Landsat Collections

Landsat Collection 2

In mid-2020, Landsat Collection 2 Level-1 and Level-2 surface reflectance and surface temperature scene-based products will be publicly available for download. 

Level-1

Level-1

Technical Information for Collection 2 Level-1.

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Level-2

Level-2

Technical Information for Collection 2 Level-2.

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Collection 1 vs Collection 2

Collection 1 vs Collection 2

Quick Reference Guide for Changes Between Collection 1 & Collection 2.

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Access Landsat Collection 1 Information

Landsat Collection 2 marks the second major reprocessing effort on the Landsat archive by the USGS that results in several data product improvements that harness recent advancements in data processing, algorithm development, and data access and distribution capabilities.

A primary characteristic of Collection 2 is the substantial improvement in the absolute geolocation accuracy of the global ground reference dataset - which improves interoperability of the Landsat archive through time. Collection 2 also includes updated global digital elevation modeling sources and calibration and validation updates.

Collection 2 includes Landsat Level-1 data for all sensors since 1972, as well as global Level-2 surface reflectance and surface temperature scene-based products from 1982 to present (excluding Landsat 1-5 Multispectral Scanner (MSS)) within defined constraints.

Collection 2 will become available in mid-2020.

Collection 1 based products, including: Landsat 8 Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Collection 1 Level-1, U.S. Landsat ARD and Level-3 Science Products data processing and downloads will remain available for at least one year after Collection 2 is publicly released.

Collection 2 Highlights 

Below is a high-level summary of the main improvements for Collection 2. For a more detailed description of Collection 2 processing, geometric, and radiometric improvements please visit the Collection 2 Level-1 webpage or review the accompanying documentation. 

  • Improved Geometric Accuracy
    Re-baselining the Landsat 8 OLI Ground Control Points (GCPs) to the European Space Agency Copernicus Sentinel-2 Global Reference Image (GRI) improves the interoperability of the global Landsat archive spatially and temporally. The January 2020: Phase 4 - Collection 2 section on the Landsat Ground Control Points webpage provides more information.  A 2019 publication shows improved accuracy in ground control by deploying a triangulation method on a continent by continent basis.
     
  • Improved Digital Elevation Modeling
    Collection 2 uses the 3-arc-second digital elevation modeling (DEM) sources listed and shown on the map below.  (Please refer to the “DATA_SOURCE_ELEVATION” field in the Level-1 metadata file to determine the DEM source used in processing.)
     
    Landsat Collection 2 Digital Elevation Modeling (DEM) sources

  • Improved Radiometric Calibration
    Collection 2 includes several radiometric calibration improvements for Landsat 5 Thematic Mapper (TM) and Landsat 8 Operational Land Imager (OLI) data, including a correction for the TIRS striping effect (See: Radiometric Accuracy Improvements).
     
  • Global Level-2 Science and Atmospheric Auxiliary Products
    New for Collection 2 is the processing and distribution of Level-2 surface reflectance and surface temperature science products for Landsat 4-5 TM, Landsat 7 ETM+ and Landsat 8 OLI/TIRS. Level-2 products are generated from Collection 2 Level-1 inputs that meet the <76 degrees Solar Zenith Angle constraint and include the required auxiliary data inputs to generate a scientifically viable product.  (Please note that Landsat 1-5 Level-2 MSS surface reflectance products will only become available upon the maturity of an operational atmospheric compensation algorithm which satisfies the USGS Landsat program requirements.) Landsat Collection 2 Atmospheric Auxiliary Data used in the processing of Collection 2 Level-2 products are available to download for users wanting to generate custom Level-2 products using the Collection 2 surface reflectance and surface temperature algorithms. 
     
  • Consistent Quality Assessment Bands
    Collection 2 Level-1 products are delivered with a Quality Assessment Band (QA_Pixel) and a Radiometric Saturation and Terrain Occlusion Quality Assessment Band (QA_RADSAT). Collection 2 Level-2 products will include the Level-1 QA bands as well as a surface reflectance aerosol QA Band (SR_QA_AEROSOL) and a surface temperature QA Band (ST_QA) to provide consistent QA information between products. 
     
  • Updated and Consistent Metadata Files
    There are several enhancements and changes between Collection 1 and Collection 2 Level-1 metadata. New to Collection 2 data is the addition of an extensible markup language (XML) to the already offered Material Library File (MTL) (Object Description Language-based) format file. The metadata files facilitate consistency, machine-to-machine scripting and rapid querying of the USGS Landsat archive.  There are also changes to the metadata fields visible on EarthExplorer and its associated applications. The Landsat Collection 2 Metadata page describes changes to each and provides files displaying the changes.
     
  • Cloud Optimized File Format
    Landsat Collection 2 Level-1 data and Level-2 products are delivered in a Cloud Optimized Georeferenced (COG) Tagged Image File Format. COGs are an extension of the current GeoTIFF file format which improves access to Geospatial datasets in a cloud-based environment by allowing users to request only the bands that they need. For additional information on the COG file format please review the Landsat Cloud Optimized GeoTIFF (COG) Data Format Control Book (DFCB).

 

Data Availability, Access, and Product Generation Timeline

Landsat Collection 2 Level-1 and Level-2 data will become available for download from USGS EarthExplorer in mid-2020. The USGS Landsat no-cost open access data policy remains intact since its inception in 2008.

A typical Landsat Collection 2 product generation timeline is illustrated below (click image to enlarge).

Landsat Collection 2 Generation Timeline

Typical Landsat 7-9 Collection 2 Product Generation Timeline

Landsat 7 ETM+ and Landsat 8 OLI/TIRS Real-Time scenes are available for download within 4-6 hours after acquisition. 

For Landsat 7 ETM+, the timeframe from acquisition (Real-Time) to Tier 1 or Tier 2 takes approximately 24-26 days to allow for application of the refined bumper mode parameters to Level-1 Real-Time scenes. For Landsat 8 OLI/TIRS, it takes approximately 14-16 days to process to a Tier 1 or Tier 2 product while refined TIRS instrument line of sight model parameters are applied to Real-Time scenes.

Level-2 Surface Reflectance and Surface Temperature products are typically available within 24 hours after a scene has been processed into Tier 1 or Tier 2.

Landsat 7 and Landsat 8 both utilize NASA's Goddard Earth Observing System Model Version 5 Forward Processing for Instrument Teams (GOES-5 FP-IT) Atmospheric Assimilation Products for Level-2 product generation.

Upon nominal launch and on-orbit checkout in mid-2021, Landsat 9 will deliver Collection 2 Level-1 Tier 1 or Tier 2 scenes within 4-6 hours of acquisition, and a Level-2 Surface Reflectance and Surface Temperature product within 3 days of acquisition. Landsat 9 will also utilize the GOES-5 FP-IT atmospheric auxiliary data product for Level-2 product generation. 

 

 

Documentation 

Users are encouraged to reference the COG Data Format Control Book (DFCB) for a detailed description of the image, product and metadata files. Together with the instrument specific Level-1 DFCBs, the COG DFCB provides a comprehensive overview of the new Landsat Collection 2 products.

Landsat Cloud Optimized GeoTIFF (COG) Data Format Control Book

Collection 2 Level-1 Documents

Collection 2 Level-2 Documents

 

Collection 2 Sample Products

Collection 2 Level-1 and Level-2 sample data products are available for download from the Landsat Sample Products page.
 

Summary of Enhancement and Improvements 

A summary of the enhancements and improvements between Collection 1 and Collection 2 is provided in this quick reference guide.