The NASA Earthdata Search application provides an easy way to find ASTER scenes, including ASTER products. ASTER products have additional processing so you will not be able to immediately download these data. You can enter a simple natural language search term such as “Aster temperature over Connecticut for 2017” or follow the guide below for a more targeted search.
ASTER L1B full scenes and ASTER products (as of this writing) are delivered oriented along the satellite path. While these data are georeferenced, they are NOT oriented with north at the top of the image. These data should be rotated into a map orientation with north being at the top of the image. This step is NOT necessary for ASTER L1T full scenes.
ENVI has a multi-step process that can perform basic atmospheric correction then convert the resulting emissivity bands to a brightness-temperature image in degrees Kelvin. When ENVI reads an ASTER AST_L1B scene it calibrates the TIR bands to proper radiance values. If you are working with one of these datasets proceed to Step 2. For the newer ASTER AST_L1T datasets ENVI opens these with “byte values” which must first be converted to floating-point radiance values as shown in Step 1.
ENVI automatically applies the proper calibration coefficients to convert the integer digital numbers to floating-point radiance values when opening a Level 1B or 1T dataset. You can easily convert these values to Top-Of-Atmosphere Reflectance in ENVI. From the Toolbox select Radiometric Correction | Radiometric Calibration and select the three-band VNIR file. Change the Calibration Type to Reflectance, enter a new filename, and click OK.
The following instructions describe how to open ASTER data using the ENVI 5.x Standard interface. You can perform the same steps in ENVI Classic under the Basic Tools menu. ASTER data sets and products are distributed in the hierarchical data format (HDF). Use the following method to properly open and calibrate these data in ENVI.
