The Shuttle Radar Topography Mission
TL;DR: The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth, using dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution.
Abstract: [1] The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution. Details of the development, flight operations, data processing, and products are provided for users of this revolutionary data set.
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TL;DR: In this paper, the authors created a new dataset of spatially interpolated monthly climate data for global land areas at a very high spatial resolution (approximately 1 km2), including monthly temperature (minimum, maximum and average), precipitation, solar radiation, vapour pressure and wind speed, aggregated across a target temporal range of 1970-2000, using data from between 9000 and 60,000 weather stations.
Abstract: We created a new dataset of spatially interpolated monthly climate data for global land areas at a very high spatial resolution (approximately 1 km2). We included monthly temperature (minimum, maximum and average), precipitation, solar radiation, vapour pressure and wind speed, aggregated across a target temporal range of 1970–2000, using data from between 9000 and 60 000 weather stations. Weather station data were interpolated using thin-plate splines with covariates including elevation, distance to the coast and three satellite-derived covariates: maximum and minimum land surface temperature as well as cloud cover, obtained with the MODIS satellite platform. Interpolation was done for 23 regions of varying size depending on station density. Satellite data improved prediction accuracy for temperature variables 5–15% (0.07–0.17 °C), particularly for areas with a low station density, although prediction error remained high in such regions for all climate variables. Contributions of satellite covariates were mostly negligible for the other variables, although their importance varied by region. In contrast to the common approach to use a single model formulation for the entire world, we constructed the final product by selecting the best performing model for each region and variable. Global cross-validation correlations were ≥ 0.99 for temperature and humidity, 0.86 for precipitation and 0.76 for wind speed. The fact that most of our climate surface estimates were only marginally improved by use of satellite covariates highlights the importance having a dense, high-quality network of climate station data.
7,558 citations
TL;DR: An overview of the GMES Sentinel-2 mission including a technical system concept overview, image quality, Level 1 data processing and operational applications is provided.
2,517 citations
Paul Sabatier University1, National Autonomous University of Mexico2, Carnegie Institution for Science3, University of São Paulo4, National University of Colombia5, Norwegian University of Life Sciences6, Amazon.com7, University of Leeds8, United Nations9, Smithsonian Tropical Research Institute10, University of Edinburgh11, Costa Rica Institute of Technology12
TL;DR: This work analyzed a global database of directly harvested trees at 58 sites, spanning a wide range of climatic conditions and vegetation types, and found a pantropical model incorporating wood density, trunk diameter, and the variable E outperformed previously published models without height.
Abstract: Terrestrial carbon stock mapping is important for the successful implementation of climate change mitigation policies. Its accuracy depends on the availability of reliable allometric models to infer oven-dry aboveground biomass of trees from census data. The degree of uncertainty associated with previously published pantropical aboveground biomass allometries is large. We analyzed a global database of directly harvested trees at 58 sites, spanning a wide range of climatic conditions and vegetation types (4004 trees ≥ 5 cm trunk diameter). When trunk diameter, total tree height, and wood specific gravity were included in the aboveground biomass model as covariates, a single model was found to hold across tropical vegetation types, with no detectable effect of region or environmental factors. The mean percent bias and variance of this model was only slightly higher than that of locally fitted models. Wood specific gravity was an important predictor of aboveground biomass, especially when including a much broader range of vegetation types than previous studies. The generic tree diameter-height relationship depended linearly on a bioclimatic stress variable E, which compounds indices of temperature variability, precipitation variability, and drought intensity. For cases in which total tree height is unavailable for aboveground biomass estimation, a pantropical model incorporating wood density, trunk diameter, and the variable E outperformed previously published models without height. However, to minimize bias, the development of locally derived diameter-height relationships is advised whenever possible. Both new allometric models should contribute to improve the accuracy of biomass assessment protocols in tropical vegetation types, and to advancing our understanding of architectural and evolutionary constraints on woody plant development.
1,750 citations
TL;DR: The Global Multi-Resolution Topography (GMRT) as discussed by the authors is a collection of bathymetry tiles with digital elevations and shaded relief imagery spanning nine magnification doublings from pole to pole.
Abstract: [1] Seafloor bathymetric data acquired with modern swath echo sounders provide coverage for only a small fraction of the global seabed yet are of high value for studies of the dynamic processes of seafloor volcanism, tectonics, mass wasting, and sediment transport that create and shape the undersea landscape. A new method for compilation of global seafloor bathymetry that preserves the native resolution of swath sonars is presented. The Global Multi-Resolution Topography synthesis consists of a hierarchy of tiles with digital elevations and shaded relief imagery spanning nine magnification doublings from pole to pole (http://www.marine-geo.org/portals/gmrt). The compilation is updated and accessible as surveys are contributed, edited, and added to the tiles. Access to the bathymetry tiles is via Web services and with WMS-enabled client applications such as GeoMapApp®, Virtual Ocean, NASA World Wind®, and Google Earth®.
1,445 citations
TL;DR: A 30-arc second resolution global topography/bathymetry grid (SRTM30_PLUS) has been developed from a wide variety of data sources as discussed by the authors, which is based on a new satellite-gravity model where the gravity-to-topography ratio is calibrated using 298 million edited soundings.
