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November 30, 2017

Many landscapes define the Earth’s surface, from bleak sandy deserts to rolling green hills. Scientists use both BRDF, defined as Bidirectional Reflectance Distribution Function, and Albedo to better understand the topography and vegetation cover of these surfaces. BRDF and Albedo provide information about solar energy output. Identifying how outgoing solar energy scatters can help scientists to better understand the dynamics of a ground surface, and can help the human population better prepare for events such as wind erosion. Wind erosion affects air quality, leads to soil loss, and stunts anthropogenic and natural vegetation growth, which can be vital for human populations.
                                                 
BRDF values are estimates of the directions that solar energy takes (scattering) as it reflects off the Earth’s surface. These values are used to estimate Albedo, which is the proportion of solar energy that is reflected from the Earth’s surface versus the energy that is absorbed. Sun and others (2017) state that remote sensing is the best way to observe these values over time, and at a global scale. This study uses BRDF and Albedo data products derived from measurements collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) Version 6, located onboard NASA’s Terra and Aqua satellites, to observe how topography and vegetation cover can influence wind erosion in Australia.
 
Chappell and others (2017) explain that flat surface areas produce a mirror BRDF reflection, meaning light is scattered in one direction. Rougher surfaces have crevasses that scatter light in many directions as it reflects back into the atmosphere. Conversely, the crevasses in rough surfaces halt the forces of wind. In Australia, flat surfaces such as deserts, and areas that have been “clear-cut” from human activity, cannot absorb wind as well as rougher surfaces, thus leaving these areas vulnerable to wind erosion and its impacts on the human population. To prevent wind erosion events from occurring in the future, ground cover can be maintained to promote a “rougher” ground surface. Li and others (2017) report that MODIS BRDF/Albedo data provide frequent observations that can be valuable when observing short- and long-term wind erosion, finding that environmental variables such as temperature and precipitation affect vegetation cover.
 
MODIS BRDF and Albedo data can also be used alongside spectral indices such as NDVI, defined as the Normalized Difference Vegetation Index, to estimate the greenness of vegetation cover. Light surfaces, such as deserts or snow typically reflect more solar energy. Instead of measuring the “greenness” of vegetation, such as NDVI, MODIS BRDF and Albedo measure the reflection of solar energy and provide scientists with an understanding of vegetation structure, which may be more relatable to non-green areas, such as deserts in Australia. Images below show a portion of southeastern Australia, comparing the daily composite Terra and Aqua Combined MODIS 500 meter resolution BRDF Measurements data (MCD43A1) (left) to the 16-day composite Terra MODIS 500 meter resolution NDVI data (MOD13A1) (right). These images allow users to better understand the topography and vegetation cover of the area, in efforts to predict and to prevent wind erosion events in the future.

Working with Daily NASA VIIRS Surface Reflectance Data

10.5067/VIIRS/VNP13A1.001
VIIRS/NPP Vegetation Indices 16-Day L3 Global 500 m SIN Grid
VNP13A1

The Suomi National Polar-Orbiting Partnership (S-NPP) NASA Visible Infrared Imaging Radiometer Suite (VIIRS) Vegetation Indices (VNP13A1) Version 1 data product provides vegetation indices by a process of selecting the best available pixel over a 16-day acquisition period at 500 meter (m) resolution. The VNP13 data products are designed after the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua Vegetation Indices product suite to promote the continuity of the Earth Observation System (EOS) mission.

The VNP13 algorithm process produces three vegetation indices: (1) Normalized Difference Vegetation Index (NDVI), (2) the Enhanced Vegetation Index (EVI), and (3) Enhanced Vegetation Index-2 (EVI2). (1) NDVI is one of the longest continual remotely sensed time series observations, using both the red and near-infrared (NIR) bands. (2) EVI is a slightly different vegetation index that is more sensitive to canopy cover, while NDVI is more sensitive to chlorophyll. (3) EVI2 is a reformation of the standard 3-band EVI, using the red band and NIR band. This reformation addresses arising issues when comparing VIIRS EVI to other EVI models that do not include a blue band. EVI2 will eventually become the standard EVI.

