Modelling global pyrogeography using data derived from satellite imagery

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia - ULVegetation burning has an important impact on the global atmosphere and vegetated land surface. Deforestation fires, peatland fires, and ecosystems with shortening fire return interval contribute substantially to the build-up of atmospheric greenhouse gases affecting environmental quality and the climate system at local and regional scales. Recognition of the role of fire in the Earth system led to its designation as an Essential Climate Variable (ECV), a physical, chemical, or biological variable that has a crucial contribution towards characterization of Earth’s climate. The central task of this thesis was the development of a new global classification and map of fire regimes, using multiple correspondence analysis and hierarchical clustering, and relying on active fire data from the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD14ML product. That work was preceded by study dedicated to a thorough screening and exploratory spatial analysis of the dataset, and led to the development of an improved algorithm for identifying individual active fire clusters, and to global analysis of size inequality in their statistical distributions. In addition to this core research, other continental-global pyrogeography studies were developed, and are presented, dealing with: the time lag between the timing of optimal fire weather conditions and peak fire season dates as a diagnostic of anthropogenic vegetation burning; the spatial non-stationarity in the parameters of the relationship between population density and area burned; and the modulation of weekly cycles of vegetation burning in African croplands by regionally dominant religious affiliation. We hope that this set of studies may constitute a useful contribution to the burgeoning topic of global pyrogeograph

Detecção remota de áreas queimadas na Amazónia brasileira

The area burned in the brazilian Amazon during June-October 2000 was mapped using SPOT-VGT images. The burned area estimate was calibrated with Landsat TM data. Pareto boundary analysis was used to evaluate the best achievable classification accuracy, for 1.1km and 8km spatial resolution imagery. Finally, we present preliminary results from an analysis of the performance of three active fire products for detecting understory fires in the Acre rainforest during 2005

Wildfires in the Amazon region 2019

Analysis of wildfire trends in the Amazon regionJRC.E.1-Disaster Risk Managemen

Highlighting biome-specific sensitivity of fire size distributions to time-gap parameter using a new algorithm for fire event individuation

Detailed spatial-temporal characterization of individual fire dynamics using remote sensing data is important to understand fire-environment relationships, to support landscape-scale fire risk management, and to obtain improved statistics on fire size distributions over broad areas. Previously, individuation of events to quantify fire size distributions has been performed with the flood-fill algorithm. A key parameter of such algorithms is the time-gap used to cluster spatially adjacent fire-affected pixels and declare them as belonging to the same event. Choice of a time-gap to define a fire event entails several assumptions affecting the degree of clustering/fragmentation of the individual events. We evaluate the impact of different time-gaps on the number, size and spatial distribution of active fire clusters, using a new algorithm. The information produced by this algorithm includes number, size, and ignition date of active fire clusters. The algorithm was tested at a global scale using active fire observations from the Moderate Resolution Imaging Spectroradiometer (MODIS). Active fire cluster size distributions were characterized with the Gini coefficient, and the impact of changing time-gap values was analyzed on a 0.5° cell grid. As expected, the number of active fire clusters decreased and their mean size increased with the time-gap value. The largest sensitivity of fire size distributions to time-gap was observed in African tropical savannas and, to a lesser extent, in South America, Southeast Asia, and eastern Siberia. Sensitivity of fire individuation, and thus Gini coefficient values, to time-gap demonstrate the difficulty of individuating fire events in tropical savannas, where coalescence of flame fronts with distinct ignition locations and dates is very common, and fire size distributions strongly depend on algorithm parameterization. Thus, caution should be exercised when attempting to individualize fire events, characterizing their size distributions, and addressing their management implications, particularly in the African savannas

Burned area mapping in the brazilian savanna using a one-class support vector machine trained by active fires

