
[Editor’s note: With over half of humanity now living in an urban environment, this exciting new remote sensing dataset can help planners better estimate global urban sprawl. I hope to use this as a foundation to refine Natural Earth’s urban polygons and mash them up against GeoNames.org features. Thanks Annemarrie!]
Republished from UW-Madison.
Center for Sustainability and the Global Environment, University of Wisconsin-Madison
The MODIS 500-m global map of urban extent was produced by Annemarie Schneider at the University of Wisconsin-Madison, in partnership with Mark Friedl at Boston University and the MODIS Land Group. The goal of this project was generate a current, consistent, and seamless circa 2001-2002 map of urban, built-up and settled areas for the Earth’s land surface. This work builds on previous mapping efforts using Moderate Resolution Imaging Spectroradiometer (MODIS) data at 1-km spatial resolution (Schneider et al., 2003; 2005), which was included as part of the MODIS Collection 4 (C4) Global Land Cover Product (Friedl et al., 2002). Here we addressed weaknesses in the first map as well as several limitations of contemporary global urban maps by developing a methodology that relies solely on newly released Collection 5 (C5) MODIS 500-m resolution data. Specifically, a supervised decision tree classification algorithm was used to map urban areas using region-specific parameters (see Schneider et al., 2009; 2010 for full details on methodology).
The intended audience for the MODIS 500-m map of urban extent is primarily the academic research community working at regional to global scales on questions related to the geophysical environment; please keep this in mind as you put the data to use.
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b. Land cover classes
In the global land cover map, the classes are defined according to the International Geosphere-Biosphere Programme (IGBP) 17-class scheme shown in Table 1.
No.
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Class name
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Description
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|
|
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1
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Evergreen Needleleaf Forest
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Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Almost all trees remain green all year. Canopy is never without green foliage.
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2
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Evergreen Broadleaf Forest
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Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Almost all trees remain green year round. Canopy is never without green foliage.
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3
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Deciduous Needleleaf Forest
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Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Trees shed their leaves during the dry season; e.g. Siberian Larix.
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4
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Deciduous Broadleaf Forest
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Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Consists of broadleaf trees with an annual cycle of leaf-on and leaf-off periods.
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5
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Mixed Forests
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Lands dominated by woody vegetation with a percent cover > 60% and height exceeding 2 meters. Consists of mixtures of either broadleaf or needleleaf trees and in which neither component exceeds 60% of landscape.
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6
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Closed Shrublands
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Lands with woody vegetation with a height less than 2 meters. The total percent cover, including the herbaceous understory, exceeds 60%. The shrub foliage can be either evergreen or deciduous.
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7
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Open Shrublands
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Lands with woody vegetation with a height less than 2 meters, and sparse herbaceous understory. Total percent cover is less than 60%. The shrub foliage can be either evergreen or deciduous.
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8
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Woody Savannas
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Lands with and herbaceous understory, typically graminoids, and with tree and shrub cover between 30-60%. The tree and shrub cover height exceeds 2 meters.
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9
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Savannas
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Lands with an herbaceous understory, typically graminoids, and with tree and shrub cover between 10-30%. The tree and shrub cover height exceeds 2 meters.
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10
|
Grasslands
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Lands with herbaceous types of cover, typically graminoids. Tree and shrub cover is less than 10%.
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11
|
Permanent Wetlands
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Lands with a permanent mosaic of water and herbaceous or woody vegetation. The vegetation can be present in either salt, brackish, or fresh water. Only wetlands covering extensive areas (i.e., more than 500 km2) will be mapped (e.g., Sud, Okavanga, Everglades).
|
12
|
Croplands
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Lands where crops comprise > 60% of the total land cover.
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13
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Urban Areas
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See (a) above.
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14
|
Cropland – Natural Vegetation Mosaic
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Lands with mosaics of crops and other land cover types in which no component comprises more than 60% of the landscape.
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15
|
Snow and Ice
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Lands under snow/ice cover for most of the year.
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16
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Barren or Sparsely Vegetated
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Lands with exposed soil, sand or rocks and has less than 10% vegetated cover during any time of the year.
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17
|
Water Bodies
|
Oceans, seas, lakes, reservoirs, and rivers. Can be either fresh or salt water bodies. Coded as 0 in the MODIS-based maps.
|