Landsat Missions

Landsat Collections

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In 2016, the USGS started reorganizing the Landsat archive into a formal tiered data Collection structure. This data Collection structure ensures that Landsat Level-1 products provide a consistent archive of known data quality to support time series analyses and data “stacking”, while controlling continuous improvement of the archive and access to all data as they are acquired.

The Collection definition consists of three categories: Tier 1, Tier 2, and Real-Time. Data in Tier 1 meet formal geometric and radiometric quality criteria. Tier 2 do not meet the Tier 1 criteria. The Real-Time Tier contains data immediately after acquisitions that use estimated parameters. Real-Time data are reprocessed and assessed for inclusion into Tier 1 or Tier 2 as soon as final parameters are available.

   
   

 

Collection 1 initially consists of Level-1 products generated from Landsat 4-5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and Landsat 8 Operational Land Imager (OLI)/Thermal Infrared Sensor (TIRS) instruments. Landsat 1-5 Multispectral Scanner (MSS) data pose their own challenges and will be processed into Collection 1 after data quality analysis and processing level investigations have been completed.

The implementation of Collections represents a significant change in the management of the Landsat Archive by ensuring consistent quality through time and across instruments, along with additional changes like metadata and file names.

Landsat Higher-Level Science Data Products will inherit characteristics of the Landsat Collection 1 Level-1 data products.

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

Landsat Collection Tiers

New Landsat Product Identifiers

Additional Data Changes Applied During Collection 1 Processing

Collection 1 Processing Timeline

Changes to EarthExplorer

Documentation

 

Landsat Collection Tiers

Landsat Collection Tiers are the inventory structure for Level-1 data products and are based on data quality and level of processing. The tier definition purpose is to support easier identification of suitable scenes for time series pixel-level analysis, and provide temporary data that are processed immediately upon downlink to be dispensed quickly in emergency response situations with limited calibration.

Tier 1 (T1)

Landsat scenes with the highest available data quality are placed into Tier 1 and are considered suitable for time-series analysis. Tier 1 includes Level-1 Precision and Terrain (L1TP) corrected data that have well-characterized radiometry and are inter-calibrated across the different Landsat instruments. The georegistration of Tier 1 scenes is consistent and within prescribed image-to-image tolerances of <12m radial root mean square error (RMSE).

Tier 2 (T2)

Landsat scenes not meeting Tier 1 criteria during processing are assigned to Tier 2. This includes Systematic Terrain (L1GT) and Systematic (L1GS) processed data, as well as any L1TP data that do not meet the Tier 1 specifications due to significant cloud cover, insufficient ground control, and other factors.  Users interested in Tier 2 scenes can analyze the RMSE and other properties to determine their suitability.

Real-Time (RT)

Newly-acquired Landsat 7 ETM+ and Landsat 8 OLI/TIRS data are processed upon downlink but use predicted ephemeris, initial bumper mode parameters, or initial TIRS line-of-sight model parameters. The data is placed in the Real-Time tier and made available for immediate download. Once the data have been reprocessed with definitive ephemeris, updated bumper mode parameters and refined TIRS parameters, the products are transitioned to either Tier 1 or Tier 2 and removed from the Real-Time tier. The transition delay from Real-Time to Tier 1 or Tier 2 is between 14 and 26 days. The follow-on Real-Time processing for Landsat 7 ETM+ and Landsat 8 OLI/TIRS are described below.

  • Landsat 8 TIRS data may not meet specifications for co-registration with OLI. TIRS line-of-sight model parameters are refined based on data acquired during biweekly calibration maneuvers and scenes are updated within 14 to 16 days of acquisition.
  • Landsat 7 ETM+ acquisitions are processed immediately using predicted ephemeris and initial bumper mode parameters and placed into the Real-Time tier. Shortly after initial processing (about 1 day), the data are reprocessed using definitive ephemeris, but still remain in the Real-Time tier. During a period of instrument trending/characterization (about 26 days), calibration parameter adjustments finalize the geometric correction model, and the data are reprocessed again and placed into Tier 1 or Tier 2.

The Tier designation (T1, T2, RT) is visible at the end of the Landsat Product Identifier, as shown in the examples below. It is also provided as an additional metadata field in EarthExplorer. Note: Historical Landsat 4-5 TM and Landsat 7 ETM+ data received from International Ground Stations supporting the Landsat Global Archive Consolidation effort are placed in either Tier 1 or Tier 2 after Collection 1 processing.

Tier 1:
Tier 2:
Real-Time:
LE07_L1TP_016039_20040918_20160211_01_T1
LT04_L1GS_017036_19821115_20160315_01_T2
LE07_L1GT_037035_20160314_20160314_01_RT

 

 

New Landsat Product Identifiers

Along with information inherited from the Landsat Pre-Collection scene ID, the new Landsat Collection 1 product identifier includes the updated processing levels, processing date, Collection number, and Collection tier category (noted in red in the graphic below).

Landsat Pre-Collection and Collection 1 Identifiers Comparison

The Landsat scene ID remains in the metadata file (MTL.txt) delivered with the Level-1 data product, and will also be visible and searchable (along with the new Collection 1 Landsat Product Identifier) in the online metadata on EarthExplorer.

Additional Data Changes Applied During Collection 1 Processing

Along with the new Landsat Product Identifier, new files and additions to metadata are also included and delivered with the Landsat Collection 1 Level-1 data products.

