Jointly managed by NASA and Japan’s Ministry of International Trade and Industry
ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is one of five imaging instruments flying on the Terra satellite launched in 1999 as part of NASA’s Earth Observing System. It is used to gather detailed data on surface temperature, emissivity, reflectance, and elevation at a relatively high spatial resolution. ASTER gathers data in 14 spectral bands: 3 visible and 11 in the infrared region of the electromagnetic spectrum. It has a nadir and backward facing Band 3 which gives it the unique ability to create digital elevation models based on stereo images. It has a revisit time of 16 days which can be a limitation for studying rapidly changing surface conditions. There might also be costs associated with acquiring some images.
Upper Left: The color infrared composite uses bands in the visible and reflected infrared. Vegetation is red, urban areas are gray; sediment in the bays shows up as lighter shades of blue. Thanks to the 15 meter (50-foot) spatial resolution, shadows of the towers along the Bay Bridge can be seen.
Upper right: A composite of bands in the short wave infrared displays differences in soils and rocks in the mountainous areas. Even though these regions appear entirely vegetated in the visible, enough surface shows through openings in the vegetation to allow the ground to be imaged.
Lower left: This composite of multispectral thermal bands shows differences in urban materials in varying colors. Separation of materials is due to differences in thermal emission properties, analogous to colors in the visible.
Lower right: This is a color coded temperature image of water temperature, derived from the thermal bands. Warm waters are in white and yellow, colder waters are blue. Suisun Bay in the upper right is fed directly from the cold Sacramento River. As the water flows through San Pablo and San Francisco Bays on the way to the Pacific, the waters warm up
The ASTER sensor consists of three separate subsystems. ASTER has a sun-synchronous polar orbit meaning it crosses over any given latitude at the same time each day. The satellite revisits the same area every 16 days.
|3 (nadir)||15m||0.76-0.86||Near Infrared|
|3 (backward)||15m||0.76-0.86||Near Infrared|
|4||30m||1.600-1.700||Short Wave Infrared|
|5||30m||2.145-2.185||Short Wave Infrared|
|6||30m||2.185-2.225||Short Wave Infrared|
|7||30m||2.235-2.285||Short Wave Infrared|
|8||30m||2.295-2.365||Short Wave Infrared|
|9||30m||2.360-2.430||Short Wave Infrared|
Unlike the Landsat program that acquires and archives all images, ASTER provides images on-demand and will only gather data on an area if a request has been submitted. Pre-existing ASTER images are archived and available through the Reverb/Echo system http://reverb.echo.nasa.gov/reverb/#utf8=%E2%9C%93&spatial_map=satellite&spatial_type=rectangle or the Land Processes Distributed Active Archive Center (LPDAAC) Data Pool https://lpdaac.usgs.gov/get_data/data_pool. A suite of products at different processing levels are available through these two sources. All existing level 1B products through the Data Pool are available at no cost. Higher processes products may have costs involved.
If your area of interest has not been archived or acquired yet, please click here http://asterweb.jpl.nasa.gov/NewReq.asp for instructions on how to request an image acquisition.
|1A||Radiance at sensor||Image data plus radiometric and geometric coefficients. Data are separated by telescope.|
|1AE||Radiance at sensor||Expedited L1AE data product created from ASTER Expedited Level-0.|
|1BE||Registered radiance at sensor||Expedited L1BE data product created from ASTER. Expedited Level - 1AE|
|2A||Registered radiance at sensor||1A data with radiometric and geometric coefficients applied|
|2||Decorrelation stretch||Enhanced color composites for each telescope|
|2||Brightness temperature||Radiance at the sensor converted to temperature|
|2||Surface radiance||Radiance corrected for atmospheric effects|
|2||Surface reflectance VNIR, SWIR||Derived from surface radiance with topographic corrections|
|2||Surface kinetic temperature||Temperature-emissivity separation algorithm applied to atmospherically corrected surface radiance data.|
|2||Surface emissivity||Temperature-emissivity separation algorithm applied to atmospherically corrected surface radiance data.|
|3||Polar Surface and Cloud Classification||Classifies each pixel of polar scenes into one of eight classes: water cloud, ice cloud, aerosol/dust, water, land, snow/ice, slush ice, and shadow.|
|3||Digital elevation model||DEM produced by stereo correlation of nadir and aft band 4 data|
|3||Orthorectified||15 orthorectified L1B radiance images in GeoTiff|
|3||Orthorectified DEM||15 orthorectified L1B images + DEM|
ASTER images typically come in a HDF-EOS file format but can be converted to Geotiff files in several projections.Tools for carrying out data transformations can be found at: https://lpdaac.usgs.gov/tools.
Java is required for viewing and selecting data in the LPDAAC Data Pool.
ASTER images can be converted into GeoTiff format making is compatible with ESRI ArcGIS and other GIS platforms. The images can be manipulated and processed in remote sensing software packages such as ENVI and ERDAS Imagine.
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