Determination of the relative ozone and PAN deposition velocities at night

Shepson, P. B.; Bottenheim, J. W.; Hastie, D. R.; Venkatram, Akula

doi:10.1029/92gl01118

Cited by 87 publications

(85 citation statements)

References 16 publications

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“…We have used the average 0 3 concentration within the NBL in the determination of Vd' To obtain this average we have assumed a linear decrease in ozone concentration with height, similar to that observed by Colbeck and Harrison (1985) and Broder and Gygax (1985), in which case Vd is given by kh/2. The values calculated in this way are directly comparable with those obtained by Broder and Gygax (1985) and Shepson et al (1992b) but will be a factor of two lower than those of Kelly et al (1984), who define Vd in terms ofthe surface concentration. The results of the determination of Vd are also presented in Table 1.…”

Section: Effect Ofthe Nbl On the Concentration Ofreactive Trace Speciessupporting

confidence: 69%

“…Cox et al, 1975;Harrison et al, 1978;Oltmans, 1981;Kelly et al, 1984;Broder and Gygax, 1985;Broder et al, 1981;Fehsenfeld et al, 1983;Lifshitz et al, 1988;Shepson et al, 1992b). The decrease has been attributed to the 03' isolated within the NBL, depositing to the surface and reacting with freshly emitted NO under the inversion.…”

Section: Effect Ofthe Nbl On the Concentration Ofreactive Trace Speciesmentioning

confidence: 99%

“…For P AN there are several cases (Singh and Salas, 1989; Shepson et al, 1992a,b;Ridley et al, 1990) where the observed nighttime minimum in PAN is attributed to deposition processes but, with the exception of Shepson et al (1992b), there is little discussion on the importance of the presence of the NBL on this deposition.…”

Section: Introducfionmentioning

confidence: 99%

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The influence of the nocturnal boundary layer on secondary trace species in the atmosphere at Dorset, Ontario

Hastie

Shepson

Sharma

et al. 1993

Atmospheric Environment. Part A. General Topics

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Abstract-The impact ofthe nocturnal boundary layer (NBL) on the concentrations of03' H 2 0 2 , PAN and CH20 has been studied for two 4-day periods, one in the summer of 1989 and the other in the spring of 1990. Where the presence of the nocturnal layer is clear, 03' PAN and CH 2 0 concentrations decrease rapidly and these species appear to be deposited to the surface. Break-up of the inversion in the morning returns concentrations to levels typical ofthe previous day. H 2 0 2 is removed much faster than the other species and it is replenished much more slowly. This appears to be due to the H 2 0 2 dissolving in water droplets resulting from the rapid cooling of the air. There is evidence for a morning maximum in PAN, likely due to the combination of high concentrations being brought downwards during the break-up of the NBL followed by thermal decomposition. Key word index:Ozone, hydrogen peroxide, formaldehyde, PAN, nocturnal boundary layer, deposition, nighttime chemistry. INTRODUCfIONField measurement studies are an important part of the atmospheric chemists' arsenal. They are performed to give data to assist in understanding specific questions in atmospheric chemistry, and for the development and evaluation of photochemical models.For convenience, most field measurements are made at the surface. However, the presence of the ground, and other local effects, can often significantly impact the observations, masking the larger scale chemical features one wishes to study. One such factor is the occurrence of a strong nocturnal boundary layer (NBL). By isolating the air being sampled from the bulk of the air aloft, for several hours each night, it often plays the principal role in determining the diurnal variation of the surface concentrations of a number of the more reactive species.In this paper we look in detail at the measurements of a number of secondary, reactive, trace gases, made at a rural site in Ontario, to see the effect of the NBL on their concentrations. The gases under study were 0 3 , HzO z , CHzO and PAN. These species have no direct emission sources, with the exception of a small amount of CHzO from combustion, and originate from atmospheric oxidation chemistry. By concentrating on these species, it is possible to focus on the chemistry that is occurring, rather than on the emission or transport processes. Furthermore, using the NBL to isolate a relatively small section of the atmosphere accentuates the observable consequences of any of these processes. Although the concentrations of this suite of species would be expected to be related, they have unique atmospheric lifetimes and decay mechanisms, and therefore they constitute a diverse set of molecules with which to probe our understanding of the system.The behaviour of ozone under the NBL is well documented (e.g. Cox et al., 1975;Harrison et al., 1978;Oltmans, 1981; Kelly et al., 1984; Broder and Gygax, 1985;Broder et al., 1981; Fehsenfeld et al., 1983;Lifshitz et al., 1988;Shepson et al., 1992b). However, the previously reported diurnal behavi...

