Spatial Science Commons^™

Remote Sensing-Based Time Series Models For Malaria Early Warning In The Highlands Of Ethiopia, A. Midekisa, G. Senay, G. M. Henebry, P. Semuniguse, M. C. Wimberly

Natural Resource Management Faculty Publications

Background

Malaria is one of the leading public health problems in most of sub-Saharan Africa, particularly in Ethiopia. Almost all demographic groups are at risk of malaria because of seasonal and unstable transmission of the disease. Therefore, there is a need to develop malaria early-warning systems to enhance public health decision making for control and prevention of malaria epidemics. Data from orbiting earth-observing sensors can monitor environmental risk factors that trigger malaria epidemics. Remotely sensed environmental indicators were used to examine the influences of climatic and environmental variability on temporal patterns of malaria cases in the Amhara region of Ethiopia. …

Projected Surface Raidiative Forcing Due To 2000-2050 Land-Cover Land-Use Albedo Change Over The Eastern United States, Christoper A. Barnes, David P. Roy, Thomas R. Loveland

GSCE Faculty Publications

Satellite-derived contemporary land-cover land-use (LCLU) and albedo data and modeled future LCLU are used to study the impact of LCLU change from 2000 to 2050 on surface albedo and radiative forcing for 19 ecoregions in the eastern United States. The modeled 2000–2050 LCLU changes indicate a future decrease in both agriculture and forested land and an increase in developed land that induces ecoregion radiative forcings ranging from −0.175 to 0.432 W m−2 driven predominately by differences in the area and type of LCLU change. At the regional scale, these projected LCLU changes induce a net negative albedo decrease (−0.001) and …

Sensitivity Analysis Of The Gems Soil Organic Carbon Model To Land Cover Land Use Classification Uncertainties Under Different Climate Scenarios In Senegal, Amadou M. Dieye, David P. Roy, N. P. Hanan, S. Lui, M. Hansen, A. Toure

GSCE Faculty Publications

Spatially explicit land cover land use (LCLU) change information is needed to drive biogeochemical models that simulate soil organic carbon (SOC) dynamics. Such information is increasingly being mapped using remotely sensed satellite data with classification schemes and uncertainties constrained by the sensing system, classification algorithms and land cover schemes. In this study, automated LCLU classification of multi-temporal Landsat satellite data were used to assess the sensitivity of SOC modeled by the Global Ensemble Biogeochemical Modeling System (GEMS). The GEMS was run for an area of 1560km2 in Senegal under three climate change scenarios with LCLU maps generated using different Landsat …

Continuity Of Landsat Obersvations: Short Term Considerations, Michael A. Wulder, Joanne C. White, Jeffrey G. Masek, John Dwyer, David P. Roy

GSCE Faculty Publications

As of writing in mid-2010, both Landsat-5 and -7 continue to function, with sufficient fuel to enable data collection until the launch of the Landsat Data Continuity Mission (LDCM) scheduled for December of 2012. Failure of one or both of Landsat-5 or -7 may result in a lack of Landsat data for a period of time until the 2012 launch. Although the potential risk of a component failure increases the longer the sensor's design life is exceeded, the possible gap in Landsat data acquisition is reduced with each passing day and the risk of Landsat imagery being unavailable diminishes for …

Exploiting The Power Law Distribution Properties Of Satellite Fire Redaiative Power Retrials: A Method To Estimate Fire Radiative Energy And Biomass Burned From Sparse Satellite Observations, S. S. Kumar, David P. Roy, L. Boschetti, R. Kremens

GSCE Faculty Publications

Instantaneous estimates of the power released by fire (fire radiative power, FRP) are available with satellite active fire detection products. The temporal integral of FRP provides an estimate of the fire radiative energy (FRE) that is related linearly to the amount of biomass burned needed by the atmospheric emissions modeling community. The FRE, however, is sensitive to satellite temporal and spatial FRP undersampling due to infrequent satellite overpasses, cloud and smoke obscuration, and failure to detect cool and/or small fires. Satellite FRPs derived over individual burned areas and fires have been observed to exhibit power law distributions. This property is …

Strategies For The Fusion Of Satellite Fire Radiative Power With Burned Area Data For Fire Radiative Energy Derivation, Luigi Boschetti, David P. Roy

