Deteksi dan Kuantifikasi Internal Wave Menggunakan Instrumen Broadband Echosounder SIMRAD EK80 di Perairan Padang Bay Bali

Abstract

Internal wave adalah peristiwa yang terjadi di laut dangkal dan laut dalam, dimana kemunculan internal wave hanya dapat terjadi jika kolom air terstratifikasi akibat adanya perbedaan densitas massa air. Penelitian ini bertujuan mendeteksi peristiwa internal wave, serta mengukur nilai acoustic backscatter dari internal wave terjadi di Selat Lombok. Data yang digunakan adalah hasil pengukuran instrument broadband echosounder SIMRAD EK80 frekuensi 200 kHz tipe pulsa continuous wave (CW) dengan data pendukung elevasi muka air, suhu, salinitas, dan densitas dari Conductivity Temperature Depth (CTD) “yoyo” selama 24 jam. Nilai hambur balik didapatkan dengan analysis menggunakan perangkat lunak Sonar5-Pro. Echogram menunjukkan adanya pembentukan nonlinearinternal wave disertai dengan adanya turbulent terjadi pada saat gelombang pasang membawa massa air dengan densitas berbeda melewati topografi kasar di Selat Lombok. Nilai backscatter hasil segmentasi berentang dari -75 dB sampai -59 dB.

Internal waves are events that occur in shallow sea and deep sea, where the appreanced of internal waves can only occurs if the water column is stratified due to differences in water mass density. This study aimed to detect internal wave events, as well as measure the acoustic backscatter value of internal waves occurring in the Lombok Strait. The data used is the measurement result of SIMRAD EK80 broadband echosounder instrument with frequency of 200 kHz continuous wave (CW) pulse type with supporting data for water level elevation, temperature, salinity, and density from Conductivity Temperature Depth (CTD) “yoyo” for 24 hours. The backscatter value was obtained by analysis using the Sonar5-Pro software. Echogram showed the formation of nonlinear internal waves accompanied by the presence of turbulence that occur when high tidal waves carry water masses from different density through rough topography in Lombok Strait. The backscatter value of the segmentation results range from -75 dB to -59 dB.