Ronan Paugam

Use of Handheld Thermal Imager Data for Airborne Mapping of Fire Radiative Power and Energy and Flame Front Rate of Spread

Infrared (IR) remote sensing is increasingly used in studies of vegetation fire behavior, and high spatiotemporal resolution investigations often require data to be collected from airborne platforms, for example, standard helicopters. This paper aims to extend the range of conditions under which low-cost “handheld” thermal imaging cameras can be employed in such studies, particularly by enabling the effective and efficient geometric correction of thermal imagery collected from such devices, even when viewing far off-nadir (e.g., out of a side door or window). The approach is based on the automated detection of a set of fixed thermal “ground control points,” coupled with the use of a linear transformation matrix for warping the raw IR imagery to a fixed coordinate system. The output set of geometrically corrected brightness temperature and radiance images can be used to derive fire radiative power (FRP) and flame front rate of spread (ROS). We demonstrate and test our IR image processing methods on a series of case study fires, ranging from a small-scale laboratory to a 945-m2 outdoor experimental burn. We compare mapped information on FRP obtained from simultaneous nadir and off-nadir views, where we find differences that are in part controlled by flame structure and/or view angle. In the large open fire case, we compare the mapped fire radiative energy and ROS to simultaneously acquired aerial photography that provides the position of fuel and flames in high detail, and we demonstrate how these data sets can be used to explore various aspects of fire behavior.

Fire evolution in the radioactive forests of Ukraine and Belarus: future risks for the population and the environment

In this paper, we analyze the current and future status of forests in Ukraine and Belarus that were contaminated after the nuclear disaster in 1986. Using several models, together with remote-sensing data and observations, we studied how climate change in these forests may affect fire regimes. We investigated the possibility of 137Cs displacement over Europe by studying previous fire events, and examined three fire scenarios that depended on different emission altitudes of 137Cs, assuming that 10% of the forests were affected by fires. Field measurements and modeling simulations confirmed that numerous radioactive contaminants are still present at these sites in extremely large quantities. Forests in Eastern Europe are characterized by large, highly fire-prone patches that are conducive to the development of extreme crown fires. Since 1986, there has been a positive correlation between extreme fire events and drought in the two contaminated regions. Litter carbon storage in the area has doubled since 1986...

Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment

In April and August 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) caused concerns about the secondary radioactive contamination that might have spread over Europe. The present paper assessed, for the first time, the impact of these fires over Europe. About 10.9 TBq of 137Cs, 1.5 TBq of 90Sr, 7.8 GBq of 238Pu, 6.3 GBq of 239Pu, 9.4 GBq of 240Pu and 29.7 GBq of 241Am were released from both fire events corresponding to a serious event. The more labile elements escaped easier from the CEZ, whereas the larger refractory particles were removed more efficiently from the atmosphere mainly affecting the CEZ and its vicinity. During the spring 2015 fires, about 93% of the labile and 97% of the refractory particles ended in Eastern European countries. Similarly, during the summer 2015 fires, about 75% of the labile and 59% of the refractory radionuclides were exported from the CEZ with the majority depositing in Belarus and Russia. Effective doses were above 1 mSv y−1 in the CEZ, but much lower in the rest of Europe contributing an additional dose to the Eastern European population, which is far below a dose from a medical X-ray.

Direct estimation of Byram’s fire intensity from infrared remote sensing imagery

Byram’s fire intensity (IB,tot; kWm–1) is one the most important and widely accepted metrics for quantifying wildfire behaviour. Calculation of IB,tot requires measurement of fuel consumption, heat of combustion and rate of spread; existing methods for obtaining these measurements are either inexact or at times impossible to obtain in the field. This paper presents and evaluates a series of remote sensing methods for directly deriving radiative fire intensity (IB,rad; kWm–1) using the Fire Radiative Power (FRP) approach applied to thermal infrared imagery of spreading vegetation fires. Comparisons between the remote sensing data and ground-sampled measurements were used to evaluate the various estimates of IB,tot, and to determine the radiative fraction (radF) of a fire’s emitted energy. Results indicate that the IB,tot along an advancing flame front can be reasonably estimated (and agrees with traditional methods of estimation (R2=0.34–0.73)) from appropriately collected time-series of remote sensing imagery without the need for ground sampling or ancillary data. We further estimate that the radF of the fire’s emitted energy varies between 0.15 and 0.20 depending on the method of calculation, which is similar to previous estimates.

The Global Fire Atlas of individual fire size, duration, speed, and direction

1 Biospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 2 Department of Earth System Science, University of California, Irvine, CA 92697, USA 3 Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA 4 Centre Europe ́en de Recherche et de Formation Avance ́e en Calcul Scientifique, URA1875, CNRS, 10 Toulouse, France. 5 Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam, Netherlands