SMEX03 ASTER Level-1B Data: Oklahoma
Summary
As part of the Soil Moisture Experiments 2003 (SMEX03), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images for 02 July 2003 and 18 July 2003 were acquired. For each day, five ASTER Level-1B scenes were mosaicked for the Oklahoma North and Oklahoma South, USA regional study areas. The data include three Visible and Near-infrared (VNIR) bands with a spatial resolution of 15 m, six Shortwave Infrared (SWIR) bands with a spatial resolution of 30 m, and five Thermal Infrared (TIR) bands with a spatial resolution of 90 m. The data are available via FTP.
These data were collected as part of a validation study for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). AMSR-E is a mission instrument launched aboard NASA's Aqua Satellite on 04 May 2002. AMSR-E validation studies linked to SMEX are designed to evaluate the accuracy of AMSR-E soil moisture data. Specific validation objectives include assessing and refining soil moisture algorithm performance; verifying soil moisture estimation accuracy; investigating the effects of vegetation, surface temperature, topography, and soil texture on soil moisture accuracy; and determining the regions that are useful for AMSR-E soil moisture measurements.
Citing These Data
The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.
Jackson, Tom. 2007. SMEX03 ASTER Level-1B Data: Oklahoma. Boulder, Colorado USA: National Snow and Ice Data Center. Digital media.
Overview Table
| Category | Description |
|---|---|
| Data format | Binary data files (little-endian) |
| Spatial coverage and resolution | Oklahoma North: Southernmost Latitude: 36.12° N Northernmost Latitude: 36.85° N Westernmost Longitude: 98.00° W Easternmost Longitude: 97.48° W Oklahoma South: Southernmost Latitude: 34.45° N Northernmost Latitude: 35.40° N Westernmost Longitude: 98.26° W Easternmost Longitude: 97.74° W VNIR: 15 m SWIR: 30 m TIR: 90 m |
| Temporal coverage and resolution | 02 July 2003 18 July 2003 Measurements were made once daily for each region. |
| Tools for accessing data | ArcView, ENVI, or other similar software package |
| File naming convention | aster_mmddyyyy_sss_bxx(x).bil |
| File size | 1.1 to 58.5 MB: binary files 1 KB: header files |
| Parameter | Radiance |
| Procedures for obtaining data | Data are available via FTP. |
Table of Contents
- Contacts and Acknowledgments
- Detailed Data Description
- Data Access and Tools
- Data Acquisition and Processing
- References and Related Publications
- Document Information
1. Contacts and Acknowledgments
Investigator(s)
Thomas Jackson
USDA ARS Hydrology Lab
Bldg. 007, Rm. 104, BARC-West
Beltsville, MD 20705 USA
Technical Contact
NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org
2. Detailed Data Description
Format
The ASTER Level-1B data are scaled radiance Data Numbers stored as 16 bit unsigned integers in little-endian byte order, and consist of one binary file per band. Each binary file is accompanied by a tab-delimited ASCII header file. Missing data are set to zero. Depending on the band, the binary files have a different number of columns and rows:
- VNIR files (bands 1-3) are 3680 columns by 5600 rows.
- SWIR files (bands 4-9) are 1840 columns by 2800 rows.
- TIR files (bands 10-14) are 614 columns by 933 rows.
To convert from Data Number (DN) to radiance
at the sensor, the unit conversion coefficients are used. Refer to Equation
1. For more information, refer to the ASTER
User Handbook (PDF, 3.6 MB).
The DN can be converted to radiance by using the following equation:
| Radiance = (DNvalue - 1) * unit conversion coefficient | (Equation 1) |
The conversion coefficients are listed in Table 1.
| Subsystem | Band No. |
Unit Conversion |
|---|---|---|
| VNIR | 1 | 0.676 |
| 2 | 0.708 | |
| 3N | 0.862 | |
| SWIR | 4 | 0.2174 |
| 5 | 0.0696 | |
| 6 | 0.0625 | |
| 7 | 0.0597 | |
| 8 | 0.0417 | |
| 9 | 0.0318 | |
| TIR | 10 | 0.006822 |
| 11 | 0.006780 | |
| 12 | 0.006590 | |
| 13 | 0.005693 | |
| 14 | 0.005225 |
File and Directory Structure
Data are available on the FTP site in the following directory: /pub/DATASETS/AVDM/data/soil_moisture/SMEX03/Oklahoma/satellite/ASTER/. Within the /ASTER/directory, there are two sub-directories as described in Table 2.
