Page Summary
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This dataset, consisting of Landsat 7 composites showing the Normalized Difference Water Index (NDWI), has been superseded by a newer version and is no longer being produced as of May 1, 2017.
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The NDWI measures the liquid water content of vegetation and ranges from -1.0 to 1.0.
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Composites are created every 8 days using the most recent pixel from all scenes within that period.
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Landsat datasets are in the public domain and can be used freely, with acknowledgement to the USGS as the data source recommended.
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This dataset is available through Google Earth Engine, which is free for research, education, and nonprofit use.
- Dataset Availability
- 1999-01-01T00:00:00Z–2017-04-23T00:00:00Z
- Dataset Provider
- USGS
- Tags
Description
These Landsat 7 composites are made from Level L1T orthorectified scenes, using the computed top-of-atmosphere (TOA) reflectance. See Chander et al. (2009) for details on the TOA computation.
As of May 1, 2017, the USGS is no longer producing Pre-Collection Landsat, and therefore this collection is complete. Please switch to a Collection 1-based dataset. See this documentation page for more information.
The Normalized Difference Water Index (NDWI) is sensitive to changes in liquid water content of vegetation canopies. It is derived from the Near-IR band and a second IR band, ≈1.24μm when available and the nearest available IR band otherwise. It ranges in value from -1.0 to 1.0. See Gao (1996) for details.
These composites are created from all the scenes in each 8-day period beginning from the first day of the year and continuing to the 360th day of the year. The last composite of the year, beginning on day 361, will overlap the first composite of the following year by 3 days. All the images from each 8-day period are included in the composite, with the most recent pixel as the composite value.
Bands
Bands
| Name | Pixel Size | Description |
|---|---|---|
NDWI |
30 meters | Normalized Difference Water Index |
Terms of Use
Terms of Use
Landsat datasets are federally created data and therefore reside in the public domain and may be used, transferred, or reproduced without copyright restriction.
Acknowledgement or credit of the USGS as data source should be provided by including a line of text citation such as the example shown below.
(Product, Image, Photograph, or Dataset Name) courtesy of the U.S. Geological Survey
Example: Landsat-7 image courtesy of the U.S. Geological Survey
See the USGS Visual Identity System Guidance for further details on proper citation and acknowledgement of USGS products.