Atmospheric turbulent structures and fire sweeps during shrub fires and implications for flaming zone behaviour

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dc.contributor.authorNoonan B
dc.contributor.authorZhang J
dc.contributor.authorValencia A
dc.contributor.authorShumacher B
dc.contributor.authorKerr J
dc.contributor.authorStrand T
dc.contributor.authorPearce G
dc.contributor.authorZawar-Reza P
dc.contributor.authorKaturji, Marwan
dc.date.accessioned2022-12-07T02:29:21Z
dc.date.available2022-12-07T02:29:21Z
dc.date.issued2022en
dc.date.updated2022-11-19T06:59:30Z
dc.description.abstractBackground. Wildfires propagate through vegetation exhibiting complex spread patterns modulated by ambient atmospheric wind turbulence. Wind gusts at the fire-front extend and intensify flames causing direct convective heating towards unburnt fuels resulting in rapid acceleration of spread. Aims. To characterise ambient and fire turbulence over gorse shrub and explore how this contributes to fire behaviour. Methods. Six experimental burns were carried out in Rakaia, New Zealand under varying meteorological conditions. The ignition process ensured a fire-line propagating through dense gorse bush (1 m high). Two 30-m sonic anemometer towers measured turbulent wind velocity at six different levels above the ground. Visible imagery was captured by cameras mounted on uncrewed aerial vehicles at 200 m AGL. Key results. Using wavelet decomposition, we identified different turbulent time scales that varied between 1 and 128 s relative to height above vegetation. Quadrant analysis identified statistical distributions of atmospheric sweeps (downbursts of turbulence towards vegetation) with sustained events emanating from above the vegetation canopy and impinging at the surface with time scales up to 10 s. Conclusions. Image velocimetry enabled tracking of ‘fire sweeps’ and characterised for the first time their lifetime and dynamics in comparison with overlying atmospheric turbulent structures. Implications. This methodology can provide a comprehensive toolkit when investigating coupled atmosphere–fire interactions.en
dc.identifier.citationKaturji M, Noonan B, Zhang J, Valencia A, Shumacher B, Kerr J, Strand T, Pearce G, Zawar-Reza P (2022). Atmospheric turbulent structures and fire sweeps during shrub fires and implications for flaming zone behaviour. International Journal of Wildland Fire.en
dc.identifier.doihttp://doi.org/10.1071/wf22100
dc.identifier.issn1049-8001
dc.identifier.urihttps://hdl.handle.net/10092/104856
dc.languageen
dc.language.isoenen
dc.publisherCSIRO Publishingen
dc.rightsAll rights reserved unless otherwise stateden
dc.rights.urihttp://hdl.handle.net/10092/17651en
dc.subjectcoherent structuresen
dc.subjectfire sweepsen
dc.subjectfire turbulenceen
dc.subjectfire–atmosphere interactionsen
dc.subjectflaming zoneen
dc.subjectimage velocimetryen
dc.subjectsurface-layer turbulenceen
dc.subjectUAVen
dc.subject.anzsrc0502 Environmental Science and Managementen
dc.subject.anzsrc0602 Ecologyen
dc.subject.anzsrc0705 Forestry Sciencesen
dc.subject.anzsrcFields of Research::37 - Earth sciences::3701 - Atmospheric sciences::370105 - Atmospheric dynamicsen
dc.subject.anzsrcFields of Research::41 - Environmental sciences::4102 - Ecological applications::410205 - Fire ecologyen
dc.subject.anzsrcFields of Research::37 - Earth sciences::3709 - Physical geography and environmental geoscience::370903 - Natural hazardsen
dc.titleAtmospheric turbulent structures and fire sweeps during shrub fires and implications for flaming zone behaviouren
dc.typeJournal Articleen
uc.collegeFaculty of Science
uc.departmentSchool of Earth and Environment
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