scholarly journals African burned area and fire carbon emissions are strongly impacted by small fires undetected by coarse resolution satellite data

2021 ◽  
Vol 118 (9) ◽  
pp. e2011160118
Author(s):  
Ruben Ramo ◽  
Ekhi Roteta ◽  
Ioannis Bistinas ◽  
Dave van Wees ◽  
Aitor Bastarrika ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Spatial Resolution ◽  
Carbon Emissions ◽  
Sub Saharan Africa ◽  
Burned Area ◽  
Fire Emissions ◽  
Coarse Spatial Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Sub Saharan ◽  
Sentinel 2

Fires are a major contributor to atmospheric budgets of greenhouse gases and aerosols, affect soils and vegetation properties, and are a key driver of land use change. Since the 1990s, global burned area (BA) estimates based on satellite observations have provided critical insights into patterns and trends of fire occurrence. However, these global BA products are based on coarse spatial-resolution sensors, which are unsuitable for detecting small fires that burn only a fraction of a satellite pixel. We estimated the relevance of those small fires by comparing a BA product generated from Sentinel-2 MSI (Multispectral Instrument) images (20-m spatial resolution) with a widely used global BA product based on Moderate Resolution Imaging Spectroradiometer (MODIS) images (500 m) focusing on sub-Saharan Africa. For the year 2016, we detected 80% more BA with Sentinel-2 images than with the MODIS product. This difference was predominately related to small fires: we observed that 2.02 Mkm2 (out of a total of 4.89 Mkm2) was burned by fires smaller than 100 ha, whereas the MODIS product only detected 0.13 million km2 BA in that fire-size class. This increase in BA subsequently resulted in increased estimates of fire emissions; we computed 31 to 101% more fire carbon emissions than current estimates based on MODIS products. We conclude that small fires are a critical driver of BA in sub-Saharan Africa and that including those small fires in emission estimates raises the contribution of biomass burning to global burdens of (greenhouse) gases and aerosols.

scholarly journals Modelling African biomass burning emissions and the effect of spatial resolution

2019 ◽  
Author(s):  
Dave van Wees ◽  
Guido R. van der Werf
Keyword(s):  
Spatial Resolution ◽  
Input Data ◽  
Large Scale ◽  
Sub Saharan Africa ◽  
Fuel Load ◽  
Burned Area ◽  
Fire Emissions ◽  
Continental Scale ◽  
Coarse Resolution ◽  
The Impact

Abstract. Large-scale fire emission estimates may be influenced by the spatial resolution of the model and input datasets used. Especially in areas with relatively heterogeneous land cover, a coarse model resolution might lead to substantial errors in estimates. In this paper, we developed a model using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations of burned area and vegetation characteristics to study the impact of spatial resolution on modelled fire emission estimates. We estimated fire emissions for sub-Saharan Africa at 500-meter spatial resolution (native MODIS burned area) for the 2002–2017 period, using a simplified version of the Global Fire Emissions Database (GFED) modelling framework, and compared this to model runs at a range of coarser resolutions (0.050°, 0.125°, 0.250°). We estimated fire emissions of 0.68 PgC yr−1 at 500-meter resolution and 0.82 PgC yr−1 at 0.25° resolution; a difference of 24 %. At 0.25° resolution, our model results were relatively similar to GFED4, which also runs at 0.25° resolution, whereas our 500-meter estimates were substantially lower. We found that lower emissions at finer resolutions are mainly the result of reduced representation errors when comparing modelled estimates of fuel load and consumption to field measurements, as part of the model calibration. Additional errors stem from the model simulation at coarse resolution and lead to an additional 0.02 PgC yr−1 difference in estimates. These errors exist due to the aggregation of quantitative and qualitative model input data; the average- or majority- aggregated values are propagated in the coarse resolution simulation and affect the model parameterization and the final result. We identified at least three error mechanisms responsible for the differences in estimates between 500-meter and 0.25° resolution simulations, besides those stemming from representation errors in the calibration process, namely: 1. biome misclassification leading to errors in parameterization, 2. errors due to the averaging of input data and the associated reduction in variability, and 3. a temporal mechanism related to the aggregation of burned area in particular. Even though these mechanisms largely neutralized each other and only modestly affect estimates at a continental scale, they lead to substantial error at regional scales with deviations up to a factor 4, and may affect large-scale estimates differently for other continents. These findings could prove valuable in improving coarse resolution models and suggest the need for increased spatial resolution in global fire emission models.

scholarly journals Modelling biomass burning emissions and the effect of spatial resolution: a case study for Africa based on the Global Fire Emissions Database (GFED)

