Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA evolution

Janssen, Ruud H. H.; Arellano, Jordi Vilà‐Guerau de; Ganzeveld, L.; Kabat, P.; Jimenez, José L.; Farmer, Delphine K.; Heerwaarden, Chiel C. van; Mammarella, Ivan

doi:10.5194/acp-12-6827-2012

Cited by 30 publications

(45 citation statements)

References 39 publications

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“…Afternoon entrainment of air from the cleaner free troposphere into the ML (and export of mixed layer air to the FT) is shown to be an important loss process for particulate nitrate. Janssen et al (2012Janssen et al ( , 2013 have similarly identified afternoon loss via FT entrainment as an important process shaping the diurnal variability of surface-level organic aerosol concentrations in forested areas that are dominated by organic aerosol. Loss of NO…”

Section: Resultsmentioning

confidence: 99%

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

et al. 2017

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Abstract. This study discusses an analysis of combined airborne and ground observations of particulate nitrate ) concentrations made during the wintertime DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically resolved observations relevant to Air Quality) study at one of the most polluted cities in the United States -Fresno, CA -in the San Joaquin Valley (SJV) and focuses on developing an understanding of the various processes that impact surface nitrate concentrations during pollution events. The results provide an explicit case-study illustration of how nighttime chemistry can influence daytime surface-level NO 3 (p) in the RL, along with daytime photochemical production, can contribute substantially to the buildup and sustaining of severe pollution episodes. The exceptionally shallow nocturnal boundary layer (NBL) heights characteristic of wintertime pollution events in the SJV intensify the importance of nocturnal production aloft in the residual layer to daytime surface concentrations. The observations also demonstrate that dynamics within the RL can influence the earlymorning vertical distribution of NO − 3 (p) , despite low wintertime wind speeds. This overnight reshaping of the vertical distribution above the city plays an important role in determining the net impact of nocturnal chemical production on local and regional surface-level NO − 3 (p) concentrations. Entrainment of clean free-tropospheric (FT) air into the boundary layer in the afternoon is identified as an important process that reduces surface-level NO − 3 (p) and limits buildup during pollution episodes. The influence of dry deposition of HNO 3 gas to the surface on daytime particulate nitrate concentrations is important but limited by an excess of ammonia in the region, which leads to only a small fraction of nitrate existing in the gas phase even during the warmer daytime. However, in the late afternoon, when diminishing solar heating leads to a rapid fall in the mixed boundary layer height (BLH), the impact of surface deposition is temporarily enhanced and can lead to a substantial decline in surface-level particulate nitrate concentrations; this enhanced deposition is quickly arrested by a decrease in surface temperature, whichPublished by Copernicus Publications on behalf of the European Geosciences Union. 14748 G. Prabhakar et al.: Particulate nitrate formation in the wintertime drops the gas-phase fraction to near zero. The overall importance of enhanced late-afternoon gas-phase loss to the multiday buildup of pollution events is limited by the very shallow nocturnal boundary layer. The case study here demonstrates that mixing down of NO − 3 (p) from the RL can contribute a majority of the surface-level NO − 3 (p) in the morning (here, ∼ 80 %), and a strong influence can persist into the afternoon even when photochemical production is maximum. The particular day-to-day contribution of aloft nocturnal NO − 3 (p) production to surface concentrations will depend on prevailing chemical and meteorological ...

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Section: Resultsmentioning

confidence: 99%

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

et al. 2017

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“…Young et al [] attributed increasing surface concentrations of SOA during the morning in Fresno, California, to downmixing of residual layer (RL) air, based on the similarity with the diurnal cycle of nitrate aerosol. Further, Janssen et al [, ] have shown that the influence of ABL dynamics on the diurnal evolution of biogenic SOA in boreal and tropical forests can be substantial. Since the potential for boundary layer development is strong over cities compared to forested areas, due to the high sensible heat fluxes over paved surfaces, it is worth to explicitly study boundary layer effects on OA concentrations over urban areas as well.…”

Section: Introductionmentioning

confidence: 99%

“…For this purpose, we combine the approaches of Dzepina et al [], Hayes et al [], and Janssen et al [, ] and conduct (1) a speciation of OA sources, (2) a comparison with observed oxygen to carbon (O:C) ratios, and (3) sensitivity analyses to (i) residual layer OA concentrations, (ii) aging, emission, and deposition assumptions.…”

