A Passive Technique to Monitor Evaporation Duct Height Using Coastal GNSS-R

We report on a coastal experiment to monitor evaporation duct height (EDH) using GPS-L1 signals scattered from the sea surface. The campaign was carried out in the South China Sea and was focused on the development of an EDH inversion technique. A high-sensitivity delay-mapping receiver was built for this purpose to collect and process direct and scattered GPS-L1 signals. The received GPS scattered signals are modeled using the bistatic radar equation. The modified refractivity profiles were measured by 12 meteorological sensors which were mounted at different heights on a vertical tower located at the same site. The results show good agreement between the inverted and measured EDHs at satellite elevation angles of 4°-9°. Based on these results, preliminary conclusions are drawn on the potential of coastal Global Navigation Satellite System-Reflectometry for EDH inversion.