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Landsat Analysis Ready Data (ARD)

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Definition

Tile Grid System

Data Products

Packaging and Filenames

Search and Download

Product Caveats

Time-series Data Stack Sample

Known Artifacts

Documentation and Resources

 

 

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Definition

Landsat Analysis Ready Data (ARD) are consistently processed to the highest scientific standards and level of processing required for direct use in monitoring and assessing landscape change. A fundamental goal for Landsat ARD is to significantly reduce the magnitude of data processing for application scientists, who currently have to download
and prepare large amounts of Landsat scene-based data for time-series investigative analysis.

Landsat Collections Level-1 scenes serve as the input for generating all Landsat ARD products.

 

Landsat ARD are available for the conterminous United States (CONUS) using the following Landsat Collection 1 data:

  • Landsat 8 Operational Land Imager (OLI)/ Thermal Infrared Sensor (TIRS) Tier 1, Tier 2
  • Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Tier 1
  • Landsat 4-5 Thematic Mapper (TM) Tier 1

For CONUS, ARD are available from 1982-present. ARD for Alaska and Hawaii will be available soon. The histograms below display Landsat ARD input data availability for Alaska and Hawaii: 

Figure 1. Landsat ARD Input Data - Alaska Figure 2. Landsat ARD Input Data - Hawaii

 

Eventually, Landsat 1-5 Multispectral Sensor (MSS) data will also be included in the ARD product suite once these data have been processed into the Landsat Collection inventory structure.

Global Landsat ARD specifications are being developed and will be announced on the USGS Landsat website and Twitter accounts when further information is available.

U.S. Landsat ARD products are generated in the Albers Equal Area (AEA) Conic map projection, processed directly from Landsat Level-1 AEA scenes through Landsat Level-2 data products using the WGS84 datum. Table 1 lists the ARD projection parameters.

Projection:  Albers Equal Area Conic
Datum: World Geodetic System 84 (WGS84)
Data Output Format:  Georeferenced Tagged Image File Format (GeoTIFF)

Landsat Analysis Ready Data Projection Parameters

  Conterminous U.S. Alaska Hawaii
First standard parallel 29.5˚ 55.0˚ 8.0˚
Second standard parallel 45.5˚ 65.0˚ 18.0˚
Longitude of central meridian -96.0˚ -154.0˚ -157.0˚
Latitude of projection origin 23.0˚ 50.0˚ 3.0˚
False Easting (meters) 0.0 0.0 0.0
False Northing (meters 0.0 0.0 0.0

Table 1. Landsat Analysis Ready Data (ARD) Projection Parameters

Tile Grid System

U.S. Landsat ARD products are processed to a common tiling scheme, which is modified from the Web-Enabled Landsat Data (WELD) system developed at South Dakota State University (SDSU) (Roy and others, 2010). The WELD-defined grid is similar to the National Land Cover Dataset (NLCD), except that WELD is based on the World Geodetic System 84 (WGS84) datum  and NLCD uses the North American Datum 1983 (NAD83), causing an approximately 0.5 pixel offset in the X and Y directions between the two grids. The U.S. Landsat ARD grid is anchored to the coordinates listed in Table 2 below. These grid origins are defined in relation to the WGS84 datum used by WELD, but are adjusted to align with the origin used by NLCD datasets.

Each tile contains 5,000 x 5,000 30-meter pixels, and includes all the pixels acquired in a given day within its extents. The ARD tile pixel dimension (number of columns and rows) is smaller than the dimensions of individual Landsat acquisitions (Landsat 8: ~6300 x ~6000 pixels; Landsat 7: ~6,166 x ~5,666 pixels).  

  • 420 tiles cover the land mass extent of the conterminous United States (CONUS). (Figure 3).
  • 110 tiles cover the land mass extent of Alaska (Figure 4).
  • 8 tiles cover the islands of Hawaii (Figure 5).

CONUS Analysis Ready Data (ARD) Tile Map
Figure 3. CONUS Landsat ARD Tile Map
Click map to view larger image, or download .pdf.

 

Alaska Analysis Ready Data (ARD) Tile Map   Hawaii Analysis Ready Data (ARD) Tile Map
Figure 4. Alaska Landsat ARD Tile Map
Click map to view larger image, or download .pdf.
  Figure 5. Hawaii Landsat ARD Tile Map
Click map to view larger image, or download .pdf.

 

 Table 2 displays the coordinates that anchor the ARD tile grid. Refer to the ARD Data Format Control Book (DFCB) for further information.

