MOD10A1 and MYD10A1 Local (Snow Cover) Attributes

Local attributes describe the data and provide summary data on the results of the snow cover algorithm. Two types of local attributes are reported: HDF predefined, and custom local attributes.

HDF Predefined Local Attributes

Attribute Name Reserved Label(s) Definition Sample Value
Label long_name Long name of the SDS Snow_covered_land
Unit units SI units of the data, if any none
Format format How the data should be viewed in Fortran format notation I3
Coordinate system coordsys Coordinate system to use for the data latitude, longitude
Range valid_range Max and min values within a selected data range 0-254
Fill Value _FillValue Data used to fill gaps in the swath 255
Calibration scale_factor
Not used Not used

Custom Local Attributes for the Day_Tile_Snow_Cover field

Attribute Name Definition Sample Value
missing_value Coded integer used to indicate missing data 0
Snow_cover_pct Areal coverage of snow 68
Cloud_cover_pct Percentage of cloud in the tile 5
Land_area_pct Percentage of land in the tile 89
Key Key to interpretation of coded integers See coded integers
Exception: 254 = non-production mask

Custom Local Attributes for the Snow_Spatial_QA field

Attribute Name Definition Sample Value
Nominal_results Percentage of pixels for which algorithm execution was nominal 95
Abnormal_results Percentage of pixels for which algorithm execution
encountered conditions outside of nominal range
Cloud_obscured Percentage of pixels that were identified as cloud 2
Invalid_input Percentage of invalid L1B input data 1
Outside relative azimuth Percentage of pixels observed at a relative azimuth range of 150° to 210°. 1
Key Explanation of the QA flag Bits 0 and 1:
00 = nominal
01 = abnormal
10 = cloud-obscured
11 = invalid

Bit 2:
0 = within azimuth limit
1 = beyond azimuth limit

Bit 3:
0 = over observation coverage min
1 = under observation coverage min