Surface-based ducting due to a shift in air masses off the coast of Wallops Island, Virginia

On 14 November 2007, the Johns Hopkins University Applied Physics Laboratory (JHU/APL) provided environmental characterization support for a US Navy radar test event, off the coast of Wallops Island, VA. Two environmental sensor systems were deployed: (1) the Automated Environmental Assessment System installed aboard the research vessel Chessie and (2) the Helicopter Atmospheric Profiler System. Chessie was located on the test range to collect near-surface environmental data in support of evaporation ducting assessments, as well as atmospheric soundings via rocketsondes to characterize upper-air refractivity conditions. Two types of helicopter flight profiles characterized evaporation and surface-based ducts. This paper summarizes the collected data, the propagation analysis, and highlights how a subtle change in meteorological conditions can significantly affect radar propagation. In addition, an analysis of the impact on radar system performance, due to the change in radar propagation conditions, is presented.