Analysis Ready Data (ARD) Tile Grid Extents

  Upper Left Tile (ul corner)   Lower Right Tile (lr corner)
  (h) (v) ulX (m) ulY (m) (h) (v) lrX (m) lrY (m)
CONUS 0 0 -2565585 3314805 32 21 2384415 14805
Alaska 0 0 -851715 2474325 16 13 1698285 374325
Hawaii 0 0 -444345 2168895 4 2 305655

1718895

Table 2. Landsat Analysis Ready Data (ARD) Tile Grid Extents

In the event an ARD tile intersects more than one row along a WRS-2 path, the northernmost row data will populate the tile from areas where rows overlap, as seen in Figure 6 below. This image shows the coverage of ARD tile h05v02 (outlined in white) compared to the WRS-2 path 44 row 27 image covering an area in central Washington state. The ARD tile also includes data from rows 26 and 28. Subsequent versions of ARD  may implement a more sophisticated compositing scheme to populate the tile from row overlap areas.

Landsat ARD Tile h05 v02 overlay on Landsat 8 WRS-2 Path 44 Row 27
Figure 6. Landsat Analysis Ready Data (ARD) tile h05v02 overlay on Landsat 8 WRS-2 path 44 row 27
Landsat ARD Product ID: LC08_CU_005002_20130603_20170713_C01_V01
Lansdsat Scene Product ID: LC08_L1TP_044027_20130603_20170310_01_T1

Data Products

U.S. Landsat ARD products consist of the following data, which are gridded to a common cartographic projection, and accompanied by metadata to enable further processing for the user while also retaining the traceability of data provenance:

  • Top of atmosphere (TA) reflectance
  • Brightness temperature (BT)
  • Surface reflectance (SR)
  • Pixel quality assessment (QA)

The current definition of Landsat ARD includes the products output by the following algorithms:

Future ARD product additions may include surface temperature (ST) data and results from land surface change detection algorithms. Subsequently, numerous products derived from ARD that are used as direct inputs to monitoring and assessment activities are in development:

  • Maps of land cover and land cover change
  • Burned Area (BA)
  • Dynamic Surface Water Extent (DSWE)
  • Fractional Snow Covered Area (fSCA)

Packaging and Filenames

U.S. Landsat ARD product package and band identifiers are both derived from the Landsat ARD Product ID. While the ARD Product ID follows the naming convention of its collection-based data source to the best extent possible, the ARD Product ID replaces WRS path and row designations with tile identifiers (i.e., HHH horizontal and VVV vertical), as an ARD tile may include data from overlapping rows.  Processing level (LLLL) and collection category (TX) are removed from the ARD Product ID as a redundancy; the Level-1 processing date is also removed from the ARD file name.

ARD products are packaged into bundles, i.e., TA reflectance, SR, and BT are delivered in separate files, each with their associated pixel quality assessment (QA) attributes. Files containing only QA bands are also provided.

ARD Packages are delivered as .tar files, named according to the terms and definitions shown below. A comprehensive Extensible Markup Language (XML) file containing all associated metadata is delivered with each ARD package. <ARD Tile XML metadata schema>.

Refer to Section 3 of the ARD Data Format Control Book (DFCB) for a listing of files included for each product package.

Landsat Analysis Ready Data (ARD) Package Terms and Definitions

LXSS_US_HHHVVV_YYYYMMDD_yyyymmdd_CCC_VVV_PRODUCT.tar
Example: ARD Package Identifier (TA): LE07_CU_016008_2015120901_20170106_C01_V01_TA.tar

Term Definition
L Landsat
X Sensor (“T” = TM, “E” = ETM+, “C” = OLI/TIRS Combined, “O” = OLI-only, “T” = TIRS-only)
SS Satellite (“04” = Landsat 4, “05” = Landsat 5, “07” = Landsat 7, “08” = Landsat 8)
US Regional grid of the U.S. (“CU” = CONUS, “AK” = Alaska, “HI” = Hawaii)
HHH Horizontal tile number
VVV Vertical tile number
 YYYYMMDD  Acquisition year (YYYY) month (MM) day (DD)
yyyymmdd Production year (yyyy) month (mm) day (dd)
CCC Level-1 Collection number (“C01,” “C02”)
VVV Analysis Ready Data (ARD) Version number (“V01,” “V02”)
PRODUCT Data product (“TA” = top of atmosphere reflectance, “BT” = brightness temperature, “SR” = surface reflectance, “ST” = land surface temperature, “QA” = quality assessment)

Table 3. Landsat Analysis Ready Data (ARD) Package Terms and Definitions

Within each ARD Package, a GeoTIFF (.tif) file is included for each band. The terms and definitions for band files are illustrated in Table 4.

