Preprints
https://doi.org/10.5194/acp-2022-610
https://doi.org/10.5194/acp-2022-610
 
13 Sep 2022
13 Sep 2022
Status: this preprint is currently under review for the journal ACP.

In Situ Microphysics Observations of Intense Pyroconvection from a Large Wildfire

David E. Kingsmill1, Jeffrey R. French2, and Neil P. Lareau3 David E. Kingsmill et al.
  • 1Cooperative Institute for Research in Environmental Studies, University of Colorado, Boulder, Colorado, USA
  • 2Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming, USA
  • 3Department of Physics, University of Nevada, Reno, Reno, Nevada, USA

Abstract. This study characterizes the size and shape distributions of 10 um to 6 mm diameter particles observed during six penetrations of wildfire-induced pyroconvection near Boise, Idaho, USA by a research aircraft over the period 29–30 August 2016. In situ measurements by the aircraft include winds, atmospheric state, bulk water content and particle concentration, size, and shape. These observations are complemented by data from airborne and ground-based radars. One of the penetrations is through a subsaturated smoke/ash plume with negligible cloud liquid water content that is characterized by an updraft of almost 36 m s-1. The size distribution of number concentration is very similar to that documented previously for a smoke plume from a prescribed fire and particle shapes exhibit qualitative and quantitative attributes comparable to ash particles created in a burn chamber. Particles sampled during this penetration are most likely pyrometeors composed of ash. Pyrocumulus clouds are probed in the other penetrations where values of relative humidity and cloud liquid water content are larger, but updrafts are weaker. Compared to the smoke-plume penetration, size distributions are mostly characterized by larger concentration and particle shapes exhibit a higher degree of circular symmetry. Particle composition in these pyrocumulus penetrations is most likely a combination of hydrometeors (ice particles) and pyrometeors (ash).

David E. Kingsmill et al.

Status: open (until 25 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

David E. Kingsmill et al.

David E. Kingsmill et al.

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Short summary
This study uses in situ aircraft measurements to characterize the size and shape distributions of 10 um to 6 mm diameter particles observed during six penetrations of wildfire-induced pyroconvection. Particles sampled in one penetration of a smoke plume are most likely pyrometeors composed of ash. The other penetrations are through pyrocumulus clouds where particle composition is most likely a combination of hydrometeors (ice particles) and pyrometeors (ash).
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