MODIS

Table of Contents

Introduction
MOD43B1 BRDF/Albedo Model Parameters Product
MOD43B3 Albedo Product
MOD43B4 NBAR Product
MOD43 Validation
MOD43C1 Albedo CMG
Science Data Sets
Local Attributes
Global Attributes
MOD43C2 BRDF CMG
MOD43C3 NBAR CMG
BRDF/Albedo Data
MODIS User Tools
Publications
Related Links

BRDF/Albedo@BU

MODIS BRDF/Albedo CMG Product (MOD43C) User's Guide

MOD43C1 CMG Albedo Product

The MOD43C1 Climate Modeling Grid (CMG) Albedo Product (MODIS/Terra Albedo 16-Day L3 Global 0.05Deg CMG) provides both the white-sky albedos and the black-sky albedos (at local solar noon) for MODIS bands 1-7 as well as for three broad bands (0.3-0.7µm, 0.7-5.0µm, and 0.3-5.0µm) at a 0.05 degree spatial resolution in global files in a geographic (lat/lon) projectionn. These albedo values are based on spatial averages of the underlying 1-km albedo data. Note that along coastlines, this means that the 1-km pixels that lie over shallow water will be averaged into the 0.05 degree CMG pixel. In addition to the spectral and broadband albedo quantities themselves, the MOD43C1 CMG Albedo Product also provides extensive quality information. The quality and inversion status of the majority of the underlying 1-km pixels is provided as well as the percentage of the underlying pixels that were present or were snow covered.

Note: Reprocessed (V004) MODIS BRDF/Albedo products from Day 2000065 (5 March 2000) have been assigned a "Validated (Level 1) Status". Users are urged to use the quality flags to isolate the highest quality full inversion results for their own science applications. MOD43B and MOD43C products will continue to be evaluated and validated by the MODIS Science Team and MODIS Validation Scientists.

Science Data Sets

While the full MOD43C1 specification should be consulted for the most current description, the product includes three Science Data Sets (SDS) for each cmg-pixel in the tile. These SDSs are Black-Sky Albedo (at local solar noon), White-Sky Albedo (both for 10 bands -- 7 spectral and 3 broad or) and Albedo_Quality (containing one 32-bit word of quality flags). They are provided in global files in a geographic (lat/lon) projection (3600 rows X 7200 columns (X 10 bands)).

The Black-Sky Albedo SDS is specified as:

  • Data Field Name: INT16 Albedo ("YDim", "XDim", "Num_Albedo_Bands"")

  • Description: Black-Sky Albedo (at local solar noon) for bands 1-7, and the vis, NIR and SW broadbands

  • Data conversions:
    file data=(Albedo / scale_factor) + add_offset
    Albedo=(file data - add_offset)*scale_factor

    • The White-Sky Albedo SDS is specified as:
  • Data Field Name: INT16 Albedo ("YDim", "XDim", "Num_Albedo_Bands"")

  • Description: White-Sky Albedo for bands 1-7, and the vis, NIR and SW broadbands

  • Data conversions:
    file data=(Albedo / scale_factor) + add_offset
    Albedo=(file data - add_offset)*scale_factor

    • The Albedo_Quality SDS is specified as:
  • Data Field Name: UINT32 Albedo_Quality("YDim","XDim")

  • Description: BRDF and albedo quality information

    • 00-01 Mandatory QA
    0 = Majority processed, good quality
    1 = Majority processed, see other QA
    2 = Majority not processed due to cloud effects
    3 = Majority not processed due to other effects
    02 Period used
    0 = 16 days
    1 = 32 days
    03-05 AM/MISR/PM
    0 = AM
    1 = AM/PM
    2 = AM/PM/MISR
    3 = AM/MISR
    4 = PM
    5 = PM/MISR
    6 = MISR
    06-07 BRDF Quality
    0 = Majority full inversion
    1 = Majority magnitude inversion
    2 = Majority Bus-in DB parameters
    (not currently used)
    3 = Majority Fill Value
    08-15 Percent Inputs
    0-100
    (percent of the processed finer resolution data that contributed to this CMG pixel)
    16-23 Percent Snow
    0-100
    24-27 Szn of Local Solar Noon
    0 = 0-5 degrees
    1 = 5-10 degrees
    2 = 10-15 degrees
    3 = 15-20 degrees
    4 = 20-25 degrees
    5 = 25-30 degrees
    6 = 30-35 degrees
    7 = 35-40 degrees
    8 = 40-45 degrees
    9 = 45-50 degrees
    10 = 50-55 degrees
    11 = 55-60 degrees
    12 = 60-65 degrees
    13 = 65-70 degrees
    14 = 70-75 degrees
    15 = 75-80 degrees
    16 = 80-90 degrees
    28-30 TBD
    31 QAfill

    Local Attributes

    In addition to the actual SDS data values produced at each pixel in a tile, each SDS is associated with a number of standard Local Attributes that apply to the data.
    For the Black-Sky and White-Sky Albedo SDSes they include:

    Name: Type: Value:
    long_name HDF-STRING "Global_Black_Sky_Albedo (or Global_White_Sky_Albedo)"
    units HDF-STRING "albedo, no units"
    valid_range HDF-int16 0, 32766
    _FillValue HDF-int16 32767
    add_offset HDF-float64 0.0
    add_offset_err HDF-float64 0.0
    calibrated_nt HDF-int32 5
    scale_factor HDF-float64 0.001
    scale_factor_err HDF-float64 0.0


    And for the Albedo_Quality SDS, they include:

    Name: Type: Value:
    long_name HDF-STRING "Aggregated_Albedo_Quality"
    units HDF-STRING "concatenated flags"
    valid_range HDF-uint32 0, 4294967294
    _FillValue HDF-uint32 4294967295

    Global Attributes (Metadata)

    In addition to the albedo and quality information (SDSs and Local Attributes) that is provided at a per-cmg-pixel level, each Level 3 MOD43C1 CMG Albedo Product also includes three types of Global Attributes or Metadata which summarize the file. These are Core, Archive, and Structural Metadata. Of particular interest to the user community are the Core Metadata QAFlags of SCIENCEQUALITYFLAG and SCIENCEQUALITYFLAGEXPLANATION and some of the AdditionalAttributes which summarize the quality of the product over that entire file (see the full MOD43C1 specification for the complete listing).
    Author:Crystal Schaaf
    Last Updated:April 2004