GSCE Faculty Publications

Instantaneous estimates of the power released by a fire (Fire Radiative Power, FRP) are available with satellite active fire detection products. Integrating FRP in time provides an estimate of the total energy released (Fire Radiative Energy, FRE), which can be converted into burned biomass estimates needed by the atmospheric emissions modeling community. While straightforward in theory, the integration of FRP in time and space is affected by temporal and spatial undersampling imposed by the satellite sensing and orbit geometry, clouds, and active fire product omission errors. Combination of active fire FRP estimates with independently derived burned area maps provides the …

Dual Scale Trend Analysis Distinguishes Climatic From Anthropogenic Effects On The Vegetated Land Surface, K. M. De Beurs, C. K. Wright, G. M. Henebry

Natural Resource Management Faculty Publications

We present a dual scale trend analysis for characterizing and comparing two contrasting areas of change in Russia and Kazakhstan that lie less than 800 km apart. We selected a global NASA MODIS (moderate resolution imaging spectroradiometer) product (MCD43C4 and MCD43A4) at a 0.05◦ (∼5.6 km) and 500 m spatial resolution and a 16-day temporal resolution from 2000 to 2008. We applied a refinement of the seasonal Kendall trend method to the normalized difference vegetation index (NDVI) image series at both scales. We only incorporated composites during the vegetative growing season which was delineated by start of season and end …

Defining A Fire Year For Reporting And Analysis Of Global Interannual Fire Variablility, Luigi Boschetti, David P. Roy

GSCE Faculty Publications

The interannual variability of fire activity has been studied without an explicit investigation of a suitable starting month for yearly calculations. Sensitivity analysis of 37 months of global MODIS active fire detections indicates that a 1-month change in the start of the fire year definition can lead, in the worst case, to a difference of over 6% and over 45% in global and subcontinental scale annual fire totals, respectively. Optimal starting months for analyses of global and subcontinental fire interannual variability are described. The research indicates that a fire year starting in March provides an optimal definition for annual global …

Radiative Forcing Over The Conterminous United States Due To Contemporary Land Cover Use Albedo Change, Christopher Barnes, David P. Roy

GSCE Faculty Publications

Recently available satellite land cover land use (LCLU) and albedo data are used to study the impact of LCLU change from 1973 to 2000 on surface albedo and radiative forcing for 36 ecoregions covering 43% of the conterminous United States (CONUS). Moderate Resolution Imaging Spectroradiometer (MODIS) snowfree broadband albedo values are derived from Landsat LCLU classification maps located using a stratified random sampling methodology to estimate ecoregion estimates of LCLU induced albedo change and surface radiative forcing. The results illustrate that radiative forcing due to LCLU change may be disguised when spatially and temporally explicit data sets are not used. …

Large Seasonal Swings In Leaf Area Of Amazon Rainforests, Ranga B. Myneni, Wenze Yang, Ramakrishna R. Nemani, Alfredo R. Huete, Robert E. Dickinson, Yuri Knyazikhin, Kamel Didan, Rong Fu, Robinson I. Negron Juarez, Sasan S. Saatchi, Hirofumi Hashimoto, Kazuhito Ichii, Nikolay V. Shabanov, Bin Tan, Piyachat Ratana, Jeffrey L. Privette, Jeffrey T. Morisette, Eric F. Vermote, David P. Roy, Robert E. Wolfe, Mark A. Friedl, Steven W. Running, Petr Votava, Nazmi El-Saleous, Sadashiva Devadiga, Yin Su, Vincent V. Salomonson

GSCE Faculty Publications

Despite early speculation to the contrary, all tropical forests studied to date display seasonal variations in the presence of new leaves, flowers, and fruits. Past studies were focused on the timing of phenological events and their cues but not on the accompanying changes in leaf area that regulate vegetation–atmosphere exchanges of energy, momentum, and mass. Here we report, from analysis of 5 years of recent satellite data, seasonal swings in green leaf area of ~25% in a majority of the Amazon rainforests. This seasonal cycle is timed to the seasonality of solar radiation in a manner that is suggestive of …

Fire-Induced Albedo Change And Its Radative Forcing At The Surface In Northern Austrailia, Y. Jin, David P. Roy

GSCE Faculty Publications

This paper investigates the impact of fire on surface albedo and the associated radiative forcing over 56% of continental Australia encompassing the fire-prone northern tropical savanna. Fire-affected areas and albedos are derived for the 2003 fire season using daily Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data. Near-infrared and total shortwave albedos are observed to generally decrease after fire occurrence. Regionally, the total shortwave albedo drops by an average of 0.024, with increasing reductions as the dry season progresses and larger reductions in grasslands than woody savannas. These fire-induced albedo changes exert a positive forcing at the surface that increases …