Internal solitary waves observation and feature extraction based on wavelet transform by Sentinel-1A in Lombok Strait, Indonesia

  • Chonnaniyah Chonnaniyah Institut Sains dan Teknologi Nahdlatul Ulama Bali (ISTNUBA)
  • Takahiro Osawa Center for Research and Application of Satellite Remote Sensing (YUCARS), Yamaguchi University
  • I Wayan Gede Astawa Karang Department of Marine Sciences, Faculty of Marine Science and Fisheries, Udayana University

Abstract

Lombok Strait is an essential pathway in trans-oceanic water mass transport. Due to this water mass transport flowing over Indonesian waters, the current is known as Indonesian Throughflow (ITF), which plays a role in the transfer of warm water masses from the Pacific to the Indian Ocean annually. Lombok Strait has intensive characteristics of the internal waves (IWs) generation because of the strong current that passes through the complex bathymetry along the strait area. IWs with large amplitude and nonlinear properties are known as Internal Solitary Waves (ISW) that can be detected by Synthetic Aperture Radar (SAR) images. A Wavelet Transform method for ISW feature extraction was applied to SAR images by Sentinel-1A (C-band). ISW packet characteristics can be distinguished from other phenomena based on their geometrical structure and shape. ISW packet pattern consists of light and dark lines which decrease intensity from front to rear. SAR observation detected 5 parameters (phase speed, soliton numbers, wavelength, first crest length, and propagation direction). The arc-like ISW in the Lombok Strait propagated to the North of the sill with average phase speeds of about 2.13 m/s and was frequently detected during the northwest monsoon (NWM). The detected soliton number is less than 6 solitons per packet with a wavelength of about 1 – 4 km, and the first crest length varies from about 12.16 km to more than 100 km. ISW detected in Sentinel-1A images were located at the bathymetry about 800 meters around the Lombok Strait area.

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Published
2024-03-12
How to Cite
CHONNANIYAH, Chonnaniyah; OSAWA, Takahiro; KARANG, I Wayan Gede Astawa. Internal solitary waves observation and feature extraction based on wavelet transform by Sentinel-1A in Lombok Strait, Indonesia. International Journal of Environment and Geosciences, [S.l.], v. 5, n. 1, p. 36-43, mar. 2024. ISSN 2549-8878. Available at: <https://ojs.unud.ac.id/index.php/ijeg/article/view/91382>. Date accessed: 21 nov. 2024. doi: https://doi.org/10.24843/ijeg.2024.v05.i01.p05.