Fire Behavior
Modeling fire spread in sagebrush steppe using FARSITE: Improving input data and simulation accuracy
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Using RAP to inform pre-fire FBFM selection increased the accuracy of FARSITE simulations compared to parameterization with the standard LANDFIRE FBFM maps, in sagebrush steppe. Additionally, the crosswalk method appeared to have regional generalizability. Flanking and backfires were the primary source of disagreements between simulated and observed fire spread in FARSITE, which are sources of error that may require modeling of lateral heterogeneity in fuels and fire processes at finer scales than used here.
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Historical wildfire ignition locations and NOAA’s hourly time series of surface weather at 2.5 km resolution are used to drive ELMFIRE to produce wildfire hazards representative of the 2022 and 2052 conditions at 30 m resolution, with the future weather conditions scaled to the IPCC CMIP5 RCP4.5 model ensemble predictions. Winds and vegetation were held constant between the 2022 and 2052 simulations, and climate change’s impacts on the future fuel conditions are the main contributors to the changes observed in the 2052 results. Non-zero wildfire exposure is estimated for 71.8 million out of 140 million properties across CONUS. Climate change impacts add another 11% properties to this non-zero exposure class over the next 30 years, with much of this change observed in the forested areas east of the Mississippi River. “Major” aggregate wildfire exposure of greater than 6% over the 30-year analysis period from 2022 to 2052 is estimated for 10.2 million properties. The FSF-WFM represents a notable contribution to the ability to produce property-specific, climate-adjusted wildfire risk assessments in the US.
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2020 was a record year for wildfires in recent history, though the area burned was close to estimates of pre-suppression burning. We should expect more of these types of fire seasons in the future. Much of the burning was destructive rather than restorative and impacts to humans were severe.
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This review and analysis of the relevant scientific literature on the subject suggest that fuel characteristics have a gradual diminishing effect on the rate of fire spread in forest and shrubland fuel types with increasing fire danger, with the effect not being observable under extreme fire danger conditions. Empirical-based fire spread models with multiplicative fuel functions generally do not capture this effect adequately. The implications of this outcome on fire spread modelling and fuels management are discussed.
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Climate-driven changes in global temperatures and aridity are directly correlated with the decreasing interval between high-elevation fires. Fire activity is increasingly disproportionate at higher elevations than that of lower elevation forests in the Western United States. Studies documented an upslope advance of high-elevation fires of roughly 7.6 m (25 ft) per year. An additional 81,500 km2 (31,500 miles2) of the western United States forested regions were exposed to fires due to increased aridity between 1984 and 2017.
Webinar recording.
Description: This webinar will provide an introduction and overview of the FlamMap modeling system and its new capabilities with focus on several new additions:
- Landscape Utility for the creation and extraction of LANDFIRE based landscape files
- Spatial version of the First Order Fire Effects Model (FOFEM)
- Additional support for raster formats
- GeoTIFFs now supported when generating landscapes
- Save Raster Outputs as Single GeoTIFF File
- Measure Tool
- New tools to edit and graph weather
Presenter: Chuck McHugh, Fire Spatial Analyst, USFS RMRS Missoula Fire Sciences Lab
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This study shows that night-time fre intensity has increased, which is linked to hotter and drier nights. Our findings are based on global satellite observations of daytime and night-time fire detections and corresponding hourly climate data, from which we determine landcover-specific thresholds of VPD (VPDt), below which fire detections are very rare (less than 95 per cent modelled chance). Globally, daily minimum VPD increased by 25 per cent from 1979 to 2020. Across burnable lands, the annual number of flammable night-time hours—when VPD exceeds VPDt—increased by 110 hours, allowing five additional nights when flammability never ceases. Across nearly one-fifth of burnable lands, flammable nights increased by at least one week across this period. Globally, night fires have become 7.2 per cent more intense from 2003 to 2020, measured via a satellite record.
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Respondents were less confident in the accuracy of wind and precipitation forecasts than relative humidity or weather forecasts more generally. The influence of weather information on the decision depended on the framing used in the choice experiment; specifically, whether respondents were told the initial strategy had been to directly or indirectly attack the fire. Across conditions, fire managers generally preferred to indirectly attack the fire. Decisions about the tactics to apply going forward were more sensitive to time in season when the fire was occurring and wind and precipitation forecasts than to other attributes.
Webinar recording.
This 1-hour webinar presents findings from a recently completed study, which was funded by the Joint Fire Science Program, on landscape fuel treatment effectiveness within recent large wildfire events in north-central Washington State. It provides an overview of climate change and wildfires and the imperative for broad-scale adaptive management to increase landscape and community resilience to future wildfires. Then reports findings on the effects of prior fuel reduction treatments, biophysical environment, and weather on fire severity. The study also evaluated fireline effectiveness and how past fuel treatments assisted in safe and effective response.
Webinar recording.
Conflagrations like the 1871 Peshtigo have reemerged as important threats across North America and around the world. Understanding the factors and the phenomena that produced the fire environment of that day is possible because of weather observations collected and recorded at the time and studies of extreme fire behavior that continue to this day. Recounting it should be a cautionary tale for our lives as we continue to live them.