Data Set ID: 

SMEX02 ASTER Level 1B Data, Iowa, Version 1

These ASTER Level 1B data include three Visible and Near-infrared (VNIR) bands, six Shortwave Infrared (SWIR) bands, and five Thermal Infrared (TIR) bands The data are L1B (radiance) data with geometric and radiometric correction.

This is the most recent version of these data.

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Data Format(s):
  • Binary
Spatial Coverage:
N: 42.73, 
S: 41.7, 
E: -93.16, 
W: -93.84
Spatial Resolution:Not SpecifiedSensor(s):ASTER
Temporal Coverage:
  • 1 July 2002
Temporal ResolutionNot specifiedMetadata XML:View Metadata Record
Data Contributor(s):Thomas Jackson, Michael Cosh

Geographic Coverage

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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. and M. Cosh. 2003. SMEX02 ASTER Level 1B Data, Iowa, Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: [Date Accessed].

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Detailed Data Description

Investigators acquired a series of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images from the Terra satellite. Three ASTER scenes were mosaicked and the regional study area extracted to form one image for each of ASTER's 14 spectral channels. These data represent a single snapshot; the satellite overpass time was 17:20 GMT on 1 July 2002. The study area is the Walnut Creek Watershed area in Iowa, USA


The data are in unsigned integer binary files in terms of scaled radiance, one file for each band, in PC byte order (little endian). There is no header information included in these files.
VNIR files (bands 1-3) are 3702 columns by 7662 rows.
SWIR files (bands 4-9) are 1852 columns by 3832 rows.
TIR files (bands 10-14) are 618 columns by 1278 rows.

The digit number (DN) was converted to radiance (W/(m2*sr*μm) using the following equation:

Radiance=(DNvalue-1)x unit conversion coefficients.

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File Naming Convention

File names use the following conventions:
where: mm = month, dd = day, yyyy = year, xx(x) = band number. For example, in the file "ASTER_07012002_b7.bil," data were collected on 1 July 2002 by the SWIR band 7.

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File Size

SWIR files are 13.5 MB, TIR files are 1.5 MB, and VNIR files are 54.1 MB.

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Total volume is 251 MB.

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Spatial Coverage

Southernmost Latitude: 41.70°N
Northernmost Latitude: 42.73°N
Westernmost Longitude: 93.84°W
Easternmost Longitude: 93.16°W

The following table shows the Universal Transverse Mercator (UTM) geographic locations of the various sensor data. (UTM coordinates are in meters.)

Easting Northing Easting Northing Easting Northing
Upper Left 431093 E 4731101 N 431077 E 4731113 N 431076 E 4731102 N
Upper Right 486608 E 4731101 N 486607 E 4731113 N 486606 E 4731102 N
Lower Left 431093 E 4616186 N 431077 E 4616183 N 431076 E 4616173 N
Lower Right 486608 E 4616186 N 486607 E 4616183 N 486606 E 4616173 N

Spatial Resolution

VNIR has 15 m resolution, SWIR has 30 m resolution, and TIR has 90 m resolution.

Projection Description

Universal Transverse Mercator (UTM) Zone 15

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Temporal Coverage

Data were collected on 1 July 2002 by the ASTER instrument.

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Parameter or Variable

Parameter Description

The parameters are VNIR, SWIR, and TIR radiance imagery. Three ASTER scenes were mosaicked and the regional study area extracted to form one image for each of ASTER's 14 spectral channels.

Sample Data Record

The following sample shows a portion of the data file "ASTER_07012002_b7.bil."

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Software and Tools

Open these files in an appropriate image processing or image viewing application.

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Data Acquisition and Processing

Sensor or Instrument Description

ASTER is an advanced optical sensor of 14 spectral channels ranging from the visible to thermal infrared region.

The high-resolution VNIR radiometer observes solar radiation reflected from Earth's surface in three visible and near-infrared bands (1-3). The spectral region is 0.52-0.86 μm. VNIR has a pointing capability of +/-24° 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 Earth's surface in the wavelength region of 1.6 - 2.43 μm (bands 4-9). SWIR can also change the boresight in the cross-track direction by +/-8.55° from nadir using a pointing mechanism.

TIR is an advanced radiometer with five spectral bands (10-14) in the thermal infrared (8-12 μm).

For more information, please see the ASTER User Guide.

The band spectral range and conversion coefficients are listed in the following table.

Sensor Band Number Spectral Range (μm) Unit Conversion Coefficient
VNIR 1 0.52-0.60 0.676
2 0.63-0.69 0.708
3N 0.78-0.86 0.862
SWIR 4 1.60-1.70 0.2174
5 2.145-2.185 0.0696
6 2.185-2.225 0.0625
7 2.235-2.285 0.0597
8 2.295-2.365 0.0417
9 2.360-2.430 0.0318
TIR 10 8.125-8.475 0.006822
11 8.475-8.825 0.006780
12 8.925-9.275 0.006590
13 10.25-10.95 0.005693
14 10.95-11.65 0.005225
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References and Related Publications

Contacts and Acknowledgments

Thomas J. Jackson, Hydrologist, Michael H. Cosh, General Physical Scientist, and Lynn McKee, Soil Scientist, USDA ARS Hydrology Lab.

Document Information


November 2003

No technical references available for this data set.

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