What is the difference between the Water Mask layer and the Water Area layer?

The GPWv4 data collection contains two similar data layers relating to water: the Water Area layer in the Land and Water Area data set and the Water Mask layer in the Data Quality Indicators data set. These data layers are both created from the same source data, but are presented in two different formats for users.

The Water Area layer provides estimates of the water area (including permanent ice and water) within each pixel. This layer can be used in conjunction with the Land Area layer to calculate the total surface area of a pixel (the sum of land area and water area).

The Water Mask layer distinguishes between pixels that are completely water and/or ice (Total Water Pixels) and pixels that also contain land (Partial Water Pixels). Pixels labelled as ‘NoData’ in the population count and population density rasters are labelled as ‘Total Water Pixels’ in the Water Mask layer.

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