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Gridded Population of the World, Version 4 (GPWv4) Preliminary Release 2
Gridded Population of the World v4 is now in beta.
Please use the beta version instead at: http://beta.sedac.ciesin.columbia.edu/data/collection/gpw-v4.
| Disclaimer |
These data represent a preliminary data release. The final data set will eventually be distributed via the NASA Socioeconomic Data and Applications Center (SEDAC), and will go through a more formal alpha and beta review process as part of that release. We encourage feedback on the data set, which can be sent to "gpw(at)ciesin.columbia.edu." |
| Overview |
GPWv4 is a gridded data product that depicts global population data from the 2010 round of Population and Housing Censuses at a scale and extent sufficient to demonstrate the spatial relationship between human populations and the environment across the globe. This population grid provides globally-consistent and spatially-explicit data for use in research, policy making, and communications and is compatible with data sets from social, economic, and Earth science fields. GPWv4 is constructed from national or subnational input areal units of varying resolutions. The native grid cell size is 30 arc-seconds, or ~1 km at the equator. Separate grids are available for population count, population density, estimated land area, and data quality indicators. The full GPWv4 data collection will consist of population estimates for the years 2000, 2005, 2010, 2015, and 2020, and will include grids for estimates of total population, age, sex, and urban/rural status. However, this preliminary release consists only of total population estimates for the year 2010. This data is being released now to allow users early access to the population grids. |
| Maps |
| Download |
The GPWv4 data sets are available to download in a .tif format. |
| Data Set Descriptions |
Gridded Population of the World, Version 4 (GPWv4): Population Count (2010), Preliminary Release 2 Gridded Population of the World, Version 4 (GPWv4): Population Density (2010), Preliminary Release 2 Gridded Population of the World, Version 4 (GPWv4): Land Area, Preliminary Release 2 Gridded Population of the World, Version 4 (GPWv4): Data Quality Indicators, Preliminary Release 2 The water mask, GL_WATERMASK.tif, distinguishes between pixels that are completely water and/or ice (Total Water Pixels) and pixels that also contain land (Partial Water Pixels). The grid GL_DATACONTEXT.tif categorizes pixels with a 0 population estimate in the population count and density grids, based on information included in the census documents. Pixels are categorized into 6 categories: Parks or Protected Area, Military District, No Households, Not Enumerated, Uninhabited, and Unknown. Pixels categorized as Unknown belong to administrative units where the data are currently being researched; these will be updated before the final data release. |
| Methods |
GPWv4 is a minimally-modeled gridded population data set that incorporates census population data from the 2010 round of censuses. Population estimates are derived by extrapolating the raw census counts to estimates for the 2010 target year. The development of GPWv4 builds upon previous versions of the data set (Tobler et al., 1997; Deichmann et al., 2001; Balk et al., 2006). The two basic inputs of GPW are non-spatial population data (i.e., tabular counts of population listed by administrative area) and spatially-explicit administrative boundary data (administrative or enumeration units). Population input data were collected at the highest resolution available from the results of the 2010 round of censuses, scheduled to occur between 2005 and 2014. Where census results were unavailable or not yet released, official population estimates from the NSO were used. Administrative boundary data were collected from multiple national mapping or planning agencies, as well as other organizations. Ideally, the boundaries are from the census cartography. The population census counts or official estimates were then matched to digital geographic boundaries. Matching was based on the common identifying codes or the unit names used in the census. A global framework of international boundaries was used to ensure consistent alignment between countries. The Global Administrative Areas version 2 (GADMv2; www.gadm.org) data set was selected as the framework as it is publicly available and frequently used in the research community. The international boundaries of census geography data sets were adjusted to the GADMv2 framework, although in cases where the resolution of the census geography far exceeded the GADMv2 boundaries, the former were kept (e.g., New Zealand, the United Kingdom, and the United States). Since countries conduct their censuses at different time periods, annual rates were used to adjust census counts to the target year of 2010 to allow for global comparison. Exponential growth rates were calculated for each administrative unit by matching the total population from the input data to those from a previous census enumeration. Annual rates of change were calculated as follows: Population estimates were adjusted to target years as follows: where r is the annual growth rate, P1 and P2 are the census population counts, Px is the population estimate in the target year, and t is the number of years between population counts.In cases where matching at the highest resolution was not possible between the two points in time, censuses were matched and growth rates were calculated at a coarser resolution (e.g., state), and applied to each unit (e.g., municipality) within that state. To create the gridded population data set, the population estimates were distributed to a 30 arc-second (~1 km) grid using an areal-weighting method. This method, also known as uniform distribution, does not make use of any other geographic data in order to spatially disaggregate the census population. Population was allocated into grid cells through the simple assumption that the population of a grid cell is an exclusive function of the land area within that pixel. For grid cells that intersect sub-national or national boundaries, population was allocated based on the proportion of the area of the each unit located in the grid cell. A water mask was applied to the data to prevent lakes, rivers, and ice-covered areas from distorting the actual population density. For this preliminary release, grids for population count and density estimates for 2010 are available at the global level. Additionally, grids of estimated land and water area and data quality grids are also provided. Additional detail of the methods and improvements made in the GPWv4 data set are described by Doxsey-Whitfield et al. (Forthcoming). Below is a preliminary version of the paper, which is forthcoming in Papers in Applied Geography: |
| Recommended Citation |
Center for International Earth Science Information Network - CIESIN - Columbia University. 2014. Gridded Population of the World, Version 4 (GPWv4), Preliminary Release 2 (2010). Palisades, NY. http://www.ciesin.columbia.edu/data/gpw-v4. Accessed DAY MONTH YEAR |
| References |
Balk, D.L., U. Deichmann, G. Yetman, F. Pozzi, S.I. Hay, and A. Nelson. 2006. Determining global population distribution: methods, applications and data. Advances in Parasitology 62:119-156. Deichmann, U., D. Balk, and G. Yetman. 2001. Transforming population data for interdisciplinary usages: From census to grid. Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC), CIESIN, Columbia University. Doxsey-Whitfield, E., K. MacManus, S.B. Adamo, L. Pistolesi, J. Squires, O. Borkovska, and S.R. Baptista. Forthcoming. Taking advantage of the improved availability of census data: A first look at the Gridded Population of the World, Version 4 (GPWv4). Papers in Applied Geography. Tobler, W., U. Deichmann, J. Gottsegen, and K. Maloy. 1997. World population in a grid of spherical quadrilaterals. International Journal of Population Geography 3:203-225. |
