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About the WELD Project

- Overview

Since January 2008, the U.S. Geological Survey has been providing free terrain-corrected and radiometrically calibrated Landsat data via the Internet. This provides the opportunity to use all the data in the U.S. Landsat archive and to consider the systematic utility of Landsat data for long-term large-area monitoring. Building on the success of the CONUS and Alaska WELD products (http://weld.cr.usgs.gov/) the WELD processing is being expanded to global scale to provide monthly and annual Landsat 30m information for any terrestrial non-Antarctic location for six 3-year epochs spaced every 5 years from 1985 to 2010.

The WELD products are developed specifically to provide consistent data that can be used to derive land cover as well as geophysical and biophysical products for assessment of surface dynamics and to study Earth system functioning. The WELD products are free and are available via the internet. The WELD products are processed so that users do not need to apply the equations and spectral calibration coefficients and solar information to convert the Landsat digital numbers to reflectance and brightness temperature, and successive products are defined in the same coordinate system and align precisely, making them simple to use for multi-temporal applications.

The products are generated on the NASA Earth Exchange (NEX) supercomputer using all the available contemporaneous Landsat 4, 5 and 7 images that were processed to L1T in support of this project at the USGS EROS.


- Data Policy

The WELD products are freely available for educational, research, or commercial applications.  If you use the WELD products please cite them following the WELD Citation guidelines.


- Funding

The WELD project is funded by the National Aeronautics and Space Administration (NASA) Making Earth System Data Records for Use in Research Environments (MEaSUREs) program under Cooperative Agreement NNX13AJ24A. The free Landsat data access and the WELD product distribution is funded by the USGS.


- Product Years Available and Planned Availability

Monthly and annual global products for six 3-year epochs (1985, 1990, 1995, 2000, 2005, 2010) are planned. Version 3.0 and older Version 2.2 products are currently available for the 2010 epoch. The epochs will be processed in reverse chronological order (i.e. 2005, 2000, ... 1985). The products may be reprocessed as improved versions of the algorithms are developed.


- WELD Team

Principal Investigator: David Roy
Scientists (algorithms and processing): Hankui Zhang & Lin Yan
Scientists (NEX processing): Petr Votava & Rama Nemani
Scientists (land cover mapping): Matthew Hansen & Alexey Egorov
Distribution System: Adam Dosch & Lisa Johnson (EROS)


Product Documentation

- Product Types

Monthly and annual global WELD products are available. The monthly product period is defined by the days in the calendar month. The annual product period is defined as the preceding year's 1st December through the current year's 30th November. For each product period the single best Landsat observation at each pixel location is selected using a compositing algorithm.

 

The Version 3.0 products have the following improvements over the Version 2.2 products:

 

- Atmospheric correction of the reflective wavelength bands to surface reflectance using the LEDAPS code, see the following papers:

 

LEDAPS algorithm description: Masek, J.G., Vermote, E.F., Saleous, N.E., Wolfe, R., Hall, F.G., Huemmrich, K.F., Gao, F., Kutler, J., & Lim, T.-K. (2006). A Landsat surface reflectance dataset for North America, 1990-2000. IEEE Geoscience and Remote Sensing Letters, 3, 68-72.

 

LEDAPS accuracy: Ju, J., Roy, D.P.,Vermote, E., Masek, J., Kovalskyy, V., 2012, Continental-scale validation of MODIS-based and LEDAPS Landsat ETM+ atmospheric correction methods, Remote Sensing of Environment, 122, 175-“184.

 

- Normalization of the surface reflectance to nadir view (0 degree view zenith) and a modelled solar zeith angle, see the following papers:

 

Normalization algorithm description: Roy, D.P., Zhang, H. K., Ju, J., Gomez-Dans, J. L., Lewis, P.E., Schaaf C.B., Sun, Q., Li, J., Huang, H., Kovalskyy, V., A general method to normalize Landsat reflectance data to nadir BRDF adjusted reflectance, Remote Sensing of Environment, 176, 255-271.

 

Modelled solar angle description: Zhang, H. K., Roy, D.P., Kovalskyy, V., Optimal solar geometry definition for global long term Landsat time series bi-directional reflectance normalization, IEEE Transactions on Geoscience and Remote Sensing, 54(3), 1410-1418.

