Development of a virtual active fire product for Africa through a synthesis of geostationary and polar orbiting satellite data

Freeborn, Patrick H.; Wooster, Martin J.; Roberts, G.; Malamud, Bruce D.; Xu, Weidong

doi:10.1016/j.rse.2009.03.013

Cited by 69 publications

(82 citation statements)

References 48 publications

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“…The greatest cause of total FRP underestimation is rather the omission of low intensity/smaller fires, that remain undetected by the coarser spatial resolution geostationary sensor but which can be detected by MODIS. The degree of FRP underestimation varies spatially and temporally (Freeborn et al, 2009), however Roberts and Wooster (2008) indicated that it is relatively stable given sufficiently wide integration periods, and all continental-scale FRE values presented herein have therefore been adjusted for these effects where stated. For the purposes of this study the raw SEVIRI-derived active fire data were gridded to a 1 • resolution and adjustments made for both missing (small or low intensity) fires incapable of being detected by SEVIRI, and the percentage cloud-cover within each grid cell that can potentially mask fires from view, the corrections being made using the methods reported in Roberts et al (2005) and Roberts and Wooster (2008).…”

Section: Dataset Description and Continental Scale Fire Dynamicsmentioning

confidence: 99%

Annual and diurnal african biomass burning temporal dynamics

2009

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Abstract. Africa is the single largest continental source of biomass burning emissions. Here we conduct the first analysis of one full year of geostationary active fire detections and fire radiative power data recorded over Africa at 15-min temporal interval and a 3 km sub-satellite spatial resolution by the Spinning Enhanced Visible and Infrared Imager (SE-VIRI) imaging radiometer onboard the Meteosat-8 satellite. We use these data to provide new insights into the rates and totals of open biomass burning over Africa, particularly into the extremely strong seasonal and diurnal cycles that exist across the continent. We estimate peak daily biomass combustion totals to be 9 and 6 million tonnes of fuel per day in the northern and southern hemispheres respectively, and total fuel consumption between February 2004 and January 2005 is estimated to be at least 855 million tonnes. Analysis is carried out with regard to fire pixel temporal persistence, and we note that the majority of African fires are detected only once in consecutive 15 min imaging slots. An investigation of the variability of the diurnal fire cycle is carried out with respect to 20 different land cover types, and whilst differences are noted between land covers, the fire diurnal cycle characteristics for most land cover type are very similar in both African hemispheres. We compare the Fire Radiative Power (FRP) derived biomass combustion estimates to burned-areas, both at the scale of individual fires and over the entire continent at a 1-degree scale. Fuel consumption estimates are found to be less than 2 kg/m 2 for all land cover types noted to be subject to significant fire activity, and for savanna grasslands where literature values are commonly reported the FRP-derived median fuel consumption estimate of 300 g/m 2 is well within commonly quoted values. Meteosatderived FRP data of the type presented here is now available freely to interested users continuously and in near realtime for Africa, Europe and parts of South America via the EUMETSAT (European Organisation for the Exploitation of

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Section: Dataset Description and Continental Scale Fire Dynamicsmentioning

confidence: 99%

Annual and diurnal african biomass burning temporal dynamics

2009

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“…Similar to the LSA SAF processing of the SEVIRI active fire pixels [31], the per-pixel FRP measured by MODIS was adjusted based on τ atm , which itself was calculated according to (i) the MODIS view zenith angle; and (ii) the TCWV matched to the timing and location of the MODIS active fire pixels. Although the SEVIRI-derived active fire dataset used here represents some of the earliest records in the operational FRP-PIXEL archive, the algorithms and FRP-PIXEL and MODIS active fire product versions have not changed since this time, and this date window conveniently overlaps the timing and/or area where Freeborn et al [57,58] assimilated the same SEVIRI and MODIS active fire products. The conclusions of this study are therefore expected to be valid for the currently produced data coming from these systems.…”

Section: Preprocessingmentioning

confidence: 99%

“…Freeborn et al [58] show that for cumulative observations of the same fires, the ratio of the annual sum of FRP measured by SEVIRI to that concurrently measured by MODIS is (i) always less than one; and (ii) spatially variable across Africa (see Figure 4 in Freeborn et al [58]). Here the seasonal sum of FRP measured by SEVIRI at the MODIS overpass times was divided by that concurrently measured by MODIS to calculate a seasonal SEVIRI-to-MODIS ratio of FRP, ϕ FRP , at 0.5° grid cell resolution, as follows: The map of ϕ FRP at 0.5° grid cell resolution ( Figure 3) indicates that seasonal sums of coincident SEVIRI and MODIS measurements of FRP agree more closely in the north and east of the CAR compared to the south and west.…”

