The "stand-alone code" is the dark-target retrieval algorithm at its essence. It offers a user an ability to see how the mathematics of the retrieval works, without the operational infrastructure. All code related to cloud masking, pixel selection and pixel aggregation has been removed, along with all routines related to HDF file processing. What is left is a "one-pixel = one-retrieval" routine. The user inputs reflectance values in seven bands, along with geolocation (latitude/longitude, angles, date), and the code outputs retrieved AOD, fine-model fraction, and diagnostics. Inputs and outputs are handled as ASCII files. It is presumed that the input data are for clear-sky and corrected for gas-absorption, as would be reported as 'Mean_Reflectance_Land' or 'Mean_Reflectance_Ocean' within in the Level 2 MODIS aerosol (M?D04) file.
Originally developed for algorithm testing, Levy and Pinker (2007) modified the stand-alone code over ocean for use as a classroom exercise. Students had the opportunity to perform aerosol retrieval "by hand" and compare with output from the routine. The paper, original code and exercises can be found here (SOON TO BE ADDED).
Currently, there are separate stand-alone codes for land and water. Both are coded in simple Fortran, and can be compiled and run without libraries. The same lookup tables (LUTs) used for standard MODIS retrievals (Collection 6) are included. Although they have been tested, a potential user is alerted that these are not "polished" or well-commented codes. Included in each 'zip' archive is the Fortran code, include files, LUTs, sample input/output and README file.