Along with the three Vegetation Indices layers, this product also includes layers for near-infrared (NIR) reflectance; three shortwave infrared (SWIR) reflectance—red, blue, and green reflectance; composite day of year; pixel reliability; view and sun angles, and a quality layer. Two low resolution browse images are also available for each VNP13A1 product: (1) EVI and (2) NDVI.

The VIIRS vegetation index product suite has reached maturity level of stage 1 validation. Visit VIIRS Land Product Quality Assessment product maturity for additional information on validation and product maturity status.

Collection

Characteristic Description
Temporal Granularity Multi-Day
Temporal Extent 2012-01-17 - Present
Spatial Extent Global
File Size ~100 MB
Coordinate System Sinusoidal
Datum N/A
File Format HDF-EOS5
Geographic Dimensions 1200 km x 1200 km

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 16
Columns/Rows 2400/2400
Pixel Size 500 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
500 m 16 days EVI

3 band Enhanced Vegetation Index

EVI 16-bit signed integer

-15000 to -13000²

N/A

-10000 to 10000

10000
500 m 16 days EVI2

2 band Enhanced Vegetation Index

EVI 16-bit signed integer

-15000 to -13000²

N/A

-10000 to 10000

10000
500 m 16 days NDVI

Normalized Difference Vegetation Index 

NDVI 16-bit signed integer

-15000 to -13000²

N/A

-10000 to 10000

10000
500 m 16 days NIR reflectance

Near-infrared Radiation reflectance (846–885 nm)

N/A 16-bit signed integer

-1000

N/A

0 to 10000

10000
500 m 16 days SWIR1 reflectance

Shortwave Infrared Radiation reflectance (1230–1250 nm)

N/A 16-bit signed integer

-1000

N/A

0 to 10000

10000
500 m 16 days SWIR2 reflectance

Shortwave Infrared Radiation reflectance (1580–1640 nm)

N/A 16-bit signed integer

-1000

N/A

0 to 10000

10000
500 m 16 days SWIR3 reflectance

Shortwave Infrared Radiation reflectance (2225–2275 nm)

N/A 16-bit signed integer

-1000

N/A

0 to 10000

10000
500 m 16 days VI Quality

Bit field that assigns each pixel a Quality Assessment (QA) attribute 

N/A 16-bit unsigned integer

65535

N/A

0 to 65534

N/A
500 m 16 days blue reflectance

Blue band reflectance (478–498 nm)

N/A 16-bit signed integer

-1000

N/A

0 to 10000

10000
500 m 16 days composite day of the year

Day of year for the pixel

Julian day 16-bit signed integer

-1

N/A

1 to 366

N/A
500 m 16 days green reflectance

Green band reflectance (545–565 nm)

N/A 16-bit signed integer

-1000

N/A

0 to 10000

10000
500 m 16 days pixel reliability

Pixel usefulness using a simple rank class

Rank 8-bit signed integer

-4 to -1³

N/A

0 to 11

N/A
500 m 16 days red reflectance

Red band reflectance (600–680 nm)

N/A 16-bit signed integer

-1000

N/A

0 to 10000

10000
500 m 16 days relative azimuth angle

Relative azimuth angle for each pixel

Degree 16-bit signed integer

-20000

N/A

-18000 to 18000

100
500 m 16 days sun zenith angle

Sun zenith angle for each pixel

Degree 16-bit signed integer

-20000

N/A

0 to 18000

100
500 m 16 days view zenith angle

View zenith angle for each pixel

Degree 16-bit signed integer

-20000

N/A

0 to 18000

100

 

¹All scale factors are to be divided.

²Fill Values for the Vegetation Index Layers

Fill Value Description
-15000 over ocean/water
-13000 over land

³Fill Values for the Pixel Reliability Layer

Fill Value Description
-4 over ocean/water
-1 over land

 

Product Quality

Product Quality information can be found in the combined User Guide and Algorithm Theoretical Basis Document (ATBD). For the “500 m 16 days pixel reliability” SDS Layer, a rank quality table for each pixel can be found in Table 5 on page 35. For the “500 m 16 days VI Quality” SDS Layer, for use with all VI’s, a bit field Quality Assurance table can be found in Table 13 on pages 43-44, with additional information available in Table 14 on page 44.

