Aircraft measurement of HONO vertical profiles over a forested region

Zhang, Ning; Zhou, Xianliang; Shepson, P. B.; Gao, Haixiao; Alaghmand, M.; Stirm, B. H.

doi:10.1029/2009gl038999

Cited by 97 publications

(143 citation statements)

References 32 publications

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“…According to their results the ground surface accounts for most (∼70 %) of the HONO formation by NO 2 conversion but also for most of the loss (∼70 %). This confirms previous results from ground based field measurements (Harrison and Kitto, 1994;Stutz et al, 2002;Veitel, 2002;Kleffmann et al, 2003;Zhang et al, 2009;Sörgel et al, 2011), aircraft profiles (Zhang et al, 2009) and modelling that the ground surface is a major source of HONO. Hence, turbulent exchange has a significant impact on near surface HONO mixing ratios as already proposed by Febo et al (1996).…”

Section: Including the Parameterized Heterogeneous Hono Formation Intsupporting

confidence: 81%

“…These authors found a good correlation of HONO with radon, which is exclusively emitted from the ground. Furthermore, profiles from recent aircraft measurements were closely related to atmospheric stability with higher HONO values close to the ground and steeper gradients during stable conditions (Zhang et al, 2009). Therefore, mixing ratios are also expected to be controlled by the mixed volume which determines the surface to volume ratio (S/V).…”

Section: Including the Parameterized Heterogeneous Hono Formation Intmentioning

confidence: 99%

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Quantification of the unknown HONO daytime source and its relation to NO<sub>2</sub>

et al. 2011

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Abstract. During the DOMINO (Diel Oxidant MechanismIn relation to Nitrogen Oxides) campaign in southwest Spain we measured simultaneously all quantities necessary to calculate a photostationary state for HONO in the gas phase. These quantities comprise the concentrations of OH, NO, and HONO and the photolysis frequency of NO 2 , j (NO 2 ) as a proxy for j (HONO). This allowed us to calculate values of the unknown HONO daytime source. This unknown HONO source, normalized by NO 2 mixing ratios and expressed as a conversion frequency (% h −1 ), showed a clear dependence on j (NO 2 ) with values up to 43 % h −1 at noon. We compared our unknown HONO source with values calculated from the measured field data for two recently proposed processes, the light-induced NO 2 conversion on soot surfaces and the reaction of electronically excited NO 2 * with water vapour, with the result that these two reactions normally contributed less than 10 % (<1 % NO 2 + soot + hν; and <10 % NO 2 * + H 2 O) to our unknown HONO daytime source. OH production from HONO photolysis was found to be larger (by 20 %) than the "classical" OH formation from ozone photolysis (O( 1 D)) integrated over the day.Correspondence to: M. Sörgel

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Section: Including the Parameterized Heterogeneous Hono Formation Intsupporting

confidence: 81%

Section: Including the Parameterized Heterogeneous Hono Formation Intmentioning

confidence: 99%

Quantification of the unknown HONO daytime source and its relation to NO<sub>2</sub>

et al. 2011

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“…Two aircraft observations have been reported. Zhang et al (2009) reported negative concentration profiles up to 2500 m altitude, while Häseler et al (2009) observed no gradients in the lowest 1000 m of the atmosphere. Flux measurements of HONO have been carried out to study the daytime sources of HONO.…”

Section: Introductionmentioning

confidence: 99%

“…Various studies show that up to 55 % of the total OH budget during the day can be attributed to HONO photolysis in the morning and throughout the day Elshorbany et al, 2009;Acker et al, 2006b;Kleffmann et al, 2005;Aumont et al, 2003). The formation rate of daytime HONO by unknown pathways has been estimated in rural and urban regions in the range of 1-35 × 10 6 molec cm −3 s −1 (Acker et al, 2006a;Zhang et al, 2009;Elshorbany et al, 2009;Kleffmann et al, 2005;Zhou et al, 2002;Su et al, 2008;Sörgel et al, 2011a;Ren et al, 2010). Based on recent laboratory and field experiments various photolytic formation pathways occurring in the gas phase and on aerosol/ground surfaces have been proposed to explain the observed daytime HONO levels (Li et al, 2008;Stemmler et al, 2006;George et al, 2005;Zhou et al, 2007;Kleffmann, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, gas-phase sources in a well-mixed boundary layer should also, in principle, lead to a fairly uniform HONO vertical distribution. However, only a few observational studies have been performed to measure daytime HONO vertical profiles (Kleffmann, 2007;Zhang et al, 2009;Villena et al, 2011;Zhou et al, 2001;Häseler et al, 2009). The results from these studies are not conclusive.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of daytime HONO vertical gradients during SHARP 2009

