Journal of East China Normal University(Natural Sc ›› 2019, Vol. 2019 ›› Issue (2): 184-194,208.doi: 10.3969/j.issn.1000-5641.2019.02.020

• Geography • Previous Articles     Next Articles

Simulation analysis for remote sensing inversion of wavelength and water depth by the Fast Fourier Transform method

SHEN Si-min1, ZHU Shou-xian1, KANG Yan-yan1, ZHANG Wen-jing2, CAO Guang-song1   

  1. 1. College of Oceanography, Hohai University, Nanjing 210098, China;
    2. College of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China
  • Received:2018-02-11 Online:2019-03-25 Published:2019-03-27

Abstract: Using the difference in remote sensing reflectivity between wave crest and trough, wavelengths can be inversed by the Fast Fourier Transform (FFT) method to derive the nearshore water depth. Remote sensing images with higher resolution are generally thought to induce less error in marine information inversion. In this study, remote sensing images were replaced by elevation data from ideal equations and numerical simulations to study the effect of data resolution on wavelength inversions and water depths. The results show that low-resolution data result in significant errors in the wavelengths and water depths. But variations in resolution make no difference in reversing the wavelengths and water depths as they reach certain levels. The sub-image size in the FFT method was also studied by simulation analysis. Larger sub-images generate less error in wavelength inversion if the wavelength doesn't vary spatially. On uneven topography, errors from wavelength and water depth inversions are small if the sub-image size is 4-8 times the wavelength and not more than the topography variation; however, when the sub-image is too large or too small, the errors will increase.

Key words: Fast Fourier Transforms (FFT), wavelength inversion, water depth inversion, simulation analysis

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