For complete information about product quality, refer to the VIIRS Land Product Quality Assessment website.

 

Known Issues

Known issues for VNP13A1 are available on the VIIRS Land Product Quality Assessment website.

PI Name: 
Kamel Didan
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MOD09CMG.006
MODIS/Terra Surface Reflectance Daily L3 Global 0.05 Deg CMG
MOD09CMG

The MOD09CMG Version 6 product provides an estimate of the surface spectral reflectance of Terra MODIS Bands 1 through 7 resampled to 5600 m pixel resolution and corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Along with MODIS bands 1 through 7 are 18 additional 5600 m resolution layers including thermal bands 20, 21, 31, and 32 in Brightness Temperature and the QA and observation bands. This product is based on a Climate Modeling Grid (CMG) for use in climate simulation models.

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Daily
Temporal Extent 2000-02-24 to Present
Spatial Extent Global
File Size 515 MB
Coordinate System Geographic Latitude and Longitude
Datum N/A
File Format HDF
Geographic Dimensions Global

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 25
Columns/Rows 7200 x 3600
Pixel Size 5600 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
Coarse Resolution Surface Reflectance Band 1

Surface Reflectance Band 1 (620-670 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 2

Surface Reflectance Band 2 (841-876 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 3

Surface Reflectance Band 3 (459-479 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 4

Surface Reflectance Band 4 (545-565 nm) 

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 5

Surface Reflectance Band 5 (1230-1250 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 6

Surface Reflectance Band 6 (1628-1652 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 7

Surface Reflectance Band 7 (2105-2155 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Solar Zenith Angle

Solar Zenith Angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
Coarse Resolution View Zenith Angle

View Zenith Angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
Coarse Resolution Relative Azimuth Angle

Relative Azimuth Angle

Degree 16-bit signed integer

0

N/A

-18000 to 18000

0.01
Coarse Resolution Ozone

Ozone Resolution

cm atm 8-bit unsigned integer

0

N/A

0 to 255

0.0025
Coarse Resolution Brightness Temperature Band 20

Band 20 Brightness Temperature (3.360-3.840 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Brightness Temperature Band 21

Band 21Brightness Temperature (3.929-3.989 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Brightness Temperature Band 31

Band 31 Brightness Temperature (10.780-11.280 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Brightness Temperature Band 32

Band 32 Brightness Temperature (11.770-12.270 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Granule Time

Granule time of day

Hours 16-bit signed integer

0

N/A

0 to 2355

N/A
Coarse Resolution Band 3 Path Radiance

Band 3 Radiance

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution QA

Quality Assurance

Bit Field 32-bit unsigned integer

0

N/A

0 to 1073741824

N/A
Coarse Resolution Internal CM

Internal Cloud Mask

Bit Field 16-bit unsigned integer

0

N/A

0 to 8191

N/A
Coarse Resolution State QA

State Quality Assurance

Bit Field 16-bit unsigned integer

0

N/A

0 to 65535

N/A
Coarse Resolution Number Mapping

Number Mapping Cloud/Snow

Bit Field 32-bit unsigned integer

0

N/A

0 to 2097151

N/A
number of 500m pixels averaged b3-7

Number of 500m pixels used in average

N/A 16-bit unsigned integer

0

N/A

0 to 200

N/A
number of 500m rej. detector

Number of 500m pixels rejected for use

N/A 8-bit unsigned integer

0

N/A

0 to 100

N/A
number of 250m pixels averaged b1-2

Number of 250m pixels used in b1-2 average

N/A 16-bit unsigned integer

0

N/A

0 to 640

N/A
n pixels averaged

Number of pixels used in average

N/A 8-bit unsigned integer

0

N/A

0 to 40

N/A

 

Product Quality

The Coarse Resolution QA, Internal CM, State QA, and Number Mapping layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret these layers.

The bit flags for the Coarse Resolution QA, Internal CM, State QA, and Number Mapping layers are given in the User Guide in Tables 10, 13, 14, and 15.

