A Study on Brightness Reversal of Internal Waves in the Celebes Sea Using Himawari-8 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.