The above image was created by reprojecting Bands 1, 4, 3 from the MOD09GA product from their native Sinusoidal to Universal Transverse Mercator (UTM) coordinates using the MODIS Reprojection Tool (MRT). The data were acquired September 12, 2000 across the red rocks region of Southeastern Utah down through the heart of New Mexico (h09v06).
The MODIS Surface Reflectance products provide an estimate of the surface spectral reflectance as it would be measured at ground level in the absence of atmospheric scattering or absorption. Low-level data are corrected for atmospheric gases and aerosols, yielding a level-2 basis for several higher-order gridded level-2 (L2G) and level-3 products.
MOD09GA provides Bands 1-7 in a daily gridded L2G product in the Sinusoidal projection, including 500-meter reflectance values and 1-kilometer observation and geolocation statistics. 500-m Science Data Sets provided for this product include reflectance for Bands 1-7, a quality rating, observation coverage, observation number, and 250-m scan information. 1-kilometer Science Data Sets provided include number of observations, quality state, sensor angles, solar angles, geolocation flags, and orbit pointers.
Version-5 MODIS/Terra Surface Reflectance products are Validated Stage 2, meaning that accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts. Although there may be later improved versions, these data are ready for use in scientific publications.
Temporal Coverage | February 24, 2000 - |
Area | ~10 degrees x 10 degrees lat/long |
File Size | ~85 MB |
Projection | Sinusoidal |
Data Format | HDF-EOS |
1-km Data Group Dimensions | 1200 x 1200 rows/columns |
1-km Data Group Science Data Sets (SDS HDF Layers) | 9 (1) |
500-m Data Group Dimensions | 2400 x 2400 rows/columns |
500-m Data Group Science Data Sets (SDS HDF Layers) | 12 (2) |
Science Data sets for MODIS Terra Surface Reflectance Daily L2G Global 1km and 500m SIN Grid V005 (MOD09GA):
DATA GROUP |
Science Data Sets (HDF Layers) (9) |
UNITS |
BIT TYPE |
FILL |
VALID RANGE |
MULTIPLY BY SCALE FACTOR |
---|---|---|---|---|---|---|
1km (1) | num_observations_1km: Number of Observations | na | 8-bit signed integer | -1 | 0–127 | na |
State_1km: Reflectance Data State QA | Bit Field | 16-bit unsigned integer | 65535 | 0–57335 | na | |
SensorZenith | Degree | 16-bit signed integer | -32767 | 0–18000 | 0.01 | |
SensorAzimuth | Degree | 16-bit signed integer | -32767 | -18000–18000 | 0.01 | |
Range: pixel to sensor | Meter | 16-bit unsigned integer | 65535 | 27000–65535 | 25 | |
SolarZenith | Degree | 16-bit signed integer | -32767 | 0–18000 | 0.01 | |
SolarAzimuth | Degree | 16-bit signed integer | -32767 | -18000–18000 | 0.01 | |
gflags: Geolocation flags | Bit Field | 8-bit unsigned integer | 255 | 0–248 | na | |
orbit_pnt: Orbit pointer | none | 8-bit signed integer | -1 | 0–15 | na | |
DATA GROUP |
Science Data Sets (HDF Layers) (12) |
UNITS |
BIT TYPE |
FILL |
VALID RANGE |
MULTIPLY BY SCALE FACTOR |
500m (2) | num_observations_500m | none | 8-bit signed integer | -1 | 0–127 | na |
sur_refl_b01: 500m Surface Reflectance Band 1 (620-670 nm) | Reflectance | 16-bit signed integer | -28672 | -100–16000 | 0.0001 | |
sur_refl_b02: 500m Surface Reflectance Band 2 (841-876 nm) | Reflectance | 16-bit signed integer | -28672 | -100–16000 | 0.0001 | |
sur_refl_b03: 500m Surface Reflectance Band 3 (459-479 nm) | Reflectance | 16-bit signed integer | -28672 | -100–16000 | 0.0001 | |
sur_refl_b04: 500m Surface Reflectance Band 4 (545-565 nm) | Reflectance | 16-bit signed integer | -28672 | -100–16000 | 0.0001 | |
sur_refl_b05: 500m Surface Reflectance Band 5 (1230-1250 nm) | Reflectance | 16-bit signed integer | -28672 | -100–16000 | 0.0001 | |
sur_refl_b06: 500m Surface Reflectance Band 6 (1628-1652 nm) | Reflectance | 16-bit signed integer | -28672 | -100–16000 | 0.0001 | |
sur_refl_b07: 500m Surface Reflectance Band 7 (2105-2155 nm) | Reflectance | 16-bit signed integer | -28672 | -100–16000 | 0.0001 | |
QC_500m: 500m Reflectance Band Quality | Bit Field | 32-bit unsigned integer | 787410671 | 0–4294966019 | na | |
Obs_cov_500m: Observation coverage | Percent | 8-bit signed integer | -1 | 0–100 |
(0.01) 0.00999999977648258 |
|
iobs_res: Observation number | none | 8-bit unsigned integer | 255 | 0–254 | na | |
q_scan: 250m scan value information | Bit Field | 8-bit unsigned integer | 255 | 0–255 | na |
The QA information below is excerpted from an HDF-EOS file of the MODIS Surface Reflectance product MOD09GA.
The MOD09GA product includes two data groups, one for the 1-km state data and one for the 500-m reflectance data. Between both, there are four bit fields subject to interpretation. Table 1 describes the 1-km QA State. Table 2 is the bit legend for the 1-km geolocation flags. Table 3 describes the 500-m QA values. Table 4 interprets the q_scan values relating 250-m to 500-m data.