We used the Visible Infrared Imaging Radiometer Suite (VIIRS) active fire data (375 m spatial resolution) to automatically extract multispectral samples and train a One-Class Support Vector Machine for burned area mapping, and applied the resulting classification algorithm to 300-m spatial resolution imagery from the Project for On-Board Autonomy-Vegetation (PROBA-V). The active fire data were screened to prevent extraction of unrepresentative burned area samples and combined with surface reflectance bi-weekly composites to produce burned area maps. The procedure was applied over the Brazilian Cerrado savanna, validated with reference maps obtained from Landsat images and compared with the Collection 6 Moderate Resolution Imaging Spectrometer (MODIS) Burned Area product (MCD64A1) Results show that the algorithm developed improved the detection of small-sized scars and displayed results more similar to the reference data than MCD64A1. Unlike active fire-based region growing algorithms, the proposed approach allows for the detection and mapping of burn scars without active fires, thus eliminating a potential source of omission error. The burned area mapping approach presented here should facilitate the development of operational-automated burned area algorithms, and is very straightforward for implementation with other sensorsinfo:eu-repo/semantics/publishedVersio

Advance EFFIS report on forest fires in Europe, Middle East and North Africa 2019

This report contains an anticipated annual summary of the fire season of 2019 with an analysis of fire danger and areas mapped in the European Forest Fire Information System (EFFIS). This report precedes that to be published in August/September 2020, which will include detailed reports prepared by countries in the Expert Group on Forest Fires.JRC.E.1-Disaster Risk Managemen

A new global burned area product for climate assessment of fire impacts

ABSTRACT Aim This paper presents a new global burned area (BA) product developed within the framework of the European Space Agency's Climate Change Initiative (CCI) programme, along with a first assessment of its potentials for atmospheric and carbon cycle modelling. Innovation Methods are presented for generating a new global BA product, along with a comparison with existing BA products, in terms of BA extension, fire size and shapes and emissions derived from biomass burnings. Main conclusions Three years of the global BA product were produced, accounting for a total BA of between 360 and 380 Mha year 21 . General omission and commission errors for BA were 0.76 and 0.64, but they decreased to 0.51 and 0.52, respectively, for sites with more than 10% BA. Intercomparison with other existing BA datasets found similar spatial and temporal trends, mainly with the BA included in the Global Fire Emissions Database (GFED4), although regional differences were found (particularly in the 2006 fires of eastern Europe). The simulated carbon emissions from biomass burning averaged 2.1 Pg C year 21

Religious affiliation modulates weekly cycles of cropland burning in Sub-Saharan Africa

Research ArticleVegetation burning is a common land management practice in Africa, where fire is used for hunting, livestock husbandry, pest control, food gathering, cropland fertilization, and wildfire prevention. Given such strong anthropogenic control of fire, we tested the hypotheses that fire activity displays weekly cycles, and that the week day with the fewest fires depends on regionally predominant religious affiliation.We also analyzed the effect of land use (anthrome) on weekly fire cycle significance. Fire density (fire counts.km-2) observed per week day in each region was modeled using a negative binomial regression model, with fire counts as response variable, region area as offset and a structured random effect to account for spatial dependence. Anthrome (settled, cropland, natural, rangeland), religion (Christian, Muslim, mixed) week day, and their 2-way and 3-way interactions were used as independent variables. Models were also built separately for each anthrome, relating regional fire density with week day and religious affiliation. Analysis revealed a significant interaction between religion and week day, i.e. regions with different religious affiliation (Christian, Muslim) display distinct weekly cycles of burning. However, the religion vs. week day interaction only is significant for croplands, i.e. fire activity in African croplands is significantly lower on Sunday in Christian regions and on Friday in Muslim regions. Magnitude of fire activity does not differ significantly among week days in rangelands and in natural areas, where fire use is under less strict control than in croplands. These findings can contribute towards improved specification of ignition patterns in regional/global vegetation fire models, and may lead to more accurate meteorological and chemical weather forecastinginfo:eu-repo/semantics/publishedVersio