Case studies of the oxidation of sulphur dioxide in a hill cap cloud using ground and aircraft based measurements

Gallagher, Martin; Downer, R. M.; Choularton, T. W.; Gay, Michel; Stromberg, I. M.; Mill, C. S.; Radojević, Miroslav; Tyler, Bonnie J.; Bandy, B. J.; Penkett, S. A.; Davies, Trevor J.; Dollard, G. J.; Jones, Brian M.

doi:10.1029/jd095id11p18517

Cited by 29 publications

(8 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The aircraft has K. M. Beswick et al: Turbulende measurements using the Aventech AIMMS20AQ 5451 been owned and run by the University of Manchester since 1984 and has been used on a wide variety of research work e.g. Smith et al (1989), Gallagher et al (1990Gallagher et al ( , 1994, Wood et al (1999), Bower et al (2000) and Webb et al (2004). Although normally hangared at Liverpool John Lennon Airport, for the duration of the CSIP campaign the aircraft was kept at Thruxton Airfield, in the centre of the CSIP operational area allowing a quick response to changing conditions.…”

Section: Cessna Instrumentationmentioning

confidence: 99%

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

et al. 2008

Self Cite

View full text Add to dashboard Cite

Abstract. The Convective Storm Initiation Project (CSIP) took place during the summers of 2004 and 2005, centred on the research radar at Chilbolton, UK. Precursors to convective precipitation were studied, using a comprehensive and broad-based range of fieldwork and modelling. The principal aim of CSIP was the detection of the primary and secondary initiation of convective cells. The Universities Facility for Atmospheric Measurements (UFAM) Cessna 182 was used to map temperature and humidity fields over a broad area within and beyond the Chilbolton radar beam. Additionally, air motion was measured using a new turbulence probe, the AIMMS20AQ. The performance of the probe is critically appraised, based on calibrations, test flights and data flights flown during CSIP intensive operating periods. In general, the probe performed well, although some aspects require more careful data interpretation which we describe in detail.

show abstract

Section: Cessna Instrumentationmentioning

confidence: 99%

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…al., 1990] indicate that the disparity between observed and predicted depletions of H202 at Great Dun Fell is probably not due to an enhanced rate of reaction between H•O 2 and S(IV) on cloud droplet surfaces. Clark et al [1990] hypothesize that the disparity is due to the postcollection reaction between H202 and S(IV), an explanation questioned by Gallagher et al [1990] who assert that systematic errors in the Great Dun Fell field measurements are compensated by the competing effect of added H202 due to cloud entrainment.…”

Section: Comparison With Other Resultsmentioning

confidence: 67%

“…and at Great Dun Fell, would be required to fully assess the magnitude of this uncertainty. Such measurements would also help to substantiate or refute the validity of the reaction rate enhancements observed byChandler et al [1988a, b, and1989] and byGallagher et al [1990]. Further differences between the Great Dun Fell and the Elk Mountain experiments are that at Elk Mountain there is little evidence for pH buffering by NH 3 or for the production of sulfate via the O3/S(IV ) reaction pathway.…”

mentioning

confidence: 77%

Sulfur dioxide oxidation in winter orographic clouds

Snider¹,

Vali²

1994

J. Geophys. Res.

View full text Add to dashboard Cite

The production of sulfate in cloud droplets, and the attendant depletion of sulfur dioxide (SO2) oxidants were studied in wintertime orographic clouds over southeastern Wyoming. By periodic (5-20 min) releases of SO 2 into the cloud the mixing ratio of SO 2 was raised to about double its background value of 0.7 parts per billion by volume (ppbv). Average values of the in-cloud reaction time, pseudo-firstorder SO 2 reaction rate, and hydrogen peroxide (H202)depletion were 400 s, 2.3 x 10 '4 s 'l, and 0.04 ppbv, respectively. The measured sulfate yields and H20 2 depletions show that H202 is the dominant oxidant for SO 2 in this situation; this finding is consistent with model results. Model simulations reveal that the O2/SO 2 reaction pathway (catalyzed by Mn(II) and Fe(III)) was competitive with the H202/802 reaction pathway on one out of the nine observation days. Organohydroperoxides were not depleted and other modeled reaction pathways (O3/SO 2 and HCHO/SO2) were inferred to be inhibited due to either the chemical (pH < 4.7) or physical (temperature below -5 øC, cloud water content less than 0.3 cm 3 m '3) properties of the cloud. The agreement found in this work between observed and predicted properties of the H202/SO2/H20 system contrasts with the work of Chandler et al. (1988a, b, 1989) and Gallagher et al. (1990) who observe a factor of 3 or larger discrepancy between laboratory and field measurements of the H202/802 reaction rate. 10-100 times shorter. Therefore in-cloud reactions constitute a major factor for regional and for global removal of SO 2. The quoted range of in-cloud lifetimes is based on laboratory kinetic investigations of the hydrogen peroxide (H202) and ozone (03) reactions with sulfur in the +4 oxidation state (S(IV)) [Hoffmann and Calvert, 1985; Hoffmann, 1986] and on data obtained in field studies [Hegg and Hobbs, 1982; Gervat et al., 1988]. However, there are important uncertainties in these values. Model calculations based on field observations conducted in northem England [Chandler et al., 1988a, b, 1989; Gallagher et al., 1990] suggest that the H202-S(IV ) reaction rate constants determined either using purified water (Hoffmann and Calvert, 1985] or using authentic precipitation samples [Lee et al., 1986] are a factor of 3-10 too low. The field studies themselves involve important uncertainties, mostly in regard to measurements of the depletion of H202. A small number of simultaneous measurements of sulfate production and of H202 depletion were obtained in experiments conducted at Great Dun Fell in the United Kingdom [Chandler et al., 1989; Clark et al., 1990; Gallagher et al., 1990]. Such data are essential if the field experiments are to be compared reliably with laboratory data and if they are to lead to identification of the dominant reaction pathways for SO 2. This information is necessary for reliable assessments of how changes in SO 2 emissions will affect sulfuric acid deposition. To help clarify the questions just discussed, studies of SO 2 oxidation to sulfate have been co...

