Wildfire Smoke Shading Observations: Impacts on Boundary Layer Mixing and Thermally Driven Smoke Transport

Carroll, Brian J.; Strobach, Edward; Baidar, Sunil; Holloway, Maxwell W.; McCarty, Brandi; Marchbanks, Richard; Brewer, W. Alan

doi:10.1029/2024JD043303

i

Wildfire Smoke Shading Observations: Impacts on Boundary Layer Mixing and Thermally Driven Smoke Transport

2025
By Carroll, Brian J. ; Strobach, Edward ; Baidar, Sunil ; ...

Details

Journal Title:

Journal of Geophysical Research: Atmospheres
Personal Author:

Carroll, Brian J. ; Strobach, Edward ; Baidar, Sunil ; Holloway, Maxwell W. ; McCarty, Brandi ; Marchbanks, Richard ; Brewer, W. Alan
NOAA Program & Office:

OAR (Oceanic and Atmospheric Research) ; CIRES (Cooperative Institute for Research in Environmental Sciences) ; CSL (Chemical Sciences Laboratory)
Description:

Smoke shading from wildfire smoke cools the surface and atmosphere below the smoke by absorbing and scattering sunlight. This has the potential to create meteorological feedback and large air quality impacts, but observations of smoke shading and induced local flows are rare. Mobile truck‐based Doppler lidar observations during the California Fire Dynamics Experiment (CalFiDE) in August and September 2022 provide a novel data set of smoke shading events. The truck‐based lidar conducted measurements of horizontal and vertical winds while underway, along with qualitative smoke backscatter, allowing a study of boundary layer (BL) dynamics in and out of the smoke shaded areas. An in situ temperature sensor on the truck recorded air temperature. Smoke shaded versus clear‐sky temperature differences of up to 8°C were observed over 12 km along a valley floor in complex terrain. Using vertical velocity variance as a measure of turbulent mixing, smoke shading reduced BL mixing by up to two orders of magnitude, preventing the development of an afternoon convective BL in some cases. Temperature gradients also resulted in thermally driven flows wherein the cold smoky air mass undercut warmer ambient air. One density current case was observed with a strong opposing flow resulting in a convergent updraft and shear‐induced vortices atop the smoke‐filled density current. In another case, the flow was impeded by complex terrain resulting in a slower‐moving smoke front and a temperature gradient that lagged behind the front.
Source:

Journal of Geophysical Research: Atmospheres, 130(13)
DOI:

https://doi.org/10.1029/2024JD043303
ISSN:

2169-897X ; 2169-8996
Format:

pdf
Publisher:

American Geophysical Union (AGU)
Document Type:

Journal Article
Funding:

Grant no. NA17OAR4320101 ; Grant no. NA22OAR4320151
License:

https://creativecommons.org/licenses/by/4.0/
Rights Information:

CC BY
Compliance:

Submitted
Main Document Checksum:

urn:sha-512:698b3dd09fe10c8805bf26aeb87c102d27a6419b46c353b093a2e72bd770d79bfd0e79b106f198bcd5767eebb25aea688d77ffdb181fcf3f617ed96b9b58880e
Download URL:

https://repository.library.noaa.gov/view/noaa/71486/noaa_71486_DS1.pdf
File Type:

[PDF - 6.80 MB ]

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