Atmospheric concentrations of the Cl atom, CIO radical, and HO radical in the coastal marine boundary layer

Chang, Chang-Tang; Liu, Tsun-Hsien; Jeng, Fu‐Tien

doi:10.1016/j.envres.2003.07.008

Cited by 83 publications

(37 citation statements)

References 18 publications

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“…With the exception of the results from Albaladejo et al [19], there is very good agreement between the results from absolute and relative rate experiments for reactions (1)- (3). Given this agreement we believe the kinetics of the reactions of chlorine atoms with C 2 H 2 , C 2 H 4 , and C 3 H 6 at ambient temperature over the pressure range 1-1000 Torr are well established.…”

Section: Discussionsupporting

confidence: 70%

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PLP–LIF study of the reactions of chlorine atoms with C2H2, C2H4, and C3H6 in 2–100 Torr of N2 diluent at 295 K

Iwasaki¹,

Chiba²,

Nakayama³

et al. 2010

Chemical Physics Letters

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Section: Discussionsupporting

confidence: 70%

“…There is increasing recognition of the importance of chlorine atoms in atmospheric chemistry both in the marine boundary layer and in locations far from coastlines [1][2][3][4]. This recognition has led to interest in the reactions of chlorine atoms with organic species.…”

Section: Introductionmentioning

confidence: 99%

PLP–LIF study of the reactions of chlorine atoms with C2H2, C2H4, and C3H6 in 2–100 Torr of N2 diluent at 295 K

Iwasaki¹,

Chiba²,

Nakayama³

et al. 2010

Chemical Physics Letters

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“…At Cl concentrations of 1×10 4 cm −3 the chemical lifetime of alkanes and alkynes towards this species is similar as that towards OH radicals (1×10 6 cm −3 ) (Finlayson-Pitts and Pitts, 2000). Results of measurements and estimates of chlorine radical concentrations in the marine BL of the tropics as well as the midlatitudes range two orders of magnitude ((0.25...30)×10 4 cm −3 , Singh et al, 1996;Wingenter et al, 1996;Lowe et al, 1999;von Glasow et al, 2002;Chang et al, 2004;Platt et al, 2004). Therefore a Cl concentration of 1×10 4 cm −3 was implemented in the reference run while additional sensitivity runs with the upper and lower limits were performed.…”

Section: Halogen Chemistrymentioning

confidence: 99%

Chemistry, transport and dry deposition of trace gases in the boundary layer over the tropical Atlantic Ocean and the Guyanas during the GABRIEL field campaign

et al. 2007

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Abstract. We present a comparison of different Lagrangian and chemical box model calculations with measurement data obtained during the GABRIEL campaign over the tropical Atlantic Ocean and the Amazon rainforest in the Guyanas, October 2005. Lagrangian modelling of boundary layer (BL) air constrained by measurements is used to derive a horizontal gradient (≈5.6 pmol/mol km −1 ) of CO from the ocean to the rainforest (east to west). This is significantly smaller than that derived from the measurements (16-48 pmol/mol km −1 ), indicating that photochemical production from organic precursors alone cannot explain the observed strong gradient. It appears that HCHO is overestimated by the Lagrangian and chemical box models, which include dry deposition but not exchange with the free troposphere (FT). The relatively short lifetime of HCHO implies substantial BL-FT exchange. The mixing-in of FT air affected by African and South American biomass burning at an estimated rate of 0.12 h −1 increases the CO and decreases the HCHO mixing ratios, improving agreement with measurements. A mean deposition velocity of 1.35 cm/s for H 2 O 2 over the ocean as well as over the rainforest is deduced assuming BL-FT exchange adequate to the results for CO. The measured increase of the organic peroxides from the ocean to the rainforest (≈0.66 nmol/mol d −1 ) is significantly overestimated by the Lagrangian model, even when using high values for the deposition velocity and the entrainment rate. Our results point at either heterogeneous loss of organic peroxides and/or their radical precursors, underestimated photodissociation or missing reaction paths of peroxy radicals not forming peroxides in isoprene chemistry. We calculate a mean integrated daytime net ozone production (NOP) in the Correspondence to: A. Stickler (alexander.stickler@env.ethz.ch) BL of (0.2±5.9) nmol/mol (ocean) and (2.4±2.1) nmol/mol (rainforest). The NOP strongly correlates with NO and has a positive tendency in the boundary layer over the rainforest.