2019 ◽  
Vol 12 (11) ◽  
pp. 4681-4703
Author(s):  
Dave van Wees ◽  
Guido R. van der Werf
Keyword(s):  
Spatial Resolution ◽  
Input Data ◽  
Large Scale ◽  
Sub Saharan Africa ◽  
Fuel Load ◽  
Burned Area ◽  
Fire Emissions ◽  
Continental Scale ◽  
Coarse Resolution ◽  
The Impact

Abstract. Large-scale fire emission estimates may be influenced by the spatial resolution of the model and input datasets used. Especially in areas with relatively heterogeneous land cover, a coarse model resolution might lead to substantial errors in estimates. We developed a model using MODerate resolution Imaging Spectroradiometer (MODIS) satellite observations of burned area and vegetation characteristics to study the impact of spatial resolution on modelled fire emission estimates. We estimated fire emissions for sub-Saharan Africa at 500 m spatial resolution (native MODIS burned area) for the 2002–2017 period, using a simplified version of the Global Fire Emissions Database (GFED) modelling framework, and compared this to model runs at a range of coarser resolutions (0.050, 0.125, 0.250∘). We estimated fire emissions of 0.68 Pg C yr−1 at 500 m resolution and 0.82 Pg C yr−1 at 0.25∘ resolution; a difference of 24 %. At 0.25∘ resolution, our model results were relatively similar to GFED4, which also runs at 0.25∘ resolution, whereas our 500 m estimates were substantially lower. We found that lower emissions at finer resolutions are mainly the result of reduced representation errors when comparing modelled estimates of fuel load and consumption to field measurements, as part of the model calibration. Additional errors stem from the model simulation at coarse resolution and lead to an additional 0.02 Pg C yr−1 difference in estimates. These errors exist due to the aggregation of quantitative and qualitative model input data; the average- or majority- aggregated values are propagated in the coarse-resolution simulation and affect the model parameterization and the final result. We identified at least three error mechanisms responsible for the differences in estimates between 500 m and 0.25∘ resolution simulations, besides those stemming from representation errors in the calibration process, namely (1) biome misclassification leading to errors in parameterization, (2) errors due to the averaging of input data and the associated reduction in variability, and (3) a temporal mechanism related to the aggregation of burned area in particular. Even though these mechanisms largely neutralized each other and only modestly affect estimates at a continental scale, they lead to substantial error at regional scales with deviations of up to a factor 4 and may affect large-scale estimates differently for other continents. These findings could prove valuable in improving coarse-resolution models and suggest the need for increased spatial resolution in global fire emission models.

scholarly journals Development of a Sentinel-2 burned area algorithm: Generation of a small fire database for sub-Saharan Africa

2019 ◽  
Vol 222 ◽  
pp. 1-17 ◽  
Author(s):  
E. Roteta ◽  
A. Bastarrika ◽  
M. Padilla ◽  
T. Storm ◽  
E. Chuvieco
Keyword(s):  
Sub Saharan Africa ◽  
Burned Area ◽  
Sub Saharan ◽  
Algorithm Generation ◽  
Sentinel 2

scholarly journals Biomass burning fuel consumption dynamics in the tropics and subtropics assessed from satellite

2016 ◽  
Vol 13 (12) ◽  
pp. 3717-3734 ◽  
Author(s):  
Niels Andela ◽  
Guido R. van der Werf ◽  
Johannes W. Kaiser ◽  
Thijs T. van Leeuwen ◽  
Martin J. Wooster ◽  
...  
Keyword(s):  
South America ◽  
Fuel Consumption ◽  
Spatial Patterns ◽  
Field Measurements ◽  
Sub Saharan Africa ◽  
Burned Area ◽  
Return Periods ◽  
Sub Saharan ◽  
In Fire ◽  
Consumption Dynamics

Abstract. Landscape fires occur on a large scale in (sub)tropical savannas and grasslands, affecting ecosystem dynamics, regional air quality and concentrations of atmospheric trace gasses. Fuel consumption per unit of area burned is an important but poorly constrained parameter in fire emission modelling. We combined satellite-derived burned area with fire radiative power (FRP) data to derive fuel consumption estimates for land cover types with low tree cover in South America, Sub-Saharan Africa, and Australia. We developed a new approach to estimate fuel consumption, based on FRP data from the polar-orbiting Moderate Resolution Imaging Spectroradiometer (MODIS) and the geostationary Spinning Enhanced Visible and Infrared Imager (SEVIRI) in combination with MODIS burned-area estimates. The fuel consumption estimates based on the geostationary and polar-orbiting instruments showed good agreement in terms of spatial patterns. We used field measurements of fuel consumption to constrain our results, but the large variation in fuel consumption in both space and time complicated this comparison and absolute fuel consumption estimates remained more uncertain. Spatial patterns in fuel consumption could be partly explained by vegetation productivity and fire return periods. In South America, most fires occurred in savannas with relatively long fire return periods, resulting in comparatively high fuel consumption as opposed to the more frequently burning savannas in Sub-Saharan Africa. Strikingly, we found the infrequently burning interior of Australia to have higher fuel consumption than the more productive but frequently burning savannas in northern Australia. Vegetation type also played an important role in explaining the distribution of fuel consumption, by affecting both fuel build-up rates and fire return periods. Hummock grasslands, which were responsible for a large share of Australian biomass burning, showed larger fuel build-up rates than equally productive grasslands in Africa, although this effect might have been partially driven by the presence of grazers in Africa or differences in landscape management. Finally, land management in the form of deforestation and agriculture also considerably affected fuel consumption regionally. We conclude that combining FRP and burned-area estimates, calibrated against field measurements, is a promising approach in deriving quantitative estimates of fuel consumption. Satellite-derived fuel consumption estimates may both challenge our current understanding of spatiotemporal fuel consumption dynamics and serve as reference datasets to improve biogeochemical modelling approaches. Future field studies especially designed to validate satellite-based products, or airborne remote sensing, may further improve confidence in the absolute fuel consumption estimates which are quickly becoming the weakest link in fire emission estimates.

