Using this form, you can calculate aerosol optical thickness (AOT) based on sun photometer measurements and simultaneous measurements of relative air mass. In order to get relative air mass, use a "solar gnomon" -- a vertical pole -- to measure the elevation angle of the sun. Then relative air mass is approximately 1/sin(elevation). The Earth/sun distance is required, in units of astronomical units (AU). For an approximate calculation, use a value of 1. Earth is farther from the sun in the summer than in the winter. In mid-June it is about 1.016 AU from the sun. In mid-January, it is about 0.984 AU from the sun.
To use this form, you will need to get your instrument's calibration constant from the Science Team.
NOTE: No error checking is done on these values.)