AMSR Unified

AMSR Unified - Advanced Microwave Scanning Radiometers
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Version History

This page provides details of the processing and algorithm history for all versions of AMSR Unified data products. For an explanation of version naming conventions such as product maturity codes and validation stages, refer to the Naming Conventions section of this page. For information about major instrument data loss periods, see the Instrument Data Loss Periods document (document content is forthcoming).

Naming Conventions

Identifying Version Numbers

Depending on the order data method you use, the version number will appear differently at the end of the product name.

If you order the data from Earthdata Search, the product name will be appended by a version number. The version is specified as a 3-digit alphanumeric code beginning with the letter 'V' (V001 indicates Version 1).

AMSR-E/AMSR2 Unified L2B Half-Orbit 25 km EASE-Grid Surface Soil Moisture V001.

If you order data from the Data Pool HTTPS directory, the version number is written at the end of the data set short name:

AU_Land.002.

Product Maturity Codes

AMSR Unified data file/granule names include a product maturity code (such as B01, T02, or V03) to indicate which version of the algorithm was used to produce the data. The product maturity code includes both a maturity level (P, R, B, T, or V) and a two-digit iteration number, such as B02 in the following file name:

AMSR_U2_L2_Land_B02_201805292336_A.he5

 

Product Maturity Code Descriptions

LevelDescription
PPreliminary - refers to non-standard, near-real-time data available from NSIDC. These data are only available for a limited time until the corresponding standard product is ingested at NSIDC.
RNear-Real-Time - refers to near-real-time data produced and distributed via the NASA Land Atmosphere Near-real-time Capability for EOS (LANCE) data system.
BBeta - indicates a developing algorithm with updates anticipated.
TTransitional - period between beta and validated where the product is past the beta stage, but not quite ready for validation. This is where the algorithm matures and stabilizes.
VValidated - products are upgraded to Validated once the algorithm is verified by the algorithm team and validated by the validation teams. Validated products have an associated validation stage. Refer to Table 2 for a description of the stages.

Validation Stage

Additionally, a stage (1, 2, or 3) may be appended to the product maturity code of Validated, such as V09-Stage3. Table 2 describes each validation stage.

Validation StageDescription
Stage 1Product accuracy is estimated using a small number of independent measurements obtained from selected locations, time periods, and ground-truth/field program efforts.
Stage 2Product accuracy is assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts.
Stage 3Product accuracy is assessed, and the uncertainties in the product are well established via independent measurements made in a systematic and statistically robust way that represents global conditions.

Data Products and Version Details

AMSR-E/AMSR2 Unified L3 Daily 6.25 km Polar Gridded 89 GHz Brightness Temperatures (AU_SI6)

Current Version: Version 1 (V001)

Maturity Details: B04 (includes both B03 and B04 updates)

Temporal Coverage: 2012-07-02 (23:18) to present

Version Changes:

  • B04: Northern Hemisphere water filter parameters were adjusted to better characterize the open water cluster during the cold months. This change affected data contained in the NH_ICEDIFF Data Fields from October through May and eliminated, on average, approximately 60% of false ice in the open ocean.
  • B03: A coding error was corrected which affected the 25km Northern Hemisphere ICEDIFF data fields with approximately 50% of the cells changing by -20 to 10 with a root mean square error of 8.
  • B03: An adjustment in the calculation of the ICEDIFF data fields was made which affected approximately 50% of all ICEDIFF data fields by +/-1.

Version History

  • B02 2012-07-02 to 2020-05-17: Since all sea ice products are produced by the same software (Delivery Algorithm Package), this version was generated as a result of reprocessing AU_SI25 to B02. There are no changes to this data in the B02 version. Only the file name has changed to reflect the new version. An error in the indexing of the brightness temperatures was corrected. This change corrected the mislabeling of 8 of the 12 brightness temperature channels in the 25km product.
  • B01 2012-07-02 to 2019-02-13: Original at-launch version of data.

AMSR-E/AMSR2 Unified L3 Daily 12.5 km Brightness Temperatures & Sea Ice Concentration Polar Grid (AU_SI12)

  • Current Version: Version 1 (V001)
  • Maturity Details: B04 (includes both B03 and B04 updates)
  • Temporal Coverage: 2012-07-02 (23:18) to present

Version Changes:

  • B04: Northern Hemisphere water filter parameters were adjusted to better characterize the open water cluster during the cold months. This change affected data contained in the NH_ICEDIFF Data Fields from October through May and eliminated, on average, approximately 60% of false ice in the open ocean.
  • B03: A coding error was corrected which affected the 25km Northern Hemisphere ICEDIFF data fields with approximately 50% of the cells changing by -20 to 10 with a root mean square error of 8.
  • B03: An adjustment in the calculation of the ICEDIFF data fields was made which affected approximately 50% of all ICEDIFF data fields by +/-1.

