Evaluating the role of NAT, NAD, and liquid H2SO4/H2O/HNO3 solutions in Antarctic polar stratospheric cloud aerosol: Observations and implications

Negro, L. A. Del; Fahey, D. W.; Donnelly, S. G.; Gao, R. S.; Keim, E. R.; Wamsley, R. C.; Woodbridge, E. L.; Dye, J. E.; Baumgardner, Darrel; Gandrud, B. W.; Wilson, John C.; Jonsson, Haflidi H.; Loewenstein, M.; Podolske, J. R.; Webster, Christopher R.; May, R. D.; Worsnop, Douglas R.; Tabazadeh, A.; Tolbert, Margaret A.; Kelly, K. K.; Chan, K. R.

doi:10.1029/97jd00764

Cited by 53 publications

(39 citation statements)

References 78 publications

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“…Simultaneous measurements of stratospheric particles and chlorine activation in Antarctica in July 1994 at temperatures below about 195 K (Kawa et al, 1997;Del Negro et al, 1997) showed no NAT particles or corresponding surface area increase. Thus, while liquid aerosol chlorine activation may occur near the threshold temperature T NAT , the two activation mechanisms are distinct.…”

Section: Heterogeneous Chemistry On Liquidsmentioning

confidence: 99%

Temperature thresholds for chlorine activation and ozone loss in the polar stratosphere

Drdla

Müller²

2012

Ann. Geophys.

122

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Abstract. Low stratospheric temperatures are known to be responsible for heterogeneous chlorine activation that leads to polar ozone depletion. Here, we discuss the temperature threshold below which substantial chlorine activation occurs. We suggest that the onset of chlorine activation is dominated by reactions on cold binary aerosol particles, without the formation of polar stratospheric clouds (PSCs), i.e. without any significant uptake of HNO 3 from the gas phase. Using reaction rates on cold binary aerosol in a model of stratospheric chemistry, a chlorine activation threshold temperature, T ACL , is derived. At typical stratospheric conditions, T ACL is similar in value to T NAT (within 1-2 K), the highest temperature at which nitric acid trihydrate (NAT) can exist. T NAT is still in use to parameterise the threshold temperature for the onset of chlorine activation. However, perturbations can cause T ACL to differ from T NAT : T ACL is dependent upon H 2 O and potential temperature, but unlike T NAT is not dependent upon HNO 3 . Furthermore, in contrast to T NAT , T ACL is dependent upon the stratospheric sulfate aerosol loading and thus provides a means to estimate the impact on polar ozone of strong volcanic eruptions and some geo-engineering options, which are discussed. A parameterisation of T ACL is provided here, allowing it to be calculated for low solar elevation (or high solar zenith angle) over a comprehensive range of stratospheric conditions. Considering T ACL as a proxy for chlorine activation cannot replace a detailed model calculation, and polar ozone loss is influenced by other factors apart from the initial chlorine activation. However, T ACL provides a more accurate description of the temperature conditions necessary for chlorine activation and ozone loss in the polar stratosphere than T NAT .

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Section: Heterogeneous Chemistry On Liquidsmentioning

confidence: 99%

Temperature thresholds for chlorine activation and ozone loss in the polar stratosphere

Drdla

Müller²

2012

Ann. Geophys.

122

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“…At temperatures below the nitric acid trihydrate (NAT) particle saturation point (TNAT) , the formation of liquid or solid particles due to mmo 3 uptake causes significant decreases in gas phase NO v concentrations [Carslaw et al, 1994[Carslaw et al, , 1997Drdla et al, 1994;Tabazadeh et al, 1994;Del Negro et al, 1997]. Particularly low temperatures cause particle growth and sedimentation, resulting in permanent removal of NOv from the air mass (denitrification).…”

Section: Introductionmentioning

confidence: 99%

Redistribution of nitric acid in the Arctic lower stratosphere during the winter of 1996–1997

Irie¹,

Koike²,

Kondo³

et al. 2001

J. Geophys. Res.

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“…These colder temperatures have been suggested in the STS ternary system [17] as prior system to form at the beginning of PSCs. A metastable ternary H 2 SO 4 -HNO 3 hydrate (H 2 SO 4 •HNO 3 •5H 2 O) is formed [18] in coexistence with binary H 2 SO 4 • kH 2 O hydrates (k =2, 3 and 4) for stratospheric temperatures between 193 K and 195 K. The STS composition implies a different PSC formation mechanism [19] than the threshold behavior associated with nitric acid trihydrated (NAT) [20] formation. STS aerosols form in a continuous uptake process from background sulfate aerosols as temperature is decreased from 210 K to 195 K. Submicrometer particles composed of STS are examined [21] to probe their phase and composition as a function of time at low-temperatures from 190 K to 203 K. The performed experiments [22] leave open two pathways for the formation of solid hydrates of HNO 3 or H 2 SO 4 acids from liquid aerosols, one hydrate forms heterogeneously on water ice below the frost point, the other forms above the frost point after homogeneous nucleation from binary HNO 3 /H 2 O solutions of which H 2 SO 4 concentrations are reduced due to strong temperature fluctuations.…”

Section: Introductionmentioning

confidence: 97%

Facet shapes and thermo-stabilities of H2SO4•HNO3 hydrates involved in polar stratospheric clouds

Verdes

Paniagua

2015

J Mol Model

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The nucleation, ice crystal shapes and thermodynamic stability of polar stratospheric clouds particles are interesting concerns owing to their implication in the ozone layer destruction. Some of these particles are formed by conformers of H2O, HNO3, and H2SO4. We carried out calculations using density functional theory (DFT) to obtain optimized structures. Several stable trimers are achieved -divided in two groups, one with HNO3 moiety, second with H2SO4 moiety- after pre-optimization at B3LYP/6-31G and subsequently optimization at B3LYP/aug-cc-pVTZ level of theory. For both most stable conformers five H2O molecules are added to their optimized trimers to calculate hydrated geometries. The OH stretching harmonic frequencies are provided for all aggregates. The zero-point energy correction (ZEPC), relative electronic energies (∆E), relative reaction Gibbs free energies ∆(∆G)k-relative, and cooling constant (K cooling ) are reported at three temperatures: 188 K, 195 K, and 210 K. Shapes given in our calculations are compared with various experimental shapes as well as comparisons with their thermo-stabilities.

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Evaluating the role of NAT, NAD, and liquid H₂SO₄/H₂O/HNO₃ solutions in Antarctic polar stratospheric cloud aerosol: Observations and implications

Cited by 53 publications

References 78 publications

Temperature thresholds for chlorine activation and ozone loss in the polar stratosphere

Temperature thresholds for chlorine activation and ozone loss in the polar stratosphere

Redistribution of nitric acid in the Arctic lower stratosphere during the winter of 1996–1997

Facet shapes and thermo-stabilities of H2SO4•HNO3 hydrates involved in polar stratospheric clouds

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