 

- Improved best-pixel compositing

 

New paper in preparation (improved over the algorithm described in: Roy, D.P., Ju, J., Kline, K., Scaramuzza, P.L., Kovalskyy, V., Hansen, M.C., Loveland, T.R., Vermote, E.F., Zhang, C., 2010, Web-enabled Landsat Data (WELD): Landsat ETM+ Composited Mosaics of the Conterminous United States, Remote Sensing of Environment, 114, 35-49).

 

- Product Map Projection and Tiling Scheme

The global WELD products are defined in the equal area sinusoidal projection. The sinusoidal projection parameters for the USGS General Cartographic Tansformation Package (GCTP) are:

Num Parameter Value Description
0 Sphere 6371007.181 Radius of reference (meters) sphere
1-3 0.0 not used
4 CentMer 0.0 Longitude of the central meridian
5 0.0 not used
6 FE 0.0 False Easting in the same units as the sphere radius
7 FN 0.0 False Northing in the same units as the sphere radius
8-14 0.0 not used

 

The global WELD products are defined in a non-overlapping grid of 5295 x 5295 30-m pixel tiles that are nested to the standard MODIS land product tiles. The MODIS land product tiles are defined in a global non-overlapping grid of 36 x 18 tiles each covering approximately 10º x 10º at the Equator. A table of the MODIS Land sinusoidal tile bounding coordinates is found here. There are 7 x 7 global WELD tiles falling in each MODIS land product tile. The global WELD product tile coordinates are referenced using two digit horizontal and vertical tile coordinates that are reflected in the HDF product filename.


- Version 3.0 Product Contents

Each Version 3.0 global WELD product pixel has 24 bands storing the information described below.

Band Name Data Type Valid Range Scale factor Units Fill Value Notes
Band1_SRF_REF int16 -2000 to 16000 0.0001 unitless -32768 The conventional Landsat 4/5/7 band numbering scheme is used.

 

Surface reflectance (SRF) derived using the LEDAPS atmospheric correction code and then subsequently BRDF adjusted to nadir view (0 degree view zenith) with a modelled solar zeith defined in NBAR_Solar_Zenith.

 

Top of atmosphere (TOA) brightness temperature (BT) is computed using standard formulae and calibration coefficients associated with each acquisition.

 

Band 6 brightness temperature data are defined at 30 m.

 

The Band62 pixel value is set to FILL if the pixel was from Landsat 4 or 5 as this band does not exist on the Landsat 4 and 5 TM sensors.
Band2_SRF_REF int16 -2000 to 16000 0.0001 unitless -32768
Band3_SRF_REF int16 -2000 to 16000 0.0001 unitless -32768
Band4_SRF_REF int16 -2000 to 16000 0.0001 unitless -32768
Band5_SRF_REF int16 -2000 to 16000 0.0001 unitless -32768
Band61_TOA_BT int16 -32767 to 32767 0.01 Degrees Celsius -32768
Band62_TOA_BT int16 -32767 to 32767 0.01 Degrees Celsius -32768
Band7_SRF_REF int16 -2000 to 16000 0.0001 unitless -32768
NDVI_SRF int16 -10000 to 10000 0.0001 unitless -32768 Normalized Difference Vegetation Index (NDVI) value generated from Band3_SRF_REF and Band4_SRF_REF.
Day_Of_Year int16 1 to 366 1 Day 0 Day of year the selected ETM+ pixel was sensed on. Note (a) days 1-334  (or 1-335) were sensed in January-November of the nonleap (or leap) current year; (b) days 335-365 (or 336-366) were sensed in December of the nonleap (or leap) previous year; (c) in the annual composite of a leap year, day 335 always means November 30.
Saturation_Flag uint8 0 to 255 1 unitless None 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.
DT_Cloud_State uint8 0, 1, 2, 200 1 unitless 255 Decision Tree Cloud Classification, 0 = not cloudy, 1 = cloudy, 2 = not cloudy but adjacent to a cloudy pixel, 200 = could not be classified reliably.
ACCA_State uint8 0, 1 1 unitless 255 ACCA Cloud Classification, 0 = not cloudy, 1 = cloudy.
Num_Of_Obs uint16 0 to 655535 1 unitless None Number of observations considered over the compositing period.
Composite_Path uint8 0 to 14 1 unitless 255 Internal compositing algorithm pathway code.
Sensor uint8 4, 5, or 7 1 unitless 255 Landsat satellite that the pixel was selected from (4 = Landsat 4 TM, 5 = Landsat 5 TM, 7 = Landsat 7 ETM+)
Sensor_Zenith int16 0 to 9000 0.01 Degrees -32768 Sensor_Zenith (nadir = 0 degrees).
Sensor_Azimuth int16 -18000 to 18000 0.01 Degrees -32768 Sensor_Azimuth.
Solar_Zenith int16 0 to 9000 0.01 Degrees -32768 Solar_Zenith of pixel observation (directly overhead = 0 degrees).
NBAR_Solar_Zenith int16 0 to 9000 0.01 Degrees -32768 Solar_Zenith used for NBAR generation of pixel surface refelectance value.
Solar_Azimuth int16 -18000 to 18000 0.01 Degrees -32768 Solar_Azimuth.
L1T_Index uint16 0 to 65535 1 unitless 65536 Index to the L1T image that the pixel was selected from (reference L1T_Index_Metadata to find the Level 1T filename).
L1T_Column uint16 0 to 65535 1 unitless 65536 Pixel column number in the input Level 1T image.
L1T_Row uint16 0 to 65535 1 unitless 65536 Pixel row number in the input Level 1T image.

