Fire is an essential element of the northern Australian ecosystems with extensive areas burnt each year. The basic climate condition of high rainfall during the summer monsoon, followed by an extended warm dry winter, along with highly combustible vegetation (much of which grows rapidly during summer and senesces during winter), creates a highly flammable environment. These vegetation conditions change under various naturally occurring climate oscillations such as El Niño–Southern Oscillation (ENSO). The present paper investigates the link between burnt areas of northern Australia, rainfall, the Southern Oscillation Index (SOI) and sea surface temperatures (SST) for a 9-year period (1997–2005). The burnt area distribution is compared with the strength and timing of the monthly averaged rainfall, SOI and SST. Results indicate a strong relationship between antecedent rainfall and ENSO indices with area burnt. This is especially strong between the burnt areas of June–October and the preceding rainfall of November–March (r = 0.90), the SOI of November–February (r = 0.78) and the SST of June–August (r = –0.64). The results from the present study reveal the ability to forecast annual burnt areas and present some of the dynamics of the climate–fire interactions and their value for management systems.

Summary This paper reports on a small-scale pilot experiment held early in the dry season near Darwin, Australia, in which fine-scale observations of several prescribed fires were made using infrared digital video. Infrared imaging is used routinely to locate fires as infrared radiation suffers little attenuation as it propagates through the smoke that normally obscures visible imagery. However, until now, little use has been made of digital video imagery in analyzing the convective-scale structure of prescribed (or wild) fires. The advantage of digital video imagery is that the individual frames can be objectively analyzed to determine the convective motion in the plane viewed by the camera. The infrared imagery shows mostly rising plumes, much like convective clouds. The flow is highly convective, and the vertical transport of heat is confined to relatively narrow thermals. The updrafts range from a few m s −1 to around 15 m s −1 . A numerical model is used to simulate one of the prescribed fires at very high-resolution. For the most part, the model predictions compare well to the observations. The model produces plumes that are around 7 m high, and spaced around 5 m apart, which is similar to that observed. The model correctly predicts the mean rate of spread of the fire to be 1.3 m s −1 . Perhaps the most serious limitations to using infrared observations of the type presented here are the difficulties in interpreting precisely the relationship between the observed infrared temperature field and the air temperature calculated by the model, and the exact connection between the infrared camera derived flow field and that calculated by the model.

In urban areas in the United Kingdom about three quarters of road accident costs arise from injuries to vulnerable users, of which pedestrians form the largest group. Whilst the distribution of these accidents with respect to type of road and crossing facility is known, there is a dearth of information regarding the exposure of pedestrians to risk in different circumstances, and the critical aspects of the interaction between road users. The aims of this research are to: a) quantify pedestrian exposure in different accident circumstances; b) establish the requirements for longer term monitoring of pedestrian activity; c) establish the balance of priorities between efforts to modify pedestrian behavior and traffic management/engineering measures; and d) provide quantitative guidance in policy development.

The object of this paper is to describe and demonstrate the necessity and utility of a coupled atmosphere-fire model: a three-dimensional, time-dependent wildfire simulation model, based on the primitive equations of motion and thermodynamics, that can represent the finescale dynamics of convective processes and capture ambient meteorological conditions.In constructing this coupled model, model resolution for both the atmosphere and the fuel was found to be important in avoiding solutions that are physically unrealistic, and this aspect is discussed. The anelastic approximation is made in the equations of motion, and whether this dynamical framework is appropriate in its usual form for simulating wildfire behavior is also considered.Two simple experiments-the first two in a series of numerical simulations using the coupled atmosphere-fire model-are presented here, showing the effect of wind speed on fire-line evolution in idealized and controlled conditions. The first experiment considers a 420-m-long fire line, and the second considers a 1500-m-long fire line, where wind speeds normal to the initial fire lines vary from 1 to 5 m s(-1). In agreement with some general observations, the short fire line remains stable and eventually develops a single conical shape, providing the wind speed is greater than about 1-2 m s(-1), while under similar conditions, the longer fire Line breaks up into multiple conical shapes. In both cases, the conical shapes are attributed to a feedback between the hot convective plumes and the near-surface convergence at the fire front. The experimental results reveal a dynamical explanation for fire-line breakup and geometry, demonstrating that the model is a valuable tool with which to investigate fire dynamics, and eventually it may be able to provide a credible scientific basis for policy decisions made by the meteorological and fire-management communities.

The extent of biomass burning in the Northern Territory, Australia, during 1992 (a year of low fire activity) was estimated using NOAA-AVHRR satellite imagery and was subsequently used to calculate the emission of gaseous compounds from biomass burning for that year. A total of 73,729 km2 was determined to have been burnt, representing 5.5% of the total Northern Territory area. The extent of biomass burning in different vegetation units in the Northern Territory was also estimated with eucalypt communities comprising 72% of the total area burnt. An estimated 29.5 x 106 tonnes of biomass was consumed by burning, resulting in the production of an estimated : 1. 11.3 Tg C as carbon dioxide, 2. 1.02 Tg C as carbon monoxide, (3) 5.23 x 10-3 Tg C as total particulate matter, 4. 26.1 x 10-3 Tg N as nitrous oxides, 5. various other trace gases. The calculated release of CO2 in this study accounts for only 41% of the estimated Australian contribution to global emmissions from biomass burning, indicating that the Australian contribution may be overestimted.

McArthur's Fire Danger Indices were developed originally as empirical models to describe fire danger in dry sclerophyll forest and grasslands of Australia. These indices are now used widely in southeastern Australia for fire danger rating and as a guideline for the issue of fire weather warnings. Nine years of historical fire reports, fire danger indices and meteorological information have been analysed objectively to develop a model to predict days of high fire activity in the mallee shrubland of northwestern Victoria. Tested on two years of independent data it was found that the use of a simple model utilising standard meteorological observations rather than the McArthur Forest Fire Danger Index reduced the false alarm rate from 98.4% to 96.7%. Although apparently a small reduction in false alarm rate, over a two year period days of high fire activity predicted incorrectly were reduced dramatically by 345 days.

Extensive regions of savanna in northern Australia burn each year. This has implications for global greenhouse gas emissions and ecological sustainability. To gain a greater understanding of the impact fire has on the environment, this project uses remote sensing to analyse the spatial and temporal distribution of fire on indigenous land. This feasibility project focuses on Maningrida, a remote aboriginal community in Northern Territory, Australia. The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard TERRA was selected for this project using bands 1 and 2 at 250-metre resolution. MODIS was chosen because it has free archived data, constant coverage and moderate resolution. Images were downloaded between March and October 2004 (dry season) and were then processed. Burn scar detection techniques (semi-automatic, change detection and visual identification) were performed to create a burnt/ unburnt mosaic of the area. Results showed that 60% of the region was burnt, with the most burning occurring in larger fires during the middle to late dry season. Early in the dry season fires were smaller and more numerous. A large proportion of fire ignition points were found in close proximity to roads and outstations. These results show the potential for MODIS to analyse spatial and temporal distribution of fire using MODIS to gain more accurate estimates of greenhouse gas emissions and provide information for land managers to use fire regimes for greater ecological sustainability.