GWELDMO v031

NASA Global Web-Enabled Landsat Data Monthly Global 30 m


PI: Hankui Zhang, David Roy

Description

The NASA Making Earth System Data Records for Use in Research Environments (MEaSUREs) Global Web-Enabled Landsat Data Monthly (GWELDMO) Version 3.1 data product provides Landsat data at 30 meter (m) resolution for terrestrial non-Antarctica locations over monthly reporting periods. GWELD data products are generated from all available Landsat 4 and 5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data in the U.S. Geological Survey (USGS) Landsat archive. The GWELD suite of products provide consistent data to derive land cover as well as geophysical and biophysical information for regional assessment of land surface dynamics.

The GWELD products include Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) for the reflective wavelength bands and to top of atmosphere (TOA) brightness temperature for the thermal bands. The products are defined in the Sinusoidal coordinate system to promote continuity of NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) land tile grid.

Provided in the GWELDMO product are layers for surface reflectance bands 1 through 5 and 7, TOA brightness temperature for thermal bands, Normalized Difference Vegetation Index (NDVI), day of year, ancillary angle, and data quality information. A low-resolution red, green, blue (RGB) browse image of bands 5, 4, 3 is also available for each granule.

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Characteristics

Improvements/Changes from Previous Versions

Version 3.1 products use Landsat Collection 1 products as input and have improved per-pixel cloud mask, new quality data, improved calibration information, and improved product metadata that enable view and solar geometry calculations.

Collection and Granule

Collection

Characteristic Description
CollectionMEaSUREs WELD and GWELD
DOI10.5067/MEaSUREs/GWELD/GWELDMO.031
File Size~280 MB
Temporal ResolutionMonthly
Temporal Extent1989-01-01 to 2001-12-31
Spatial ExtentGlobal (Non-Antarctic)
Coordinate SystemSinusoidal
DatumWorld Geodetic System (WGS84)
File FormatHDF-EOS
Geographic Dimensions150 km x 150 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers24
Columns/Rows5295 x 5295
Pixel Size30 m

Layers

SDS Name Description Units Data Type Fill Value No Data Value Valid Range Scale Factor
Band1_SRF_REF Band 1 Surface Reflectance N/A 16-bit signed integer -32768 N/A -2000 to 16000 0.0001
Band2_SRF_REF Band 2 Surface Reflectance N/A 16-bit signed integer -32768 N/A -2000 to 16000 0.0001
Band3_SRF_REF Band 3 Surface Reflectance N/A 16-bit signed integer -32768 N/A -2000 to 16000 0.0001
Band4_SRF_REF Band 4 Surface Reflectance N/A 16-bit signed integer -32768 N/A -2000 to 16000 0.0001
Band5_SRF_REF Band 5 Surface Reflectance N/A 16-bit signed integer -32768 N/A -2000 to 16000 0.0001
Band61_TOA_BT Band 6 Top of Atmosphere and Brightness Temperature resampled to 30 m; low gain °C 16-bit signed integer -32768 N/A -32767 to 32767 0.01
Band62_TOA_BT Band 6 Top of Atmosphere and Brightness Temperature resampled to 30 m; high gain °C 16-bit signed integer -32768 N/A -32767 to 32767 0.01
Band7_SRF_REF Band 7 Surface Reflectance N/A 16-bit signed integer -32768 N/A -2000 to 16000 0.0001
NDVI_SRF Normalized Difference Vegetation Index (NDVI) value N/A 16-bit signed integer -32768 N/A -10000 to 10000 0.0001
Day_Of_Year Day of year the selected Landsat pixel was acquired Day 16-bit signed integer 0 N/A 1 to 366 N/A
Saturation_Flag The least significant bit to the most significant bit corresponds to bands 1, 2, 3, 4, 5, 61, 62, 7; with a bit set to 1 signifying saturation in that band and 0 not saturated Bit Field 8-bit unsigned integer N/A N/A 0 to 255 N/A
DT_Cloud_State Decision Tree Cloud Classification Class 8-bit unsigned integer 255 N/A 0 to 2, 200 N/A
ACCA_State Automatic Cloud Cover Assessment Algorithm (ACCA) Classification Class 8-bit unsigned integer 255 N/A 0, 1 N/A
Num_Of_Obs Number of observations considered over the composition period Number 16-bit unsigned integer N/A N/A 0 to 65534 N/A
Composite_Path Internal compositing algorithm pathway code N/A 8-bit unsigned integer N/A N/A 0 to 15 N/A
Sensor Landsat satellite that the pixel was selected from (4=Landsat 4 TM, 5=Landsat 5 TM, 7 = Landsat 7 ETM+) N/A 8-bit unsigned integer 255 N/A 0 to 254 N/A
Sensor_Zenith Sensor zenith (nadir = 0 degrees) Degree 16-bit signed integer -32768 N/A 0 to 9000 0.01
Sensor_Azimuth Sensor azimuth Degree 16-bit signed integer -32768 N/A -18000 to 18000 0.01
Solar_Zenith Solar zenith of pixel observation (directly overhead = 0 degrees) Degree 16-bit signed integer -32768 N/A 0 to 9000 0.01
Solar_Azimuth Sensor azimuth Degree 16-bit signed integer -32768 N/A -18000 to 18000 0.01
NBAR_Solar_Zenith Solar zenith used for NBAR generation of pixel surface reflectance value Degree 16-bit signed integer -32768 N/A 0 to 9000 0.01
L1T_Index Index to the L1T image that the pixel was selected from N/A 16-bit unsigned integer 65535 N/A 0 to 65534 N/A
L1T_Column Pixel column number in the input Level 1T image N/A 16-bit unsigned integer 65535 N/A 0 to 10000 N/A
L1T_Row Pixel row number in the input Level 1T image N/A 16-bit unsigned integer 65535 N/A 0 to 10000 N/A

Cloud State Classes

Class Description
0 Not cloudy
1 Cloudy
2 Not cloudy but adjacent to a cloudy pixel
200 Could not be classified reliably

Automatic Cloud Cover Assessment (ACCA) Classes

Class Description
0 Not cloudy
1 Cloudy

Product Quality

GWELD Version 3.1 product quality information can be found on the GWELD Project website.

Known Issues

GWELDMO known issues can be found in Section 4 of the Algorithm Theoretical Basis Document (ATBD).

Documentation

Using the Data

Access Data

Citation

DOI: 10.5067/MEaSUREs/GWELD/GWELDMO.031

About the Image

NASA Global Web-Enabled Landsat monthly surface reflectance band 5-4-3 data from the GWELDMO031 product over Citrus County, Florida, acquired November 2011.

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