Abstract: A new 30-arc second resolution global topography/bathymetry grid (SRTM30_PLUS) has been developed from a wide variety of data sources. Land and ice topography comes from the SRTM30 and ICESat topography, respectively. Ocean bathymetry is based on a new satellite-gravity model where the gravity-to-topography ratio is calibrated using 298 million edited soundings. The main contribution of this study is the compilation and editing of the raw soundings, which come from NOAA, individual scientists, SIO, NGA, JAMSTEC, IFREMER, GEBCO, and NAVOCEANO. The gridded bathymetry is available for ftp download in the same format as the 33 tiles of SRTM30 topography. There are 33 matching tiles of source identification number to convey the provenance of every grid cell. The raw sounding data, converted to a simple common format, are also available for ftp download.
1,255 citations
References
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01 Mar 2000
TL;DR: In this paper, the authors present a review of the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering, including cartography, geodesy, land cover characterization, and natural hazards.
Abstract: Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristic of the surface. By exploiting the phase of the coherent radar signal, interferometry has transformed radar remote sensing from a largely interpretive science to a quantitative tool, with applications in cartography, geodesy, land cover characterization, and natural hazards. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.
3,042 citations
"The Shuttle Radar Topography Missio..." refers background in this paper
...Massonnet, 1997; Madsen and Zebker, 1998; Rosen et al., 2000 ]....
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...baseline) [Fielding et al., 1995; Coltelli et al., 1996; Rosen et al., 2000 ], and ScanSAR, where radar beams were electronically steered in elevation to increase the swath width....
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...The emergence, in the 1990s, of synthetic aperture radar (SAR) interferometry [Zebker and Goldstein, 1986; Massonnet, 1997; Madsen and Zebker, 1998; Rosen et al., 2000 ] placed the possibility of efficiently and affordably creating a global digital elevation model within the grasp of spacefaring nations....
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TL;DR: In this paper, an approach to 'unwrapping' the 2 pi ambiguities in the two-dimensional data set is presented, where it is found that noise and geometrical radar layover corrupt measurements locally, and these local errors can propagate to form global phase errors that affect the entire image.
Abstract: Interferometric synthetic aperture radar observations provide a means for obtaining high-resolution digital topographic maps from measurements of amplitude and phase of two complex radar images. The phase of the radar echoes may only be measured modulo 2 pi; however, the whole phase at each point in the image is needed to obtain elevations. An approach to 'unwrapping' the 2 pi ambiguities in the two-dimensional data set is presented. It is found that noise and geometrical radar layover corrupt measurements locally, and these local errors can propagate to form global phase errors that affect the entire image. It is shown that the local errors, or residues, can be readily identified and avoided in the global phase estimation. A rectified digital topographic map derived from the unwrapped phase values is presented.
2,246 citations
"The Shuttle Radar Topography Missio..." refers methods in this paper
...This process is called phase unwrapping, and a number of algorithms have been invented to optimize the process [e.g., Goldstein et al., 1988 ]....
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TL;DR: For 11 days in February 2000, the Shuttle Radar Topography Mission (SRTM) successfully recorded by interferometric synthetic aperture radar (InSAR) data of the entire land mass of the earth between 60°N and 57°S.
Abstract: For 11 days in February 2000, the Shuttle Radar Topography Mission (SRTM) successfully recorded by interferometric synthetic aperture radar (InSAR) data of the entire land mass of the earth between 60°N and 57°S. The data acquired in C- and X-bands are processed into the first global digital elevation models (DEMs) at 1 arc sec resolution, by NASA-JPL and German aerospace center (DLR), respectively. From the perspective of the SRTM-X system, we give in this paper an overview of the mission and the DEM production, as well as an evaluation of the DEM product quality. Special emphasis is on challenges and peculiarities of the processing that arose from the unique design of the SRTM system, which has been the first single-pass interferometer in space.
1,686 citations
Journal Article•
TL;DR: The National Elevation Dataset (NED) as discussed by the authors is a raster product that provides elevation data coverage of the entire United States and its island territories in a seamless format with consistent projection, resolution, elevation units and horizontal and vertical datums.
Abstract: The National Elevation Dataset (NED) is a raster product that provides elevation data coverage of the entire United States and its island territories in a seamless format with consistent projection, resolution, elevation units and horizontal and vertical datums. It is the result of the maturation of the U.S. Geological Survey elevation production program, in which national coverage of quadrangle-based digital elevation models has been completed. Specifications and production techniques for the NED are given. The NED fulfills many of the concepts of framework geospatial data as envisioned for the National Spatial Data Infrastructure, allowing users to focus on analysis rather than data preparation. The NED provides basic elevation data for many geographic information system applications and is maintained and updated regularly. The USGS is making several seamless datasets including NED available through the Internet.
1,301 citations
TL;DR: The most successful 11-day flight of the Shuttle Radar Topography Mission (SRTM) was completed on February 22, 2000 by the Space Shuttle Endeavour landing at Kennedy Space Center.
Abstract: On February 22, 2000, the Space Shuttle Endeavour landed at Kennedy Space Center, completing the highly successful 11-day flight of the Shuttle Radar Topography Mission (SRTM). Onboard were over 300 high-density tapes containing data for the highest resolution digital topographic map of Earth ever made.
SRTM is a cooperative project between the National Aeronautics and Space Administration (NASA) and the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense. The mission was designed to use a single-pass radar interferometer to produce a digital elevation model (DEM) of the Earth's land surface between about 60 north and 56 south latitude. When completed, the DEM will have 30-m pixel spacing and about 15-m vertical accuracy. Two ortho-rectified image mosaics, one from the ascending passes with illumination from the southeast, and one from descending passes with illumination from the southwest, will also be produced (Figure 1).
1,128 citations
"The Shuttle Radar Topography Missio..." refers background in this paper
...Department of Defense (DOD), and DLR [ Farr and Kobrick, 2000; Werner, 2001]....
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