Table 1: 1-kilometer State QA Descriptions (16-bit)
Note that all bit flags in this SDS can be applied to the respective 500m and 250m reflectance data.
Bit No. |
Parameter Name |
Bit Comb. |
state_1km |
---|---|---|---|
0–1 | cloud state | 00 | clear |
01 | cloudy | ||
10 | mixed | ||
11 | not set, assumed clear | ||
2 | cloud shadow | 1 | yes |
0 | no | ||
3–5 | land/water flag | 000 | shallow ocean |
001 | land | ||
010 | ocean coastlines and lake shorelines | ||
011 | shallow inland water | ||
100 | ephemeral water | ||
101 | deep inland water | ||
110 | continental/moderate ocean | ||
111 | deep ocean | ||
6–7 | aerosol quantity | 00 | climatology |
01 | low | ||
10 | average | ||
11 | high | ||
8–9 | cirrus detected | 00 | none |
01 | small | ||
10 | average | ||
11 | high | ||
10 | internal cloud algorithm flag | 1 | cloud |
0 | no cloud | ||
11 | internal fire algorithm flag | 1 | fire |
0 | no fire | ||
12 | MOD35 snow/ice flag | 1 | yes |
0 | no | ||
13 | Pixel is adjacent to cloud | 1 | yes |
0 | no | ||
14 | BRDF correction performed | 1 | yes |
0 | no | ||
15 | internal snow mask | 1 | snow |
0 | no snow |
Table 2: 1-kilometer Geolocation Flags (16-bit)
Bit No. |
Parameter Name |
Bit Comb. |
state_1km |
---|---|---|---|
0–1 | cloud state | 00 | clear |
01 | cloudy | ||
10 | mixed | ||
11 | not set, assumed clear | ||
2 | cloud shadow | 1 | yes |
0 | no | ||
3–5 | land/water flag | 000 | shallow ocean |
001 | land | ||
010 | ocean coastlines and lake shorelines | ||
011 | shallow inland water | ||
100 | ephemeral water | ||
101 | deep inland water | ||
110 | continental/moderate ocean | ||
111 | deep ocean | ||
6–7 | aerosol quantity | 00 | climatology |
01 | low | ||
10 | average | ||
11 | high | ||
8–9 | cirrus detected | 00 | none |
01 | small | ||
10 | average | ||
11 | high | ||
10 | internal cloud algorithm flag | 1 | cloud |
0 | no cloud | ||
11 | internal fire algorithm flag | 1 | fire |
0 | no fire | ||
12 | MOD35 snow/ice flag | 1 | yes |
0 | no | ||
13 | Pixel is adjacent to cloud | 1 | yes |
0 | no | ||
14 | BRDF correction performed | 1 | yes |
0 | no | ||
15 | internal snow mask | 1 | snow |
0 | no snow |
Table 3: 500-meter QA Descriptions (32-bit)
Bit No. |
Parameter Name |
Bit Comb. |
QC_500m |
---|---|---|---|
0–1 | MODLAND QA bits | 00 | corrected product produced at ideal quality all bands |
01 | corrected product produced at less than ideal quality some or all bands | ||
10 | corrected product not produced due to cloud effects all bands | ||
11 | corrected product not produced due to other reasons some or all bands may be fill value [Note that a value of (11) overrides a value of (01)]. | ||
2–5 | band 1 data quality four bit range | 0000 | highest quality |
1000 | dead detector; data interpolated in L1B | ||
1001 | solar zenith >= 86 degrees | ||
1010 | solar zenith >= 85 and < 86 degrees | ||
1011 | missing input | ||
1100 | internal constant used in place of climatological data for at least one atmospheric constant | ||
1101 | correction out of bounds pixel constrained to extreme allowable value | ||
1110 | L1B data faulty | ||
1111 | not processed due to deep ocean or clouds | ||
6–9 | band 2 data quality four bit range | SAME AS BAND ABOVE | |
10–13 | band 3 data quality four bit range | SAME AS BAND ABOVE | |
14–17 | band 4 data quality four bit range | SAME AS BANDABOVE | |
18–21 | band 5 data quality four bit range | SAME AS BAND ABOVE | |
22–25 | band 6 data quality four bit range | SAME AS BAND ABOVE | |
26–29 | band 7 data quality four bit range | SAME AS BAND ABOVE | |
30 | atmospheric correction performed | 1 | yes |
0 | no | ||
31 | adjacency correction performed | 1 | yes |
0 | no |
The 250-m samples are for each of four quadrants within a 500-m cell. The first line/sample is in the upper left (north-west) corner of the image.
Table 4: 250-meter Scan Value Information Description (8-bit)
Bit No. |
Parameter Name |
Bit Comb. |
q_scan |
---|---|---|---|
0 | missing observation in quadrant 4 [+0.5 row, +0.5 column] | 1 | yes |
0 | no | ||
1 | missing observation in quadrant 3 [+0.5 row, -0.5 column] | 1 | yes |
0 | no | ||
2 | missing observation in quadrant 2 [-0.5 row, +0.5 column] | 1 | yes |
0 | no | ||
3 | missing observation in quadrant 1 [-0.5 row, -0.5 column] | 1 | yes |
0 | no | ||
4 | scan of observation in quadrant 4 [+0.5 row, +0.5 column] | 1 | same |
0 | different | ||
5 | scan of observation in quadrant 3 [+0.5 row, +0.5 column] | 1 | same |
0 | different | ||
6 | scan of observation in quadrant 2 [+0.5 row, +0.5 column] | 1 | same |
0 | different | ||
7 | scan of observation in quadrant 1 [+0.5 row, +0.5 column] | 1 | same |
0 | different |
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