Results 1 - 10 of 212

Global wildland fire emission model (GWEM): evaluating the use of global area burnt satellite data

by Judith J. Hoelzemann, Martin G. Schultz, Guy P. Brasseur, Claire Granier, Muriel Simon - Journal of Geophysical Research , 2004
"... [1] The new Global Wildland Fire Emission Model (GWEM) has been developed on the basis of data from the European Space Agency’s monthly Global Burnt Scar satellite product (GLOBSCAR) and results from the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ-DGVM). GWEM computes monthly emissions of ..."
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[1] The new Global Wildland Fire Emission Model (GWEM) has been developed on the basis of data from the European Space Agency’s monthly Global Burnt Scar satellite product (GLOBSCAR) and results from the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ-DGVM). GWEM computes monthly emissions of more than 40 chemical compounds and aerosols from forest and savanna fires. This study focuses on an evaluation of the GLOBSCAR data set. The GWEM version presented here makes use of the Moderate-Resolution Imaging Spectroradiometer (MODIS) land cover map.

2005), Spatially complete global spectral surface albedos: Value-added datasets derived from Terra MODIS land products

by Eric G. Moody, Michael D. King, Senior Member, Steven Platnick, Crystal B. Schaaf, Feng Gao, M. D. King, S. Platnick, Earth Sciences Directorate - IEEE Trans. Geosci. Remote Sens
"... (white-sky) albedo and direct beam directional hemispherical (blacksky) albedo from observations acquired by the MODIS instruments aboard NASA’s Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal information on the land surface’s radiative ..."
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(white-sky) albedo and direct beam directional hemispherical (blacksky) albedo from observations acquired by the MODIS instruments aboard NASA’s Terra and Aqua satellite platforms have provided researchers with unprecedented spatial, spectral, and temporal information on the land surface’s radiative characteristics. Cloud cover, which curtails retrievals, and the presence of ephemeral and seasonal snow limit the snow-free data to approximately half the global land surfaces on an annual equal-angle basis. This precludes the MOD43B3 albedo products from being used in some remote sensing and ground-based applications, climate models, and global change research projects. An ecosystem-dependant temporal interpolation technique is described that has been developed to fill missing or seasonally snow-covered data in the official MOD43B3 albedo product. The method imposes pixel-level and local regional ecosystem-dependent phenological behavior onto retrieved pixel temporal data in such a way as to maintain pixel-level spatial and spectral detail and integrity. The phenological curves are derived from statistics based on the MODIS
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Cluster Ensemble Selection

by Xiaoli Z. Fern, Wei Lin , 2008
"... This paper studies the ensemble selection problem for unsupervised learning. Given a large library of different clustering solutions, our goal is to select a subset of solutions to form a smaller but better performing cluster ensemble than using all available solutions. We design our ensemble select ..."
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This paper studies the ensemble selection problem for unsupervised learning. Given a large library of different clustering solutions, our goal is to select a subset of solutions to form a smaller but better performing cluster ensemble than using all available solutions. We design our ensemble selection methods based on quality and diversity, the two factors that have been shown to influence cluster ensemble performance. Our investigation revealed that using quality or diversity alone may not consistently achieve improved performance. Based on our observations, we designed three different selection approaches that jointly consider these two factors. We empirically evaluated their performances in comparison with both full ensembles and a random selection strategy. Our results indicated that by explicitly considering both quality and diversity in ensemble selection, we can achieve statistically significant performance improvement over full ensembles.
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Climate controls on the variability of fires in the tropics and subtropics, Global Biogeochem

by Guido R. Van Der Werf, James T. R, Louis Giglio, Nadine Gobron, A. J. Dolman - Cy
"... [1] In the tropics and subtropics, most fires are set by humans for a wide range of purposes. The total amount of burned area and fire emissions reflects a complex interaction between climate, human activities, and ecosystem processes. Here we used satellite-derived data sets of active fire detectio ..."
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[1] In the tropics and subtropics, most fires are set by humans for a wide range of purposes. The total amount of burned area and fire emissions reflects a complex interaction between climate, human activities, and ecosystem processes. Here we used satellite-derived data sets of active fire detections, burned area, precipitation, and the fraction of absorbed photosynthetically active radiation (fAPAR) during 1998–2006 to investigate this interaction. The total number of active fire detections and burned area was highest in areas that had intermediate levels of both net primary production (NPP; 500–1000 g C m 2 year 1) and precipitation (1000–2000 mm year 1), with limits imposed by the length of the fire season in wetter ecosystems and by fuel availability in drier ecosystems. For wet tropical forest ecosystems we developed a metric called the fire-driven deforestation potential (FDP) that integrated information about the length and intensity of the dry season. FDP partly explained the spatial and interannual pattern of fire-driven deforestation across tropical forest regions. This climate-fire link in combination with higher precipitation rates in the interior of the Amazon suggests that a negative feedback on fire-driven deforestation