Each Version 3.0 global WELD tile product has the following metadata that summarizes all the pixels in the tile.

Name Data Type Valid Range Units Description
PRODUCT_VERSION String N/A unitless Product version number (3.0., …) also reflected in the filename.
PGE_VERSION String N/A unitless Internal version number of Product Generation Executive used to produce particular tile, not necessarily reflected in the filename.
INPUT_POINTER String N/A unitless Internal list of input filenames used for production.
L1T_Index_Metadata String N/A unitless List of Level 1T filenames and indices (reference with L1T_Index band pixel value) and the corresponding Level 1T image MTL file specified center solar zenith and solar azimuth values.
Mean_B1 Float -0.1 to 1.0 unitless Mean band 1 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B2 Float -0.1 to 1.0 unitless Mean band 2 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B3 Float -0.1 to 1.0 unitless Mean band 3 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B4 Float -0.1 to 1.0 unitless Mean band 4 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B5 Float -0.1 to 1.0 unitless Mean band 5 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B6 Float -200 to 300 Degrees Celsius Mean band 6 brightness temperature computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile
Mean_B7 Float -0.1 to 1.0 unitless Mean band 7 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_NDVI Float -0.1 to 1.0 unitless Mean NDVI computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_Solar_Zenith Float 0 to 90 degrees Mean solar zenith angle computed from all non-fill pixels in the tile.

Mean_NBAR_Solar_Zenith

Float 0 to 90 degrees

Mean NBAR solar zenith angle computed from all non-fill pixels in the tile.

Percent_Saturated Float 0.0 to 100.0 Percentage Percentage of non-fill pixels in the tile that were flagged as saturated in any band (Saturation_Flag != 0).
Percent_ACCA_Cloudy Float 0.0 to 100.0 Percentage Percentage of non-fill pixels in the tile that were flagged as ACCA Cloudy (ACCA == 1).
Percent_DT_Cloudy Float 0.0 to 100.0 Percentage Percentage of non-fill pixels in the tile that were flagged as DT cloudy (ACCA == 1).
Mean_JDOY Int 1 to 366 Day Mean Julian Day of Year of non-fill pixels in the tile.
Min_JDOY Int 1 to 366 Day Minimum Julian Day of Year of non-fill pixels in the tile.
Max_JDOY Int 1 to 366 Day Maximum Julian Day of Year of non-fill pixels in the tile.
Number_Valid_Obs Int 0 to 28037025 Count The number of non-fill pixels in the tile.
Number_Valid_Noncloudy_Obs Int 0 to 28037025 Count The number of non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Count_L1T Int 0 to 10000 Count Count of the number of unique L1T images present in the tile.
Sensor_List String 4 | 5 or 5 | 7 Unitless List of Landsat satellites present in the tile.
Number_Valid_Sensor_Obs String 0 to 28037025 | 0 to 28037025 Count The number of non-fill pixels in the tile for each satellite indexed by Sensor_List.


- Version 2.2 Product Contents

Each Version 2.2 global WELD product pixel has 23 bands storing the information described below.

Band Name Data Type Valid Range Scale factor Units Fill Value Notes
Band1_TOA_REF int16 -32767 -- 32767 0.0001 unitless -32768 The conventional Landsat 4/5/7 band numbering scheme is used.

 

Top of atmosphere (TOA) reflectance and brightness temperature (BT) are computed using standard formulae and calibration coefficients associated with each acquisition.

