Landsat Reprocessing Events
The USGS consistently delivers high quality Landsat products suitable for science research and analysis. On occasion, Landsat data may need to be reprocessed. Reprocessing events may be planned, or may be immediate, depending on the magnitude of the reason reprocessing is needed. Large-scale reprocessing efforts are rare and contain most or all of a specific dataset and are planned in advance.
Occasional Reprocessing Events
Occasionally, small-scale reprocessing events are required due to one of the reasons described below. When Landsat data are reprocessed during these events, all affected products are removed and regenerated using the newly processed data. Affected products include Level-1, U.S. Analysis Ready Data (ARD) and Level-2, /Level-3 science products.
Corrections: Satellite, Sensor, Processing Systems
When satellite, sensor, or data processing system components experience anomalies or disconnects, already-archived data may need to be reprocessed. The number of affected Level-1 products vary each event. On occasion, reprocessing is required well beyond the date when products are initially generated to allow complete investigation about the required changes and to implement changes for successful product processing. One example is the reprocessing that took place after moon intrusion was discovered in July 2023. Details about data reprocessing events can be found on the Landsat Collection 2 Reprocessing Events webpage.
Other: Data Storage and Distribution System Issues
Landsat storage and distribution systems occasionally experience network outages that disrupt the flow of data to the distribution source. Reprocessing is performed when warranted.
Landsat Global Archive Consolidation (LGAC) Initiative
The Landsat Global Archive Consolidation (LGAC) initiative began in 2010 to bring Landsat 1-7 data that had been downlinked and stored at Landsat International Grounds Stations (IGS) into the USGS Landsat archive. While LGAC may not be considered rare, as much of the data captured and held internationally were unique relative to each ground station's area of coverage, some of the data received are duplicates of data already held in the USGS archive. When a duplicate Level-1 product is generated with the same or a better-quality score, the already existing Level-1 and subsequent products are removed and replaced with data from the newly processed Level-1 scene.
NEW 09/2024: The Landsat Reprocessing Events application allows you to search and locate Landsat products that have been reprocessed and categorized in one of the Occasional Reprocessing sections described above.
Large-scale Reprocessing Events
Large-scale reprocessing events are rare and may affect a single entire Landsat dataset, or they may affect multiple Landsat datasets – and all the products contained in them. Previous large-scale reprocessing events include the first-year reprocessing of the entire Landsat 9 Level-1 inventory to apply updated calibration updates. Details about large scale reprocessing events are posted on the Landsat Collection 2 Reprocessing Events webpage.
When Landsat data are reprocessed during large-scale events, the already existing products affected (Level-1, U.S. Analysis Ready Data (ARD) and Level-2, /Level-3) are removed and regenerated using the newly processed data.
How do you know if products over your study area have been reprocessed?
When Landsat Level-1 products are reprocessed, the latest updated calibration parameters are applied to the data. While this may not drastically change the data, scientific comparisons may indicate differences when comparing the original to the newly generated product.
Landsat Level-1 Product Identifiers clearly display the processing date (i.e., LE07_L1GT_135040_20000418_20240612_02_T2). In this example, a new Collection 2 Level-1 product was generated when data was received from an IGS in support of the LGAC effort in 2024. The newly generated Level-1 product replaced the product that was originally-processed into Collection 2 in 2020.
How to locate reprocessed Landsat products
There are several ways to locate Landsat products that have been reprocessed during large-scale or occasional events. Visit the links below to access to the USGS Inventory.
- Conduct a search using EarthExplorer: Enter a date range of the processing date on the Additional Criteria tab.
- The Landsat Bulk Metadata Service contains files of Landsat Level-1, Level-2 and U.S. ARD products. These files are updated daily.
- The USGS EROS Machine-to-Machine (M2M) Application Programming Interface (API) is an alternative method of searching and acquiring data from the USGS/EROS data inventories.
Announcements will be made on the Landsat Missions Web Site and USGS Landsat social media accounts when large-scale or occasional reprocessing events are required, to ensure all users are aware of the affected products and timeframe of the reprocessing.
Please contact USGS EROS Customer Services with any questions about Landsat reprocessing events.
Related Content
Landsat Reprocessing Events Search Application
The Landsat Reprocessing Application allows you to discover scene and tile products that have been changed by reprocessing.
Related Content
Landsat Reprocessing Events Search Application
The Landsat Reprocessing Application allows you to discover scene and tile products that have been changed by reprocessing.