Section: Identifying Regions Of Interest (Rois)mentioning

confidence: 99%

Evaluating the SEVIRI Fire Thermal Anomaly Detection Algorithm across the Central African Republic Using the MODIS Active Fire Product

et al. 2014

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Satellite-based remote sensing of active fires is the only practical way to consistently and continuously monitor diurnal fluctuations in biomass burning from regional, to continental, to global scales. Failure to understand, quantify, and communicate the performance of an active fire detection algorithm, however, can lead to improper interpretations of the spatiotemporal distribution of biomass burning, and flawed estimates of fuel consumption and trace gas and aerosol emissions. This work evaluates the performance of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) Fire Thermal Anomaly (FTA) detection algorithm using seven months of active fire pixels detected by the Moderate Resolution Imaging Spectroradiometer (MODIS) across the Central African Republic (CAR). Results indicate that the omission rate of the SEVIRI FTA detection algorithm relative to MODIS varies spatially across the CAR, ranging from 25% in the south to 74% in the east. In the absence of confounding artifacts such as sunglint, uncertainties in the background thermal characterization, and cloud cover, the regional variation in SEVIRI's omission rate can be attributed to a coupling between SEVIRI's low spatial resolution detection bias (i.e., the inability to detect fires below a OPEN ACCESSRemote Sens. 2014, 6 1891 certain size and intensity) and a strong geographic gradient in active fire characteristics across the CAR. SEVIRI's commission rate relative to MODIS increases from 9% when evaluated near MODIS nadir to 53% near the MODIS scene edges, indicating that SEVIRI errors of commission at the MODIS scene edges may not be false alarms but rather true fires that MODIS failed to detect as a result of larger pixel sizes at extreme MODIS scan angles. Results from this work are expected to facilitate (i) future improvements to the SEVIRI FTA detection algorithm; (ii) the assimilation of the SEVIRI and MODIS active fire products; and (iii) the potential inclusion of SEVIRI into a network of geostationary sensors designed to achieve global diurnal active fire monitoring.

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“…Such improvements probably become more necessary as satellite-derived burned area and fire radiative power (FRP) products related to large-area wildfire fuel consumption become more mature (e.g. Roy et al, 2008;Freeborn et al, 2009;Giglio et al, 2009;Kaiser et al, 2009;Xu et al, 2010;van der Werf et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Field determination of biomass burning emission ratios and factors via open-path FTIR spectroscopy and fire radiative power assessment: headfire, backfire and residual smouldering combustion in African savannahs

et al. 2011

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Abstract. Biomass burning emissions factors are vital to quantifying trace gas release from vegetation fires. Here we evaluate emissions factors for a series of savannah fires in Kruger National Park (KNP), South Africa using groundbased open path Fourier transform infrared (FTIR) spectroscopy and an IR source separated by 150-250 m distance. Molecular abundances along the extended open path are retrieved using a spectral forward model coupled to a nonlinear least squares fitting approach. We demonstrate derivation of trace gas column amounts for horizontal paths transecting the width of the advected plume, and find for example that CO mixing ratio changes of ∼0.01 µmol mol −1 [10 ppbv] can be detected across the relatively long optical paths used here. Though FTIR spectroscopy can detect dozens of different chemical species present in vegetation fire smoke, we focus our analysis on five key combustion products released preferentially during the pyrolysis (CH 2 O), flaming (CO 2 ) and smoldering (CO, CH 4 , NH 3 ) processes. We demonstrate that well constrained emissions ratios for these gases to both CO 2 and CO can be derivedCorrespondence to: M. J. Wooster (martin.wooster@kcl.ac.uk) for the backfire, headfire and residual smouldering combustion (RSC) stages of these savannah fires, from which stagespecific emission factors can then be calculated. Headfires and backfires often show similar emission ratios and emission factors, but those of the RSC stage can differ substantially. The timing of each fire stage was identified via airborne optical and thermal IR imagery and ground-observer reports, with the airborne IR imagery also used to derive estimates of fire radiative energy (FRE), allowing the relative amount of fuel burned in each stage to be calculated and "fire averaged" emission ratios and emission factors to be determined. These "fire averaged" metrics are dominated by the headfire contribution, since the FRE data indicate that the vast majority of the fuel is burned in this stage. Our fire averaged emission ratios and factors for CO 2 and CH 4 agree well with those from prior studies conducted in the same area using e.g. airborne plume sampling. We also concur with past suggestions that emission factors for formaldehyde in this environment appear substantially underestimated in widely used databases, but see no evidence to support suggestions by Sinha et al. (2003) of a major overestimation in the emission factor of ammonia in works such as Andreae and Merlet (2001) and Akagi et al. (2011). We also measure somewhat higher CO and NH 3 emission ratios and factors Published by Copernicus Publications on behalf of the European Geosciences Union. 11592 M. J. Wooster et al.: OP-FTIR determination of biomass burning emission ratios than are usually reported for this environment, which is interpreted to result from the OP-FTIR ground-based technique sampling a greater proportion of smoke from smouldering processes than is generally the case with methods such as airborne sampling. Finally, our results sugg...

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Development of a virtual active fire product for Africa through a synthesis of geostationary and polar orbiting satellite data

Cited by 69 publications

References 48 publications

Annual and diurnal african biomass burning temporal dynamics

Annual and diurnal african biomass burning temporal dynamics

Evaluating the SEVIRI Fire Thermal Anomaly Detection Algorithm across the Central African Republic Using the MODIS Active Fire Product

Field determination of biomass burning emission ratios and factors via open-path FTIR spectroscopy and fire radiative power assessment: headfire, backfire and residual smouldering combustion in African savannahs

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