Simulation study of SAR imaging of multi-source internal wave wakes in underwater vehicle

Abstract

Hydrodynamic wake signatures generated by underwater vehicles are critical targets in ocean-based anti-submarine detection. Synthetic Aperture Radar (SAR), with its all-weather, all-day, and high-resolution capabilities, shows significant potential in the detection of internal wave wakes. This study develops a comprehensive SAR imaging simulation model by integrating multi-source internal wave wake theories, the wave action conservation equation, and a modulated facet scattering model. Focusing on three typical types of internal wave wakes—Lee waves, forced internal waves, and collapsed internal waves—induced by underwater vehicles in stratified oceans, the model systematically simulates the full process from wave field generation and current-wave modulation to electromagnetic scattering and SAR imaging. After comprehensive validation across internal wave fields, surface wake fields, modulated wind-wave spectra, and scattering coefficients, the model was further employed to investigate the modulation effects of various parameters, including vehicle speed, depth, radar frequency band, and incidence angle, on the wake characteristics in SAR images. Results indicate that under typical stratification conditions in the South China Sea, Lee waves dominate the wake pattern at low speeds, while at higher speeds, the contribution from wake-induced internal waves becomes more pronounced, leading to clearly distinguishable wake signatures in SAR imagery at peak Lee wave speed and beyond. Furthermore, l-band and cross-polarized radar configurations are more favorable for wake detection, and the relative motion between radar platform and submarine also influences the observed wake features. This research provides theoretical foundation and simulation tools for remote sensing detection of underwater targets via internal wave wakes.