 

Band 6 brightness temperature data are resampled to 30 m.

 

The Band62 pixel value is set to FILL if the pixel was from Landsat 4 or 5 as this band does not exist on the Landsat 4 and 5 TM sensors.
Band2_TOA_REF int16 -32767 -- 32767 0.0001 unitless -32768
Band3_TOA_REF int16 -32767 -- 32767 0.0001 unitless -32768
Band4_TOA_REF int16 -32767 -- 32767 0.0001 unitless -32768
Band5_TOA_REF int16 -32767 -- 32767 0.0001 unitless -32768
Band61_TOA_BT int16 -32767 -- 32767 0.01 Degrees Celsius -32768
Band62_TOA_BT int16 -32767 -- 32767 0.01 Degrees Celsius -32768
Band7_TOA_REF int16 -32767 -- 32767 0.0001 unitless -32768
NDVI_TOA int16 -10000 -- 10000 0.0001 unitless -32768 Normalized Difference Vegetation Index (NDVI) value generated from Band3_TOA_REF and Band4_TOA_REF.
Day_Of_Year int16 1 -- 366 1 Day 0 Day of year the selected ETM+ pixel was sensed on. Note (a) days 1-334  (or 1-335) were sensed in January-November of the nonleap (or leap) current year; (b) days 335-365 (or 336-366) were sensed in December of the nonleap (or leap) previous year; (c) in the annual composite of a leap year, day 335 always means November 30.
Saturation_Flag uint8 0 -- 255 1 unitless None 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.
DT_Cloud_State uint8 0, 1, 2, 200 1 unitless 255 Decision Tree Cloud Classification, 0 = not cloudy, 1 = cloudy, 2 = not cloudy but adjacent to a cloudy pixel, 200 = could not be classified reliably.
ACCA_State uint8 0, 1 1 unitless 255 ACCA Cloud Classification, 0 = not cloudy, 1 = cloudy.
Num_Of_Obs uint16 0 to 655535 1 unitless None Number of observations considered over the compositing period.
Composite_Path uint8 0 to 14 1 unitless 255 Internal compositing algorithm pathway code.
Sensor uint8 4, 5, or 7 1 unitless 255 Landsat satellite that the pixel was selected from (4 = Landsat 4 TM, 5 = Landsat 5 TM, 7 = Landsat 7 ETM+)
Sensor_Zenith int16 0 to 9000 0.01 Degrees -32768 Sensor_Zenith (nadir = 0 degrees).
Sensor_Azimuth int16 -18000 to 18000 0.01 Degrees -32768 Sensor_Azimuth.
Solar_Zenith int16 0 to 9000 0.01 Degrees -32768 Solar_Zenith (directly overhead = 0 degrees).
Solar_Azimuth int16 -18000 to 18000 0.01 Degrees -32768 Solar_Azimuth.
L1T_Index uint16 0 to 65535 1 unitless 65536 Index to the L1T image that the pixel was selected from (reference L1T_Index_Metadata to find the Level 1T filename).
L1T_Column uint16 0 to 65535 1 unitless 65536 Pixel column number in the input Level 1T image.
L1T_Row uint16 0 to 65535 1 unitless 65536 Pixel row number in the input Level 1T image.

Each Version 2.2 global WELD tile product has the following metadata that summarizes all the pixels in the tile.