| Directory | Description |
|---|---|
| OKN | Contains all Oklahoma North files for each sample date, two files per spectral band: one binary file and one header file |
| OKS | Contains all Oklahoma South files for each sample date, two files per spectral band: one binary file and one header file |
File Naming Convention
Files are named according to the following convention:
aster_mmddyyyy_sss_bxx(x).bil
aster_mmddyyyy_sss_bxx(x).hdr
where:
| Variable | Description |
|---|---|
| mm | 2-digit month |
| dd | 2-digit day |
| yyyy | 4-digit year |
| sss | Site (oks = Oklahoma South, okn = Oklahoma North) |
| bxx(x) | Band number (for example, b03N refers to Band 3, Nadir-looking) |
| .bil | Indicates that this is a Band-Interleaved-by-Line binary data file. |
| .hdr | Indicates that this is a header file. |
Example: aster_07022003_okn_b10.bil (contains 02 July 2003 band 10 data for the Oklahoma North regional study area)
File Size
The binary data files range in size from 1.1 to 58.5 MB. The header files are 1 KB each.
Spatial Coverage
Data coverage includes the Oklahoma North and Oklahoma South regional study areas:
Oklahoma North:
Southernmost Latitude: 36.12° N
Northernmost Latitude: 36.85° N
Westernmost Longitude: 98.00° W
Easternmost Longitude:
97.48° W
Oklahoma South:
Southernmost Latitude: 34.45° N
Northernmost Latitude: 35.40° N
Westernmost Longitude: 98.26° W
Easternmost Longitude:
97.74° W
A detailed geographic description of the data set is shown in Table 4. The coordinates are in the Universal Transverse Mercator (UTM) Zone 14 projection and World Geodetic System (WGS) 84 datum.
| Site | Subsystem | Image Coordinates (Northing and Easting) | |||
| Upper left | Upper right | Lower left | Lower right | ||
| OKS | VNIR | 555600E 3920100N |
618000E 3920100N |
555600E 3812100N |
618000E 3812100N |
| SWIR | 555600E 3920100N |
618000E 3920100N |
555600E 3812100N |
618000E 3812100N |
|
| TIR | 555570E 3920130N |
617940E 3920130N |
555570E 3812130N |
617940E 3812130N |
|
| OKN | VNIR | 585795E 4081005N |
640995E 4081005N |
585795E 3997005N |
640995E 3997005N |
| SWIR | 585780E 4081020N |
640980E 4081020N |
585780E 3997020N |
640980E 3997020N |
|
| TIR | 585720E 4081050N |
640980E 4081050N |
585780E 3997080N |
640980E 3997080N |
|
Spatial Resolution
VNIR, SWIR, and TIR have different resolutions: 15, 30, and 90 meters, respectively. Each ASTER scene covers an area of approximately 60 x 60 km.
Projection
Universal Transverse Mercator (UTM): Zone 14, World Geodetic System 1984 (WGS 84)
Temporal Coverage
Data were collected once daily for each region on 02 July 2003 and 18 July 2003. These data should be used with the recognition that they represent a single point in time. Satellite overpass times for each date and location are listed below:
- Satellite overpass times for 02 July 2003 were 17:24:47 and 17:25:13 GMT for Oklahoma North and Oklahoma South, respectively.
- Satellite overpass times for 18 July 2003 were 17:24:13 and 17:24:39 GMT for Oklahoma North and Oklahoma South, respectively.
Parameter or Variable
The parameter of this data set is radiance as expressed in units of W/(m2*sr*μm).
Parameter Description
Radiance is the measure of the amount of electromagnetic radiation reflected or emitted by an object or surface.
