U.S. Navy’s Coupled Mesoscale Modeling in Support of Atmospheric Refraction and Electromagnetic Propagation Prediction

Presenter: 
Tracy Haack, Naval Research Laboratory, Monterey, California
Event Location: 
BCCMWS 100
Event Date: 
Thursday, March 24, 2016 - 3:00pm
Event Type: 
SCMSS Seminar Series

Abstract

Over the last two decades advancements in numerical weather prediction (NWP) and the increase in spatial resolutions due to computational resources and massive parallel processing, have made possible high fidelity characterization of vertical gradients in the lower atmosphere that form the surface and boundary layer. This detail has resulted in mesoscale modeling of atmospheric refractive properties which depend upon pressure, temperature and water vapor pressure. The refractive index is most sensitive to the vertical distributions with the ‘wet’ term (water vapor pressure) roughly four times larger than the ‘dry’ term (temperature).

In this presentation, the U.S. Navy’s Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) is investigated with field data from several coastal and littoral measurement campaigns to determine real-time operational modeling and predictive capability of atmospheric refractivity. Analysis of COAMPS surface and boundary layer gradients denote regions where important refractive effects cause ‘anomalous propagation ‘ of radio frequency (RF) signals. These RF signals, from radars or communications for example, can propagate far beyond the horizon in ducting conditions associated with negative gradients in ‘modified’ refractivity, or alternatively they may be strongly attenuated in sub-refractive conditions associated with strong positive gradients, whereby targets well within line-of-site are not sensed by the radar. Research strategies at the Naval Research Lab aim to improve both the mesoscale modeling of the local environment and how the simulated environment is used in electromagnetic RF propagation models to gain a better understanding of sensor performance during Naval operations.

Speaker Information

Tracy Haack is a scientist at the Naval Research Laboratory in Monterey, California.

More information about him and his work can be found here.