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Large Fires (large + fire)

Distribution by Scientific Domains

Earth and Environmental Science	50%

Selected Abstracts

Remote extinguishing of large fires with powder aerosols

FIRE AND MATERIALS, Issue 5 2006
Article first published online: 9 JAN 200, Mikhail Krasnyansky
Abstract A new method for distant extinguishing of fire spreading in an extended closed volume such as a mine working, storehouse, subway tunnel, electric cable channels, etc. is proposed. A novel extinguishing agent based on a stable mixture of superfine ammonium phosphate [NH4H2PO4] and modified fumed silica [SiO2,CH3] is supplied to the fire by a powerful ventilator. The properties of the extinguishing agent (average particle size, airborne residence time, distance of transfer by the air stream) have been studied in an experimental chamber (100 m3). A test extinguishing of a large-scale fire has been performed in an experimental tunnel 180 m in length. Extinguishing agent consumption, dynamics of temperature change over the tunnel length and composition of fire gases were recorded in this test. The influence of foam concentration, addition of nitrogen and halons to aerosol, were also studied. Copyright © 2006 John Wiley & Sons, Ltd. [source]

POSTFIRE SUCCESSION IN AN ADIRONDACK FOREST,

GEOGRAPHICAL REVIEW, Issue 4 2007
Susy Svatek Ziegler
ABSTRACT. Landscape diversity has increased with the surprising postfire establishment of aspen at upper elevations (700,945 meters above sea level) in the High Peaks of Adirondack Park in upstate New York. Tree seedlings returned quickly to the charred slopes west of Noonmark Mountain after an accidental fire consumed the forest in 1999. Aspen stands have replaced the spruce-fir-birch forests in the burned area even though mountain paper birch is expected to colonize burned sites at these elevations. Environmental conditions, historical events, and unique circumstances help explain why quaking aspen and bigtooth aspen rather than paper birch blanket the burned mountainside. Climate change over the past century to warmer, wetter conditions may have fostered this marked shift in species composition. In the unburned firebreak that people cleared to contain the flames, pin cherry has regenerated from seeds stored in the soil for nearly a century. The history of pin cherry on the site suggests that large fires or severe windthrow may have been more common in the region than was previously documented. [source]

Postfire response of North American boreal forest net primary productivity analyzed with satellite observations

GLOBAL CHANGE BIOLOGY, Issue 8 2003
Jeffrey A. Hicke
Abstract Fire is a major disturbance in the boreal forest, and has been shown to release significant amounts of carbon (C) to the atmosphere through combustion. However, less is known about the effects on ecosystems following fire, which include reduced productivity and changes in decomposition in the decade immediately following the disturbance. In this study, we assessed the impact of fire on net primary productivity (NPP) in the North American boreal forest using a 17-year record of satellite NDVI observations at 8- km spatial resolution together with a light-use efficiency model. We identified 61 fire scars in the satellite observations using digitized fire burn perimeters from a database of large fires. We studied the postfire response of NPP by analyzing the most impacted pixel within each burned area. NPP decreased in the year following the fire by 60,260 g C m,2 yr,1 (30,80%). By comparing pre- and postfire observations, we estimated a mean NPP recovery period for boreal forests of about 9 years, with substantial variability among fires. We incorporated this behavior into a carbon cycle model simulation to demonstrate these effects on net ecosystem production. The disturbance resulted in a release of C to the atmosphere during the first 8 years, followed by a small, but long-lived, sink lasting 150 years. Postfire net emissions were three times as large as from a model run without changing NPP. However, only small differences in the C cycle occurred between runs after 8 years due to the rapid recovery of NPP. We conclude by discussing the effects of fire on the long-term continental trends in satellite NDVI observed across boreal North America during the 1980s and 1990s. [source]

Atmospheric conditions associated with the exceptional fire season of 2003 in Portugal

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2006
Ricardo M. Trigo
Abstract The summer of 2003 was characterised by exceptional warm weather in Europe, particularly during the first two weeks of August, when a devastating sequence of large fires was observed, reaching an amount of circa 450 000 ha, the largest figure ever recorded in Portugal in modern times. They were concentrated in two relatively confined regions of Portugal and a considerable proportion of burnt area was due to fires started on the 2nd and 3rd of August. It is shown that the 850 hPa temperature values observed over Portugal for the 1st and 2nd of August 2003 were the highest recorded since 1958. Using data from synoptic stations covering the entire Portuguese territory, the event was characterised in fine detail, including the evolution of both maximum and minimum temperatures, surface relative humidity, and wind anomaly fields. The different spatial extent of maximum and minimum temperatures is analysed leading to the new all-time Portuguese records of 47.3 °C for maximum and 30.6 °C for minimum temperatures that were recorded on the 1st of August near the main area of occurrence of the largest fire. Finally, it is shown that the summer of 2003 was preceded by a wet winter followed by a very dry month of May, a precipitation anomalous regime that contributed to a climatic background that favoured the role played by the early August heatwave and the associated meteorological surface conditions. Copyright © 2006 Royal Meteorological Society [source]

Effects of climate on occurrence and size of large fires in a northern hardwood landscape: historical trends, forecasts, and implications for climate change in Témiscamingue, Québec

APPLIED VEGETATION SCIENCE, Issue 3 2009
C. Ronnie Drever
Abstract Questions: What climate variables best explain fire occurrence and area burned in the Great Lakes-St Lawrence forest of Canada? How will climate change influence these climate variables and thereby affect the occurrence of fire and area burned in a deciduous forest landscape in Témiscamingue, Québec, Canada? Location: West central Québec and the Great Lakes-St Lawrence forest of Canada. Methods: We first used an information-theoretic framework to evaluate the relative role of different weather variables in explaining occurrence and area burned of large fires (>200 ha, 1959-1999) across the Great Lakes-St Lawrence forest region. Second, we examined how these weather variables varied historically in Témiscamingue and, third, how they may change between the present and 2100 according to different scenarios of climate change based on two Global Circulation Models. Results: Mean monthly temperature maxima during the fire season (Apr-Oct) and weighted sequences of dry spells best explained fire occurrence and area burned. Between 1910 and 2004, mean monthly temperature maxima in Témiscamingue showed no apparent temporal trend, while dry spell sequences decreased in frequency and length. All future scenarios show an increase in mean monthly temperature maxima, and one model scenario forecasts an increase in dry spell sequences, resulting in a slight increase in forecasted annual area burned. Conclusion: Despite the forecasted increase in fire activity, effects of climate change on fire will not likely affect forest structure and composition as much as natural succession or harvesting and other disturbances, principally because of the large relative difference in area affected by these processes. [source]