During the summer of 2016, the USGS will make changes to manage the Landsat archive as a tiered Collection of Landsat data. A Collection will provide a stable environmental record. If significant radiometric or geometric changes are required, all data will be reprocessed and a new Collection will be released. The tiered structure clearly identifies the subset of the Landsat archive that meets radiometric and geometric criteria suitable for time series analysis and the creation of data stacks/cubes, while continuing to provide access to the entire Landsat archive.
In this article, we highlight the top-level changes that are required to implement Collection 1 this year. More details about these changes are available on the Landsat Collections Web page.
In order to apply the changes required for Collection 1, it is necessary to reprocess the existing data held in the Landsat archive and create Collection 1 Level-1 data products.
Starting July 2016, reprocessing will begin for Landsat 4-5 (L4-5) Thematic Mapper (TM) and Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) scenes. Data will start becoming available early August 2016. Current estimates indicate that it will take about 9 months to reprocess the L4-5 TM and L7 ETM+ data in the USGS archive.
In October 2016, reprocessing will begin for Landsat 8 (L8) Operational Land Imager (OLI)/Thermal Infrared Sensor (TIRS) scenes. Data will start becoming available November 2016.
Landsat 1-5 Multispectral Scanner (MSS) data will be considered after the TM, ETM+ and OLI/TIRS reprocessing efforts are completed.
The reprocessing of each data set will start with the most recently acquired data and move backwards into the archive, and process the conterminous United States first, followed by international areas.
The following actions are required to implement Collection 1. (Please refer to the Landsat Collections Web page for more information.)
Initially, Collection 1 Level-1 data products will be available only on EarthExplorer.
Landsat 7 ETM+ SLC-on and the Landsat 7 ETM+ SLC-off will combine to become L7 ETM+
On EarthExplorer, the Pre-Collection data sets will be retained for 6 months after each data set has completed reprocessing to Collection 1. Newly acquired L7 and L8 data will be processed and placed into both the Pre-Collection and Collection 1 data sets for continuity until the reprocessing campaigns for each data set have been completed.
TM and ETM+ Collection 1 Level-1 data product samples are available from the Landsat Collections Web page. Users are encouraged to download and analyze the data, and contact User Services with any questions.
Users may be aware of the artifacts contained the current provisional Landsat 8 Surface Reflectance (L8SR) data products. After extensive research and redevelopment, a new version of the algorithm is ready for release, and it will improve L8 Surface Reflectance data products.
By July 1, 2016, L8SR will be renamed “Land Surface Reflectance Code” (LaSRC) and the following updates will be implemented:
Users are encouraged to analyze the newly processed data products and contact User Services with any questions.
The Landsat Surface Reflectance Higher-Level Data Products Web page also contains details and documentation about LaSRC.
Esri User Conference June 27-July 1, 2016 - San Diego, California
2016 Summer Landsat Science Team Meeting July 26-28, 2016 - SDSU, Brookings, South Dakota
Geological Society of America (GSA) September 25–28, 2016 – Denver, Colorado
American Geophysical Union (AGU) December 12-16, 2016 – San Francisco, California
Association of American Geographers (AAG) April 5-9, 2017 – Boston, Massachusetts
Ice covering Beaufort Sea near the Arctic Ocean typically reaches full-blown breakup by late May each year as air and water temperatures warm, and as daylight turns longer. But 2016 has been dramatically different.
This year, significant breakup and fracturing of the sea ice had occurred by mid-April, as seen in these Landsat 8 images acquired almost exactly a year apart. On April 13, 2015, the ice is largely intact, though fracturing has begun. A year later, on April 15, 2016, much more open water is visible.
Ice specialists with NASA say this year's breakup is attributable to unusually warm air temperatures during the first months of the year, and to strong winds caused by a stalled high-pressure system over the area. The same warmth that fueled the massive Fort McMurray wildfire in northern Alberta earlier in May is part of the weather pattern affecting the Beaufort Sea.
Though the region was once covered by thicker, multi-year ice, it now has largely seasonal, first-year ice that is thinner, weaker, and more easily broken up by strong winds. While the early breakup hints to the possibility that 2016 could ultimately witness the lowest sea ice extent in the history of satellite recording, that, of course, will depend on the weather conditions in the coming months. Future Landsat acquisitions will help scientists monitor the area and visualize changes.
This and other interesting images can be viewed and downloaded from the Land Remote Sensing Program Image Collections Web page.