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“…The rate constant of the reaction Cl + CHBr 3 → HCl + CBr 3 is approximately 1.5 times larger than the rate constant of the reaction OH + CHBr 3 → H 2 O + CBr 3 in the lower atmosphere. Cl concentrations in the lower atmosphere are between 10 3 to 10 6 cm −3 (Chang et al, 2004;Finlayson-Pitts, 1993) while OH concentrations are higher than 10 6 cm −3 . For most cases the degradation of CHBr 3 by chlorine can be therefore neglected.…”

Section: Marécal Et Al: Modelling Of Bromoform Transport and Chemmentioning

confidence: 99%

What do we learn about bromoform transport and chemistry in deep convection from fine scale modelling?

Marécal

Pirre²,

Krysztofiak³

et al. 2012

Atmos. Chem. Phys.

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Abstract. Bromoform is one of the most abundant halogenated Very Short-Lived Substances (VSLS) that possibly contributes, when degradated, to the inorganic halogen loading in the stratosphere. In this paper we present a detailed modelling study of the transport and the photochemical degradation of bromoform and its product gases (PGs) in a tropical convective cloud. The aim was to explore the transport and chemistry of bromoform under idealised conditions at the cloud scale. We used a 3-D cloud-resolving model coupled with a chemistry model including gaseous and aqueous chemistry. In particular, our model features explicit partitioning of the PGs between the gas phase and the aqueous phase based on newly calculated Henry's law coefficients using theoretical methods. We ran idealised simulations for up to 10 days that were initialised using a tropical radiosounding of atmospheric conditions and using outputs from a global chemistry-transport model for chemical species. Two simulations were run with stable atmospheric conditions with a bromoform initial mixing ratio of 40 pptv (part per trillion by volume) and 1.6 pptv up to 1 km altitude. The first simulation corresponds to high bromoform mixing ratios that are representative of real values found near strong localised sources (e.g. tropical coastal margins) and the second to the global tropical mean mixing ratio from observations. Both of these simulations show that the sum of bromoform and its PGs significantly decreases with time because of dry deposition, and that PGs are mainly in the form of HBr after 2 days of simulation. Two further simulations are conducted; these are similar to the first two simulations but include perturbations of temperature and moisture leading to the development of a convective cloud reaching the tropical tropopause layer (TTL). Results of these simulations show an efficient vertical transport of the bromoform from the boundary layer to the upper troposphere and the TTL. The bromoform mixing ratio in the TTL is up to 45 % of the initial boundary layer mixing ratio. The most abundant organic PGs, which are not very soluble, are also uplifted efficiently in both simulations featuring the convective perturbation. The inorganic PGs are more abundant than the organic PGs, and their mixing ratios in the upper troposphere and in the TTL depend on the partitioning between inorganic soluble and insoluble species in the convective cloud. Important soluble species such as HBr and HOBr are efficiently scavenged by rain. This removal of Br y by rain is reduced by the release of Br 2 (relatively insoluble) to the gas phase due to aqueous chemistry processes in the cloud droplets. The formation of Br 2 in the aqueous phase and its subsequent release to the gas phase makes a non negligible contribution to the high altitude bromine budget in the case of the large bromoform (40 pptv) initial mixing ratios. In this specific, yet realistic case, this Br 2 production process is important for the PG budget in the upper troposphere and in the TTL above con...

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Atmospheric concentrations of the Cl atom, CIO radical, and HO radical in the coastal marine boundary layer

Cited by 83 publications

References 18 publications

PLP–LIF study of the reactions of chlorine atoms with C2H2, C2H4, and C3H6 in 2–100 Torr of N2 diluent at 295 K

PLP–LIF study of the reactions of chlorine atoms with C2H2, C2H4, and C3H6 in 2–100 Torr of N2 diluent at 295 K

Chemistry, transport and dry deposition of trace gases in the boundary layer over the tropical Atlantic Ocean and the Guyanas during the GABRIEL field campaign

What do we learn about bromoform transport and chemistry in deep convection from fine scale modelling?

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