 

Known Issues

Striping due to a dead detector is noticeable for bands 5, 6, and 7 in scenes acquired February 24 through October 31, 2000. Corrections were implemented to reduce the striping in data acquired after November 1, 2000. Users should always check the band quality for dead detectors even though reflectance values may be in the valid range. For complete information about the MOD09CMG known issues please refer to the MODIS Land Quality Assessment website.

MOD09CMG V006 image

Subset of MOD09CMG. Acquired November 7, 2004. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MOD09A1.006
MODIS/Terra Surface Reflectance 8-Day L3 Global 500 m SIN Grid
MOD09A1

The MODIS Terra MOD09A1 Version 6 product provides an estimate of the surface spectral reflectance of Terra MODIS Bands 1 through 7 corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Along with the seven 500 m reflectance bands is a quality layer and four observation bands. For each pixel, a value is selected from all the acquisitions within the 8-day composite period. The criteria for the pixel choice include cloud and solar zenith. When several acquisitions meet the criteria the pixel with the minimum channel 3 (blue) value is used.

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Multi-Day
Temporal Extent 2000-02-24 to Present
Spatial Extent Global
File Size 59 MB
Coordinate System Sinusoidal
Datum N/A
File Format HDF
Geographic Dimensions 1200 km x 1200 km

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 13
Columns/Rows 2400 x 2400
Pixel Size 500 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
sur_refl_b01

Surface Reflectance Band 1 (620-670 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b02

Surface Reflectance Band 2 (841-876 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b03

Surface Reflectance Band 3 (459-479 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b04

Surface Reflectance Band 4 (545-565 nm) 

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b05

Surface Reflectance Band 5 (1230-1250 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b06

Surface Reflectance Band 6 (1628-1652 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b07

Surface Reflectance Band 7 (2105-2155 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_qc_500m

Surface reflectance 500m band quality control flags

Bit Field 32-bit unsigned integer

4294967295

N/A

0 to 4294966531

N/A
sur_refl_szen

MODIS solar zenith angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
sur_refl_vzen

MODIS view zenith angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
sur_refl_raz

MODIS relative azimuth angle

Degree 16-bit signed integer

0

N/A

-18000 to 18000

0.01
sur_refl_state_500m

Surface reflectance 500m state flags

Bit Field 16-bit unsigned integer

65535

N/A

0 to 57343

N/A
sur_refl_day_of_year

Day of the year for the pixel

Julian day 16-bit unsigned integer

65535

N/A

1 to 366

N/A

 

Product Quality

The sur_refl_qc_500m and sur_refl_state_500m layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret these layers.

In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the QC layers.

The quality bit flags for sur_refl_qc_500m and the sur_refl_state_500m are given in the User Guide in Tables 10 and 13.

 

Known Issues

Striping due to a dead detector is noticeable for bands 5, 6, and 7 in scenes acquired February 24 through October 31, 2000. Corrections were implemented to reduce the striping in data acquired after November 1, 2000. Users should always check the band quality for dead detectors even though reflectance values may be in the valid range. For complete information about the MOD09A1 known issues please refer to the  MODIS Land Quality Assessment website

MOD09A1 V006 image

MOD09A1. Acquired October 15, 2004. Tile H11V05. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MYD09A1.006
MODIS/Aqua Surface Reflectance 8-Day L3 Global 500 m SIN Grid
MYD09A1

The MODIS Aqua MYD09A1 Version 6 product provides an estimate of the surface spectral reflectance of Aqua MODIS Bands 1 through 7 corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Along with the seven 500m reflectance bands is a quality layer and four observation bands. For each pixel, a value is selected from all the acquisitions within the 8-day composite period. The criteria for the pixel choice include cloud and solar zenith. When several acquisitions meet the criteria the pixel with the minimum channel 3 (blue) value is used.

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Multi-Day
Temporal Extent 2002-07-04 to Present
Spatial Extent Global
File Size 59 MB
Coordinate System Sinusoidal
Datum N/A
File Format HDF
Geographic Dimensions 1200 km x 1200 km

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 13
Columns/Rows 2400 x 2400
Pixel Size 500 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
sur_refl_b01

Surface Reflectance Band 1 (620-670 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b02

Surface Reflectance Band 2 (841-876 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b03

Surface Reflectance Band 3 (459-479 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b04

Surface Reflectance Band 4 (545-565 nm) 

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b05

Surface Reflectance Band 5 (1230-1250 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b06

Surface Reflectance Band 6 (1628-1652 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b07

Surface Reflectance Band 7 (2105-2155 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_qc_500m

Surface reflectance 500m band quality control flags

Bit Field 32-bit unsigned integer

4294967295

N/A

0 to 4294966531

N/A
sur_refl_szen

MODIS solar zenith angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
sur_refl_vzen

MODIS view zenith angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
sur_refl_raz

MODIS relative azimuth angle

Degree 16-bit signed integer

0

N/A

-18000 to 18000

0.01
sur_refl_state_500m

Surface reflectance 500m state flags

Bit Field 16-bit unsigned integer

65535

N/A

0 to 57343

N/A
sur_refl_day_of_year

Day of the year for the pixel

Julian day 16-bit unsigned integer

65535

N/A

1 to 366

N/A

 

Product Quality

The sur_refl_qc_500m and sur_refl_state_500m layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret these layers.

In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the QC layers.

The quality bit flags for sur_refl_qc_500m and the sur_refl_state_500m are given in the User Guide in Tables 10 and 13.

 

Known Issues

For complete information about the MYD09A1 known issues please refer to the MODIS Land Quality Assessment website.

MYD09A1 V006 image

MOD09Q1. Acquired October 15, 2004. Tile H11V05. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MYD09Q1.006
MODIS/Aqua Surface Reflectance 8-Day L3 Global 250 m SIN Grid
MYD09Q1

The MYD09Q1 Version 6 product provides an estimate of the surface spectral reflectance of Aqua MODIS Bands 1 and 2 corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Provided along with the two 250 m MODIS bands is one additional layer, the Surface Reflectance QC 250 m band. For each pixel, a value is selected from all the acquisitions within the 8-day composite period. The criteria for the pixel choice include cloud and solar zenith. When several acquisitions meet the criteria the pixel with the minimum channel 3 (blue) value is used.

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Multi-Day
Temporal Extent 2002-07-04 to Present
Spatial Extent Global
File Size 56 MB
Coordinate System Sinusoidal
Datum N/A
File Format HDF
Geographic Dimensions 1200 km x 1200 km

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 4
Columns/Rows 4800 x 4800
Pixel Size 250 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
sur_refl_b01

Surface Reflectance Band 1

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b02

Surface Reflectance Band 2

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_state_250m

Surface Reflectance 250m State flags

Bit Field 16-bit unsigned integer

65535

N/A

0 to 57343

N/A
sur_refl_qc_250m

Surface Reflectance 250m Band Quality Control flags

Bit Field 16-bit unsigned integer

65535

N/A

0 to 32767

N/A

 

 

Product Quality

The sur_refl_state_250m and sur_refl_qc_250m layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the QC layers.

In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the QC layer.

The QA bit flags for the sur_refl_state_250m and sur_refl_qc_250m layers are given in the User Guide in Tables 13 and 9 respectively.

 

Known Issues

For complete information about the MYD09Q1 known issues please refer to the MODIS Land Quality Assessment website.

MYD09Q1 V006 image

MYD09Q1. Acquired December 2, 2004. Tile H11V05. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MYD09GQ.006
MODIS/Aqua Surface Reflectance Daily L2G Global 250 m SIN Grid
MYD09GQ

The MYD09GQ Version 6 product provides an estimate of the surface spectral reflectance of Aqua MODIS 250 m bands 1 and 2 corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Along with the 250 m bands are the QC 250 m layer and five observation layers. This product is intended to be used in conjunction with the quality and viewing geometry information of the 500 m product (MYD09GA).

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Daily
Temporal Extent 2002-07-04 to Present
Spatial Extent Global
File Size 84 MB
Coordinate System Sinusoidal
Datum N/A
File Format HDF
Geographic Dimensions 1200 km x 1200 km

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 8 minimum1
Columns/Rows 4800 x 4800
Pixel Size 250 m

¹If the "L2G Storage Format" metadata value is "full" additional data layers are present with the suffix _f. If the "L2GStorageFormat" metadata value is "compact" additional data layers are present with the suffix _c.

