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AMSR-E Data Versions

Jump to Temporal Coverage table below.

The version number appears:

• At the end of a data set title if you order data from SNOWI or the Warehouse Inventory Search Tool (WIST), for example: AMSR-E/AQUA MONTHLY L3 GLOBAL SNOW WATER EQUIVALENT EASE-GRIDS V001.

• In the Data Pool FTP directory name for each product, for example: AE_MoSno.001.

Several AMSR-E products have multiple algorithms applied. This means that each product may have a different algorithm covering different dates. These algorithms are identified in the AMSR-E data file names such as B01, B02, or B03. Refer to the Temporal Coverage table on this page. Characteristics of each algorithm are described in the following section.

Algorithm Characteristics

Version 2 (V002) Products:

AMSREL1A:

This improved version features empirical corrections to the Aqua scan azimuth and satellite flight direction. With corrected sun azimuth, sun elevation, earth azimuth, and earth incidence angles, the geometric accuracy of AMSR-E 89 GHz data improved to within 2 km, compared to Version 1 AMSREL1A data.

AE_L2A:

V08-Stage3: This validated version of the algorithm includes updated global attributes and inventory metadata to reflect a version change from B07 to V08. There were no changes to the science algorithm from B07 to V08.

V09-Stage3: This version corrects the errors in the resampled 89.0 GHz Horizontal data fields (89.0H_Res.#_TB) which were discovered in March 2008. Only V08 files from 19 June 2002 00:29 through 4 November 2004 05:43 contained the bad data. For more information, please see the AMSR-E L2A Brightness Temperatures: Bad Resampled 89 GHz Horizontal Data news brief on the AMSR-E News page.

AE_Land:

T06: Updated the product maturity code status to Transitional (T). There are no algorithm changes from version B05 to T06.

T07: Converted the algorithm code to run on Linux. There were no changes to the science algorithm in this version.

T08: Changed the processing code to produce only a QA file when there is no L2A brightness temperature data qualified for retrieval. There were no changes to the science algorithm in this version. Only being used for reprocessing. T06 is still being used in forward processing.

AE_Land3:

T05: Changes to this algorithm include:

• Updated the product maturity code status to Transitional (T). There are no algorithm changes from version T04 to T05.
• Converted the algorithm code to run on Linux. This version is not compatible with SGI IRIX.

AE_Ocean:

V05-Stage2: Changes to this algorithm include:

• Updated global attributes and inventory metadata to reflect product maturity change from Beta to Validated.
• Improved beamfilling correction to account for different footprint sizes of different frequencies.
• A new expression for the rain column height that yields more accurate rain flags is the third byte of the Ocean_products_quality_flag, which identify the proximity and intensity of rain. This is useful for quality assessment of SST and wind speed. The meanings of the rain flags have not changed.

V06-Stage2: Converted the algorithm code to run on Linux. There were no changes to the science algorithm in this version.

AE_DyOcn, AE_WkOcn, and AE_MoOcn:

V03-Stage2: Changes to this algorithm include:

• Updated the product maturity code status to Validated (V). There are no algorithm changes from version V02 to V03.
• Converted the algorithm code to run on Linux. This version is not compatible with SGI IRIX.

AE_Rain:

V09-Stage2: This validated version of the algorithm includes updated global attributes and inventory metadata to reflect a version change from B08 to V09. There were no changes to the science algorithm from B08 to V09.

V10-Stage2: Converted the algorithm code to run on Linux. There were no changes to the science algorithm in this version.

AE_RnGd:

V06-Stage2: Changes to this algorithm include:

• Updated the product maturity code status to Validated (V).
• Skipped duplicate (overlapping) scans in consecutive L2A files.
• Improved L2A brightness temperature binning for monthly ocean grids.
• Updated the leap second ancillary file to include the leap second which occurred at the end of 2005.
• Converted the algorithm code to run on Linux. This version is not compatible with SGI IRIX.
• Added a shell script that is used during installation.
• Set the default system stacksize parameter to unlimited.

AE_SI6, AE_SI12, and AE_SI25:

T07: Data never produced using this algorithm version. Algorithm updates included the following:

• Updated the product maturity code status to Transitional (T).
• Updated the sea ice concentration parameters.
• Converted the algorithm code to run on Linux. This version is not compatible with SGI IRIX.
• Set the default system stacksize parameter to unlimited.
• Added a shell script that is used during installation.
• Added new flag values for the 12.5 km snow depth product such as:
  • 140 indicates multiyear sea ice
  • 150 indicates variability in snow depth
  • 160 indicates snow melt.

T08: An NSIDC DAAC Data Priority panel asked that the AMSR-E sea ice temperature grids be removed from the 25 km product because of inherent ambiguities between changes in the physical temperature of the ice and changes in the ice emissivity. Instead, the panel suggested that an AMSR-E sea ice drift product be developed.  Also, this algorithm includes all modifications made in version T07.

