Mesoscale modeling of coastal refractivity

Atmospheric refraction can substantially alter the propagation path and intensity of microwave transmissions from radars and communication systems. Pronounced anomalous propagation of microwave radiation generally is associated with shallow, strongly capped marine atmospheric boundary layer (MABL) conditions. These conditions are quite prevalent in coastal California's summertime climatology. Dramatic variations in marine layer thickness and wind speed have been associated with changes in coastal orientation. Consequently, the height of electromagnetic (EM) trapping layers, which tend to occur at the base of the MABL inversion, can also be significantly influenced by changes in the coastline. The authors investigate the spatial variability of EM propagation in the MABL coastal regime with a fully stratified, nonhydrostatic mesoscale modeling system: The Navy's Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS), and data from two coastal field experiments: The Variability of Coastal Atmospheric Refractivity (VOCAR) experiment and The Coastal Waves 1996 experiment (CW96).