Annual NLCD Spectral Change Day of Year
The Annual National Land Cover Database (NLCD) Spectral Change Day of Year product represents the day-of-year (DOY) on which a significant deviation in Landsat surface reflectance was detected within the calendar year of the map product. Spectral changes represent abrupt non-phenological changes in the reflectance of the land surface through time that may or may not be related to land cover change.
Landsat surface reflectance data through time are used to calculate the timing for spectral change. Surface reflectance responds to changes in the physical properties of the land surface, as measured in different wavelengths by one or more Landsat spectral bands. For example, a high intensity wildfire in a forested area produces both a substantial change in surface reflectance and a thematic class change within the NLCD land cover legend. Other changes, such as those produced by drought or precipitation, may produce a significant change in vegetative greenness but still fall within the same land cover class. The value range 1-366 represents the day of year the spectral change occurred, with no change represented by 0.
See the Science User Product Guide for a discussion about the underlying change detection algorithm.
Data Access
Products can be accessed via the data access page.
Documents
Additional information on Annual NLCD and Annual NLCD science products can be found in the Science User Product Guide
Annual NLCD Citation
Annual NLCD has no restrictions on the use of science products. Annual NLCD does ask that if you use the data as part of a publication or presentation that you use the following citation below; however, it is not a requirement to use the data.
U.S. Geological Survey (USGS), 2024, Annual NLCD Collection 1 Science Products: U.S. Geological Survey data release, https://doi.org/10.5066/P94UXNTS
Back to the Annual NLCD Product Suite page.
The Annual National Land Cover Database (NLCD) Spectral Change Day of Year product represents the day-of-year (DOY) on which a significant deviation in Landsat surface reflectance was detected within the calendar year of the map product. Spectral changes represent abrupt non-phenological changes in the reflectance of the land surface through time that may or may not be related to land cover change.
Landsat surface reflectance data through time are used to calculate the timing for spectral change. Surface reflectance responds to changes in the physical properties of the land surface, as measured in different wavelengths by one or more Landsat spectral bands. For example, a high intensity wildfire in a forested area produces both a substantial change in surface reflectance and a thematic class change within the NLCD land cover legend. Other changes, such as those produced by drought or precipitation, may produce a significant change in vegetative greenness but still fall within the same land cover class. The value range 1-366 represents the day of year the spectral change occurred, with no change represented by 0.
See the Science User Product Guide for a discussion about the underlying change detection algorithm.
Data Access
Products can be accessed via the data access page.
Documents
Additional information on Annual NLCD and Annual NLCD science products can be found in the Science User Product Guide
Annual NLCD Citation
Annual NLCD has no restrictions on the use of science products. Annual NLCD does ask that if you use the data as part of a publication or presentation that you use the following citation below; however, it is not a requirement to use the data.
U.S. Geological Survey (USGS), 2024, Annual NLCD Collection 1 Science Products: U.S. Geological Survey data release, https://doi.org/10.5066/P94UXNTS
Back to the Annual NLCD Product Suite page.