Analysis and optimization of the MODIS Leaf Area Index algorithm retrievals over broadleaf forests

by Nikolay V. Shabanov, Dong Huang, Wenze Yang, Bin Tan, Yuri Knyazikhin, Ranga B. Myneni, Douglas E. Ahl, Stith T. Gower, Alfredo R. Huete, Luiz Eduardo O. C. Aragão, Yosio Edemir Shimabukuro - IEEE Trans. Geosci. Remote Sens , 2005
"... Abstract—Broadleaf forest is a major type of Earth’s land cover with the highest observable vegetation density. Retrievals of biophysical parameters, such as leaf area index (LAI), of broadleaf forests at global scale constitute a major challenge to modern remote sensing techniques in view of low se ..."
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Abstract—Broadleaf forest is a major type of Earth’s land cover with the highest observable vegetation density. Retrievals of biophysical parameters, such as leaf area index (LAI), of broadleaf forests at global scale constitute a major challenge to modern remote sensing techniques in view of low sensitivity (saturation) of surface reflectances to such parameters over dense vegetation. The goal of the performed research is to demonstrate physical principles of LAI retrievals over broadleaf forests with the Moderate Resolution Imaging Spectroradiometer (MODIS) LAI algorithm and to establish a basis for algorithm refinement. To sample natural variability in biophysical parameters of broadleaf forests, we selected MODIS data subsets covering deciduous broadleaf forests of the eastern part of North America and evergreen broadleaf forests of Amazonia. The analysis of an annual course of the Terra MODIS Collection 4 LAI product over broadleaf
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Myneni, “Validation of Moderate Resolution Imaging Spectroradiometer leaf area index product in croplands of Alpilles

by Bin Tan, Jiannan Hu, Ping Zhang, Dong Huang, Nikolay Shabanov, Marie Weiss, Yuri Knyazikhin, Ranga B. Myneni - France,” J. Geophys. Res.—Atmos
"... collected in a 3 3 km agricultural (grasses and cereal crops) area near Avignon, France, and 30 m resolution Enhanced Thematic Mapper (ETM+) image. Estimates of the accuracy, precision, and uncertainty with which the ETM+ data convey information about LAI underlie the derivation of a 30 m resolution ..."
Abstract - Cited by 25 (11 self) - Add to MetaCart
collected in a 3 3 km agricultural (grasses and cereal crops) area near Avignon, France, and 30 m resolution Enhanced Thematic Mapper (ETM+) image. Estimates of the accuracy, precision, and uncertainty with which the ETM+ data convey information about LAI underlie the derivation of a 30 m resolution reference LAI map by accounting for both field measurement and satellite observation errors. The 30 m reference LAI was then extrapolated from sampling points to a 58 km 2 area without loss in the quality and was degraded to a 1 km resolution LAI map. The latter was taken as a reference to assess the quality of the MODIS LAI product. Comparison of the reference and corresponding MODIS retrievals suggests that Collection 4 MODIS LAI is accurate to within an accuracy of 0.3 with a precision and uncertainty of 0.23 and 0.38, respectively. It was found that the Collection 3 MODIS land cover product, input to the Collection 4 operational LAI algorithm, misclassified the 58 km 2 area as broadleaf crops. The use of correct biome type in the operational processing improves the accuracy in LAI by a factor of 2 with an almost unchanged precision and uncertainty. Our results also indicate that the retrieval of LAI from satellite data is an
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Satellite remote sensing and hydrologic modeling for flood inundation mapping in Lake Victoria basin: Implications for hydrologic prediction in ungauged basins

