Joint French-German radar measurements for the determination of the refractive index in the maritime boundary layer

Abstract

To predict the performance of coastal and shipborne radars, it is essential to assess the propagation characteristics of electromagnetic waves in the maritime boundary layer. To be independent upon environmental measurements, which are generally not as precise and reliable as they have to be for a proper input to simulation programs, usually based upon parabolic equation models, a method to retrieve the refractive index gradients in the low troposphere is the Refractivity from Clutter (RFC) algorithm. The propagation factor is computed from the received clutter power and is iteratively processed in order to retrieve the refractive index profiles. Under a respective French-German technical agreement a measurement program concerning radar propagation in the maritime boundary layer has been initiated, with contributions from ONERA-CERT, DGA MI/TN, Fraunhofer-FHR and the German Technical Center for Ships and Naval Weapons (WTD 71). The paper gives an overview on the RFC met hod with examples from the previous campaigns. It describes the experimental set-up and its methodology

Millimeter wave propagation above the sea surface during the Squirrel campaign

“…All these parameters are measured with groundbased and airborne meteorological sensors together with sea-borne meteorological sensors like buoys and catamarans as well as various shipborne measurement instruments [7,8].…”

Analysis of radar sea clutter data acquired during the MARLENE measurement campaign

“…Therefore, it is essential to study the returns from radar sea clutter for developing future generations of radar sensors. In this paper, we focus on sea clutter data acquired during a coastal experiment called MARLENE (for MediterraneAn Rfc and sea cLutter ENvironment Experiment [1]), which was performed within the framework of the French German technical cooperation [2]. This experiment aims at characterizing sea clutter level and fluctuation of the coastal environment for different sea states, radar bands, polarizations and grazing angles, analyzing the impact of ducting conditions on propagation and improving RFC systems.…”

Observations of anomalous propagation over waters near Sweden

“…A number of measurement campaigns have also been conducted in the Baltic sea, mainly focused on studying evaporation ducts. During these campaigns a combination of in situ measurements, radiosondes, and microwave measurements were performed and reported (see, e.g., Scholz and Förster, 2003;Förster et al, 2004;Essen et al, 2004;Förster and Riechen, 2006;Essen et al, 2012;Danklmayer et al, 2013Danklmayer et al, , 2015Danklmayer et al, , 2016a.…”