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What are Landsat Collection 1 Tiers?

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Question:

What are Landsat Collection 1 Tiers?

Answer:

Landsat Tiers are the inventory structure for Landsat Collection 1 Level-1 data products and are based on data quality and level of processing. All scenes in the Landsat archive are assigned to a Collection category.

During Collection 1 processing, all Landsat scenes in the USGS archive are assigned to a specific “Tier”, have well-characterized radiometric quality, are cross-calibrated among the different Landsat sensors, and support rapid and easy identification of suitable scenes for time-series pixel level analysis.

Tier 1

Landsat scenes with the highest available data quality are placed into Tier 1 and are considered suitable for time-series processing analysis. Tier 1 includes Level-1 Precision Terrain (L1TP) processed data that have well-characterized radiometry and are inter-calibrated across the different Landsat sensors. The georegistration of Tier 1 scenes will be consistent and within prescribed tolerances [<=12 m root mean square error (RMSE)]. All Tier 1 Landsat data can be considered consistent and inter-calibrated (regardless of sensor) across the full collection.

 

Tier 2

Landsat scenes not meeting Tier 1 criteria during processing are assigned to Tier 2. This includes Systematic terrain (L1GT) and Systematic (L1GS) processed scenes, as well as any L1TP scenes 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 the suitability for use in individual applications and studies.

 

Real-Time (Temporary designation)

Newly acquired L7 and L8 data require a period of evaluation and calibration adjustment after acquisition, which can vary from days to weeks. Newly acquired data are processed immediately based on preliminary calibration coefficients, assigned to the temporary Real-Time (RT) Tier, and made available for download. When definitive calibration information becomes available, RT scenes are reprocessed and assigned to the appropriate Tier 1 or Tier 2 category.

For Landsat 7, a Real-Time scene will be processed into either Tier 1 or Tier 2  within about 26 days after acquisition, to allow final calibration and bumper mode parameters to be applied.

For Landsat 8, it takes 14 to 16 days after acquisition for a Real-Time scene to be processed into either Tier 1 or Tier 2, in order to apply updated Thermal Infrared Sensor (TIRS) line-of-sight model parameters.

The Tier designation 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 on EarthExplorer.

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

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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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Page Last Modified: 06/22/17 05:09 pm
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