R. A. Sohlberg's research while affiliated with University of Maryland, College Park and other places

Publications (24)

Article
Two decades of global annual fractional vegetation cover products have been derived using daily surface reflectance and land surface temperature data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Terra satellite. These MODIS Vegetation Continuous Fields (VCF) products are unique and a distinct advance over...
Article
Data from the Moderate Resolution Imaging Spectro-radiometer (MODIS) on-board the Earth Observing System Terra and Aqua satellites are processed using a land water mask to determine when an algorithm no longer needs to be run or when an algorithm needs to follow a different pathway. Entering the fourth reprocessing (Collection 6 (C6)) the MODIS tea...
Article
Full-text available
The availability of a dense time series of satellite observations at moderate (30 m) spatial resolution is enabling unprecedented opportunities for understanding ecosystems around the world. A time series of data from Landsat was used to generate a series of three maps at decadal time step to show how surface water has changed from 1991 to 2011 in...
Article
Full-text available
Over the past 3 decades the Arctic has seen substantial warming. Previous local to regional scale studies have shown a considerable reduction in the size of lakes in this region. The subsequent exposure of carbon- and methane-rich sediments and the direct changes in surface albedo feed back into the drivers of regional and global climate change. Un...
Article
Land cover change occurs at various spatial and temporal scales. For example, large-scale mechanical removal of forests for agro-industrial activities contrasts with the small-scale clearing of subsistence farmers. Such dynamics vary in spatial extent and rate of land conversion. Such changes are attributable to both natural and anthropogenic facto...
Article
Full-text available
Accurate depiction of the land and water is critical for the production of land surface parameters from remote sensing data products. Certain parameters, including the land surface temperature, active fires and surface reflectance, can be processed differently when the underlying surface is water as compared with land. Substantial errors in the und...
Article
Global temperatures have been rising for the past several decades. The impact of the rising temperatures is expected to be greatest in the Arctic region where ice and permafrost can be melted and longer snow/ice free periods may result in greater evaporation. We will show results from analyzing the 10 year MODIS data record at 250m resolution. Prel...
Article
Surface water bodies play an important role in local and regional climate variability with water being an agent in exchanging heat between land and atmosphere. A remote sensing based (Landsat TM/ETM+) time series analysis was performed in the tundra region of the high northern latitudes of North America (Northern Canada) to determine the changes in...
Article
Accurate characterization of the location and areal extent of inland water bodies represents an important parameter for a variety of scientific studies, ranging from landscape-scale studies of surface hydrology to continental and global-scale studies of land surface-atmosphere interactions. A highly distinctive feature of the sub-arctic and arctic...
Article
Using continous fields of percent forest cover from MODIS data, an approach to monitor change has been developed. The algorithm utilizes a regression tree to automatically generate annual global estimates of forest cover. The 500 meter MODIS data represent an intermediate resolution appropriate for monitoring many types of human-induced land cover...
Article
Full-text available
The first results of the Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation continuous field algorithm's global percent tree cover are presented. Percent tree cover per 500-m MODIS pixel is estimated using a supervised regression tree algorithm. Data derived from the MODIS visible bands contribute the most to discriminating tree cover...
Conference Paper
Data from the Moderate Resolution Imaging Spectroradiometer (MODIS) represent a marked advance in global land cover mapping. The 500 m time series data have an improved spectral/spatial response when compared to heritage instruments. This study presents the first results from the Vegetation Continuous Fields algorithm of the MODIS land cover produc...
Article
A suite of vegetation assessment and monitoring products have been developed using the 250m and 500m resolution visible and infrared data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard NASA's Terra and Aqua spacecraft. These products utilize the daily MODIS temporal resolution to capture the phenologic signal and...
Article
The Vegetative Cover Conversion (VCC) product is designed to serve as a global alarm for land cover change caused by anthropogenic activities and extreme natural events. MODIS 250 m surface reflectance data availability was limited both spatially and temporally in the first year after launch due to processing system constraints. To address this sit...
Article
The continuous fields Moderate Resolution Imaging Spectroradiometer (MODIS) land cover products are 500-m sub-pixel representations of basic vegetation characteristics including tree, herbaceous and bare ground cover. Our previous approach to deriving continuous fields used a linear mixture model based on spectral endmembers of forest, grassland an...
Conference Paper
This paper addresses land cover and land cover change applications using spectral time series data from NASA's Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Terra satellite. Special attention is given to the comparative advantages of MODIS over polar orbiting remote sensing heritage instru...
Article
Accurate estimates of global and regional tree cover are crucial for the study of biogeochemical cycles, ecosystem assessment, and land management. Changes in tree cover are equally important as they represent perturbations of the earth system. We present two new products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) instru...
Article
Full-text available
This paper on reports the production of a 1 km spatial resolution land cover classification using data for 1992-1993 from the Advanced Very High Resolution Radiometer (AVHRR). This map will be included as an at-launch product of the Moderate Resolution Imaging Spectroradiometer (MODIS) to serve as an input for several algorithms requiring knowledge...
Article
Seven Landsat Multispectral Scanner (MSS) scenes in central Africa were coregistered with 8 km resolution data from the 1987 AVHRR Pathfinder Land data set. Percent forest cover in each 8 km grid cell was derived from the classified MSS scenes. Linear relationships between percent forest cover and 30 multitemporal metrics derived from all AVHRR opt...
Article
Mapping tree cover as a continuous variable allows for the use of such maps in assessing forest degradation. Prototype tree cover data sets have been generated for the globe using AVHRR data. These continuous fields allow for improved depictions of heterogeneous areas such as ecotones and disturbed areas. By overlaying ecoregion and political maps...

