Determination of an air mass using nephelometer measurements and the Navy Aerosol Model

The origin of an air mass is an important factor in predicting performance of electrooptical systems in coastal environments. The aerosol content varies significantly depending upon whether the air mass is anthropogenic or natural, marine or continental, rural or urban. Measurement of radon concentration is a traditional method used to determine the origin of an air mass, but sensitive radon monitors are not readily available. A method of determining aerosol concentration from more easily obtainable three-wavelength nephelometer measurements can be used in conjunction with the Navy Aerosol Model to determine the air mass characteristic. This paper explores this process, using data collected during an EOPACE (Electrooptical Propagation Assessment in Coastal Environments) experiment in November 1996. Radon and nephelometer data were collected, along with a full complement of meteorological and aerosol data, during a wide range of meteorological conditions.