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
num_observations

Number of observations per 250m pixel

N/A 8-bit signed integer

-1

N/A

0 to 127

N/A
sur_refl_b01_1

Surface Reflectance Band 1

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b02_1

Surface Reflectance Band 2

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
QC_250m_1

Surface Reflectance 250m Quality Assurance

Bit Field 16-bit unsigned integer

2995

N/A

0 to 4096

N/A
obscov_1

Observation coverage

Percent 8-bit signed integer

-1

N/A

0 to 100

0.01
iobs_res_1

Observation number

N/A 8-bit unsigned integer

255

N/A

0 to 254

N/A
orbit_pnt_1

Orbit pointer

N/A 8-bit signed integer

-1

N/A

0 to 15

N/A
granule_pnt _1

Granule pointer

N/A 8-bit unsigned integer

255

N/A

0 to 254

N/A

 

Product Quality

The QC_250m_1 layer is stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret this layer.

In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the QC layers.

The QA bit flags for the QC_250m_1 layer is given in Table 8 of the User Guide on page 19.

 

Known Issues

For complete information about the MYD09GQ known issues please refer to the MODIS Land Quality Assessment website.

MYD09GQ V006 image

MYD09GQ. Acquired December 3, 2004. Tile H11V05. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MYD09GA.006
MODIS/Aqua Surface Reflectance Daily L2G Global 1 km and 500 m SIN Grid
MYD09GA

The MYD09GA Version 6 product provides an estimate of the surface spectral reflectance of Aqua MODIS Bands 1 through 7 corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Provided along with the 500 m reflectance and four observation bands are a set of nine 1 km observation bands. The reflectance layers from the MYD09GA are used as the source data for many of the MODIS land products.

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Daily
Temporal Extent 2002-07-04 to Present
Spatial Extent Global
File Size 84 MB
Coordinate System Sinusoidal
Datum N/A
File Format HDF
Geographic Dimensions 1200 km x 1200 km

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 22
Columns/Rows 1000 m: 1200 x 1200, 500 m: 2400 x 2400
Pixel Size 1000 m and 500 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
num_observations_1km

Number of observations within a  pixel

N/A 8-bit signed integer

-1

N/A

0 to 127

N/A
state_1km_1

1km Reflectance Data State QA

Bit Field 16-bit unsigned integer

65535

N/A

0 to 57335

N/A
SensorZenith_1

Zenith angle to sensor

Degree 16-bit signed integer

-32767

N/A

0 to 18000

0.01
SensorAzimuth_1

Azimuth angle to sensor

Degree 16-bit signed integer

-32767

N/A

-18000 to 18000

0.01
Range_1

Distance to sensor

Meters 16-bit unsigned integer

0

N/A

27000 to 65535

25
SolarZenith_1

Zenith angle to sun

Degree 16-bit signed integer

-32767

N/A

0 to 18000

0.01
SolarAzimuth_1

Azimuth angle to sun

Degree 16-bit signed integer

-32767

N/A

-18000 to 18000

0.01
gflags_1

Geolocation flags

Bit Field 8-bit unsigned integer

255

N/A

0 to 248

N/A
orbit_pnt_1

Orbit pointer

N/A 8-bit signed integer

-1

N/A

0 to 15

N/A
granule_pnt _1

Granule pointer

N/A 8-bit unsigned integer

255

N/A

0 to 254

N/A
num_observations_500m

Number of observations per 500m pixel

N/A 8-bit signed integer

-1

N/A

0 to 127

N/A
sur_refl_b01_1¹

Surface Reflectance Band 1

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b02_1¹

Surface Reflectance Band 2

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b03_1

Surface Reflectance Band 3

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b04_1

Surface Reflectance Band 4

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b05_1

Surface Reflectance Band 5

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b06_1

Surface Reflectance Band 6

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b07_1

Surface Reflectance Band 7

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
QC_500m_1

Surface Reflectance 500m Quality Assurance

Bit Field 32-bit unsigned integer

787410671

N/A

0 to 4294966019

N/A
obscov_500m_1

Observation coverage

Percent 8-bit signed integer

-1

N/A

0 to 100

0.01
iobs_res_1

Observation number

N/A 8-bit unsigned integer

255

N/A

0 to 254

N/A
q_scan_1²

250m scan value information

N/A 8-bit unsigned integer

255

N/A

0 to 254

N/A

¹Data layers sur_refl_b01_1 and sur_refl_b02_1 may not always be present.