scholarly journals Carbon Lock-In and Sustainable Growth Challenges : Evidence from Sub-Saharan Africa

2020 ◽  
pp. 01-25
Author(s):  
Aminatou Kemajou Pofoura ◽  
Huaping Sun ◽  
Maxwell Opuni Antwi ◽  
Charles Kwarteng Antwi
Keyword(s):  
Carbon Emissions ◽  
Path Dependency ◽  
Sub Saharan Africa ◽  
Financial Resources ◽  
Low Carbon ◽  
Income Per Capita ◽  
Short Run ◽  
Per Capita ◽  
Sub Saharan ◽  
Lock In

This research seeks to investigate the risks of carbon lock-in by examining the potential factors influencing carbon dioxide emissions levels in Sub-Saharan Africa. Given this, we employed a panel Sub-Saharan Africa comprised of 35 countries in the sub-region, from 2000 to 2014 with cross-sectional dependence among variables. We used the Two-step robust System Generalized Method of Moments to estimate the influencing factors of carbon emissions level that create path dependency. The main findings are: (1) income per capita, urbanization, and financial resources contribute to the increase of carbon emissions level in the Sub-Saharan Africa countries, in the short-run; (2) we noticed that in the short-run, the impacts of fossil fuels per capita, energy intensity and total energy consumption are insignificant; (3) in the long-run, income per capita, urbanization and financial resources increase carbon emissions level; (4) from various factors that increase carbon emissions level, these factors form a path dependency that slow the introduction of low-carbon systems, thus, creating carbon lock-in in the Sub-Saharan Africa countries. Considering this, policymakers and governments should ensure the strict compliance of environmental regulations by financial institutions and organizations, promote low-carbon cities during economic transformation, and encourage investments in low-carbon projects. The government should also educate and build awareness on the effects of environmental pollution on population health, provide incentives for energy conservation and promote the use of clean products to avoid future risks of lock-in in the sub-region.

scholarly journals Crop Area Mapping in Southern and Central Malawi With Google Earth Engine

2021 ◽  
Vol 3 ◽  
Author(s):  
Seth Peterson ◽  
Greg Husak
Keyword(s):  
Spatial Resolution ◽  
Test Data ◽  
Google Earth ◽  
Reference Points ◽  
Sub Saharan Africa ◽  
High Temporal Resolution ◽  
Smallholder Farms ◽  
Google Earth Engine ◽  
Crop Area ◽  
Sentinel 2

Agriculture in sub-Saharan Africa consists primarily of smallholder farms of rainfed crops. Historically, satellite data were too coarse to account for the heterogeneity in these landscapes. Sentinel-2 data have improved spectral resolution and much higher spatial resolution (10 m) than previously available satellites with global coverage, such as Landsat or MODIS, making mapping smallholder farms possible. Spectral mixture analysis was used to convert the Sentinel-2 signal into fractions of green vegetation, non-photosynthetic vegetation, soil, and shade endmembers. Very high spatial resolution imagery in Google Earth Pro was used to identify locations of crop and natural vegetation classes, with over 20,000 reference points interpreted. The high temporal resolution of Sentinel-2 (5 days repeat) allows for classification of landcover based on the phenological signal, with natural areas having smoothly varying amounts of photosynthetic vegetation annually, while cropped areas show more abrupt changes, and also the presence of bare soil due to agricultural activity at some point during the year. We summarized the endmember values using monthly medians, extracted values for the reference data points, randomly split them into training and test data sets, and input the training data into the random forests algorithm in Google Earth Engine to map crop area. We divided southern and central Malawi into tiles, and found crop/no crop classification accuracies on the test data for each tile to be between 87 and 93%. The 10 m map of crop area was aggregated to the district level and showed an R2 of 0.74 with ground-based statistics from the Malawi government and 0.79 with a remotely sensed product developed by the USGS.

