In-situ observations and modeling of small nitric acid-containing ice crystals

Voigt, Christiane; Kärcher, B.; Schläger, Hans; Schiller, C.; Krämer, M.; Reus, M. de; Vössing, H.; Borrmann, Stephan; Mitev, Valentin

doi:10.5194/acp-7-3373-2007

Cited by 42 publications

(44 citation statements)

References 29 publications

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“…Observations from recent aircraft campaigns have confirmed laboratory studies indicating HNO 3 uptake by cloud ice (Zondlo et al, 1997;Abbatt, 1997;Kondo et al, 2003;Voigt et al, 2006Voigt et al, , 2007Popp et al, 2007;Scheuer et al, 2010); thus frozen precipitation may play an important role in modulating O 3 production by lightning or aircraft sources of NO x in the upper troposphere. While there are clear differences in the interaction of gas-phase species with ice and liquid water, most models that include scavenging by frozen precipitation do not make any distinction between cold and warm clouds.…”

Section: Introductionsupporting

confidence: 64%

Toward a more physical representation of precipitation scavenging in global chemistry models: cloud overlap and ice physics and their impact on tropospheric ozone

2012

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Abstract. Uptake and removal of soluble trace gases and aerosols by precipitation represents a major uncertainty in the processes that control the vertical distribution of atmospheric trace species. Model representations of precipitation scavenging vary greatly in their complexity, and most are divorced from the physics of precipitation formation and transformation. Here, we describe a new large-scale precipitation scavenging algorithm, developed for the UCI chemistrytransport model (UCI-CTM), that represents a step toward a more physical treatment of scavenging through improvements in the formulation of the removal in sub-gridscale cloudy and ambient environments and their overlap within the column as well as ice phase uptake of soluble species. The UCI algorithm doubles the lifetime of HNO 3 in the upper troposphere relative to a scheme with commonly used fractional cloud cover assumptions and ice uptake determined by Henry's Law and provides better agreement with HNO 3 observations. We find that the process of ice phase scavenging of HNO 3 is a critical component of the tropospheric O 3 budget, but that NO x and O 3 mixing ratios are relatively insensitive to large differences in the removal rate. Ozone abundances are much more sensitive to the lifetime of HNO 4 , highlighting the need for better understanding of its interactions with ice and for additional observational constraints.

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Section: Introductionsupporting

confidence: 64%

Toward a more physical representation of precipitation scavenging in global chemistry models: cloud overlap and ice physics and their impact on tropospheric ozone

2012

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“…4 in more detail, we note that similar arguments were used to explain the in situ observations of high molar ratios of ∼5×10 −5 in nascent cirrus ice particles forming and growing at temperatures near 202 K and HNO 3 partial pressures similar to those encountered during CIRRUS-III (Voigt et al, 2007). In this case, it was proposed that sulfate aerosol particles dissolve large amounts of gaseous HNO 3 prior to freezing.…”

Section: Nitric Acid Uptake In Developing Contrailsmentioning

confidence: 96%

Airborne measurements of the nitric acid partitioning in persistent contrails

et al. 2009

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Abstract. This study reports the first systematic measurements of nitric acid (HNO 3 ) uptake in contrail ice particles at typical aircraft cruise altitudes. During the CIRRUS-III campaign cirrus clouds and almost 40 persistent contrails were probed with in situ instruments over Germany and Northern Europe in November 2006. Besides reactive nitrogen, water vapor, cloud ice water content, ice particle size distributions, and condensation nuclei were measured during 6 flights. Contrails with ages up to 12 h were detected at altitudes 10-11.5 km and temperatures 211-220 K. These contrails had a larger ice phase fraction of total nitric acid (HNO ice 3 /HNO tot 3 = 6%) than the ambient cirrus layers (3%). On average, the contrails contained twice as much HNO ice 3 as the cirrus clouds, 14 pmol/mol and 6 pmol/mol, respectively. Young contrails with ages below 1 h had a mean HNO ice 3 of 21 pmol/mol. The contrails had higher nitric acid to water molar ratios in ice and slightly higher ice water contents than the cirrus clouds under similar meteorological conditions. The differences in ice phase fractions and molar ratios between developing contrails and cirrus are likely caused by high plume concentrations of HNO 3 prior to contrail formation. The location of the measurements in the upper region of frontal cirrus layers might account for slight differences in the ice water content between contrails and adjacent cirrus clouds. The observed dependence of molar ratios as a function of the mean ice particle diameter suggests that icebound HNO 3 concentrations are controlled by uptake of exhaust HNO 3 in the freezing plume aerosols in young contrails and subsequent trapping of ambient HNO 3 in growing ice particles in older (age > 1 h) contrails.

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“…Higher oxidized NO y species are reduced to NO using a heated Au converter and CO gas as catalyst. Particle-phase NO y is detected by oversampling of particles in a forward facing subisokinetic inlet and evaporation and reduction of condensed NO y in the heated inlet and Au converter (Voigt et al, 2007). The nominal accuracy and precision of the gas-phase measurements are 10%/5% (NO) and 15%/7% (NO y ).…”

Section: Field Observationsmentioning

confidence: 99%

Evidence for heterogeneous chlorine activation in the tropical UTLS

et al. 2011

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Abstract. Airborne in-situ observations of ClO in the tropics were made during the TROCCINOX (Aracatuba, Brazil, February 2005) and SCOUT-O 3 (Darwin, Australia, November/December 2005) field campaigns. While during most flights significant amounts of ClO (≈10-20 parts per trillion, ppt) were present only in aged stratospheric air, instances of enhanced ClO mixing ratios of up to 40 ppt -significantly exceeding those expected from gas phase chemistry -were observed in air masses of a more tropospheric character. Most of these observations are associated with low temperatures or with the presence of cirrus clouds (often both), suggesting that cirrus ice particles and/or liquid aerosol at low temperatures may promote significant heterogeneous chlorine activation in the tropical upper troposphere lower stratosphere (UTLS). In two case studies, particularly high levels of ClO observed were reproduced by chemistry simulations only under the assumption that significant denoxification had occurred in the observed air. However, to reproduce the ClO observations in these simulations, O 3 mixing ratios higher than observed had to be assumed, and at least for one of these flights, a significant denoxification is in contrast to the observed NO levels, suggesting that the coupling of chlorine and nitrogen compounds in the tropical UTLS may not be completely understood.

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In-situ observations and modeling of small nitric acid-containing ice crystals

Cited by 42 publications

References 29 publications

Toward a more physical representation of precipitation scavenging in global chemistry models: cloud overlap and ice physics and their impact on tropospheric ozone

Toward a more physical representation of precipitation scavenging in global chemistry models: cloud overlap and ice physics and their impact on tropospheric ozone

Airborne measurements of the nitric acid partitioning in persistent contrails

Evidence for heterogeneous chlorine activation in the tropical UTLS

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