Comparison of detectability of ship wake components between C-Band and X-Band synthetic aperture radar sensors operating under different slant ranges

Abstract

The detectability of wake components is affected by influencing parameters, which can be categorized into ship properties, environmental conditions and image acquisition settings. The characteristics of influences of most influencing parameters on the detectability are established. However, a consequent investigation and systematization of influences regarding differences in settings of various SARs have not been published.In this study, data from four different SARs missions, namely TerraSAR–X (TSX), CosmoSkymed (CSK), Sentinel–1 (S1) and RADARSAT–2 (RS2), were collected and analyzed with focus on detectability of ship wake components. The sensors operate on different orbit altitudes and radar frequency bands: TSX and CSK work with X–Band, S1 and RS2 work with C–Band. Using methods from the field of Data Science, the detectability of wake components is modelled for each of the four sensors using machine leaning by the support vector machine (SVM) method. The created SVM-models are then compared in order to derive statements regarding relative detectability of individual wake components. A measure of detectability model’s uncertainty and an alternative analysis based on accumulated backscattering statistics is presented to support the derived statements.In conclusion, sensors with shorter slant ranges and X–Band in comparison to C–Band were found to be better suited for the detection of ship wakes. However, these characteristics only hold for wake components detectable due to the Bragg scattering mechanism, i.e. Kelvin wake arms and V-narrow wakes. No significant difference for near and far field of turbulent wakes is recognized.