Airborne measurements of NO_x, tracer species, and small particles during the European Lightning Nitrogen Oxides Experiment

Abstract

[1] Airborne in situ measurements of NO, NO 2 , NO y , CO, CO 2 , O 3 , J(NO 2 ), and CN were performed in European thunderstorms during the field experiment EULINOX in July 1998. The measurements in the upper troposphere show enhanced NO x (= NO + NO 2 ) concentrations within thunderstorms and their outflow at horizontal scales from 300 m to several 100 km. The maximum NO mixing ratio measured inside a thundercloud close to lightning (the aircraft was also hit by a small lightning strike) was 25 ppbv. A regional NO x enhancement of 0.5 ppbv over central Europe could be traced back to a thunderstorm event starting $24 hours earlier over Spain. The fractions of NO x in thunderclouds which are produced by lightning and convectively transported from the polluted boundary layer are determined by using CO 2 and CO as tracers for boundary layer air. The analyses show that on average about 70% of the NO x increase measured in the anvil region was found to result from production by lightning and about 30% from NO x in the boundary layer. Thunderstorms are also strong sources of small particles. The peak CN concentrations measured within thunderstorm outflows (>30,000 particles STP cm À3 ) were distinctly higher than in the polluted boundary layer. The amount of NO x produced per thunderstorm and NO produced per lightning flash was estimated. The results imply that the annual mean NO x budget in the upper troposphere over Europe is dominated by aircraft emissions (0.1 TgN yr À1 ) in comparison to lightning production ($0.03 TgN yr À1 ). On the global scale, NO x produced by lightning (mean 3 TgN yr À1 ) prevails over aircraft-produced NO x (0.6 TgN yr À1 ).

Modeling lightning-NO<sub><i>x</i></sub> chemistry on a sub-grid scale in a global chemical transport model

“…Lange et al (2001) measured NO spikes of 3.5 ppb during the STREAM (Stratosphere-Troposphere Experiment by Aircraft Measurements) campaign associated with a matured storm over Ontario. Several peaks of NO mixing ratios from 0.7 to 6 ppb were also observed during EULINOX (European Lightning Nitrogen Oxides Project; Huntrieser et al, 2002) over Germany in July 1998. The LINOX (Lightning NOx) aircraft campaign recorded NO spikes from 0.75 to 1.25 ppb (Huntrieser et al, 1998) related to thunderstorms over Europe on 30 July 1996.…”

“…In the case of large NO x injection by lightning, the NO x content (∼ 40 ppt in unpolluted atmosphere) becomes close (a few ppb, according to in situ measurements; Dye et al, 2000;Huntrieser et al, 2002) to the surrounding ozone (60 ± 24 ppb) (Jaéglé et al, 1998). The ozone evolution within the plume is described by Reactions (R2)-(R6).…”

“…We defined these values using in situ measurements. The surface area (S T ) and the radius (R) for aerosols are defined such that S T = 0.28 m −1 and R = 1 µm −1 (Huntrieser et al, 2002); for ice, these are S T = 0.03 m −1 and R = 30 µm −1 (Knollenberg et al, 1993). In addition, the reaction probabilities of NO x on aerosols and ice crystals γ aerosols N 2 O 5 = 0.02 (Evans and Jacob, 2005) and γ ice N 2 O 5 = 0.03 (Sander et al, 2006), respectively, were used for our box model simulations.…”

Rapid intercontinental air pollution transport associated with a meteorological bomb

“…Values reported in the literature for the NO x produced per cloud-to-ground lightning flash vary considerably, for instance 6.7×10 26 molecules flash −1 (Price et al, 1997), 1.25-12.5×10 25 molecules flash −1 (Stith et al, 1999), or 8.1×10 25 molecules flash −1 (Huntrieser et al, 2002). DeCaria et al (2000) estimated that 3×10 26 molecules CGflash −1 are carried by the downdrafts.…”

“…Given the inefficient vertical transport of boundary-layer NO x , both aircraft (Ziereis et al, 2000) and, especially, lightning (Huntrieser et al 2002;Jeker et al 2000) emissions of NO x are thought to play important roles in the free troposphere. Indeed, large-scale NO x plumes have been found in the upper troposphere over North America (Brunner et al, 1998), that possibly were produced by lightning.…”