A Lidar Technique for Adjusting Aerosol Model Number Densities Close to the Ocean Surface
Abstract
With the Navy's interest in FLIR detectors at submarine periscope heights, it is important to get more detailed information on the atmospheric characteristics at FLIR wavelengths (3 to 5 and 8 to 12 microns) in the first few meters above the ocean. This information is particularly important for predicting the performance of electro-optical systems operating against skimmer- type missiles approaching a ship or submarine from beyond the horizon. A technique is introduced by which the total number density of the LOWTRAN 7 Navy Aerosol Model (NAM) the kernel for the Naval Oceanic Vertical Aerosol Model) is adjusted to represent existing conditions close to the ocean surface. Measurements of bulk meteorological parameters at a reference height above the ocean surface are used to generate stability dependent logarithmic profiles of temperature and relative humidity. These profiles are used with the aerosol model to determine aerosol extinction and backscatter coefficient variations close to the ocean surface. Using the single-scatter lidar (light detection and ranging) equation, these parameters are then used to calculate a range compensated power, S(R), returned from scattering volumes at different heights in the modeled atmosphere. An iterative method is used by which the calculated S(R) values are adjusted to agree with the corresponding measured values obtained with a lidar operating at 1.06 microns and directed at the ocean over a slant path from an altitude of 10 meters. Examples are presented of extinction coefficient variations with height above the ocean surface, calculated using the original and adjusted size distributions for different surface wind speed conditions and air mass characteristics.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1990
- Accession Number
- ADA232042
Entities
People
- H. G. Hughes
- M. R. Paulson