Retrieving Sea Wave Spectra Based on High Resolution Satellite Imagery under Different Conditions of Wave Generation

Abstract

A method for retrieving sea wave spectra from space images of high spatial resolution has been developed for various conditions of wave generation based on the use of retrieving operators in the form of spatial-frequency filters, the parameters of which are adjusted to real conditions. The adequacy of the method is tested using the data of multidisciplinary experiments carried out in the coastal waters of the Black Sea and in the open waters of the Pacific Ocean near Hawaii by comparing the wave spectra in the frequency range 0.29-0.59 Hz (wavelengths 4.5-20 m) retrieved from the satellite images of the QuickBird and Resurs-P satellites with the spectra measured using wave buoys. The value of the retrieving parameter of the spatial-frequency filter for the section of the power-law decay of the wave frequency spectrum is updated based on the results of the studies. This value is estimated as -0.05 applied to complex wave formation conditions (long fetch, wave system of wind waves and various swell waves), which differs from the previously estimated values of -0.43 in the conditions of limited fetch.

Validation of the Satellite Method for Measuring Spectra of Spatially Inhomogeneous Sea Waves

“…It is known that the state of sea waves is quite fully described using the spatial and frequency energy spectra of sea waves [1]. Methods for remote measurement of these spectra are being actively developed [3,[15][16][17][19][20][21][22].…”

“…In turn, the retrieval of wave spectra from satellite images makes it possible to obtain a one-time spectral characteristic of waves for a large water area [3,15,16]. Moreover, this approach facilitates the study of offshore water areas [17,18].…”

“…To adequately apply the multi-parameter retrieving operator under various wave formation conditions, the parameters were previously refined in [17,19,20]. To do this, we used the results of the comparison of remotely measured spectra of the rough sea surface with the data of sea truth measurements, which were carried out using sensors installed on a stationary hydrophysical platform and on floating buoys [17,18]. As a result of comparison in the range of power-law decay of the frequency spectrum, a correction for the parameters of the retrieving operator was previously obtained.…”

“…As a result of comparison in the range of power-law decay of the frequency spectrum, a correction for the parameters of the retrieving operator was previously obtained. The resulting correction corresponds to wave formation in the water area, where mixed waves are observed including both wind waves under the conditions of large fetch and swell waves [17][18][19].…”

Method of Studying Modulation Effects of Wind and Swell Waves on Tidal and Seiche Oscillations

“…The phenomenon of modulation of short-period waves on long waves is currently widely used in the field of non-contact methods for sea surface monitoring. These processes are mainly investigated during space monitoring by means of analyzing optical [1,2] and radar images [3,4] received from the satellites to restore the structure of the rough sea surface. A two-scale model of the sea surface was used in analysis of radar images.…”