²Description information for the q_scan_1 layer is given in Table 17 of the User Guide. Please note this layer may not be present in all products.

 

Product Quality

The state_1km_1 and QC_500m_1 layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE tools is available to the user community to help parse and interpret these layers.

In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the QC layers.

The QA bit flags for the state_1km_1 and the QC_500m_1 layers are given in the User Guide in table 13 and 10 respectively.

 

Known Issues

For complete information about the MYD09GA known issues please refer to the MODIS Land Quality Assessment website.

MYD09GA V006 image

MYD09GA. Acquired December 3, 2004. Tile H11V05. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MYD09CMG.006
MODIS/Aqua Surface Reflectance Daily L3 Global 0.05 Deg CMG
MYD09CMG

The MYD09CMG Version 6 product provides an estimate of the surface spectral reflectance of Aqua MODIS Bands 1 through 7 resampled to 5600 m pixel resolution and corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Along with MODIS bands 1 through 7 are 18 additional 5600 m resolution layers including thermal bands 20, 21, 31, and 32 in Brightness Temperature and the QA and observation bands. This product is based on a Climate Modeling Grid (CMG) for use in climate simulation models.

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Daily
Temporal Extent 2002-07-04 to Present
Spatial Extent Global
File Size 515 MB
Coordinate System Geographic Latitude and Longitude
Datum N/A
File Format HDF
Geographic Dimensions Global

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 25
Columns/Rows 7200 x 3600
Pixel Size 5600 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
Coarse Resolution Surface Reflectance Band 1

Surface Reflectance Band 1 (620-670 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 2

Surface Reflectance Band 2 (841-876 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 3

Surface Reflectance Band 3 (459-479 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 4

Surface Reflectance Band 4 (545-565 nm) 

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 5

Surface Reflectance Band 5 (1230-1250 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 6

Surface Reflectance Band 6 (1628-1652 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Surface Reflectance Band 7

Surface Reflectance Band 7 (2105-2155 nm)

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution Solar Zenith Angle

Solar Zenith Angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
Coarse Resolution View Zenith Angle

View Zenith Angle

Degree 16-bit signed integer

0

N/A

0 to 18000

0.01
Coarse Resolution Relative Azimuth Angle

Relative Azimuth Angle

Degree 16-bit signed integer

0

N/A

-18000 to 18000

0.01
Coarse Resolution Ozone

Ozone Resolution

cm atm 8-bit unsigned integer

0

N/A

0 to 255

0.0025
Coarse Resolution Brightness Temperature Band 20

Band 20 Brightness Temperature (3.360-3.840 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Brightness Temperature Band 21

Band 21Brightness Temperature (3.929-3.989 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Brightness Temperature Band 31

Band 31 Brightness Temperature (10.780-11.280 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Brightness Temperature Band 32

Band 32 Brightness Temperature (11.770-12.270 μm)

Kelvin 16-bit unsigned integer

0

N/A

0 to 40000

0.01
Coarse Resolution Granule Time

Granule time of day

Hours 16-bit signed integer

0

N/A

0 to 2355

N/A
Coarse Resolution Band 3 Path Radiance

Band 3 Radiance

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
Coarse Resolution QA

Quality Assurance

Bit Field 32-bit unsigned integer

0

N/A

0 to 1073741824

N/A
Coarse Resolution Internal CM

Internal Cloud Mask

Bit Field 16-bit unsigned integer

0

N/A

0 to 8191

N/A
Coarse Resolution State QA

State Quality Assurance

Bit Field 16-bit unsigned integer

0

N/A

0 to 65535

N/A
Coarse Resolution Number Mapping

Number Mapping Cloud/Snow

Bit Field 32-bit unsigned integer

0

N/A

0 to 2097151

N/A
number of 500m pixels averaged b3-7

Number of 500m pixels used in average

N/A 16-bit unsigned integer

0

N/A

0 to 200

N/A
number of 500m rej. detector

Number of 500m pixels rejected for use

N/A 8-bit unsigned integer

0

N/A

0 to 100

N/A
number of 250m pixels averaged b1-2

Number of 250m pixels used in b1-2 average

N/A 16-bit unsigned integer

0

N/A

0 to 640

N/A
n pixels averaged

Number of pixels used in average

N/A 8-bit unsigned integer

0

N/A

0 to 40

N/A

 

 

Product Quality

The Coarse Resolution QA, Internal CM, State QA, and Number Mapping layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret these layers.