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Section: Effect Ofthe Nbl On the Concentration Ofreactive Trace Speciessupporting

confidence: 69%

Section: Effect Ofthe Nbl On the Concentration Ofreactive Trace Speciesmentioning

confidence: 99%

See 1 more Smart Citation

The influence of the nocturnal boundary layer on secondary trace species in the atmosphere at Dorset, Ontario

Hastie

Shepson

Sharma

et al. 1993

Atmospheric Environment. Part A. General Topics

View full text Add to dashboard Cite

show abstract

“…It is generally felt that daytime measurements, after the breakup of the NBL, are truly representative because of the high turbulence, especially in the summer. The interpretation of nighttime data is more difficult because of the stratification of the atmosphere (Hastie et al, 1993;Shepson et al, 1992). The flights of 1 August allow us to examine this problem for both N0 2 and 0 3 , For these compounds, N0 2 has a surface source whereas 0 3 has a surface sink.…”

Section: How Representative Are Ground-based Measurements?mentioning

confidence: 99%

Vertical nitrogen dioxide and ozone concentrations measured from a tethered balloon in the Lower Fraser Valley

Pisano

McKendry

Steyn

et al. 1997

Atmospheric Environment

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Abstract-A series of vertical profiles of temperature, relative humidity, N0 2 and 0, were determined in lhe Lower Fraser Valley, British Columbia, as part oClhe PACIFIC '93 field study. Data from one day show very slructured vertical distributions of all parameters in the morning, as expected from the limited vertical mixing under the nocturnal inversion. N0 2 concentrations of 20ppbv were observed 300 m above the surface, while the surface concentrations were -2 ppbv. Ozone and nitrogen oxide chemislry were observed at all altitudes throughout the PBL. Titration of 0, by NO to produce N0 2 was observed in layers above the ground, under the influence of the NBL. An increase in odd oxygen lhroughout lhe PBL, during the morning and early afternoon, shows "smog chemistry" is occurring even though the groundbased 0J measurements suggest this day was not particularly chemically active. However, once the NBL has dissipated, the ground-based measurements seem representative of lhe entire PBL.

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“…Thus the assumption that dry deposition is the primary sink of HCHO during night remains effectively valid. Because the nocturnal boundary layer depth is critical to estimating the nighttime dry deposition velocity, a comparative method with nighttime ozone decay rates is used to circumvent the unobserved nocturnal boundary layer depth as in previous studies (Shepson et al, 1992;Sumner et al, 2001). Assuming that nocturnal production and loss from OH cancel, we calculate the first-order loss rate constant from the averaged logarithmic [HCHO] decay during the middle of the night (01:00 ∼ 04:00) to be −0.27 h −1 .…”

Section: Observed Formaldehyde Sinks and Inferred Dry Depositionmentioning

confidence: 99%

Observations of elevated formaldehyde over a forest canopy suggest missing sources from rapid oxidation of arboreal hydrocarbons

et al. 2010

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Abstract.To better understand the processing of biogenic VOCs (BVOCs) in the pine forests of the US Sierra Nevada, we measured HCHO at Blodgett Research Station using Quantum Cascade Laser Spectroscopy (QCLS) during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX) of late summer 2007. Four days of the experiment exhibited particularly copious HCHO, with midday peaks between 15-20 ppbv, while the other days developed delayed maxima between 8-14 ppbv in the early evening. From the expansive photochemical data set, we attempt to explain the observed HCHO concentrations by quantifying the various known photochemical production and loss terms in its chemical budget. Overall, known chemistry predicts a factor of 3-5 times less HCHO than observed. By examining diurnal patterns of the various budget terms we conclude that, during the high HCHO period, local, highly reactive oxidation chemistry produces an abundance of formaldehyde at the site. The results support the hypothesis of previous work at Blodgett Forest suggesting that large quantities of oxidation products, observed directly above the ponderosa pine canopy, Correspondence to: W. Choi (wschoi@ucdavis.edu) are evidence of profuse emissions of very reactive volatile organic compounds (VR-VOCs) from the forest. However, on the majority of days, under generally cooler and more moist conditions, lower levels of HCHO develop primarily influenced by the influx of precursors transported into the region along with the Sacramento plume.

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Determination of the relative ozone and PAN deposition velocities at night

Cited by 87 publications

References 16 publications

The influence of the nocturnal boundary layer on secondary trace species in the atmosphere at Dorset, Ontario

The influence of the nocturnal boundary layer on secondary trace species in the atmosphere at Dorset, Ontario

Vertical nitrogen dioxide and ozone concentrations measured from a tethered balloon in the Lower Fraser Valley

Observations of elevated formaldehyde over a forest canopy suggest missing sources from rapid oxidation of arboreal hydrocarbons

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