Aerosol Particle Size Measurements at San Nicolas Island during CEWCOM-78.
Abstract
Particulate aerosol size spectra obtained during the CEWCOM-78 exercise (8-22 May 1978) at San Nicolas Island, California, are presented for the particle size range 0.745 micrometers diameter as measured with a PMS Axially Scattering Spectrometer Probe. In addition, an informal account of the daily meteorological and visibility conditions as observed visually from several vantage points on the island is given to help in the interpretation of the aerosol and optical data collected during the measurement session. These observations point out: (1) the need for slant path optical transmission measurements due to the generally strong, vertical gradient in visibility in the lowest 300m or so above sea level, (2) the general susceptibility of Sites A and D to surf-generated aerosols and the additional susceptibility to dust for winds above 10m/sec, (3) the suitability of the upper two levels of the NRL tower for representative aerosol measurements except possibly during near calm wind conditions, (4) the suitability of SNI as a site for obtaining optical transmission measurements in maritime clouds, and (5) the existence of a newly observed phenomenon in which the downward vortex of air behind large, breaking or cresting waves in high wind situations prevents much of the crest-generated spray from becoming airborne. This mechanism may help explain the recently reported cases where the particle concentrations are lower and the visibilities are better in high wind situations than is to be expected from aerosol models where particle number densities increase indefinitely with wind speed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 09, 1979
- Accession Number
- ADA068329
Entities
People
- Richard K. Jeck
Organizations
- United States Naval Research Laboratory