scholarly journals Signature of tropical fires in the diurnal cycle of tropospheric CO as seen from Metop-A/IASI

2014 ◽  
Vol 14 (19) ◽  
pp. 26003-26039 ◽  
Author(s):  
T. Thonat ◽  
C. Crevoisier ◽  
N. A. Scott ◽  
A. Chédin ◽  
R. Armante ◽  
...  
Keyword(s):  
Burned Area ◽  
Tropical Region ◽  
Fire Emissions ◽  
Diurnal Difference ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Emissions Inventories ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact ◽  
Local Emissions

Abstract. Five years (July 2007–June 2012) of CO tropospheric columns derived from the IASI hyperspectral infrared sounder onboard Metop-A are used to study the impact of fires on the concentrations of CO in the mid-troposphere. Following Chédin et al. (2005, 2008), who showed the existence of a daily tropospheric excess of CO2 quantitatively related to fire emissions, we show that tropospheric CO also displays a diurnal signal with a seasonality that is in very good agreement with the seasonal evolution of fires given by GFED3.1 (Global Fire Emission Database) emissions and MODIS (Moderate Resolution Imaging Spectroradiometer) burned area. Unlike daytime or nighttime CO fields, which mix local emissions with nearby emissions transported to the region of study, the day-night difference of CO allows to highlight the CO signal due to local fire emissions. A linear relationship is found in the whole tropical region between CO fire emissions from the GFED3.1 inventory and the diurnal difference of IASI CO (R2 ~ 0.6). Based on the specificity of the two main phases of the combustion (flaming vs. smoldering) and on the vertical sensitivity of the sounder to CO, the following mechanism is proposed to explain such a CO diurnal signal: at night, after the passing of IASI at 9.30 p.m. LT, a large amount of CO emissions from the smoldering phase is trapped in the boundary layer before being uplifted the next morning by natural and pyro-convection up to the free troposphere, where it is seen by IASI at 9.30 a.m. LT. The results presented here highlight the need for developing complementary approaches to bottom-up emissions inventories and for taking into account the specificity of both the flaming and smoldering phases of fire emissions in order to fully take advantage of CO observations.

scholarly journals Exploitation of Sentinel-2 Time Series to Map Burned Areas at the National Level: A Case Study on the 2017 Italy Wildfires

2019 ◽  
Vol 11 (6) ◽  
pp. 622 ◽  
Author(s):  
Federico Filipponi
Keyword(s):  
Time Series ◽  
Spatial Resolution ◽  
Satellite Data ◽  
High Spatial Resolution ◽  
National Level ◽  
Burned Area ◽  
Commission Error ◽  
Burned Areas ◽  
Sentinel 2

Satellite data play a major role in supporting knowledge about fire severity by delivering rapid information to map fire-damaged areas in a precise and prompt way. The high availability of free medium-high spatial resolution optical satellite data, offered by the Copernicus Programme, has enabled the development of more detailed post-fire mapping. This research study deals with the exploitation of Sentinel-2 time series to map burned areas, taking advantages from the high revisit frequency and improved spatial and spectral resolution of the MSI optical sensor. A novel procedure is here presented to produce medium-high spatial resolution burned area mapping using dense Sentinel-2 time series with no a priori knowledge about wildfire occurrence or burned areas spatial distribution. The proposed methodology is founded on a threshold-based classification based on empirical observations that discovers wildfire fingerprints on vegetation cover by means of an abrupt change detection procedure. Effectiveness of the procedure in mapping medium-high spatial resolution burned areas at the national level was demonstrated for a case study on the 2017 Italy wildfires. Thematic maps generated under the Copernicus Emergency Management Service were used as reference products to assess the accuracy of the results. Multitemporal series of three different spectral indices, describing wildfire disturbance, were used to identify burned areas and compared to identify their performances in terms of spectral separability. Result showed a total burned area for the Italian country in the year 2017 of around 1400 km2, with the proposed methodology generating a commission error of around 25% and an omission error of around 40%. Results demonstrate how the proposed procedure allows for the medium-high resolution mapping of burned areas, offering a benchmark for the development of new operational downstreaming services at the national level based on Copernicus data for the systematic monitoring of wildfires.

Financial development and carbon emissions in Sub-Saharan Africa

2021 ◽  
Author(s):  
Chukwuemeka Chinonso Emenekwe ◽  
Robert Ugochukwu Onyeneke ◽  
Chibuikem Uzoma Nwajiuba
Keyword(s):  
Financial Development ◽  
Carbon Emissions ◽  
Sub Saharan Africa ◽  
Sub Saharan
Sign in / Sign up

Export Citation Format

Share Document