show abstract

“…3.`Seeder-feeder rose' from Holme Moss and Abergavenny (total = 60 events) (National Power, 1994a, b) below pH 4 and the reaction with O 3 being more important above pH 5. Several ®eld experiments have been conducted at Great Dun Fell (GDF) in Cumbria (Chandler et al, 1988a, b;Gallagher et al, 1990) with the objective of measuring the oxidation rate of SO 2 in cloud. Great Dun Fell is part of the Pennine ridge in northern England that is frequently covered by a cap-cloud.…”

Section: The Eects Of the Presence Of Orographic Cloud On The Chemistmentioning

confidence: 99%

Parametrisation of the orographic enhancement of precipitation and deposition in a long-term, long-range transport model

Lee

Kingdon

Garland

et al. 2000

Annales Geophysicae

Self Cite

View full text Add to dashboard Cite

Orographic enhancement of wet deposition arising from the`seeder-feeder' eect is, by necessity, highly parametrised in long-range transport models of acid deposition that are long-term (i.e. annual average) and spatially resolved at tens of kilometres. Here, we describe a mechanistic approach to the incorporation of these mechanisms into such a model. The model formulation required the following: precipitation rate by direction and quanti®cation of the fractions that are orographic and non-orographic; treatment of the fast oxidation of sulfur dioxide in clouds; the directionality of the seeder-feeder process; and a quantitative basis for increasing wet deposition factors to account for the seeder-feeder process. The directionality of non-orographic precipitation was determined from meteorological data at 47 sites across the UK. Orographic precipitation varies on a much ®ner scale than can be interpolated from measurements, and thus a modelling approach was adopted. The directionality of the seederfeeder eect was taken from measurements. The enhancement factor of the orographic component of precipitation, assumed to represent feeder-rain, was determined from a review of measurements. Fast oxidation of sulfur dioxide is an observed phenomenon in cap-cloud, but limited in duration. An adjustment was made to the sulfur dioxide oxidation rate in the model in locations where cap-cloud was assumed to be present. The results from the model were compared with UK deposition budgets and enhanced wet deposition maps. The revised parametrisation underestimated the UK wet deposition budgets of oxidised N and S, but spatial patterns of deposition were improved for much of the UK. It was concluded that this was a satisfactory outcome given the constraints of the statistical approach of weighting of deposition at receptors utilising straight line trajectories. The sensitivity of the model to directional constraints of seeder-feeder enhancement was tested and it was concluded that a fairly narrow constraint resulted in similar estimations to a broader one, and the broader constraint was thus adopted as frontal conditions which result in the process arrive from a fairly broad band of directions. When enhancement was allowed to occur from all directions, UK wet deposition of oxidised N and S was increased by 10%. The sensitivity to the enhancement factor on wet deposition was tested and found to be relatively robust. An increase in the enhancement factor from 2 to 6 resulted in increases in UK wet deposition of oxidised N and S of 9 and 6%, respectively.

show abstract

Case studies of the oxidation of sulphur dioxide in a hill cap cloud using ground and aircraft based measurements

Cited by 29 publications

References 19 publications

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

Sulfur dioxide oxidation in winter orographic clouds

Parametrisation of the orographic enhancement of precipitation and deposition in a long-term, long-range transport model

Contact Info

Product

Resources

About