Propagation Characteristics of Internal Waves in the Strait of Gibraltar Based on MODIS Remote Sensing Images

A geostationary meteorological satellite is located at a fixed point above the equator, which can continuously observe internal waves and provides great advantages in research on changes in the generation and propagation of internal waves. The scale of internal waves in the Celebes Sea is large, which is still very obvious in geostationary meteorological satellite images with a lower spatial resolution. This study considers continuous remote sensing images of geostationary meteorological satellite Himawari-8 to analyze the bright and dark features of internal waves in the Celebes Sea in optical remote sensing images. The solar zenith angle, sensor zenith angle and relative azimuth angle of internal waves in six images are calculated, and the changes are 12.45°, 0.20° and 3.44°, respectively, within 50 min. Moreover, based on the normalized sunglint radiance theory, the critical solar viewing angle is proposed and verified. The results indicate that the bright and dark features of internal waves when passing through sunglint and non-sunglint areas are greatly reversed, and the critical solar viewing angles are 18.73° and 27.41°, respectively. In this study, geostationary meteorological satellite Himawari-8 images are analyzed to study on the brightness reversal phenomenon of internal waves for the first time, and a unique brightness change in internal waves during the propagation process is revealed, which has not been reported in existing research.

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Studies of Internal Waves in the Strait of Georgia Based on Remote Sensing Images

Remote Sensing ◽

10.3390/rs11010096 ◽

2019 ◽

Vol 11 (1) ◽

pp. 96 ◽

Cited By ~ 2

Author(s):

Caixia Wang ◽

Xin Wang ◽

Jose C. B. Da Silva

Keyword(s):

Remote Sensing ◽

Internal Waves ◽

River Mouth ◽

Temporal Distribution ◽

Tidal Currents ◽

River Plume ◽

Remote Sensing Images ◽

Strait Of Georgia ◽

Narrow Channels ◽

Propagating Waves

This paper analyzes over 500 sets of internal waves in the Strait of Georgia (British Columbia, Canada) based on a large number of satellite remote sensing images. The spatial and temporal distribution of internal waves in the central region of the strait are discussed via statistical analysis. Possible generation origins of the observed internal waves are divided into three categories based on their different propagation directions and geographical locations: (1) the interaction between the narrow channels to the south of the Strait and the tidal currents, leading to the formation of mainly eastward and northward propagating waves; (2) the interaction between the tidal currents and the topography near Point Roberts, resulting in mainly westward propagating waves; (3) excitation by river plume, mainly near Fraser River mouth, leading to the formation of mainly westward waves along the direction of the river plume. The relation between the occurrence of internal waves in remote sensing images and wind or tide level is also discussed. It is found that most of the observed internal waves occur at low tides. However, due to the influence of the river, the eastward propagating internal waves near the river mouth seldom occur at the lowest tide. Also, internal waves are captured more easily by remote sensing images in summer due to the lower wind speed than winter and therefore the seasonal distribution of internal waves in remote sensing images may not be able to completely represent the real situation in the study area. Finally, combining the in situ measured data and model output data, the Benjamin-Ono equation is found to satisfyingly simulate the characteristic parameters of the studied internal waves.

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