Multicomponent aerosol dynamics model UHMA: model development and validation

Korhonen, Hannele; Lehtinen, K. E. J.; Kulmala, Markku

doi:10.5194/acpd-4-471-2004

Cited by 45 publications

(44 citation statements)

References 7 publications

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“…The model used in this study was UHMA (University of Helsinki Multicomponent Aerosol model [ Korhonen et al , 2004]), which is a size segregated aerosol dynamics box model that was developed for studies of multicomponent tropospheric aerosol particle populations. It has all basic aerosol dynamical mechanisms for clear sky conditions implemented: nucleation, condensation, coagulation and dry deposition.…”

Section: Methodsmentioning

confidence: 99%

Iodine dioxide nucleation simulations in coastal and remote marine environments

et al. 2009

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Aerosol dynamical box model simulations of coastal new particle formation were performed in order to investigate the nucleation and growth mechanisms in this environment. In the simulations the nucleating vapor was assumed to be iodine dioxide (OIO). Both Eulerian and Lagrangian type simulations were made and compared with observations. We tested three nucleation mechanisms: kinetic nucleation of OIO (K × [OIO]2), activation of clusters by OIO (A × [OIO]) and sulphuric acid‐induced activation of clusters containing OIO (B × [OIO] × [H2SO4]). All the nucleation mechanisms provided reasonable results, although the growth of particles due to condensation is inadequate in kinetic nucleation cases as compared with experimental measurements. Growth of newly formed particles could be assisted by any low‐volatility vapors should their concentration exceed 109 cm−3. Using the obtained values of coefficients K, A, and B we found that nucleation driven by iodine compounds in remote marine areas is possible, but by OIO and H2SO4 alone, only a minor fraction of newly formed particles is likely to reach detectable sizes. Owing to the scavenging by coagulation with background aerosol particles, few of them will likely reach climatically relevant sizes by acting as seed particles for other low‐volatility vapors. In order to elucidate the significance of our results, more detailed measurements of OIO source and photolysis rates, dimensions of precursor areas, and particle chemical composition are needed.

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Section: Methodsmentioning

confidence: 99%

Iodine dioxide nucleation simulations in coastal and remote marine environments

et al. 2009

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“…Such days were classified as class II events. Class Ia events are event days during which the new mode is clearly distinguishable from the pre‐existing particle population for the whole duration of the event, making these days good candidates for modelling case studies (Korhonen et al, 2004, Boy et al, 2006). On these days, the size distribution is dominated by the new particles.…”

Section: Methodsmentioning

confidence: 99%

New aerosol particle formation in different synoptic situations at Hyytiälä, Southern Finland

Sogacheva

Saukkonen

Nilsson

et al. 2008

Tellus B: Chemical and Physical Meteorology

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A B S T R A C TWe examine the meteorological conditions favourable for new particle formation as a contribution to clarifying the responsible processes. Synoptic weather maps and satellite images over Southern Finland for [2003][2004][2005] were examined, focusing mainly on air mass types, atmospheric frontal passages, and cloudiness. Arctic air masses are most favourable for new aerosol particle formation in the boreal forest. New particle formation tends to occur on days after passage of a cold front and on days without frontal passages. Cloudiness, often associated with frontal passages, decreases the amount of solar radiation, reducing the growth of new particles. When cloud cover exceeds 3-4 octas, particle formation proceeds at a slower rate or does not occur at all. During 2003During -2005, the conditions that favour particle formation at Hyytiälä (Arctic air mass, post-cold-frontal passage or no frontal passage and cloudiness less than 3-4 octas) occur on 198 d. On 105 (57%) of those days, new particle formation occurred, indicating that these meteorological conditions alone can favour, but are not sufficient for, new particle formation and growth. In contrast, 53 d (28%) were classified as undefined days; 30 d (15%) were non-event days, where no evidence of increasing particle concentration and growth has been noticed.

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“…The aerosol particle dynamics was investigated using the University of Helsinki Multicomponent Aerosol model (UHMA) described in detail by Korhonen et al (2004). The model incorporates the major microphysical processes that affect the aerosol under clear sky conditions, namely nucleation, coagulation, multicomponent condensation, and dry deposition.…”

Section: Methodsmentioning

confidence: 99%

Is nucleation capable of explaining observed aerosol integral number increase during southerly transport over Scandinavia?

Tunved

Korhonen

Ström

et al. 2006

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T Using a pseudo-Lagrangian approach, changes in aerosol size distribution was investigated during southerly transport under clear sky conditions from Finnish Lapland to Hyytiälä. Seventy-nine individual transport cases were considered. The mean transport distance was 700 km and mean transport time 66 h. On average, a sevenfold increase in Aitken mode number concentration could be observed. An increase in number concentration was observed in virtually all the cases. Several of the studied cases were associated with indications of nucleation at the receptor site. Six of the cases were simulated in detail utilizing a box-model approach. Aerosol dynamics was evaluated using the University of Helsinki Multi-component Aerosol model. Particle formation was assumed to be controlled by a kinetic nucleation mechanism. Growth of particles was suggested to be controlled by, except water and ammonia, sulphuric acid, and some unknown species with saturation vapour pressure of 3 × 10 6 cm −3 . This product was supposed to derive from terpene oxidation by hydroxyl radical, ozone, and nitrate radical.The investigation strongly suggests nucleation events occurring over large scales to be responsible for the observed number increase during transport under modelled conditions. Using a simplified two layer structure of the lowermost troposphere, we highlight the role of vertical exchange. Modelled growth rates were found to be in agreement with observational data, in the order of 1-2 nm h -1 . In order to reproduce the observed growth rates, a molar yield of condensable products from terpene oxidation of 10% was required. Concentration of sulphuric acid and condensable organic vapours were on average 3 × 10 6 and 1.5 × 10 7 cm −3 , respectively.

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Multicomponent aerosol dynamics model UHMA: model development and validation

Cited by 45 publications

References 7 publications

Iodine dioxide nucleation simulations in coastal and remote marine environments

Iodine dioxide nucleation simulations in coastal and remote marine environments

New aerosol particle formation in different synoptic situations at Hyytiälä, Southern Finland

Is nucleation capable of explaining observed aerosol integral number increase during southerly transport over Scandinavia?

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