The bit flags for the Coarse Resolution QA, Internal CM, State QA, and Number Mapping layers are given in the User Guide in Tables 10, 13, 14, and 15.

 

Known Issues

For complete information about the MYD09CMG known issues please refer to the MODIS Land Quality Assessment website.

MYD09CMG V006 image

Subset of MYD09CMG. Acquired November 4, 2007. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False
10.5067/MODIS/MOD09Q1.006
MODIS/Terra Surface Reflectance 8-Day L3 Global 250 m SIN Grid
MOD09Q1

The MOD09Q1 Version 6 product provides an estimate of the surface spectral reflectance of Terra MODIS Bands 1 and 2 corrected for atmospheric conditions such as gasses, aerosols, and Rayleigh scattering. Provided along with the two 250 m MODIS bands is one additional layer, the Surface Reflectance QC 250 m band. For each pixel, a value is selected from all the acquisitions within the 8-day composite period. The criteria for the pixel choice include cloud and solar zenith. When several acquisitions meet the criteria the pixel with the minimum channel 3 (blue) value is used.

Validation at stage 3 has been achieved for all MODIS Surface Reflectance products.

Improvements/Changes from Previous Versions

  • Improvements to the aerosol retrieval and correction algorithm, and use of new aerosol retrieval look-up tables.
  • Refinements to the internal snow, cloud, and cloud shadow detection algorithms. Uses BRDF database to better constraint the different threshold used.
  • Processes ocean bands to create a new Surface Reflectance Ocean product and provide QA data sets for these bands.
  • Improved discrimination of salt pans from cloud and snow, and flag salt pans in QA band.

Collection

Characteristic Description
Temporal Granularity Multi-Day
Temporal Extent 2000-02-24 to Present
Spatial Extent Global
File Size 56 MB
Coordinate System Sinusoidal
Datum N/A
File Format HDF
Geographic Dimensions 1200 km x 1200 km

 

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers 4
Columns/Rows 4800 x 4800
Pixel Size 250 m

 

Data Layer Characteristics

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
sur_refl_b01

Surface Reflectance Band 1

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_b02

Surface Reflectance Band 2

N/A 16-bit signed integer

-28672

N/A

-100 to 16000

0.0001
sur_refl_state_250m

Surface Reflectance 250m State flags

Bit Field 16-bit unsigned integer

65535

N/A

0 to 57343

N/A
sur_refl_qc_250m

Surface Reflectance 250m Band Quality Control flags

Bit Field 16-bit unsigned integer

65535

N/A

0 to 32767

N/A

 

Product Quality

The sur_refl_state_250m and sur_refl_qc_250m layers are stored in an efficient bit-encoded manner. The unpack_sds_bits executable from the LDOPE Tools is available to the user community to help parse and interpret the QC layers.

In addition to data access and transformation processes, AppEEARS also has the capability to unpack and interpret the QC layer.

The QA bit flags for the sur_refl_state_250m and sur_refl_qc_250m layers are given in the User Guide in Tables 13 and 9 respectively.

 

Known Issues

Striping due to a dead detector is noticeable for bands 5, 6, and 7 in scenes acquired February 24 through October 31, 2000. Corrections were implemented to reduce the striping in data acquired after November 1, 2000. Users should always check the band quality for dead detectors even though reflectance values may be in the valid range. For complete information about the MOD09Q1 known issues please refer to the MODIS Land Quality Assessment website.

MOD09Q1 V006 image

MOD09Q1. Acquired October 15, 2004. Tile H11V05. Southeast US.

PI Name: 
Eric Vermote
Other Tools: 
Decommissioned: 
False

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