Section: Introductionmentioning

confidence: 99%

Influence of local production and vertical transport on the organic aerosol budget over Paris

et al. 2017

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We performed a case study of the organic aerosol (OA) budget during the MEGAPOLI campaign during summer 2009 in Paris. We combined aerosol mass spectrometer, gas phase chemistry, and atmospheric boundary layer (ABL) data and applied the MXL/MESSy column model. We find that during daytime, vertical mixing due to ABL growth has opposing effects on secondary organic aerosol (SOA) and primary organic aerosol (POA) concentrations. POA concentrations are mainly governed by dilution due to boundary layer expansion and transport of POA‐depleted air from aloft, while SOA concentrations are enhanced by entrainment of SOA‐rich air from the residual layer (RL). Further, local emissions and photochemical production control the diurnal cycle of SOA. SOA from intermediate volatility organic compounds constitutes about half of the locally formed SOA mass. Other processes that previously have been shown to influence the urban OA budget, such as aging of semivolatile and intermediate volatility organic compounds (S/IVOC), dry deposition of S/IVOCs, and IVOC emissions, are found to have minor influences on OA. Our model results show that the modern carbon content of the OA is driven by vertical and long‐range transport, with a minor contribution from local cooking emissions. SOA from regional sources and resulting from aging and long‐lived precursors can lead to high SOA concentrations above the ABL, which can strongly influence ground‐based observations through downward transport. Sensitivity analysis shows that modeled SOA concentrations in the ABL are equally sensitive to ABL dynamics as to SOA concentrations transported from the RL.

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“…The vast majority of nucleation events have been observed to take place during daytime , suggesting the central role of photochemical reactions and possible assistance by turbulent mixing in the atmosphere (Janssen et al, 2012). Systematic investigation of this topic has, however, been hampered by (i) the possibility of having more than one active nucleation mechanism in the atmosphere, (ii) the apparent and nonlinear participation of several different vapours in the nucleation process (Berndt et al, 2010;Paasonen et al, 2010;Zhang, 2010;Metzger et al, 2010;Riccobono et al, 2012;Bzdek et al, 2012), and (iii) the coupling of both nucleation and growth with meteorological conditions and the presence of pre-existing larger particles (Boulon et al, 2011;Kuang et al, 2010;Wu et al, 2011).…”

Section: A Hirsikko Et Al: Multiple Daytime Nucleation Events In Somentioning

confidence: 99%

Multiple daytime nucleation events in semi-clean savannah and industrial environments in South Africa: analysis based on observations

et al. 2013

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Recent studies have shown very high frequencies of atmospheric new particle formation in different environments in South Africa. Our aim here was to investigate the causes for two or three consecutive daytime nucleation events, followed by subsequent particle growth during the same day. We analysed 108 and 31 such days observed in a polluted industrial and moderately polluted rural environments, respectively, in South Africa. The analysis was based on two years of measurements at each site. After rejecting the days having notable changes in the air mass origin or local wind direction, i.e. two major reasons for observed multiple nucleation events, we were able to investigate other factors causing this phenomenon. Clouds were present during, or in between most of the analysed multiple particle formation events. Therefore, some of these events may have been single events, interrupted somehow by the presence of clouds. From further analysis, we propose that the first nucleation and growth event of the day was often associated with the mixing of a residual air layer rich in SO₂ (oxidized to sulphuric acid) into the shallow surface-coupled layer. The second nucleation and growth event of the day usually started before midday and was sometimes associated with renewed SO₂ emissions from industrial origin. However, it was also evident that vapours other than sulphuric acid were required for the particle growth during both events. This was especially the case when two simultaneously growing particle modes were observed. Based on our analysis, we conclude that the relative contributions of estimated H₂SO₄ and other vapours on the first and second nucleation and growth events of the day varied from day to day, depending on anthropogenic and natural emissions, as well as atmospheric conditions

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Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA evolution

Cited by 30 publications

References 39 publications

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

Influence of local production and vertical transport on the organic aerosol budget over Paris

Multiple daytime nucleation events in semi-clean savannah and industrial environments in South Africa: analysis based on observations

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