AE_DySno, AE_5DSno, and AE_MoSno:

T08: Changes to this algorithm include:

• Updated the product maturity code status to Transitional (T).There are no algorithm changes from version T07 to T08.
• Converted the algorithm code to run on Linux. This version is not compatible with SGI IRIX.
• Improved input list error checking.
• Set the default system stacksize parameter to unlimited.

Version 1 (V001) Products:

AE_L2A:

B01: Original at-launch version of data.

B02: Corrects problems with the AMSR-E 89 GHz A-feedhorn by producing data from the 89 GHz B-feedhorn only.

B03: Offers improved calibration because the coefficients no longer depend on SSM/I or TMI. Data are also closer to real time. AE_L2A continues to derive data from the AMSR-E 89 GHz-B feedhorn because of problems with the 89 GHz-A feedhorn.

B04: Changes to this algorithm include:

• The name of the unsampled elements changed from Level1B to not-resampled.
• Degree units are more consistent, for example, deg rather than deg. for both angle and temperature.
• Level-2A metadata include CoRegistrationParameterA1 and CoRegistrationParameterA2 fields.
• Position_in_Orbit was written as an 8-byte number rather than 4-byte.
• Data include new fields for geostationary satellite glint and effective cold target temperature.
• The ProcessingVersionNumber swath attribute was eliminated.

B05: Changes to this algorithm include:

• Improved geolocation.
• Increased Earth Incidence angle to two bytes.
• Augmented the Scan_Quality_Flag with a spin rate flag and a flag indicating when observations are not all on the Earth.

B06: Corrected rounding error in the RangeEndingTime swath attribute and metadata item.

B07: The purpose of this algorithm is to:

• Correct the earth incidence angle calculation to correct for instrument roll.
• Modify along-scan antenna temperature adjustment using the new roll angle.
• Correct geolocation errors.
• Update the resampling weights of the 6.9 and 10.6 GHz channels.
• Recalibrate the hot load and revise the method for computing the effective hot load temperature.
• Introduce a flagging algorithm for RFI from European Geostationary TV satellites.
• Correct for the August-September 2003 Aqua pitch error.
• Correct for lunar radiation entering the cold mirror.
• Match the 89A and 89B observations when doing resampling.
• Use UT1 time to compute Earth rotation angle for geolocation accuracy and to avoid discontinuity in the geolocations parameters when a leap second occurs.
• Assign units, scale factor, and offset to all data fields.
• Modify swath attributes and data arrays.

AE_Land:

B01: Original at-launch version of data.

B02: Changes to this algorithm include:

• The number of pixels per scan changed from 196 to 243 (the full swath width).
• Updated land and surface type classification parameters and regression parameters.
• Updated brightness temperature quality assessment to prevent out-of-bounds brightness temperatures from being gridded.
• A new frozen ground classification.
• Using the difference of the 10.6V GHz and 18.0V GHz as the only criteria for defining Radio Frequency Interference (RFI). If the difference is greater than or equal to 5.0, the pixel is flagged as contaminated with RFI.
• Upgrades to the surface type classification to indicate combinations of surface types.

B03: Minor modification to the soil moisture QC within the science code.

B04: Update L2A reader for version 5 L2A.

B05: Updates to accommodate the L2A version B07 format changes.

AE_Land3:

B01: Original at-launch version of data.

B02: Input Level-2B product uses full swath (243 pixels). Combines Surface Type and Inversion QC Flag 1 from the Level-2B product to form the Inversion QC Flag field.

B03: Corrects structural metadata error, introduced in B02, in which the corner coordinates were incorrectly expressed in degrees. This caused any geolocation function or software that used the HDF-EOS library, including spatial subsetting via the WIST, to return erroneous results. In B03, the corner coordinates are properly expressed in meters.

B04: Accommodates L2 Land transitional file input.

AE_Ocean:

B01: Original at-launch version of data.

B02: Updated the L2A reader in preparation for version B04 L2A.

B03: Changes to this algorithm include:

• A salinity correction.
• A more sophisticated post hoc correction for anomalies.
• RFI identification and flagging.
• An update to the L2A reader to accommodate version 5 L2A format.
• Use of full swath.
• A new flag added to the ocean_products_quality_flag array to identify geostationary satellite RFI.
• Detection of sea ice using the NASA Team Sea Ice Algorithm.
• The redefinition of default values in arrays to eliminate ambiguity.
• The addition of units for all fields.
• Updates to the quality flags.

B04: Updates to accommodate the L2A version B07 format changes.

AE_DyOcn, AE_WkOcn, and AE_MoOcn:

B01: Original at-launch version of data.

B02: This algorithm uses full swath, which includes the addition of units for all parameters and excludes observations that meet any of the following conditions:

• The TB ice flag and the climate ice flag indicate the presence of ice.
• Contamination by sun glint or RFI.
• L2B ocean parameter(s) out of bounds.
• Suspect L2B ocean quality flags.