New Files included in Collection 1 Level-1 data products:

Additional Metadata (MTL.txt) fields:

New Cloud Cover Algorithm:

  • The C Function of Mask (CFMask) algorithm identify fill, cloud, cloud confidence, cloud shadow, and snow/ice in Landsat 4-5, Landsat 7, and Landsat 8 scenes for representation in the Quality Assessment (QA) band.

Specific for Landsat 8 OLI/TIRS:

Processing Level Designation Changes

The processing level designations have changed for Collection 1 Level-1 data products. The table below displays the Landsat Pre-Collection processing levels, along with the Collection 1 Level-1 processing levels.

Landsat Level-1 Processing Levels

Calibration Parameter File (CPF) Name Changes

Calibration Parameter Files (CPF) provide radiometric and geometric coefficients needed for processing of raw, uncorrected Landsat image data. Each timeframe specific CPF contains calibration coefficients that have been adjusted to correct for the time varying performance of the sensor.

The Collection 1 CPF file name includes the Collection number to uniquely link CPFs to specific Collections. During the transition to a new Collections, two CPFs will be maintained.

Pre-Collection:
Collection 1:
L7CPF20140401_20140630.03
LE07CPF_20140401_20140630_01.03

 

 

LXSSCPF_YYYYMMDD_yyyymmdd_CC.NN
L = Landsat (constant)
X = Sensor (“C” = OLI/TIRS Combined, “E” = ETM+, “T” = TM, “M”= MSS)
SS = Satellite (e.g. “07” = Landsat 7, “08” = Landsat 8)
CPF = Three-letter CPF designator
YYYYMMDD = Effective Starting Date (YYYY) / Month (MM) / Day (DD)
yyyymmdd = Effective Ending Date (yyyy) / Month (mm) / Day (dd)
CC = Collection number (“01”,”02”)
NN = Version Number for this file (starts with 00)

Response Linearization Look Up Tables (RLUT) Name Changes (Landsat 8 only)

Response Linearization Look Up Tables (RLUT) are additional files that accompany Calibration Parameter Files (CPF) and contain a mapping look up table to linearize the output of the OLI and TIRS detectors.   Like the CPF file names, the Collection RLUT files will have a different naming convention to support Collections.

Pre-Collection:
Collection 1:
L8RLUT20130211_20431231v09.h5
LC08RLUT_20130211_20431231_01_09.h5

 

 

LXSSRLUT_YYYYMMDD_yyyymmdd_CC.NN
L = Landsat (constant)
X = Sensor (“C” = OLI/TIRS Combined, “E” = ETM+, “T” = TM, “M”= MSS)
SS = Satellite (e.g. “07” = Landsat 7, “08” = Landsat 8)
RLUT = Four-letter RLUT designator
YYYYMMDD = Effective Starting Date (YYYY) / Month (MM) / Day (DD)
yyyymmdd = Effective Ending Date (yyyy) / Month (mm) / Day (dd)
CC = Collection number (“01”,”02”)
NN = Version Number for this file (starts with 00)

 

Collection 1 Processing Timeline

Collection 1 processing for Landsat 4-5 TM, Landsat 7 ETM+, and Landsat 8 OLI/TIRS data is complete and data products are available for download from EarthExplorer.

Landsat 1-5 Multispectral Scanner (MSS) data will be processed into Collection 1 after data quality analysis and processing level investigations are complete at the end of 2017.

Please NOTE:

  • Effective April 30, 2017, only newly-acquired Landsat 7 ETM+ and Landsat 8 OLI/TIRS scenes are being processed into the Landsat Collection 1 inventory; the Landsat Pre-Collection inventory is no longer being populated with newly-acquired data.
  • Users downloading Landsat Pre-Collection data may experience longer than expected download times.
  • The Landsat Pre-Collection inventory will no longer be available after October 1, 2017. Users are strongly encouraged to use only Landsat Collection 1 in their applications.

 

Changes to EarthExplorer

Initially, Collection 1 Level-1 data products are available only on EarthExplorer. Changes to the USGS Global Visualization Viewer (GloVis) and the LandsatLook Viewer are being considered to accomodate the Collection 1 archive.

The EarthExplorer Data Set tab clearly displays Landsat Archive Collection 1 and Pre-Collection Level-1 data sets, as shown in the graphic below.

Note: The following changes regarding the Collection 1 consolidation of Landsat 7 and Landsat 8 Pre-Collection dataset names:

  • Landsat 8 OLI/TIRS and Landsat 8 OLI/TIRS Pre-WRS-2 are combined to L8 OLI/TIRS
  • Landsat 7 ETM+ SLC-on and the Landsat 7 ETM+ SLC-off are combined to L7 ETM+
     

EarthExplorer Dataset tab showing Collection 1 Level-1 datasets

The Additional Criteria tab for each Collection 1 data set also allows users to select parameters for each Landsat sensor (i.e., Landsat 7 SLC-on/SLC-off, T1/T2/RT, or RMSE range).

Documentation

Collection Definition Document (coming soon)

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Landsat represents the world's longest continuously acquired collection of space-based moderate-resolution land remote sensing data. Four decades of imagery provides a unique resource for those who work in agriculture, geology, forestry, regional planning, education, mapping, and global change research. Landsat images are also invaluable for emergency response and disaster relief.

 

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