Landsat  Analysis Ready Data (ARD) Image Product Terms and Definitions

LXSS_US_HHHVVV_YYYYMMDD_yyyymmdd_CCC_VVV_PRODUCTBAND
Example: ARD Image Product Identifier (TA)  LE07_CU_016008_20151209_20160118_C01_V01_TAB4

Term Definition
L Landsat
X Sensor (“T” = TM, “E” = ETM+, “C” = OLI/TIRS Combined, “O” = OLI-only, “T” = TIRS-only)
SS Satellite (“04” = Landsat 4, “05” = Landsat 5, “07” = Landsat 7, “08” = Landsat 8)
US Regional grid of the U.S. (“CU” = CONUS, “AK” = Alaska, “HI” = Hawaii)
HHH Horizontal tile number
VVV Vertical tile number
 YYYYMMDD  Acquisition year (YYYY) month (MM) day (DD)
yyyymmdd Production year (yyyy) month (mm) day (dd)
CCC Level-1 Collection number (“C01,” “C02”)
VVV Analysis Ready Data (ARD) Version number (“V01,” “V02”)
PRODUCT Data product (“TA” = top of atmosphere reflectance, “BT” = brightness temperature, “SR” = surface reflectance, “ST” = land surface temperature, “SOA” = solar azimuth angle, “SOZ” = solar zenith angle, “SEA” = sensor azimuth angle, “SEZ” = sensor zenith angle, “PIXELQA” = pixel quality attributes, “RADSATQA” = radiometric saturation, “LINEAGEQA” = lineage index, “SRATMOSOPACITYQA” = internal Landsat 4-7 surface reflectance atmospheric opacity, “SRCLOUDQA” = internal Landsat 4-7 surface reflectance quality, “SRAEROSOLQA” = internal Landsat 8 surface reflectance aerosol parameters)
BAND Band Number (such as “B1” for reflectance products)

Table 4. Landsat  Analysis Ready Data (ARD) Image Product Terms and Definitions

Individual band specifications and other important information about each ARD data product, along with the QA bit index values, can be found in the ARD Data Format Control Book (DFCB).

Search and Download

U.S. Landsat ARD products are available for search and download from EarthExplorer. The ARD dataset is the first one listed under the Landsat section on the Data Set tab, as shown in Figure 7 below.

EarthExplorer Landsat Data Sets
Figure 7. EarthExplorer Data Set tab showing Landsat ARD

The file sizes of Landsat ARD products vary greatly, and they have the possibility of being significantly larger than the standard Landsat Level-1 data products users may be accustomed to. Table 5 lists the estimated average, minimum, and maximum file sizes observed in the current sample Landsat ARD data products.

Estimated Average, Minimum, and Maximum Tile Sizes in Landsat ARD Sample Data Products

ARD Products (per tile)

Est. average
(MB)

Est. minimum
(MB)
Est. maximum
(MB)
Top of atmosphere (TA) reflectance 74.2 3.5 349.5
Surface reflectance (SR) 82.4 3.3 331.9
Brightness temperature (BT) 6.9 0.7 36.1
Pixel quality information (QA) 3.1 0.6 12.5
Full resolution browse image (.jpg) 2.7 - -
Metadata (.xml) .06 - -

Table 5.  Estimated Average, Minimum, and Maximum Tile Sizes of Landsat ARD Sample Data Products

Product Caveats

Due to the structure of the ARD grid compared to the traditional Landsat path/row designations, users are encouraged to study their areas of interest to determine which tile(s) are best suited for their scientific application.

For some tiles, there may not be sufficient data to fill the tile, depending on where the path/row scene is located within the tile. The images below of sample tile h26v08 in Western Pennsylvania indicate this caveat.

h26v08 - Landsat 8: May 11, 2015   h26v08 - Landsat 4 TM: November 25, 1982
ARD Image: h26v08_L8_20150511
Figure 8. LC08_CU_026008_20150511_20170729_C01_V01
    ARD Image: h26v08_L4_19821125
Figure 9. LT04_CU_026008_19821125_20170511_C01_V01
   

 

h26v08 - Landsat 8: July 2, 2014

 

h26v08  - Landsat 5 TM: March 7, 2009

ARD Image: h26v08_L8_20140702
Figure 10. LC08_CU_026008_20140702_20170729_C01_V01

 

ARD Image: h26v08_L5_20090307

Figure 11. LT05_CU_026008_20090307_20170728_C01_V01

Time-series Data Stack Samples

Advanced users interested in visualizing and analyzing a complete time-series 'stack' of ARD from 1984-2013 can access the tiles covering the state of California in this directory.  NOTE: California Landsat ARD Tile stacks range in size from 51 GB to 479 GB.

Known Artifacts

Interesting artifacts have been discovered in Landsat ARD during science validation and analysis. The ARD Artifacts page describes each artifact, and as ARD research continues, any additional information will be added.

Documentation and Resources

U.S. Landsat Analysis Ready Data (ARD) Data Format Control Book (DFCB) .pdf (772 KB)

Landsat ARD Tile Conversion Tool

Landsat ARD Shapefiles:   CONUS .zip (21.4 KB)  Alaska .zip (9.8 KB)  Hawaii .zip (2.0 KB)

Landsat ARD USGS Technical Announcement

Ask Questions

Contact USGS User Services with any Landsat ARD-related questions.
 

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