Atmospheric Correction Parameter Calculator
Profile Averaging Techniques


The atmospheric profiles are generated by NCEP. They incorporate satellite and surface data to predict a global atmosphere at 28 altitudes. These modeled profiles are sampled on a 1x1 degress grid and are generated every six hours. The Calculator provides two methods of resampling the grid for the specific inputted site: Use atmospheric profile for closest integer lat/long or Use interpolated atmospheric profile for given lat/long.


Use atmospheric profile for closest integer lat/long:
The closest 1x1 degree grid corner is established; in the figure, this is (x,y+1). This corner's profile is extracted from the NCEP files for the two times before (t6x) and after (t6x+6) the inputted time (t0). The weighted average of the two corners is calculated and used as the atmospheric profile.


Use interpolated atmospheric profile for given lat/long:
The profiles are extracted for the four grid corners [ (x,y), (x,y+1), (x+1,y), (x+1,y+1) ] surrounding the inputted location for the two times before (t6x) and after (t6x+6) the inputted time (t0). The corner profiles are interpolated for each time, then the resulting time profiles are interpolated to the inputted location.

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