Citations

... Collection 6 is the most accurate MODIS fractional cover product to date and has been improved from previous collections with updated input data (DiMiceli et al., 2021). The data are distributed as a global tiled grid in Sinusoidal projection at a spatial resolution of 250 m. ...
... Retrievals over the coastal area have the slopes farthest to unity (between 0.36 and 0.94) and higher intercepts (between − 0.0004 and 0.088) attributable to complex surface type and mixed water/land pixels and biases from cloud/foam/sediment contaminations (Anderson et al., 2013). Further enhancements are required by refining the surface reflectance estimations (Limbacher and Kahn, 2019), improved water/land mask (Carroll et al., 2017;, and aerosol model that considers the hygroscopic properties of aerosol particles at Table 12 Confusion matrix showing the correlation between aerosol products over the mountainous area. Cells with values > 0.8 are shaded. ...
... Taking advantage of the long time series of imagery at a medium resolution and frequent revisit time, many have used the Landsat imagery archive to characterize wetland change over time [13][14][15][16][17][18]. Commonly, previous efforts have sought to identify changes in surface water extent, creating maps of surface water presence/absence with spectral indices [13][14][15][16]19], such as the Dynamic Surface Water Extent (DSWE) [20]. ...
... The 5th versions of MOD44W products are only one image of the global surface water, and the spatial resolution is 250 m. It has been proven to be reliable and can be used as the basis of sample collection [26]. ...
... Since 2001, 250-m resolution red and near-infrared data have been added through the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, with a repeat cycle for temperate areas of one day. 1 MODIS also includes data in blue, green, mid-infrared (500 m), and many thermal bands (1000 m). The extended wavelength capabilities of MODIS permit much improved atmospheric characterization and the preparation of many specialized land-cover products [21]. It will be extremely useful for change detection and analysis when its archive becomes long enough. ...
... This index which has been largely used to assess fire severity (e.g. Bobbe et al., 2001;Hudak et al., 2004; for further details see the review of French et al., 2008) was used here as a proxy for the vegetation change rate over time, which should indirectly take into account disturbance events like fires. dNBR was calculated from Landsat 7 ETM+ and Landsat 8 ETM+ single date images of NIR and SWIR bands for the period between 1990 and 2016. ...
... Roy et al., 2008a;Friedl et al., 2010), none directly addresses the issue of deforestation, particularly in near real-time. Most MODIS-based analyses to date have been retrospective or quantify changes in the landscape in yearly or decadal time steps (Carrol et al., 2004;Zhan et al., 2002). Routine production of global MODIS-based land cover change maps has been attempted (Zhan et al., 2000) but has yet to come to fruition. ...
... The validation showed that the WBD-NAHL dataset had high overall accuracy and significantly improved upon the ability of the existing global JRC water maps for detecting small water (e.g., smaller than 0.006 km 2 ) than the existing global JRC water maps. These small water bodies consist of nearly half the total water bodies in the tundra and boreal forest regions of North America and generally experience faster cycling of water, material, and energy than larger water bodies (Winslow et al., 2014;Carroll et al., 2011;Messager et al., 2016). The improved WBD-NAHL dataset may provide more accurate inputs for hydrological estimates, which are vital components for understanding and modeling the pan-Arctic hydrological, biochemical, and energy cycling. ...
... Vegetation Continuous Fields (VCF) product is a representation of the earth's terrestrial surface as gradients of three components, i.e. Percent Tree Cover (PTC), Percent Non-Tree Cover (PNC) and Percent Bare Land (PBL) (Carroll et al., 2010). MODIS VCF data layers were semi-automated by algorithms in virtue of machine learning regression tree-based model. ...
... The past few decades have witnessed a series of global land cover (GLC) mapping efforts (Ban, Gong, and Giri 2015;Gómez, White, and Wulder 2016). As shown in Table 1, coarse spatial resolution GLC products included the 1-km International Geosphere-Biosphere Programme Data and Information System Cover map (DISCover) circa 1992 (Loveland et al. 2000); the 1-km University of Maryland land cover map (UMD) circa 1992 (Hansen et al. 2000); the 1-km Global Land Cover 2000 map (GLC2000) (Bartholome and Belward 2005); the 300-m European Space Agency Climate Change Initiative (ESA-CCI) land cover product from 1992 to 2020 (ESA 2017); the 500-m Moderate Resolution Imaging Spectroradiometer (MODIS) land cover product (MOD12Q1) from 2001 to 2020 (Friedl et al. 2010;Sulla-Menashe et al. 2019); and the 5-km annual dynamics of global land cover dataset (GLASS-GLC) (Liu et al. 2020b). In 2008, the United States Geological Survey (USGS) provided free access to the whole Landsat archive Wulder et al. 2012). ...