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Gridded Population of the World, version 3 (GPWv3) is the latest developments in the rendering of human populations in a common geo-referenced framework, produced by the Center for International Earth Science Information Network (CIESIN) of the Earth Institute at Columbia University. GPWv3 depicts the distribution of human population across the globe. It is the most detailed version of GPW to date with more than three times the amount of data as version 2, and includes population estimates to 2015. Developed between 2003 and 2005, GPWv3 provides globally consistent and spatially explicit human population information and data for use in research, policy making, and communications. GPWv3 incorporates a number of improvements to the two prior iterations of GPW. Input administrative data have been improved for nearly all of the 232 countries included in the dataset. (The number of administrative units has increased three-fold since GPWv2 and twenty-fold since GPWv1.) Additionally, the input data years have been updated for over two-thirds of the countries. The population data estimates, previously only available for 1990 and 1995, are also now provided for the period 1990–2015, by quinquennial years. The population estimates for 2005, 2010, and 2015 were produced in collaboration with the United Nations Food and Agriculture Programme (FAO) as GPW: Future Estimates. Finally, the map collection has been vastly expanded to include population density, and sub-national administrative boundary maps at country, continental, and global levels.  +
HYDRO1k is a geographic database developed to provide comprehensive and consistent global coverage of topographically derived data sets, including streams, drainage basins and ancillary layers derived from the USGS' 30 arc-second digital elevation model of the world (GTOPO30). HYDRO1k provides a suite of geo-referenced data sets, both raster and vector, which will be of value for all users who need to organize, evaluate, or process hydrologic information on a continental scale. Developed at the U.S. Geological Survey's Center for Earth Resources Observation and Science (EROS), the HYDRO1k project's goal is to provide to users, on a continent by continent basis, hydrologically correct DEMs along with ancillary data sets for use in continental and regional scale modeling and analyses.  +
HydroSHEDS is a mapping product that provides hydrographic information for regional and global-scale applications in a consistent format. It offers a suite of geo-referenced data sets (vector and raster) at various scales, including river networks, watershed boundaries, drainage directions, and flow accumulations. HydroSHEDS is based on high-resolution elevation data obtained during a Space Shuttle flight for NASA's Shuttle Radar Topography Mission (SRTM). The goal of developing HydroSHEDS was to generate key data layers to support regional and global watershed analyses, hydrological modeling, and freshwater conservation planning at a quality, resolution and extent that had previously been unachievable. Available resolutions range from 3 arc-second (approx. 90 meters at the equator) to 5 minute (approx. 10 km at the equator) with seamless near-global extent.  +
International Bathymetric Chart of the Arctic Ocean (IBCAO). The goal of this initiative is to develop a digital data base that contains all available bathymetric data north of 64 degrees North, for use by mapmakers, researchers, and others whose work requires a detailed and accurate knowledge of the depth and the shape of the Arctic seabed. IBCAO Version 3.0 represents the largest improvement since 1999 taking advantage of new data sets collected by the circum-Arctic nations, opportunistic data collected from fishing vessels, data acquired from US Navy submarines and from research ships of various nations. Built using an improved gridding algorithm, this new grid is on a 500 meter spacing, revealing much greater details of the Arctic seafloor than IBCAO Version 1.0 (2.5 km) and Version 2.0 (2.0 km). The area covered by multibeam surveys has increased from ~6 % in Version 2.0 to ~11% in Version 3.0.  +
Latest version (5.0) The latest version of the "Global Map of Irrigation Areas" is version 5, which can be downloaded from this page. The documentation of the map includes an explanation of the methodology, information per country, an assessment of the map quality, and references to the background and history of the irrigation mapping project. The map shows the amount of area equipped for irrigation around the year 2005 in percentage of the total area on a raster with a resolution of 5 minutes. Additional map layers show the percentage of the area equipped for irrigation that was actually used for irrigation and the percentages of the area equipped for irrigation that was irrigated with groundwater, surface water or non-conventional sources of water. An explanation of the different terminology to indicate areas under irrigation is given in this glossary. Please note that information for the additional layers on area actually irrigated or on the water source for irrigation was derived from statistical survey data (e.g. census reports). Therefore all grid cells belonging to the same statistical unit will have the same value. Consequently, the accuracy at pixel level will be very limited, depending on the size of the statistical unit. Users are requested to refer to the map as follows: "Stefan Siebert, Verena Henrich, Karen Frenken and Jacob Burke (2013). Global Map of Irrigation Areas version 5. Rheinische Friedrich-Wilhelms-University, Bonn, Germany / Food and Agriculture Organization of the United Nations, Rome, Italy".  +
Layers (NetCDF) of monthly and yearly average suspended sediment flux in global rivers, predicted by the WBMsed model.  +
