Radar Signatures and Ocean Color Response of Internal Wave-Wave Interactions Between the Lombok Strait and the Flores Sea
I Wayan Gede Astawa Karang(1,2*), I Gede Hendrawan (1,2), I Made Dwita Krisnanda (1), I Gusti Bagus Sila Dharma (1), I Wayan Krisna Eka Putra (3), I Made Mahendra Wicaksana Karang (1), Jonson Lumban Gaol (4)

1) Faculty of Marine Science and Fisheries, Udayana University, Indonesia
2) Centre for Remote Sensing and Ocean Sciences (CReSOS), Udayana University, Indonesia
3) Universitas Pendidikan Ganesha, Indonesia
4) Department of Marine Science and Technology, Bogor Agricultural University, Indonesia

Abstract

Many internal solitary wave (IWs) patterns have been observed in satellite images, particularly in the Lombok Strait and Flores Sea. However, there are no studies that have been made on internal wave interaction patterns in this area. Internal wave interactions may result in exceptionally large amplitudes in the interaction zone, which in turn pose threats to underwater structures. In this paper, we analyze the surface manifestation of internal wave-wave interaction patterns observed in satellite images of the Flores Sea. The data used are a Sentinel-1 SAR image (October 28, 2018) and a GCOM-C optical image (October 29, 2018). The methods applied to both images consist of preprocessing, image enhancement, and pattern extraction. The analysis of both images indicated the presence of internal wave packets propagating in the Lombok Strait and Flores Sea with soliton wavelengths of 3.9-5.0 km and phase velocities of 2.5-26 m/s. Analysis of the wave interactions revealed a clear grid-like interaction pattern, formed by the meeting of two non-linear internal wave packets originating from different sources. The first packet, propagating northward, was identified as originating from the Lombok Strait, while the second packet was propagating from the northeast. This ^woven^ pattern is a manifestation of a series of X-type interactions, forming rhomboid-shaped cells on the sea surface, with each grid cell area ranging from 19.3 - 21.4 km2. From visual analysis of the imagery, the angle between the wave crests is estimated to be approximately \(115\circ \) , indicating an interaction angle between the wave propagation directions of approximately \(65\circ \). This study indicates that both radar and optical are capable of detecting the surface manifestation of complex interactions by two or more internal wave packets. Further studies will focus on quantitative analysis of wave parameters to understand the impact of these interactions on local marine productivity.

Keywords: Internal Waves, Internal Wave-Wave Interaction, Sentinel-1, GCOM-C, grid-like interaction pattern, Flores Sea, Lombok Strait

Topic: Topic B: Applications of Remote Sensing