Aerosol optical thickness (AOT) calculations if you know relative air mass

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.)

atmospheric pressure: mb     Earth-sun radius: AU     relative air mass: (dimensionless)
Channel, red (r) or green(g):
Sun photometer calibration constant (Vo) for specified channel: V
observed dark voltage: V    observed sun voltage: V

aerosol optical thickness (AOT) (dimensionless) ONLY POSITIVE AOT VALUES HAVE MEANING!
percent transmission %

Click here when you're done.