Folder Albedo (MCD43C3)

albedoAlbedo is a reflection coefficient that describes the reflecting power of a surface. It is a ratio of the reflected to incident radiation of a surface. Albedo values are dimensionless with values from zero (no reflection) to one (perfect reflection). Fresh snow, for example, will have values near 0.9 and charcoal will have values near 0.04. Albedo depends on the frequency of radiation; therefore the standard MODIS product for Albedo includes data layers for MODIS Bands 1 through 7.

Accurately measuring albedo at high latitudes is challenging. Reflectance measurements made at high solar zenith angles pose difficulties in calibration and atmospheric correction. About half of available satellite observations during the sunlit season Summary of Products in the Arctic are obtained under conditions where the solar zenith angle exceeds 70° resulting in lower-quality results.

The standard MODIS product includes data for black sky albedo (BSA) and white sky albedo (WSA). Actual albedo is a combination of the BSA and WSA albedo, and will depend on the particular atmospheric conditions when observations are made. An accuracy assessment of the MODIS standard albedo product to in-situ measurements on the Greenland ice sheet (Stroeve et al. 2005) found that at most solar zenith angles, the BSA and WSA bracket the actual albedo, and at 50° local solar noon zenith angles, BSA and WSA were identical and therefore close to actual albedo. Additionally it was found that during spring and autumn when the solar zenith angle often exceeds 50°, the quality of the MODIS albedos was often flagged as poor (e.g., a backup algorithm was used and the statistical differences between the BSA and WSA had more to do with backup versus main algorithm retrievals than with BSA versus WSA).

This MODIS product is available on a 16-day acquisition cycle, but produced every 8 days. For the CAFF System, the first production of every month has been provided. Note: The Albedo layers of this product require a scale factor that can be found in the Appendix.

 

For usage please see ABDS Data Policy
Suggested citation:
CAFF (2015). Albedo: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

 

 

Bacic Info

Data Set Characteristics

Temporal Coverage February 24, 2000 -
Area Global
File Size ~185 MB
Projection Latitude/Longitude Grid
Data Format HDF-EOS
Dimensions 3600 x 7200 rows/columns
Resolution 0.05 degrees (5600 meters)
Science Data Sets (SDS HDF Layers) 24

Layers

Science Data Sets

(HDF Layers) 24

UNITS

BIT TYPE

FILL

VALID RANGE

MULTIPLY BY SCALE FACTOR

Albedo_BSA_Band_1 (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_2 (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_3 (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_4 (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_5 (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_6 (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_7 (Black Sky Albedo) Albedo, no units 116-bit unsigned integer 6 32767 0–32766 0.0010
Albedo_BSA_Band_vis (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_nir (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_BSA_Band_shortwave (Black Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_1 (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_2 (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766  
Albedo_WSA_Band_3 (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_4 (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_5 (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_6 (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_7 (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_vis (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_nir (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010
Albedo_WSA_Band_shortwave (White Sky Albedo) Albedo, no units 16-bit unsigned integer 32767 0–32766 0.0010

The table below lists the four Science Data Sets representing Quality in the Albedo, with applicable QC bit legends. Note that Local_Solar_Noon, Percent_Inputs, and Percent_Snow do not utilize their full 0–254 range (see below).

Bit Comb. BRDF_Albedo_Quality
0 best quality, 75% or more with best full inversions
1 good quality, 75% or more with full inversions
2 Mixed, 75% or less full inversions and 25% or less fill values
3 All magnitude inversions or 50% or less fill values
4 50% or more fill values
255 FillValue
   
  Local_Solar_Noon
0–254 Zenith Angle at local solar noon (0–180 degrees)
255 FillValue
   
  Percent_Inputs
0–254 Percent of the processed finer resolution data which contributed to this CMG pixel (0–100%)
255 FillValue
   
  Percent_Snow
0–254 Percent of underlying data flagged as snow (0–100%)
255 FillValue

 

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