et al. 2013

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Nitrous acid (HONO) acts as a major precursor of the hydroxyl radical (OH) in the urban atmospheric boundary layer in the morning and throughout the day. Despite its importance, HONO formation mechanisms are not yet completely understood. It is generally accepted that conversion of NO₂ on surfaces in the presence of water is responsible for the formation of HONO in the nocturnal boundary layer, although the type of surface on which the mechanism occurs is still under debate. Recent observations of higher than expected daytime HONO concentrations in both urban and rural areas indicate the presence of unknown daytime HONO source(s). Various formation pathways in the gas phase, and on aerosol and ground surfaces have been proposed to explain the presence of daytime HONO. However, it is unclear which mechanism dominates and, in the cases of heterogeneous mechanisms, on which surfaces they occur.

Vertical concentration profiles of HONO and its precursors can help in identifying the dominant HONO formation pathways. In this study, daytime HONO and NO₂ vertical profiles, measured in three different height intervals (20–70, 70–130, and 130–300 m) in Houston, TX, during the 2009 Study of Houston Atmospheric Radical Precursors (SHARP) are analyzed using a one-dimensional (1-D) chemistry and transport model. Model results with various HONO formation pathways suggested in the literature are compared to the the daytime HONO and HONO/NO₂ ratios observed during SHARP. The best agreement of HONO and HONO/NO₂ ratios between model and observations is achieved by including both a photolytic source of HONO at the ground and on the aerosol. Model sensitivity studies show that the observed diurnal variations of the HONO/NO₂ ratio are not reproduced by the model if there is only a photolytic HONO source on aerosol or in the gas phase from NO₂^* + H₂O. Further analysis of the formation and loss pathways of HONO shows a vertical dependence of HONO chemistry during the day. Photolytic HONO formation at the ground is the major formation pathway in the lowest 20 m, while a combination of gas-phase, photolytic formation on aerosol, and vertical transport is responsible for daytime HONO between 200–300 m a.g.l. HONO removal is dominated by vertical transport below 20 m and photolysis between 200–300 m a.g.l

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Evidence for a nitrous acid (HONO) reservoir at the ground surface in Bakersfield, CA, during CalNex 2010

et al. 2014

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Measurements of HONO (g) were validated to be free of known interferences for wet chemical instrumentation. The accumulation of nitrite into particulate matter was found to be enhanced when gaseous mixing ratios of HONO (g) were highest. Reactive uptake of HONO (g) on to lofted dust and the ground surface, forming a reservoir, is a potential mechanism to explain these observations. The AIM-IC HONO (g) measurements were parameterized in a chemical model to calculate the ground surface daytime HONO (g) source strength at 4.5 m above the surface, found to be on the order of 1.27 ppb h À1, to determine the relative importance of a surface reservoir. If all deposited nighttime HONO (g) is reemitted the following day, up to 30% of the daytime HONO (g) source at CalNex-SJV may be accounted for. The observations of HONO (g) and NO 2 À (p) in Bakersfield, during CalNex, suggest a surface sink and source of HONO (g) . Extension of currently accepted unknown daytime HONO (g) source reactions to include a potential surface HONO (g) reservoir should therefore be sound, but quantitation of the relative contributions of each surface source toward daytime HONO (g) production remains to be resolved.

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Aircraft measurement of HONO vertical profiles over a forested region

Cited by 97 publications

References 32 publications

Quantification of the unknown HONO daytime source and its relation to NO<sub>2</sub>

Quantification of the unknown HONO daytime source and its relation to NO<sub>2</sub>

Modeling of daytime HONO vertical gradients during SHARP 2009

Evidence for a nitrous acid (HONO) reservoir at the ground surface in Bakersfield, CA, during CalNex 2010

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Aircraft measurement of HONO vertical profiles over a forested region

Cited by 97 publications

References 32 publications

Quantification of the unknown HONO daytime source and its relation to NO&lt;sub&gt;2&lt;/sub&gt;

Quantification of the unknown HONO daytime source and its relation to NO&lt;sub&gt;2&lt;/sub&gt;

Modeling of daytime HONO vertical gradients during SHARP 2009

Evidence for a nitrous acid (HONO) reservoir at the ground surface in Bakersfield, CA, during CalNex 2010

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Quantification of the unknown HONO daytime source and its relation to NO<sub>2</sub>

Quantification of the unknown HONO daytime source and its relation to NO<sub>2</sub>