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WRF-Fire simulation of pyro-convection under the influence of low-level jet wind profiles
| Content Provider | Semantic Scholar |
|---|---|
| Author | Katurji, Marwan Simpson, Chris Seto, Donny |
| Copyright Year | 2015 |
| Abstract | Blowup wildland fire behaviour is characterised by a sudden increase in the fire intensity or forward rate of spread that precludes direct control. It is often accompanied by extreme pyro-convection and can pose a serious risk to firefighters. Blowups are difficult to predict due to our limited understanding of their environmental thresholds and the underlying driving physical processes. Low-level jets, a fairly common feature of the atmospheric boundary layer, have previously been observed at a number of blowups. However, there is currently no well-tested causal theory to explain this apparent connection between low-level jets and blowup fire behaviour. In this study, a two-way coupled atmosphere-fire model is used to conduct a series of idealised simulations that examine the sensitivity of modelled pyro-convective plume dynamics to variations in the low-level jet height and wind shear above the jet. The Weather Research and Forecast (WRF) numerical weather prediction model is used here in a large-eddy simulation configuration, and coupled to the WRF-Fire wildland fire physics module. Sensible and latent heat fluxes are calculated in WRF-Fire and can directly modify the potential temperature and water vapour mixing ratio in WRF, allowing the modelled fire to modify the local atmospheric dynamics. This dynamic feedback allows WRF and WRF-Fire to directly model the development of a pyroconvective plume under the influence of a low-level jet. The model simulations show only a limited sensitivity of the pyro-convective plume dynamics to the presence of a low-level jet and the variation in jet properties. In particular, the level of tilting and total vertical development of the plume, in addition to the resolved turbulent kinetic energy within the core of the plume, display some differences due to variations in the wind shear above the jet. It seems likely that the fire intensity is too high to allow for more pronounced variations in the plume properties, and future work will focus on fuel types with a lower fuel mass per unit area. |
| File Format | PDF HTM / HTML |
| DOI | 10.36334/modsim.2015.a4.katurji |
| Alternate Webpage(s) | http://www.mssanz.org.au/modsim2015/A4/katurji.pdf |
| Alternate Webpage(s) | https://doi.org/10.36334/modsim.2015.a4.katurji |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