Version History

  • B02 2012-07-02 to 2020-05-17: Since all sea ice products are produced by the same software (Delivery Algorithm Package), this version was generated as a result of reprocessing AU_SI25 to B02. There are no changes to this data in the B02 version. Only the file name has changed to reflect the new version. An error in the indexing of the brightness temperatures was corrected. This change corrected the mislabeling of 8 of the 12 brightness temperature channels in the 25km product.
  • B01 2012-07-02 to 2019-02-13: Original at-launch version of data.

AMSR-E/AMSR2 Unified L3 Daily 25 km Brightness Temperatures & Sea Ice Concentration Polar Grid (AU_SI25)

  • Current Version: Version 1 (V001)
  • Maturity Details: B04 (includes both B03 and B04 updates)
  • Temporal Coverage: 2012-07-02 (23:18) to present

Version Changes:

  • B04: Northern Hemisphere water filter parameters were adjusted to better characterize the open water cluster during the cold months. This change affected data contained in the NH_ICEDIFF Data Fields from October through May and eliminated, on average, approximately 60% of false ice in the open ocean.
  • B03: A coding error was corrected which affected the 25km Northern Hemisphere ICEDIFF data fields with approximately 50% of the cells changing by -20 to 10 with a root mean square error of 8.
  • B03: An adjustment in the calculation of the ICEDIFF data fields was made which affected approximately 50% of all ICEDIFF data fields by +/-1.

Version History

  • B02 2012-07-02 to 2020-05-17: Since all sea ice products are produced by the same software (Delivery Algorithm Package), this version was generated as a result of reprocessing AU_SI25 to B02. There are no changes to this data in the B02 version. Only the file name has changed to reflect the new version. An error in the indexing of the brightness temperatures was corrected. This change corrected the mislabeling of 8 of the 12 brightness temperature channels in the 25km product.
  • B01 2012-07-02 to 2019-02-13: Original at-launch version of data.

AMSR-E/AMSR2 Unified L2B Half-Orbit 25 km EASE-Grid Surface Soil Moisture (AU_Land)

  • Current Version: Version 1 (V001)
  • Maturity Details: B02
  • Temporal Coverage: 2012-07-02 (23:18) to present

Version Changes: The B02 update corrects an error that caused only half of each swath to be processed.

Version History: B01 2012-07-02 to 2019-02-13: Original at-launch version of data.

AMSR-E/AMSR2 Unified L3 Global Daily 25 km EASE-Grid Snow Water Equivalent (AU_DySno)

  • Current Version: Version 1 (V001)
  • Maturity Details: B01
  • Temporal Coverage: 2012-07-02 (23:18) to present

Version Changes: Original at-launch version of data.

AMSR-E/AMSR2 Unified L3 Global 5-Day 25 km EASE-Grid Snow Water Equivalent (AU_5DSno)

  • Current Version: Version 1 (V001)
  • Maturity Details: B01
  • Temporal Coverage: 2012-07-02 (23:18) to present

Version Changes: Original at-launch version of data.

AMSR-E/AMSR2 Unified L3 Global Monthly 25 km EASE-Grid Snow Water Equivalent (AU_MoSno)

  • Current Version: Version 1 (V001)
  • Maturity Details: B01
  • Temporal Coverage: 2012-07-02 (23:18) to present

Version Changes: Original at-launch version of data.

AMSR-E/AMSR2 Unified L2B Global Swath Surface Precipitation (AU_Rain)

  • Current Version: Version 1 (V001)
  • Maturity Details: V02 (Validated, Stage 2)
  • Temporal Coverage: 2002-07-02 to present

Version Changes

Changes for Validation Stage 2 include:

  • The value for "missing" (-9999.0) in the ProbabilityofPrecip variable was too large for the data type (byte). As a result, a small number of missing ProbabilityofPrecip values were recorded as "36" (i.e., 36%). This problem was corrected by changing the ProbabilityofPrecip value for "missing" to -99, to correspond with the byte data type.
  • The SunGlintAngle datatype was changed to short integer (16-bit, unsigned).

Version History

  • November 2022: Added AMSR-E portion of the data set (2002-06-01 to 2011-10-04)
  • October 2020: Validated, Stage 2
  • August 2020: Validated, Stage 1 (original at-launch version)

AMSR-E/AMSR2 Unified L2B Global Swath Ocean Products (AU_Ocean)

  • Current Version: Version 1 (V001)
  • Maturity Details: V01 (Validated, Stage 1)
  • Temporal Coverage: 2002-06-01 to present
    • Note: no coverage from 2011-10-05 to 2012-07-01 (end of AMSR-E to beginning of AMSR2)

Version History

  • June 2023: Added AMSR-E portion of data set (2002-06-01 to 2011-10-04)
  • December 2021: Validated, Stage 1 (original at-launch version)

AMSR-E/AMSR2 Unified L3 Global Daily Ascending/Descending .25x.25 deg Ocean Grids (AU_DyOcn)

  • Current Version: Version 1 (V001)
  • Maturity Details: V01 (Validated, Stage 1)
  • Temporal Coverage: 2002-06-01 to present
    • Note: no coverage from 2011-10-05 to 2012-07-01 (end of AMSR-E to beginning of AMSR2)

Version History

  • October 2024: Validated, Stage 1 (original at-launch version)