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ISLSCP II Global Population of the World
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Summary:

Global Population of the World (GPW) translates census population data to a latitude-longitude grid so that population data may be used in cross-disciplinary studies. There are three data files with this data set for the reference years 1990 and 1995. Over 127,000 administrative units and population counts were collected and integrated from various sources to create the gridded data.

In brief, GPW was generated using the following steps:

As with any global data set based on multiple data sources, the spatial and attribute precision of GPW is variable. The level of detail and accuracy, both in time and space, vary among the countries for which data were obtained.

Additional Documentation:

This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. A complete description of the data, it's derivation, acknowledgements, and references provided by the ISLSCP II Data Management Staff is included with this data set as a companion file named 1_global_population_doc.pdf .

ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water and energy cycle. The data were acquired from a number of U.S. and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.

ISLSCP is one of several projects of Global Energy and Water Cycle Experiment (GEWEX) [http://www.gewex.org/] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.

Related Data Set:

ISLSCP II Global Gridded Gross Domestic Product (GDP), 1990

Data Citation:

Cite this data set as follows:

Balk, D., U. Deichmann, and G. Yetman. 2010. ISLSCP II Global Population of the World. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection.  Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/975

File Information:

The archived data sets for ISLSCP II have been organized by categories. This data set is in the socioeconomic category---a collection of societal and economics-based data sets.

Data Set Spatial Extent: Global gridded

Westernmost Longitude: -180 W

Easternmost Longitude: 180 E

Northernmost Latitude: 90 N

Southernmost Latitude: -90 S

Projection: Geographic

Data Set Spatial Resolution: one, half, and quarter degree in both latitude and longitude

Data Set Temporal Extent: annual for the years 1990 and 1995

Data File Format

All of the data files in each data set within the ISLSCP Initiative II data collection are in ESRI ASCII GRID format for ArcInfo. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows.

There are 3 data files (.zip) in this data set with a spatial resolution of one degree (1d), half degree (hd), and quarter degree (qd) respectively:

Land Area - gpw_land_area_xdeg.zip
gpw_land_area_xx.asc: Global gridded land area (square km of land per cell).
xx can be 1d, hd, and qd, denoting the spatial resolution.
Note that there is less land area near the poles, because of the stretching of the pole region due to the equal-area projection.

Population Counts - gpw_populations_counts_xdeg.zip
gpw_pop_counts_xx_YYYYa.asc: Global gridded population counts (persons per square km per cell).
xx can be 1d, hd, and qd, denoting the spatial resolution.
YYYY is the year (1990 or 1995), and if there is an "a" after the year, the data has been adjusted by the United Nations. For example: gpw_pop_counts_1d_1990a.asc

Population Density -gpw_populations_density_xdeg.zip
gpw_pop_density_xx_YYYYa.asc: Global gridded population density (persons per cell).
xx can be 1d, hd, and qd, denoting the spatial resolution.

Within each .zip file, for each spatial resolution, there is a data file (*.asc), a differences file (*.dif), and a change map file (*.changemap.asc).

*.changemap.asc - Gridded ASCII map showing the differences between the ISLSCP II land/water mask and the original data set in ESRI ASCII GRID fromat for ArcInfo.

*.dif  - ASCII tables of "differences", points in the original file that did not match the ISLSCP II Land/Water mask, and were removed from the ASCII map files.

*.asc  - Gridded ASCII population count maps, population density maps, and land area maps in ESRI ASCII GRID format for ArcInfo.

Data file naming conventions are further described in the 1_global_population_doc.pdf  and 0_global_population_readme.txt

References:

Center for International Earth Science Information Network (CIESIN), Columbia University; International Food Policy Research Institute (IFPRI); and World Resources Institute (WRI).2000. Gridded Population of the World (GPW), Version 2. Palisades, NY: CIESIN,Columbia University. Available at http://sedac.ciesin.columbia.edu/gpw-v2/index.html?main.html&2.

CIA World Factbook (1990, 1991, 1992 editions), Central Intelligence Agency, Office of Public Affairs, Washington, DC, 20505.

 Sachs, J. D., Mellinger, A. D. and J. L. Gallup, (2001), The Geography of Poverty and Wealth, Scientific American, 284:70-75. doi:10.1038/scientificamerican0301-70

World Bank World Tables of Economic and Social Indicators, 1950-1992, Inter-University Consortium for Political and Social Research (ICPSR version 6159), P.O. Box 1248, Ann Arbor, MI, 48106. http://www.icpsr.umich.edu:8080/ICPSR-SERIES/00076.xml .  

Data Access:

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC)[http://www.daac.ornl.gov].

Data Archive Contact Information:

E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952