Low Elevation Transmission Measurements at EOPACE Part I: Molecular and Aerosol Effects

An analysis is presented showing the effects of molecules and aerosols on atmospheric transmission data obtained during the Electro-Optical Propagation Assessment in Coastal Environments (EOPACE) campaign carried out in San Diego during March and April, 1996. Mid wave infrared transmission was measured over San Diego Bay along a 14.9 km path and a 7.0 km path at heights less than 4 meters above the water. Simultaneous meteorological measurements were obtained from two buoys placed at the mid-points of each path. An aerosol spectrometer was used to measure the aerosol size distribution over each transmission path. Data were analyzed with MODTRAN and Mie theory. The conclusion of this and the next two papers is that low altitude infrared transmission is a complex phenomenon whose mean value may be controlled either by molecular absorption, aerosol scattering, or refractive focusing, and whose fluctuating value is controlled by scintillation. ©2005 Copyright SPIE - The International Society for Optical Engineering