Lithology describes the geochemical, mineralogical, and physical properties of rocks. It plays a key role in many processes at the Earth surface, especially the fluxes of matter to soils, ecosystems, rivers, and oceans. The Lithological map of the World is based on the Global Lithological Map database v1.1 (GLiM, Hartmann and Moosdorf, 2012). GLiM represents the rock types of the emerged surface of the Earth using 1,235,400 polygons assembled from 92 regional geological maps, translated into lithological units using additional literature. According to the GLiM, the total surface of continents and islands is covered by 64 % sediments (a third of which is carbonates), 13% metamorphics, 7% plutonics, and 6% volcanics, and 10% are covered by water or ice. The high resolution of the GLiM allows observation of regional lithological distributions which often vary from the global average. The GLiM enables regional analysis of Earth surface processes at global scales. A coarse gridded version of the GLiM is available at the PANGEA Database (, the original GIS data are downloadable using this link (  +
Multiple general circulation models were run for paleoclimate simulations at 21, 6, and 0 (pre-inudstrial) ka.  +
NARWidth is composed of planform morphometric measurements of North American rivers at approximately mean discharge. It was created using image processing algorithms on Landsat TM and ETM+ imagery. NARWidth is intended to be used in a wide variety of scientific and engineering applications including hydrologic, hydraulic, and biogeochemical models.  +
NGDC is the US national archive for multibeam bathymetric data and presently holds over 15.7 million nautical miles of ship tracklines (1187 surveys) received from sources worldwide. In addition to deepwater data, the multibeam database also includes hydrographic multibeam survey data from the NOS. Associated NOS data products, including 3D images and grids, are available via the NOS Hydrographic Survey Data Map Service.  +
NGDC's GEODAS Marine Trackline Geophysics database contains bathymetry, magnetics, gravity and seismic navigation data collected during marine cruises from 1953 to the present. Coverage is worldwide. Data sources include both US and foreign oceanographic institutions and government agencies. This database is distributed both On-line and on DVD using the GEODAS Search and Retrieval software. Searches by geographic area, year of cruise, institution, platform, cruise, date or parameter are available. Downloads can be customized to area, parameter and format. Digital data files are in the MGD77 exchange format, and contain a documentation header record and a series of data records. Header records document the content and structure of the data records. Data records contain geophysical data (bathymetry, magnetics, gravity and seismic shot-point ids) with time and position. NGDC also archives analog geophysical data including seismic reflection and refraction, side-scan sonar, and other data types. Analog underway geophysical data are inventoried and searchable through the GEODAS Search and Retrieval software. NGDC is pleased to accept contributions of underway geophysical data on almost any media, preferably in the MGD77 format. Any data received are in the international public domain, readily available globally to any interested individual or group.  +
NOAA was engaged in a program to compile Great Lakes bathymetric data and make them readily available to the public, especially to the communities concerned with Great Lakes science, pollution, coastal erosion, response to climate changes, threats to lake ecosystems, and health of the fishing industry. This program was managed by NGDC and relied on the cooperation of NOAA/Great Lakes Environmental Research Laboratory, NOAA/National Ocean Service, the Canadian Hydrographic Service, other agencies, and academic laboratories. Compilation of new bathymetry for the Great Lakes was an important part of this program, carried out cooperatively between NOAA (NGDC and GLERL), and the Canadian Hydrographic Service. This new bathymetry provided a more detailed portrayal of lakefloor topography, and revealed some lakefloor features seen for the first time.  +
NOAA's National Centers for Environmental Information (NCEI) builds and distributes high-resolution, coastal digital elevation models (DEMs) that integrate ocean bathymetry and land topography to support NOAA's mission to understand and predict changes in Earth's environment, and conserve and manage coastal and marine resources to meet our Nation's economic, social, and environmental needs. They can be used for modeling of coastal processes (tsunami inundation, storm surge, sea-level rise, contaminant dispersal, etc.), ecosystems management and habitat research, coastal and marine spatial planning, and hazard mitigation and community preparedness. Bathymetric, topographic, and shoreline data used in DEM compilation are obtained from various sources, including NCEI, the U.S. National Ocean Service (NOS), the U.S. Geological Survey (USGS), the U.S. Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and other federal, state, and local government agencies, academic institutions, and private companies. DEMs cell size ranges from 1/9 arc-second (~3 meters) to 36 arc-seconds (~1 km).  +
On-line access to information on historical (archived) water levels and streamflow. Using map-based or text-based searches, users can locate over 1200 hydrometric stations measuring water levels and view hydrographs of historical waer level and streamflow data. Alternatively, users can use a separate tool to select and access historical data from over 2500 active stations and 5500 discontinued stations. In addition, a third tool allows users to generate historical water level and/or streamflow statistics for any of these (more than) 8000 stations.  +
OneGeology's aim is to create dynamic digital geological map data for the world. It is an international initiative of the geological surveys of the world who are working together to achieve this ambitious and exciting venture. Please follow the links in this section to find out more about OneGeology, what it is, why we are doing it and how such a big initiative can be achieved.  +
