## DESCRIPTION

i.modis.qc Extracts Requested Quality Assessment flags from the following MODIS products: MOD09A1, MOD09Q1, and MOD11A2. This does include MOD09A1 QA_state_500m layer (see Notes).

    MOD09A1/Q1: MODLAND QA Bits. bits=[0-1]

- [00]= class 0: Corrected product produced at ideal quality -- all bands
- [01]= class 1: Corrected product produced at less than ideal quality -- some or all bands
- [10]= class 2: Corrected product NOT produced due to cloud effect -- all bands
- [11]= class 3: Corrected product NOT produced due to other reasons -- some or all bands maybe be fill value (Note that a value of [11] overrides a value of [01])

    MOD09Q1: Cloud State. bits=[2-3]

- [00]= class 0: Clear -- No clouds
- [01]= class 1: Cloudy
- [10]= class 2: Mixed
- [11]= class 3: Not Set ; Assumed Clear

    MOD09Q1: Band-wise Data Quality 250m bits=[4-7][8-11]
    MOD09A1: Band-wise Data Quality 500m bits=[2-5][6-9][10-13][14-17][18-21][22-25][26-29]

- [0000]= class 0: highest quality
- [0111]= class 1: noisy detector
- [1000]= class 2: dead detector; data interpolated in L1B
- [1001]= class 3: solar zenith ge 86 degrees
- [1010]= class 4: solar zenith ge 85 and lt 86 degrees
- [1011]= class 5: missing input
- [1100]= class 6: internal constant used in place of climatological data for at least one atmospheric constant
- [1101]= class 7: correction out of bounds, pixel constrained to extreme allowable value
- [1110]= class 8: L1B data faulty
- [1111]= class 9: not processed due to deep ocean or cloud
- Class 10-15: Combination of bits unused

    MOD09A1/Q1: Atmospheric correction bit=[12]/[30]

- [0]= class 0: Not Corrected product
- [1]= class 1: Corrected product

    MOD09A1/Q1: Adjacency correction bit=[13]/[31]

- [0]= class 0: Not Corrected product
- [1]= class 1: Corrected product

    MOD09Q1: Different orbit from 500m product, bit=[14]

- [0]= class 0: same orbit as 500m
- [1]= class 1: different orbit from 500m

    MOD11A2: Mandatory QA Flags bits=[0-1]

- [00]= class 0: LST produced, good quality, not necessary to examine more detailed QA
- [01]= class 1: LST produced, other quality, recommend examination of more detailed QA
- [10]= class 2: LST not produced due to cloud effects
- [11]= class 3: LST not produced primarily due to reasons other than cloud

    MOD11A1: Data Quality Flag bits=[2-3]

- [00]= class 0: Good data quality of L1B in bands 31 and 32
- [01]= class 1: Other quality data
- [10]= class 2: TBD
- [11]= class 3: TBD

    MOD11A1: Emis Error Flag bits=[4-5]

- [00]= class 0: Average emissivity error le 0.01
- [01]= class 1: Average emissivity error le 0.02
- [10]= class 2: Average emissivity error le 0.04
- [11]= class 3: Average emissivity error gt 0.04

    MOD11A1: LST Error Flag bits=[6-7]

- [00]= class 0: Average LST error le 1
- [01]= class 1: Average LST error le 2
- [10]= class 2: Average LST error le 3
- [11]= class 3: Average LST error gt 3

    MOD11A2: Mandatory QA Flags bits=[0-1]

- [00]= class 0: LST produced, good quality, not necessary to examine more detailed QA
- [01]= class 1: LST produced, other quality, recommend examination of more detailed QA
- [10]= class 2: LST not produced due to cloud effects
- [11]= class 3: LST not produced primarily due to reasons other than cloud

    MOD11A2: Data Quality Flag bits=[2-3]

- [00]= class 0: Good data quality of L1B in 7 TIR bands
- [01]= class 1: Other quality data
- [10]= class 2: TBD
- [11]= class 3: TBD

    MOD11A2: Emis Error Flag bits=[4-5]

- [00]= class 0: Average emissivity error le 0.01
- [01]= class 1: Average emissivity error le 0.02
- [10]= class 2: Average emissivity error le 0.04
- [11]= class 3: Average emissivity error gt 0.04

    MOD11A2: LST Error Flag bits=[6-7]

- [00]= class 0: Average LST error le 1
- [01]= class 1: Average LST error le 2
- [10]= class 2: Average LST error le 3
- [11]= class 3: Average LST error gt 3

    MOD09A1s: Cloud State bits=[0-1]

- [00]= class 0: clear
- [01]= class 1: cloudy
- [10]= class 2: mixed
- [11]= class 3: not set, assumed clear

    MOD09A1s: Cloud shadow bits=[2]

- [0]= class 0: yes
- [1]= class 1: no

    MOD09A1s: Land/Water Flag bits=[3-5]

- [000]= class 0: Shallow ocean
- [001]= class 1: Land
- [010]= class 2: Ocean coastlines and lake shorelines
- [011]= class 3: Shallow inland water
- [100]= class 4: Ephemeral water
- [101]= class 5: Deep inland water
- [110]= class 6: Continental/moderate ocean
- [111]= class 7: Deep ocean

    MOD09A1s: Aerosol Quantity bits=[6-7]

- [00]= class 0: Climatology
- [01]= class 1: Low
- [10]= class 2: Average
- [11]= class 3: High

    MOD09A1s: Cirrus detected bits=[8-9]

- [00]= class 0: None
- [01]= class 1: Small
- [10]= class 2: Average
- [11]= class 3: High

    MOD09A1s: Internal Cloud Algorithm Flag bits=[10]

- [0]= class 0: Cloud
- [1]= class 1: No cloud

    MOD09A1s: Internal Fire Algorithm Flag bits=[11]

- [0]= class 0: Fire
- [1]= class 1: No fire

    MOD09A1s: MOD35 snow/ice flag bits=[12]

- [0]= class 0: Yes
- [1]= class 1: No

    MOD09A1s: Pixel adjacent to cloud bits=[13]

- [0]= class 0: Yes
- [1]= class 1: No

    MOD09A1s: BRDF correction performed bits=[14]

- [0]= class 0: Yes
- [1]= class 1: No

    MOD09A1s: Internal Snow Mask bits=[15]

- [0]= class 0: Snow
- [1]= class 1: No snow

## NOTES

In MOD09A1: It seems that cloud related info is not filled properly in the standard QC (MOD09A1 in this module) since version 3, State-QA 500m images (MOD09A1s in this module) should be used (see Vermote et al., 2008).

## TODO

Add one Day products.

## SEE ALSO

i.vi

## REFERENCES

- MODIS Products
- Vermote E.F., Kotchenova S.Y., Ray J.P. MODIS Surface Reflectance User's Guide. Version 1.2. June 2008. MODIS Land Surface Reflectance Science Computing Facility. Homepage

## AUTHOR

Yann Chemin

Last changed: $Date: 2013-01-22 22:18:02 -0800 (Tue, 22 Jan 2013) $