by Sadiq I. Khan, Yang Hong, Jiahu Wang, Koray K. Yilmaz, Jonathan J. Gourley, Robert F. Adler, G. Robert Brakenridge, Fritz Policelli, Shahid Habib, Daniel Irwin - IEEE Trans. Geosci. Remote Sens , 2011
"... Abstract—Floods are among the most catastrophic natural dis-asters around the globe impacting human lives and infrastruc-ture. Implementation of a flood prediction system can potentially help mitigate flood-induced hazards. Such a system typically re-quires implementation and calibration of a hydrol ..."
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Abstract—Floods are among the most catastrophic natural dis-asters around the globe impacting human lives and infrastruc-ture. Implementation of a flood prediction system can potentially help mitigate flood-induced hazards. Such a system typically re-quires implementation and calibration of a hydrologic model using in situ observations (i.e., rain and stream gauges). Recently, satel-lite remote sensing data have emerged as a viable alternative or supplement to in situ observations due to their availability over vast ungauged regions. The focus of this study is to integrate the best available satellite products within a distributed hydrologic model to characterize the spatial extent of flooding and associated hazards over sparsely gauged or ungauged basins. We present a methodology based entirely on satellite remote sensing data to set up and calibrate a hydrologic model, simulate the spatial extent of flooding, and evaluate the probability of detecting inun-dated areas. A raster-based distributed hydrologic model, Coupled Routing and Excess STorage (CREST), was implemented for the
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Analyzing the global human appropriation of net primary production - processes, trajectories, implications. An introduction

by Karl-heinz Erb, Fridolin Krausmann, Veronika Gaube, Simone Gingrich, Karl-heinz Erb, Fridolin Krausmann, Veronika Gaube, Simone Gingrich, Alberte Bondeau - Ecological Economics , 2009
"... Special Section “Analyzing the global human appropriation of net primary production: Trajectories, processes and implications” ..."
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Special Section “Analyzing the global human appropriation of net primary production: Trajectories, processes and implications”

Global distribution and density of constructed impervious surfaces

by Christopher D Elvidge , Benjamin T Tuttle , Paul S Sutton , Kimberly E Baugh , Ara T Howard , Cristina Milesi , Budhendra Bhuduri , Ramakrishna Nemani - Sensors
"... Abstract: We present the first global inventory of the spatial distribution and density of constructed impervious surface area (ISA). Examples of ISA include roads, parking lots, buildings, driveways, sidewalks and other manmade surfaces. While high spatial resolution is required to observe these f ..."
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Abstract: We present the first global inventory of the spatial distribution and density of constructed impervious surface area (ISA). Examples of ISA include roads, parking lots, buildings, driveways, sidewalks and other manmade surfaces. While high spatial resolution is required to observe these features, the product we made is at one km2 resolution and is based on two coarse resolution indicators of ISA. Inputs into the product include the brightness of satellite observed nighttime lights and population count. The reference data used in the calibration were derived from 30 meter resolution ISA estimates of the USA from the U.S. Geological Survey. Nominally the product is for the years 2000-01 since both the nighttime lights and reference data are from those two years. We found that 1.05% of the United States land area is impervious surface (83,337 km2) and 0.43 % of the world's land Sensors 2006, 6 2 2 surface (579,703 km2) is constructed impervious surface. China has more ISA than any other country (87,182 km2), but has only 67 m2 of ISA per person, compared to 297 m2 per person in the USA. Hyrdologic and environmental impacts of ISA begin to be exhibited when the density of ISA reaches 10% of the land surface. An examination of the areas with 10% or more ISA in watersheds finds that with the exception of Europe, the majority of watershed areas have less than 0.4% of their area at or above the 10% ISA threshold. The authors believe the next step for improving the product is to include reference ISA data from many more areas around the world.
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Generating plausible crop distribution and performance maps for Sub-Saharan Africa using a spatially disaggregated data fusion and optimization approach. Liangzhi

by Liangzhi You, Liangzhi You, Stanley Wood, Stanley Wood, Ulrike Wood-sichra, Ulrike Wood-sichra - FOOD POLICY RESEARCH INSTITUTE www.ifpri.org IFPRI HEADQUARTERS 2033 K Street, NW Washington, DC 20006-1002 USA Tel.: +1-202-862-5600 Fax: +1-202-467-4439 Email: ifpri@cgiar.org IFPRI ADDIS ABABA P. O. Box 5689 Addis Ababa, Ethiopia Tel.: +251 11 6463215 , 2007
"... of 15 agricultural research centers that receive principal funding from governments, private foundations, and international and regional organizations, most of which are members of the ..."
Abstract - Cited by 16 (3 self) - Add to MetaCart
of 15 agricultural research centers that receive principal funding from governments, private foundations, and international and regional organizations, most of which are members of the
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