MOD10_L2 and MYD10_L2 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 Fill_Value Data used to fill gaps in the swath 255
Calibration scale_factor
scale_factor_err
add_offset
add_offset_err
calibrated_nt
Not used Not used

Custom Local Attributes for Snow Cover field

Attribute Name Definition Sample Value
Key Key to meaning of data in the SDS

0: Missing
1: No decision
11: Night
25: Snow-free land
37: Lake or inland water
39: Open water (ocean)
50: Cloud obscured
100: Snow-covered lake ice
200: Snow
254: Detector saturated
255: Fill

Valid EV Obs Band 1 Percentage² of valid observations from Level 1B in Band 1 of the swath 100.0
Valid EV Obs Band 2 Percentage² of valid observations from Level 1B in Band 2 of the swath 100.0
Valid EV Obs Band 4 Percentage² of valid observations from Level 1B in Band 4 of the swath 100.0
Valid EV Obs Band 6 Percentage² of valid observations from Level 1B in Band 6 of the swath 100.0
Saturated EV Obs Band 1 Percentage² of saturated observations from Level 1B in Band 1 of the swath 0.342
Saturated EV Obs Band 2 Percentage² of saturated observations from Level 1B in Band 2 of the swath 0.287
Saturated EV Obs Band 4 Percentage² of saturated observations from Level 1B in Band 4 of the swath 0.779
Saturated EV Obs Band 6 Percentage² of saturated observations from Level 1B in Band 6 of the swath 0.698
Auto_check_QA If all the data and intermediate calculations did not exceed a 15% limit of anomalous conditions, the snow cover algorithm result is considered acceptable; otherwise, it is questionable "Acceptable"

Custom Local Attributes for the Snow Cover Pixel QA field

Attribute Name Definition Sample Value
Key Explanation of the QA flag Bits 0 and 1:
00 = nominal
01 = abnormal
10 = cloud-obscured
11 = invalid

Bit 2:
0 = nominal
1 = averaged or replaced

Bit 3:
0 = within 45° scan angle
1 = beyond 45° scan angle

Bit 4:
0 = nominal
1 = high band 6 uncertainty index

Bit 5:
0 = cloud mask used
1 = cloud mask not used

Bit 6:
0 = nominal
1 = noisy level 1b data

Bit 7:
0 = nominal
1 = unusable level 1b data
Invalid_input Percentage of invalid L1B input data 1
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
2
Cloud_obscured Percentage of pixels that were identified as cloud 2

¹ These percentages are based on the number of land pixels in the swath. Only land pixels are analyzed for snow cover.

² These percentages are based on the total number of pixels in the swath (x dimensions * y dimensions).

³ These percentages are based on the number of inland water pixels in the swath.