Citation

Peterson DA, Thapa LH, Saide PE, Soja AJ, Gargulinski EM, Hyer EJ, Weinzierl B, Dollner M, Schöberl M, Papin PP, Kondragunta S, Camacho CP, Ichoku C, Moore RH, Hair JW, Crawford JH, Dennison PE, Kalashnikova OV, Bennese CE, Bui TP, DiGangi JP, Diskin GS, Fenn MA, Halliday HS, Jimenez J, Nowak JB, Robinson C, Sanchez K, Shingler TJ, Thornhill L, Wiggins EB, Winstead E, Xu C. Bull. Am. Meterol. Soc. 2022; 103(9): E2140-E2167.

Copyright

(Copyright © 2022, American Meteorological Society, Publisher Allen Press)

DOI

10.1175/BAMS-D-21-0049.1

PMID

unavailable

Abstract

The 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field experiment obtained a diverse set of in situ and remotely sensed measurements before and during a pyrocumulonimbus (pyroCb) event over the Williams Flats fire in Washington State. This unique dataset confirms that pyroCb activity is an efficient vertical smoke transport pathway into the upper troposphere and lower stratosphere (UTLS). The magnitude of smoke plumes observed in the UTLS has increased significantly in recent years, following unprecedented wildfire and pyroCb activity observed worldwide. The FIREX-AQ pyroCb dataset is therefore extremely relevant to a broad community, providing the first measurements of fresh smoke exhaust in the upper troposphere, including from within active pyroCb cloud tops. High-resolution remote sensing reveals that three plume cores linked to localized fire fronts, burning primarily in dense forest fuels, contributed to four total pyroCb "pulses." Rapid changes in fire geometry and spatial extent dramatically influenced the magnitude, behavior, and duration of pyroCb activity. Cloud probe measurements and weather radar identify the presence of large ice particles within the pyroCb and hydrometers below cloud base, indicating precipitation development. The resulting feedbacks suggest that vertical smoke transport efficiency was reduced slightly when compared with intense pyroCb events reaching the lower stratosphere. Physical and optical aerosol property measurements in pyroCb exhaust are compared with previous assumptions. A large suite of aerosol and gas-phase chemistry measurements sets a foundation for future studies aimed at understanding the composition of smoke plumes lifted by pyroconvection into the UTLS and their role in the climate system.

Language: en