Sample Data Record
Figure 1 shows a sample image from this data set.
 |
| Figure 1. Oklahoma North 02 July 2003 Sample Image |
3. Data Access and Tools
Data Access
Data are available via FTP.
Volume
The total data volume is approximately 900 MB.
Software and Tools
Tools appropriate for viewing these data are ArcView, ENVI, or other similar software packages.
Related Data Collections
- AMSR-E Soil Moisture Validation Data: Data sets from SMEX campaigns available at NSIDC.
- AMSR-E/Aqua Data at NSIDC: AMSR-E standard products available at NSIDC.
4. Data Acquisition and Processing
Sensor or Instrument Description
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is an advanced multispectral imager launched on board NASA's Terra spacecraft in December 1999. ASTER covers a wide spectral region with 14 bands from the visible to the thermal infrared with high spatial, spectral, and radiometric resolution. An additional backward-looking near-infrared band provides stereo coverage.
ASTER consists of three subsystems, or sensors. The high-resolution VNIR radiometer observes solar radiation reflected from the Earth's surface in three visible and near-infrared bands (1-3). The VNIR radiometer has a pointing capability of plus or minus 24 degrees from nadir in the cross-track direction. The radiometer is calibrated in orbit using halogen lamps. SWIR is a high-resolution, multispectral radiometer that detects reflected solar radiation from the Earth's surface (bands 4-9). SWIR can also change the boresight in the cross-track direction by plus or minus 8.55 degrees from nadir using a pointing mechanism. TIR is an advanced radiometer with five spectral bands (10-14) to detect emitted, thermal infrared radiation. See the ASTER User Handbook (PDF, 3.6 MB) for more information. Refer to Table 5 for spectral ranges.
| Subsystem | Band No. |
Spectral Range |
|---|---|---|
| VNIR | 1 | 0.52-0.60 |
| 2 | 0.63-0.69 | |
| 3N | 0.78-0.86 | |
| SWIR | 4 | 1.60-1.70 |
| 5 | 2.145-2.185 | |
| 6 | 2.185-2.225 | |
| 7 | 2.235-2.285 | |
| 8 | 2.295-2.365 | |
| 9 | 2.360-2.430 | |
| TIR | 10 | 8.125-8.475 |
| 11 | 8.475-8.825 | |
| 12 | 8.925-9.275 | |
| 13 | 10.25-10.95 | |
| 14 | 10.95-11.65 |
Data Acquisition Methods
For each day, five ASTER scenes were mosaicked to form one image. The smaller regional study areas of Oklahoma North and Oklahoma South were then extracted. Data are Level-1B with geometric and radiometric corrections applied.
5. References and Related Publications
Abrams, Michael and Simon Gaskin. ASTER User Handbook: Advanced Spaceborne
Thermal Emission and Reflection Radiometer. Version 2.
Jet Propulsion Laboratory. http://asterweb.jpl.nasa.gov/content/03_data/04_Documents/aster_user_guide_v2.pdf,
3.6 MB.
Please see the USDA
SMEX 03 Web
site for in-depth information on the science mission and goal of the SMEX project.
6. Document Information
Acronyms and Abbreviations
The following acronyms and abbreviations are used in this document:
| AMSER-E | Advanced Scanning Microwave Radiometer - Earth Observing System |
| ASTER | Advanced Spaceborne Thermal Emission and Reflection Radiometer |
| DN | Data Number |
| ENVI | Environment for Visualizing Images |
| FTP | File Transfer Protocol |
| JPL | Jet Propulsion Laboratory |
| NSIDC | National Snow and Ice Data Center |
| OKN | Oklahoma North |
| OKS | Oklahoma South |
| SMEX03 | Soil Moisture Experiment 2003 |
| SWIR | Shortwave Infrared |
| URL | Uniform Resource Locator |
| USDA | United States Department of Agriculture |
| UTM | Universal Transverse Mercator |
| TIR | Thermal Infrared |
| VNIR | Visible and Near-Infrared |
| WGS 84 | World Geodetic System 1984 |
Document Creation Date
December 2007
Document URL
http://nsidc.org/data/docs/daac/nsidc0325_smex03_aster_level1b_ok.gd.html
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