Get Data


To learn more about Earthdata Login and to register for an account, please see How to Register with Earthdata Login. Once you have logged in, data can be downloaded via a Web browser, command line, or client. For help with downloading data, please see Options Available for Bulk Downloading Data from HTTPS with Earthdata Login.


Data Set ID:

SMEX03 ASTER Level-1B Data: Oklahoma, Version 1

This data set contains mosaicked Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images for the Oklahoma North and Oklahoma South, USA regional study areas.

Geographic Coverage

  • Infrared Wavelengths > Infrared Radiance
  • Infrared Wavelengths > Thermal Infrared
  • Visible Wavelengths > Visible Radiance
Spatial Coverage:
  • N: 36.85, S: 36.12, E: -97.48, W: -98

  • N: 35.4, S: 34.45, E: -97.74, W: -98.26

Spatial Resolution:
  • 30 m x 30 m
  • 15 m x 15 m
  • 90 m x 90 m
Temporal Coverage:
  • 18 July 2003
  • 2 July 2003
Temporal Resolution: Not specified
Data Format(s):
  • Binary
  • ASCII Text
Platform(s) TERRA
Sensor(s): ASTER
Version: V1
Data Contributor(s): Thomas Jackson, NSIDC User Services
Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Jackson, T. 2008. SMEX03 ASTER Level-1B Data: Oklahoma, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: [Date Accessed].

Back to Top

Collapse All / Open All

Detailed Data Description


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.

Table 1: Unit Conversion Coefficients
Subsystem Band

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
Background color on
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.

Table 2: Directory Description
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
Background color on
File Naming Convention

Files are named according to the following convention:



Table 3: Description of File Name Variables
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)

Background color on
File Size

The binary data files range in size from 1.1 to 58.5 MB. The header files are 1 KB each.

Background color on

The total data volume is approximately 900 MB.

Background color on
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.

Table 4: Geolocation of the Images
Site Subsystem Image Coordinates (Northing and Easting)
Upper left Upper right Lower left Lower right
OKS VNIR 555600E
SWIR 555600E
TIR 555570E
OKN VNIR 585795E
SWIR 585780E
TIR 585720E

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.


Universal Transverse Mercator (UTM): Zone 14, World Geodetic System 1984 (WGS 84)

Background color on
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.

Background color on
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

Background color on

Software and Tools

Software and Tools

Tools appropriate for viewing these data are ArcView, ENVI, or other similar software packages.

Background color on

Data Acquisition and Processing

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.

Background color on
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.

Table 5: Subsystem Spectral Ranges
Subsystem Band

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

Background color on

References and Related Publications

Contacts and Acknowledgments

Thomas Jackson
USDA ARS Hydrology Lab
Bldg. 007, Rm. 104, BARC-West
Beltsville, MD 20705 USA

Document Information


December 2007

No technical references available for this data set.
No FAQs or How Tos available for this data set.

Access complete Knowledge Base

Questions? Please contact:
NSIDC User Services
Phone: 1 303 492-6199