Accession Number:

ADA232042

Title:

A Lidar Technique for Adjusting Aerosol Model Number Densities Close to the Ocean Surface

Descriptive Note:

Technical rept.

Corporate Author:

NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA

Personal Author(s):

Report Date:

1990-12-01

Pagination or Media Count:

20.0

Abstract:

With the Navys 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, SR, returned from scattering volumes at different heights in the modeled atmosphere. An iterative method is used by which the calculated SR 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.

Subject Categories:

  • Meteorology
  • Infrared Detection and Detectors
  • Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE