraction non-attributable to commonly measured compounds. The turbulence-driven segregation of OH and its reactants can cause substantial modification of averaged reaction rates, and thus of the total OH reactivity, when compared to a perfectly mixed assumption. We study the impact of turbulent mixing on the OH reactivity with Large-Eddy Simulations from the Meso-NH model coupled on-line with a 5 detailed chemistry mechanism in two contrasted regimes. Our findings show that the non-mixing of isoprene (resp. aldehydes) and OH leads to 30% decrease (resp. 16% increase) of the mean reaction rate at the top of the boundary layer and consequently to 9% decrease (resp. 5% increase) of the OH total reactivity in a biogenic (resp. anthropogenic) environment. Moreover, the total OH reactivity is highest inside thermals in both cases.

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Total OH reactivity measurement in a BVOC dominated temperate forest during a summer campaign, 2014

Cited by 29 publications

References 50 publications

Hygroscopicity of Organic Aerosols and Their Contributions to CCN Concentrations Over a Midlatitude Forest in Japan

Hygroscopicity of Organic Aerosols and Their Contributions to CCN Concentrations Over a Midlatitude Forest in Japan

Hygroscopicity and cloud condensation nucleus activity of forest aerosol particles during summer in Wakayama, Japan

LES study of the impact of moist thermals on the oxidative capacity of the atmosphere in southern West Africa

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