Effects of Assimilation of Surface Temperature Data on the Evaporation Duct and Propagation Predictions

Abstract

The evaporation duct is an ubiquitous feature over the world's oceans responsible for trapping electromagnetic energy from surface emitters. The height of the evaporation duct (EDH) is often used to determine if ship-board radars and communications systems will be adversely affected by the environment. EDHs typically range from 2 to 40 meters and can vary substantially with surface stability, wind speed, and low-level humidity, particularly within 100 km from shore where temporal and spatial variations in the environment are the norm. A study was conducted to measure sea surface and air temperature from a specially instrumented ocean glider during a 30-day deployment off of San Diego, California. Improvements to the surface layer and evaporation duct modeling resulted from assimilation of the glider measurements into a numerical weather prediction (NWP) model. We show the impact of these data on the prediction of electromagnetic energy propagating from a surface radio frequency (RF) sensor.