Uptake of NO_y on wave‐cloud ice particles

Abstract

Abstract. In a flight through a wave cloud during SUCCESS on 2 sampling opportunity since the particles are only minutes old and May 1996, simultaneous forward-and aft-facing NOy inlets were likely nucleated on sulfuric acid aerosols [Jensen et al., this issue]. used to infer the amount of condensed-phase NOy present on ice particles that were up to a few minutes old. Condensed-phase 2. Measurements amounts were 25-75 pptv, or 10-20% of gas-phase NOy. Given The "aft-inlet" NOy was sampled through a horizontal inlet the rapid HNO 3 uptake on ice observed in the laboratory, a model calculation implies that virtually all of the gas-phase HNO3 will be tube oriented perpendicular to the aircraft window. The tube's end depleted in the first 1-2 minutes after the appearance of ice. Thus face was a 45" cut, oriented 45" away from directly aft. This inlet , though for the ice cloud ice particles is the subject of this paper. particles of interest here, 10-20 [tm in diameter, the enhancement The partitioning of NOy between the gas and condensed phases factors are very close to the high-mass limit and so not as sizeis an important aspect of the NOy budget. Species will be subject dependent as for the smaller particles in PSCs. Since the highto different chemical and transport processes depending on mass limit is well-defined, and simply equal to the ratio of the true whether they are in the gas or condensed phase. Photolytic and air speed and the known flow velocity inside the inlet tube, chemical reactions will be different, and the vertical transport will enhancement factor errors due to flow around the inlet are be different, as particles will sediment. The presence of NOy minimal. The high-mass enhancement factor is altitude-dependent species in ice particles could result from several processes: (1) since a constant mass flow is drawn into the inlet. It has a value of They could be in the ice nuclei responsible for ice formation. (2) 43 for the case described in this paper at 41 kft. Integrations of Their presence could result from chemical conversions that occur the size-dependent enhancement factor over the particle size in/on the particles and that leave the product species in the spectrum give values which are generally within a few percent of condensed phase. Or, (3) they could be adsorbed onto the ice this upper limit when in the wave cloud and not at the very edge. surface during or after growth.On the other hand, the flow around the fuselage could also impact During SUCCESS we employed forward-and aft-facing inlets particle concentrations. Using the semi-empirical approach of to measure NOy. Since cloud ice particles are collected with King [1984], we have estimated a shadow zone depth for 10o[tm enhanced efficiency by the forward-facing inlet and discriminated diameter particles of 4 cm at the fuselage station (530 in.) of the against by the aft, the difference between the two simultaneous inlet. The inlet stuck out 37 cm into the flow, and at this point the NOy measurements enables a measurement of the amount...

HO<sub>2</sub>NO<sub>2</sub> and HNO<sub>3</sub> in the coastal Antarctic winter night: a "lab-in-the-field" experiment

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An overview of snow photochemistry: evidence, mechanisms and impacts

“…Cirrus clouds, for example, are radiatively important in the atmosphere and also provide surfaces for heterogeneous reactions. Laboratory studies have shown that HNO 3 can be taken up by ice surfaces at tropospheric temperatures (e.g., Hudson et al, 2002) and observations of uptake of HNO 3 by cirrus are accumulating (e.g., Weinheimer et al, 1998;Popp et al, 2004;Ziereis et al, 2004). A long-standing issue within atmospheric chemistry is that numerical models generally overestimate HNO 3 /NO x ratios in the upper troposphere (e.g., Chatfield, 1994;Brunner et al, 2005).…”

Airborne measurements of the nitric acid partitioning in persistent contrails

“…The interaction of HNO 3 and cirrus ice crystals was investigated experimentally during several field campaigns from the tropics to the Arctic (Weinheimer et al, 1998;Schlager et al, 1999;Kondo et al, 2003;Popp et al, 2004;Ziereis et al, 2004;Voigt et al, 2006). Voigt et al (2006) summarized these measurements in terms of average nitric acid to water molar ratios (µ=HNO ice 3 /H 2 O ice ) in cirrus ice particles and ice-bound fractions of total nitric acid (φ =HNO ice 3 /HNO tot 3 ).…”