Presented are four companion digital models of the age, age uncertainty, spreading rates and spreading asymmetries of the world's ocean basins as geographic and Mercator grids with 2 minute resolution. The grids include data from all the major ocean basins as well as detailed reconstructions of back-arc basins. The age, spreading rate and asymmetry at each grid node is determined by linear interpolation between adjacent seafloor isochrons in the direction of spreading. Ages for ocean floor between the oldest identified magnetic anomalies and continental crust are interpolated by geological estimates of the ages of passive continental margin segments. The age uncertainties for grid cells coinciding with marine magnetic anomaly identifications, observed or rotated to their conjugate ridge flanks, are based on the difference between gridded age and observed age. The uncertainties are also a function of the distance of a given grid cell to the nearest age observation, and the proximity to fracture zones or other age discontinuities. Asymmetries in crustal accretion appear to be frequently related to asthenospheric flow from mantle plumes to spreading ridges, resulting in ridge jumps towards hotspots. We also use the new age grid to compute global residual basement depth grids from the difference between observed oceanic basement depth and predicted depth using two alternative age-depth relationships. The new set of grids helps to investigate prominent negative depth anomalies, which may be alternatively related to subducted slab material descending in the mantle or to asthenospheric flow. A combination of our digital grids and the associated relative and absolute plate motion model with seismic tomography and mantle convection model outputs represent a valuable set of tools to investigate geodynamic problems.  +
RESSED is a Microsoft® Access ® database containing information from the original Soil Conservation Service (SCS) datasheets (SCS Form 34) for the United States. The database is provided for download (i.e., this website does not contain tools for utilizing the RESSED database). The Subcommittee on Sedimentation hopes to provide updates to this database via periodic postings on this site. Such database improvements may be predicated on acquisition of adequate funding for RESSED. Additionally, scanned copies of the original data sheets are available for selected viewing, downloading, or printing. The data sheets are in Adobe® Acrobat® Portable Document Format (PDF).  +
Sage contains a compilation of monthly mean river discharge data for over 3500 sites worldwide. The data sources are RivDis2.0, the United States Geological Survey, Brazilian National Department of Water and Electrical Energy, and HYDAT-Environment Canada. The period of record for each station is variable, from 3 years to greater than 100. All data is in m3/s.  +
TPXO6.2 is a medium-resolution, 1/4o x 1/4o global model developed by Gary Egbert and coworkers at Oregon State University. The model domain includes ocean cavities under the floating ice shelves. The principal assimilated data set is TOPEX/Poseidon (T/P) satellite radar altimetry, between +/-66o latitude. However, the model also includes patches for various "coastal" oceans, including the Antarctic (assimilating tide gauge data used in circum-Antarctic inverse model CADA00.10 and the Ross Sea height-based inverse model Ross_Inv_2002, and the Arctic (cf. the Arctic inverse model AOTIM-5). TPXO6.2 is one of the most accurate global tidal solutions, particularly for high latitudes since it utilizes recent Antarctic grounding line information and Antarctic and Arctic tide height data. The load tide associated with TPXO6.2 (denoted "TPXO62_load") is a correction to TPXO6.2 to account for the deformation of the solid earth due to the added weight of water above it. The correction is usually a few percent of the local tidal amplitude. The load tide is used to correct the ocean tide to a geocentric tide height (e.g., the displacement of the ocean's free surface as measured by a satellite altimeter. The load tide is roughly out-of-phase with the ocean tide. Thus, adding the predicted load tide to the ocean tide leads to smaller tide heights. For altimetry, this means that the altimetrically-observed tide-forced variation of, say, an ice shelf surface, is typically less than the ocean tide. The load tide (or, more precisely, the "ocean self attraction and loading" term), is also required to correct the barotropic pressure gradient (i.e., sea surface slope) in the shallow water wave equations used to run dynamically based tide models. The load tide is not the same as the earth's own body-tide response to lunar and solar gravitation: the body tide must be estimated separately from solid-earth models if required. However, the load tide is defined under continents as well as under the ocean: ocean tides force deformation of the earth's crust well inland of the coastal boundary (see the above figure). TPXO62_load is distributed with a Matlab Graphical User Interface ("GUI") called "TMD" (the Tide Model Driver). TMD can be used to quickly access and browse the model, and to make load tide height predictions. The TMD package also contains scripted functions for use in batch-mode Matlab processing. For an overview of the GUI and scripts, view or download the README PDF file. For FORTRAN access, please go to the Oregon State "OTIS" web page.  
TRMM, during its mission and broad sampling footprint between 35°N and 35°S, is providing some of the first detailed and comprehensive dataset on the four dimensional distribution of rainfall and latent heating over vastly undersampled oceanic and tropical continental regimes. Combined with concurrent measurement of the atmosphere's radiation budget, estimates of the total diabatic heating are being realized for the first time ever on a global scale. TRMM will fill many gaps in our understanding of rainfall properties and their variation. These includes: # frequency distributions of rainfall intensity and areal coverage; # the partitioning of rainfall into convective and stratiform categories; # the vertical distribution of hydrometeors (including the structure and intensity of the stratiform region bright band); # variation of the timing of heaviest rainfall - particularly nocturnal intensification of large mesoscale convective systems over the oceans, and diurnal intensification of orographically and sea-breezed forced systems over land. TRMM will enable mapping of larger time and space variations of rainfall in quasi-periodic circulation anomalies, such as the Madden-Julian oscillation in the western Pacific and ENSO over the broader Pacific basin.  +