Articles | Volume 16, issue 4
Atmos. Chem. Phys., 16, 2243–2254, 2016
https://doi.org/10.5194/acp-16-2243-2016
Atmos. Chem. Phys., 16, 2243–2254, 2016
https://doi.org/10.5194/acp-16-2243-2016

Research article 26 Feb 2016

Research article | 26 Feb 2016

Anvil microphysical signatures associated with lightning-produced NOx

Jeffrey L. Stith1, Brett Basarab2,a, Steven A. Rutledge2, and Andrew Weinheimer1 Jeffrey L. Stith et al.
  • 1National Center for Atmospheric Research, Box 3000, Boulder, Colorado 80307, USA
  • 2Colorado State University, 3915 W Laport Ave, Fort Collins, Colorado 80523, USA
  • anow at: Global Weather Corporation, Boulder, Colorado, USA

Abstract. Thunderstorm anvils were studied during the Deep Convective Clouds and Chemistry experiment (DC3), using in situ measurements and observations of ice particles and NOx together with radar and Lightning Mapping Array measurements. A characteristic ice particle and NOx signature was found in the anvils from three storms, each containing high lightning flash rates in the storm core prior to anvil sampling. This signature exhibits high concentrations of frozen droplets (as measured by a Cloud Droplet Probe) coincident with lower NOx on the edges of the anvil. The central portion of these anvils exhibited a high degree of aggregation of these frozen droplets and higher levels of NOx. In contrast, a deep convective cell with low lightning flash rates had high concentrations of both frozen droplets and aggregated frozen droplets in its anvil's central region. A conceptual model for these results is presented and applied to the observations from each of these storms. High NOx concentrations are often found where aggregation of frozen droplets has occurred, which may be a reflection of aggregation by electrical forces in the regions where lightning is occurring, although the level of NOx for a given concentration of aggregates varies from storm to storm. These observations between anvil microphysics and lightning and/or NOx signatures suggest that lightning data may be an important tool to characterize or infer the microphysical, radiative, and chemical properties of thunderstorm anvils.

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Short summary
Lightning-produced NOx and ice particles were studied using airborne measurements in thunderstorm anvil clouds during the Deep Convective Clouds and Chemistry experiment (DC3). These data were compared with radar and Lightning Mapping Array (LMA) measurements. A characteristic signature was found in three anvils that relates the occurrence of frozen cloud droplets and aggregates of frozen droplets to the presence of lightning-produced NOx in these storms.
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