Name Data Type Valid Range Units Description
PRODUCT_VERSION String N/A unitless Product version number (2.2., …) also reflected in the filename.
PGE_VERSION String N/A unitless Internal version number of Product Generation Executive used to produce particular tile, not necessarily reflected in the filename.
INPUT_POINTER String N/A unitless Internal list of input filenames used for production.
L1T_Index_Metadata String N/A unitless List of Level 1T filenames and indices (reference with L1T_Index band pixel value) and the corresponding Level 1T image MTL file specified center solar zenith and solar azimuth values.
Mean_B1 Float -0.1 to 1.0 unitless Mean band 1 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B2 Float -0.1 to 1.0 unitless Mean band 2 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B3 Float -0.1 to 1.0 unitless Mean band 3 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B4 Float -0.1 to 1.0 unitless Mean band 4 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B5 Float -0.1 to 1.0 unitless Mean band 5 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_B6 Float -200 to 300 Degrees Celsius Mean band 6 brightness temperature computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile
Mean_B7 Float -0.1 to 1.0 unitless Mean band 7 reflectance computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_NDVI Float -0.1 to 1.0 unitless Mean NDVI computed from all non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Mean_Solar_Zenith Float 0 to 90 degrees Mean solar zenith angle computed from all non-fill pixels in the tile.
Percent_Saturated Float 0.0 to 100.0 Percentage Percentage of non-fill pixels in the tile that were flagged as saturated in any band (Saturation_Flag != 0).
Percent_ACCA_Cloudy Float 0.0 to 100.0 Percentage Percentage of non-fill pixels in the tile that were flagged as ACCA Cloudy (ACCA == 1).
Percent_DT_Cloudy Float 0.0 to 100.0 Percentage Percentage of non-fill pixels in the tile that were flagged as DT cloudy (ACCA == 1).
Mean_JDOY Int 1 to 366 Day Mean Julian Day of Year of non-fill pixels in the tile.
Min_JDOY Int 1 to 366 Day Minimum Julian Day of Year of non-fill pixels in the tile.
Max_JDOY Int 1 to 366 Day Maximum Julian Day of Year of non-fill pixels in the tile.
Number_Valid_Obs Int 0 to 28037025 Count The number of non-fill pixels in the tile.
Number_Valid_Noncloudy_Obs Int 0 to 28037025 Count The number of non-fill and non-cloudy (ACCA == 0 && DT != 1) pixels in the tile.
Count_L1T Int 0 to 10000 Count Count of the number of unique L1T images present in the tile.
Sensor_List String 4 | 5 or 5 | 7 Unitless List of Landsat satellites present in the tile.
Number_Valid_Sensor_Obs String 0 to 28037025 | 0 to 28037025 Count The number of non-fill pixels in the tile for each satellite indexed by Sensor_List.


- Filename convention

The product filename is descriptive, simple, and amenable to scripting.

 

Version 3.0 HDF Product Filename Convention
L<ss>.Globe.<period>.<year>.hh<xx>vv<yy>>.h<x>v<y>.doy<min DOY>to<max DOY>.NBAR.v<version number>.hdf
  Valid Range Notes
<ss> 04 / 05 / 07 / 08 / 45 / 57 Combination of contemporaneous Landsat sensors (4, 5, 7) used in the product.
<Period> annual

 

month01/month02/, …,/month12 

 

Annual products are generated from a year of Landsat data sensed from December 1st of the previous year to November 30th of the current year. Monthly products generated from the Landsat data sensed in that month.
<Year> 1983, 1985, ... , 2011 Year the data sensed (monthly products).

 

Year the January to November data sensed (annual products).
<xx> 00, 01, ..., 35 Horizontal MODIS land tile coordinate.
<yy> 00, 01, ..., 17 Vertical MODIS land tile coordinate.
<x> 0, 1, …, 6 Horizontal WELD tile coordinate within the MODIS land tile.
<y> 0, 1, …, 6 Vertical WELD tile coordinate within the MODIS land tile.
<min DOY> 001, 002, …, 366 Minimum non-fill Day_Of_Year pixel value present in the tile.
<max DOY> 001, 002, …, 366 Maximum non-fill Day_Of_Year pixel value present in the tile.
<Version Number> 3.0, … Major and minor algorithm version changes reflected in the first and second digits respectively.

 

Version 2.2 HDF Product Filename Convention
L<ss>.Globe.<period>.<year>.hh<xx>vv<yy>>.h<x>v<y>.doy<min DOY>to<max DOY>.v<version number>.hdf
  Valid Range Notes
<ss> 04 / 05 / 07 / 08 / 45 / 57 Combination of contemporaneous Landsat sensors (4, 5, 7) used in the product.
<Period> annual

 

month01/month02/, …,/month12 

 

Annual products are generated from a year of Landsat data sensed from December 1st of the previous year to November 30th of the current year. Monthly products generated from the Landsat data sensed in that month.
<Year> 1983, 1985, ... , 2011 Year the data sensed (monthly products).

 

Year the January to November data sensed (annual products).
<xx> 00, 01, ..., 35 Horizontal MODIS land tile coordinate.
<yy> 00, 01, ..., 17 Vertical MODIS land tile coordinate.
<x> 0, 1, …, 6 Horizontal WELD tile coordinate within the MODIS land tile.
<y> 0, 1, …, 6 Vertical WELD tile coordinate within the MODIS land tile.
<min DOY> 001, 002, …, 366 Minimum non-fill Day_Of_Year pixel value present in the tile.
<max DOY> 001, 002, …, 366 Maximum non-fill Day_Of_Year pixel value present in the tile.
<Version Number> 2.2, … Major and minor algorithm version changes reflected in the first and second digits respectively.

