Accession Number : ADA326854

Title :   Mesoscale Atmospheric Simulations of Marine-Layer Structure and Refractivity in the Southern California Bight.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : Williams, Robert T., Jr

PDF Url : ADA326854

Report Date : 18 JUN 1997

Pagination or Media Count : 132

Abstract : Calculation of electromagnetic (EM) propagation in the littoral (marine coastal zone) can be a challenging problem for current numerical propagation models because of the sparsity of meteorological data necessary to describe the propagation medium. It is believed, however, that with sufficient improvement such models can simulate characteristics of the marine boundary layer depth, inversion height, and inversion strength, on temporal scales from an hour to several days. It may also be possible to estimate the subgrid scale statistics of the critical fields. The Penn State/National Center for Atmospheric Research non-hydrostatic mesoscale model (MM5) is used to test the predictability of marine temperature and moisture structures in the coastal zone of Southern California during the VOCAR (Variability of Coastal Atmospheric Refractivity) experiment of 1993. Hundreds of soundings taken at several sites in the VOCAR study area are analyzed to characterize the dependence of atmospheric refractivity and marine layer structure on time of day and distance offshore. High vertical resolution numerical simulations are performed using MMS and are evaluated against the special data over a period of about one week. The ability of a mesoscale numerical model to predict both short term (1-6 hours) and longer range (days) variations in marine layer structure and refractivity is demonstrated. The major conclusions are that the numerical model is capable of predicting (1) the basic evolution of marine boundary layer depth over a period of 7 days, (2) inversion structures in temperature and water vapor that account for the observed strength of trapping and ducting layers in the refractivity (M) profiles, and (3) gravity wave propagation in and above the marine boundary layer

Descriptors :   *ELECTROMAGNETIC WAVE PROPAGATION, *MARINE ATMOSPHERES, MATHEMATICAL MODELS, COMPUTERIZED SIMULATION, COASTAL REGIONS, LAYERS, THESES, BOUNDARY LAYER, HIGH RESOLUTION, DEPTH, CALIFORNIA, MOISTURE, LITTORAL ZONES, ATMOSPHERIC REFRACTION, WATER VAPOR, OFFSHORE, GRAVITY WAVES.

Subject Categories : Meteorology
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE