MISR Level 2 Aerosol and Land Versioning

Data Product Specification Rev Q (PDF).

The entire mission is being reprocessed at this level.

AEROSOL:

• Revised optical depth upper bound for the Dark Water algorithm. In prior versions, optical depth upper bound was determined using a minimum equivalent reflectance, selected from among all "clear" subregions, including subregions over both land and water. Beginning in this version, for Dark Water only, we choose a minimum equivalent reflectance from among only subregions over water. This prevents subregions over land from influencing the optical depth upper bound for the Dark Water algorithm.

  No change was made in the calculation of optical depth upper bound for the Heterogeneous Land algorithm.

• Removed histogram binning algorithm for calculating mean and standard deviation for single-scattering albedo and spherical/non-spherical particle property fractional amounts. Replaced the histogram binning algorithm with a simple mean and standard deviation of successful mixtures. This impacts the follows parameters:

  • RegMeanSpectralSSA
  • RegStDevSpectralSSA
  • RegMeanSpectralOptDepthFraction (particle types 4 and 5 only)
  • RegStDevSpectralOptDepthFraction (particle types 4 and 5 only)

• Revised calculation of mean and standard deviation of optical depth fraction to weight by optical depth. This applies to all particle types (i.e. small, medium, large, spherical, and non-spherical). This impacts the follows parameters:

  • RegMeanSpectralOptDepthFraction (all types)
  • RegStDevSpectralOptDepthFraction (all types)

• For best estimate single-scattering albedo and particle property fractional amounts, report the result for the single successful mixture with the lowest combined residual. Uncertainty estimates are no longer available for these parameters. The following parameters are impacted:

  • RegBestEstimateSpectralSSA
  • RegBestEstimateSpectralSSAUnc (not available; all fill value)
  • RegBestEstimateSpectralOptDepthFraction
  • RegBestEstimateSpectralOptDepthFractionUnc (not available; all fill value)
  • RegBestEstimateNumberFraction
  • RegBestEstimateNumberFractionUnc (not available; all fill value)
  • RegBestEstimateVolumeFraction
  • RegBestEstimateVolumeFractionUnc (not available; all fill value)

• Revised all "LowestResid" parameters to exclude mixtures which are not successful. That is, the lowest residual mixture is selected from among successful mixtures only, rather than all mixtures.

• Added surface radiance contribution to RegLowestResidMixtureEqRefl reported for Heterogeneous Land algorithm. Prior versions included only the path radiance.

• Fixed minor bug in calculation of 70.4 km resolution optical depth parameters.

• Added parameter "RegParticlePropertyQA" to aerosol product. This parameter is set to "bad" (1) where the green band optical depth is less than 0.15.

• Reorganized grouping of fields within the HDF-EOS file structure. The following new groupings are added: RegParamsPerMixture, RegParamsAlgDiagnostics, RegParamsEqRefl, RegParamsGeometry, and RegParamsEnvironmental.

• Removed the following fields from the aerosol product:

  • RegWgtdMeanSpectralOptDepth
  • RegWgtdStDevSpectralOptDepth
  • RegLowestResidCombinedResidMax
  • RegMeanAngstromExponent
  • RegStDevAngstromExponent
  • RegMeanNumberFraction
  • RegStDevNumberFraction
  • RegMeanVolumeFraction
  • RegStDevVolumeFraction
  • RegSpectralSSAHistogramCounts
  • RegSpectralSSAHistogramMeans
  • RegSpectralNonsphericalOptDepthFractionHistogramCounts
  • RegSpectralNonsphericalOptDepthFractionHistogramMeans
  • RegNonsphericalNumberFractionHistogramCounts
  • RegNonsphericalNumberFractionHistogramMeans
  • RegNonsphericalVolumeFractionHistogramCounts
  • RegNonsphericalVolumeFractionHistogramMeans

LAND:

• Added parameter "LandQA" to land surface product. This parameter is set to "bad" (1) where optical depth is greater than 0.3.

Ancillary file changes:

• Added angstrom exponents and spectral phase functions to ACP_MIXTURE file. New fields are "Angstrom exponent" and "Mixture Spectral Phase Functions".

New ancillary files:

• MISR_AM1_TASC_<month>_<year>_F02_04.hdf (starting November 01 2009)
• MISR_AM1_AS_SCI_CONFIG_F12_0020.txt
• MISR_AM1_ACP_MIXTURE_F06_0021.hdf

• Stage 3 Validated: Aerosol optical depths, Surface albedos and BRFs
• Stage 2 Validated: Aerosol Angstrom exponent, aerosol single-scattering albedo, aerosol particle size and shape fractional amounts

Data Product Specification Rev O (PDF).

AEROSOL:

• Use higher quality "AngularSignatureCloudMask" rather than "FeatureRefASCM" for cloud screening in polar regions.
• Fix dark water suitability logic to require all channels used in the retrieval to have at least 32 clear subregions.
• Update ozone correction coefficients in the blue, green and red bands as follows:
  

        band   previous value    new value
        blue   4.26E-6           5.67E-6
        green  1.05E-4           1.04E-4
        red    5.09E-5           4.89E-5
        nir    3.94E-6           3.94E-6 (unchanged)
        

• Add brightness test to aerosol retrieval applicability logic. This should eliminate many cloud retrieval blunders.
• Disable use of optically-thick algorithm. This will reduce coverage over dark water and should also help to eliminate some cloud retrieval blunders.
• Revise polar (snow/ice) cloud screening logic to include RCCM input. This should help to eliminate some cloud retrieval blunders. Retrieval coverage could increase or decrease depending on the RCCM.
• Removed the following obsolete/unused fields from aerosol product:
  RegSfcRetrOptDepthUnc, OptDepthDWCalcPerBand, OptDepthOTACalcPerBand, ChisqAbsCalcPerBand, RelHumidProfile, RelHumidProfileSrc, StratAerFlag, StratAerOptDepth, StratAerOptDepthSrc, CirrFlag, CirrOptDepth, CirrOptDepthSrc
• Added the following fields to the Aerosol product: 
  RegLamSurfEqRefl (currently not used),
  WaterLeavEqReflExp (currently not used),
  RegSurfTypeFlag

New ancillary files:

• MISR_AM1_AS_SCI_CONFIG_F10_0018.txt

Data Product Specification Rev N (PDF).

AEROSOL:

• Updated component particle fractional amounts in ACP mixture file.
• Changed cloud screening logic, for polar scenes only, such that ASCM value "ClearLC", and SDCM value "NearSurfaceLC" are both considered cloudy, rather than clear.

New ancillary files:

• MISR_AM1_ACP_MIXTURE_F05_0020.hdf
• MISR_AM1_AS_SCI_CONFIG_F09_0017.txt

• Stage 1 Validated: MRPV (BRFModParam), NDVI; LAI and FPAR (excluding needleleaf forest)

Data Product Specification Rev L (PDF).

AEROSOL:

• Mixture equivalent reflectance (RegBestFitMixtureEqRefl) is now reported. Previously this field was present, but contained only fill value.
• The content of the APOP and mixture files is now copied into the aerosol product in new Vgroups named "Component Particles Information" and "Mixture Information". Included with this information are new metadata attributes containing text format tables that provide a summary of the component particle properties and mixture properties.
• Fixed minor bug in the calculation of subregional variability (SubrVar), occuring only at locations where ellipsoid or terrain data quality indicator (RDQI) is 1, which is very rare.

LAND:

• HDRF uncertainty is now reported for each camera and band, rather than averaged over cameras. A new field LandHDRFUnc is added. The old field LandHDRFUncCamAvg is removed.
• Fixed bug in calculation of BHR uncertainty (LandBHRRelUnc), occuring only at locations where fewer than nine cameras are available. BHR uncertainty is unchanged at locations where all nine cameras are available.

New ancillary files:

• MISR_AM1_ACP_APOP_F05_0014.hdf
• MISR_AM1_ACP_MIXTURE_F05_0019.hdf

• Stage 1 Validated: surface radiative parameters: BRF, HDRF, DHR, and BHR

Data Product Specification Rev I (PDF).

AEROSOL:

• Add stricter constraint to aerosol retrievals over heterogeneous surfaces.

LAND:

• Fix bug which caused some FPAR values to be reported with anomalously high values.

New ancillary files:

• MISR_AM1_AS_SCI_CONFIG_F07_0014.txt

• Stage 2 Validated: aerosol optical depth over heterogeneous surfaces and dark water

Data Product Specification Rev G (PDF).

AEROSOL:

• Add Level 1 orbit-QA flag to product.

LAND:

• Add Level 1 orbit-QA flag to product.

Data Product Specification Rev F (PDF).

AEROSOL:

• The calculation of optical uncertainty over heterogeneous surfaces was modified. The calculation of chisquare-geometric was modified. Determination of a region's suitability for the algorithm to retrieve aerosols over heterogeneous surfaces was changed: instead of using a surface contrast threshold, a new test is used which is based on a weighted mean equivalent reflectance threshold. A regional angular correlation screening test was added to aerosol retrievals over land. Success of aerosol retrievals over land is now dependent upon the spread in optical depths retrieved per band. Minor field name changes were implemented in the aerosol QA file and the aerosol flag legends vdata.

LAND:

• Two parameters (chisquare-smooth and HDRF uncertainty) were modified to remove their dependency upon the ARP.

New ancillary files:

• MISR_AM1_AS_SCI_CONFIG_F05_0007.txt
• MISR_AM1_CART_F01_0001.hdf

• Beta: Aerosol parameters retrieved using algorithm for homogeneous surfaces.
• Provisional: All aerosol parameters except those retrieved using algorithm for homogeneous surfaces.

LAND:

• Beta: Land surface radiation parameters for PAR spectral regions.
• Provisional: All land surface radiation parameters except those for PAR spectral regions.

Major upgrade to Level 2 aerosol product, incorporating several changes and additions.
For details, see Release Description L2 AS V2.1.4.

New ancillary files:

• MISR_AM1_AS_SCI_CONFIG_F03_0003.txt

• Replace illegal value (0) found in AerCompModId field of aerosol product with valid fill value (253).

LAND:

• Fix bug affecting BRF fields in land surface product so that correct fill values (253 and 65533) are used instead of incorrect values (126 and 0).