AE_Rain:

B01: Original at-launch version of data.

B02: First public version of data. The number of pixels per scan changed from 392 to 486 (the full swath width).

B03: Corrects low tropical coastal rainfall retrievals and modifies calculations of cold season coastal rainfall estimates to eliminate false rain signatures, which also eliminates most true rainfall signatures for this condition. The algorithm also eliminates rainfall retrievals over ocean when the sun glint is greater than 20 degrees.

B04: Corrects errors resulting from the AMSR-E 89 GHz-A feedhorn failure. The number of pixels per scan changed from 468 to 392.

B05: Improves low coastal rain rates.

B06: Rain rate is now calculated for surface types of "possible ice over coast."

B07: Update L2A reader for version 5 L2A.

B08: Updates to accommodate the L2A version B07 format changes.

AE_RnGd:

B01: Original at-launch version of data.

B02: First public version of data. Modified the L2B Rain rate product reader so that the full swath width of the L2B product can be used. Updated to prevent any missing data from being counted in the L2B histogram

B03: Corrects low tropical coastal rainfall retrievals and modifies calculations of cold season coastal rainfall estimates to eliminate false rain signatures, which also eliminates most true rainfall signatures for this condition. The algorithm also eliminates rainfall retrievals over ocean when the sun glint is greater than 20 degrees. In only AE_RnGd, the B03 algorithm lowers the upper limit for acceptable brightness temperatures over ocean and corrects minor errors in the processing code.

B04: Updates to L2A reader for version B05 L2A.

B05: Updates to accommodate the L2A version B07 format changes.

AE_SI6, AE_SI12, and AE_SI25:

B01: Original at-launch version of data.

B02: First public version of data. The following B02 algorithm changes apply only to data derived from the Bootstrap sea ice algorithm:

• Uses the full swath.
• Updates emissivity values based on date.
• Updates intercept parameters used in line-fitting routines.
• Adds 37H GHz to the argument list for Southern Hemisphere routines.
• Eliminates overlapping scans between passes.
• Updates weather filter parameters.
• Updates brightness temperature tie points for ice concentration.

B03: The following B03 algorithm changes apply only to data derived from the Bootstrap sea ice algorithm:

• Uses the 37H GHz channel in the sea ice concentration algorithm.
• Updates emissivity values.
• Significantly updates the bootstrap sea ice concentration algorithm.
• Adds brightness temperatures to threshold checks.
• Modifies the brightness temperature upper limit value from 350 K to 320 K.

Also, a known issue exists in this version. In the HDF-EOS structural metadata, the eccentricity squared projection parameter is rounded to only four significant digits, whereas the program actually uses a value with seven significant digits (0.006694 vs. 0.006693883).

B04: This algorithm adapts to the B04 L2A format changes.

B05: This algorithm includes:

• Incorporation of the TLSCF L2A B05 reader.
• Calculation of Southern Hemisphere parameters based on the NASA Team 2 algorithm instead of the Bootstrap algorithm.
• Modification of difference arrays in Southern Hemisphere; all difference arrays now reflect the difference in the Bootstrap algorithm from the stored NASA Team 2 algorithm.
• Updates to error reporting.
• Updates for local only Global Hydrology and Climate Center Science Investigator-led Processing System (GHCC-SIPS) HDF-EOS version 2.13 grid API (GDapi.c) to store the eccentricity squared projection parameter to 9 decimal places in the structural metadata.

B06: Updates to accommodate the L2A version B07 format changes.

AE_DySno, AE_5DSno, and AE_MoSno:

B01: Original at-launch version of data.

B02: First public version of data. SWE values were reduced by a factor of two to correct for an over-estimation of SWE. The number of pixels per scan changed from 196 to 243 for these three products.

B03: This algorithm:

• Contains ancillary file updates.
• Uses satellite attitude information.
• Adds brightness temperature limit checks.
• Eliminates checks for rain, cold rain, and wet snow.
• Eliminates explicit definition of xdim and ydim in the grid setup.

B04: This algorithm adapts to the B04 L2A format changes.

B05: This algorithm includes:

• Updates to the forest cover ancillary files. Two MODIS products are now used to help correct for forest attenuation.
• The daily product retrievals are now performed on the AMSR-E individual T_b samples, which are then averaged to the EASE-Grid 25x25 km Northern and Southern Hemisphere projection grid.
• Retrievals are calibrated for snow depth with a snow density climatology file used to convert snow depth to Snow Water Equivalent (SWE).

B06: Updates to accommodate the L2A version B07 format changes.

B07: Added the scale factor attribute to Snow Water Equivalent arrays.

Temporal Coverage of AMSR-E Products by Algorithm

Times are reported in UTC (hh:mm). Blank fields indicate the product was never generated with that algorithm.

AMSREL1A:
Version 1: 2002-06-22 (00:11) to 2005-03-01 (00:14)

Version 2: 2005-03-01 (00:14) to present.

Page last updated: 08/18/08