AI-generated Key Takeaways
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This Landsat 7 dataset provides 32-day Normalized Difference Water Index (NDWI) composites from 1999 to 2017, derived from Level L1T orthorectified scenes using top-of-atmosphere reflectance.
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The dataset is deprecated and users are advised to switch to the Collection 1-based dataset LANDSAT/LE07/C01/T1_32DAY_NDWI due to the USGS discontinuing Pre-Collection Landsat production.
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NDWI values range from -1.0 to 1.0 and are sensitive to changes in liquid water content within vegetation canopies.
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The composites include all scenes within each 32-day period, using the most recent pixel as the composite value, resulting in potential overlap between the last composite of one year and the first of the next.
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Landsat datasets are public domain and can be used freely, but require acknowledgement of the USGS as the data source.
- Dataset Availability
- 1999-01-01T00:00:00Z–2017-04-07T00:00:00Z
- 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 32-day period beginning from the first day of the year and continuing to the 352nd day of the year. The last composite of the year, beginning on day 353, will overlap the first composite of the following year by 20 days. All the images from each 32-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.