 



Product Quality

- Known Version 2.2 Product Issues

The HDFEOS metadata ProjParam is corrupted in the 2009-2011 Version 2.2. monthly and annual products. Currently the Sinusoidal projection parameters are stored as "ProjParams=(6371007.181000,)6371007.181000,)0,0,0,0,0,0,0,0,0,0,0)" they should be stored as "ProjParams=(6371007.181000,0,0,0,0,0,0,0,0,0,0,0)". This will be fixed in the next reprocessing.


- Product Improvements on Previous Versions

There were no publicly available global WELD products prior to V2.2. The V2.2 products will be reprocessed to Version 3.0. Version 3.0 products may be reprocessed as improved versions of the algorithms are developed.


- Product Accuracy/Consistency

No formal assessment of the WELD product accuracy/consistency has been undertaken but are a function of the accuracy/consistency of the Landsat L1T geolocation, calibration and the LEDAPS atmospheric correction processes.



How To Obtain WELD Products

- HDF

The HDF tiled products are available via HTTP at http://globalweld.cr.usgs.gov/collections

 

Note that both the Version 2.2 and Version 3.0 HDF products are available.


- GeoTIFF

GeoTIFF format products are available for all or select bands and in user defined regions via a global What You See Is What You Get (WYSIWYG) WELD Internet distribution interface at http://globalweld.cr.usgs.gov

 

Note that only Version 3.0 products are available via the WYSIWYG.

 


- Single Pixel Time Series

WELD product pixel values for any 30m pixel location, selected either interactively or by entering the pixel latitude and longitude coordinates, may be ordered via a global What You See Is What You Get (WYSIWYG) WELD Internet distribution interface at http://globalweld.cr.usgs.gov. The ordered pixel values for all years of available product are emailed to the user in a simple comma separated text format with the relevant band scale factors and offsets applied.



WELD Product Distribution Metrics

Distribution metrics for the Global What You See Is What You Get WELD Internet distribution interface are available at http://globalweld.cr.usgs.gov/request_metrics.php

The HTTP distribution metrics are tabulated below:
Number of WELD tiles Download Volume (GB)
2014 September 708 163.30
2014 October 1572 495.53
2014 November 10578 3550.46
2014 December 54642 11308.24
2015 January 5632 1831.67
2015 February 19945 5407.95
2015 March 37824 9055.87
2015 April 4648 1189.78
2015 May 15900 2943.37
2015 June 1946 457.21
2015 July 16778 6132.53
2015 August 4408 1390.32
2015 September 137120 31162.73
2015 October 145 45.64
2015 November 244 69.25
2015 December 2173 698.67
Total 314,263 74.12 TB

Software Tools

WELD HDF tile coordinate calculator

This tool allows one to find the global WELD tile and pixel coordinates, or the Sinusoidal map coordinates of a specified geographic coordinate (Forward Mapping), or to find the geographic coordinates of a specified global WELD pixel location (Inverse Mapping). This standalone version is available for computers running Unix/Linux operating systems; the C source code and installation instructions can be downloaded.


WELD Tile to GeoTIFF

This tool converts WELD tile products from HDF format to GeoTIFF format. This standalone code runs on Linux/Unix operating systems and the C source code and installation instructions can be downloaded.


Links


WELD Citation

If you wish to cite the WELD products in a report or publication please cite:

Roy, D.P., Ju, J., Kline, K., Scaramuzza, P.L., Kovalskyy, V., Hansen, M.C., Loveland, T.R., Vermote, E.F., Zhang, C., 2010, Web-enabled Landsat Data (WELD): Landsat ETM+ Composited Mosaics of the Conterminous United States, Remote Sensing of Environment, 114: 35-49.

 

If you use a WELD product generated graphic or browse image please insert the text "WELD" somewhere that is clearly visible. 


Frequently Asked Questions (FAQ)

This page is currently being developed in response to user questions.
Meanwhile please examine the CONUS/Alaska FAQ at http://globalmonitoring.sdstate.edu/projects/weld/


WELD Help Email


 

This web site is hosted at the Geospatial Sciences Center of Excellence (GSCE), South Dakota State University.
The contents of this web site were written by the GSCE WELD staff. This site was last updated February 4th 2016.