Karakteristik Elevasi Muka Air Laut di Selat Madura
Authors: Ashari Sofyana , Wicaksono Ashari , Nuzula Nike Ika , Siswanto Aries Dwi 
Published: November 2024

Abstrak. Penelitian ini bertujuan untuk memahami karakteristik elevasi muka air laut di Selat Madura dengan memanfaatkan data altimetri dan divalidasi menggunakan data tide gauges. Data pengukuran diambil pada bulan Agustus 2022. Metode analisa menggunakan statistik dan FFT untuk memperoleh nilai komponen pasang surut dan elevasi air laut rata-rata. Hasil penelitian menunjukkan variasi nilai SSH di wilayah perairan Indonesia berkisar 0.4 - 0.8 m dan ± 0.6 m di Selat Madura, sedangkan hasil analisa tide gauge menunjukkan 1.2 – 1.4 m. Ada perbedaan signifikan dan ditunjukkan oleh nilai RMSE pada stasiun Surabaya 0.81; Kalianget 0.98; dan Probolinggo 0.94. Data tide gauges diolah lebih lanjut menggunakan metode admiralty sehingga diperoleh 15 komponen harmonik pasang surut, terdiri atas komponen diurnal [M1, K1, O1, P1, Q1, J1, OO1], semidiurnal [M2, S2, K2, N2, L2, 2N2], dan shallow water [M4 dan MS4], sehingga diketahui dominasi komponen diurnal (P1 dan K1) di stasiun pengukuran Surabaya dan Kalianget maupun komponen semidiurnal (N2 dan L2) di stasiun pengukuran Probolinggo. Hasil analisis FFT menunjukkan tipe pasang surut di Selat Madura tergolong tipe pasang surut campuran condong ganda/semidiurnal dengan nilai elevasi muka air laut tidak jauh berbeda pada tiga lokasi pengukuran. Nilai HHWL tertinggi di stasiun Probolinggo (3.3455 m), nilai LLWL terendah di stasiun Kalianget (0.5493 m). Nilai MSL masing-masing stasiun Surabaya, stasiun Kalianget, dan stasiun Probolinggo secara berturut-turut 1.4262 m; 1.2616 m; dan 1.8541 m. Perbedaan nilai MSL sesuai hasil analisa data altimetri dan tide gauge berkaitan dengan lokasi penelitian yang berada di wilayah pantai. Diharapkan bahwa penggunaan metode FFT dapat digunakan sebagai salah satu alternatif dalam mengetahui karakteristik pasang surut dari stasiun pengukuran yang tersebar di Selat Madura.Abstract This study aims to understand the characteristics of sea level elevation in the Madura Strait by tide gauges and SSH data at three stations around the Madura Strait. Measurement was taken in August 2022. The analysis used statistics and FFT approach. The variation of SSH in Indonesian waters ranges from 0.4 - 0.8 m and ± 0.6 m in the Madura Strait, while the results of tide gauge analysis show 1.2 - 1.4 m. There is a significant difference and is shown by the RMSE value at Surabaya station 0.81; Kalianget 0.98; and Probolinggo 0.94. The tide gauge data were also further processed using the admiralty method to obtain 15 tidal harmonic components, consisting of diurnal component [M1, K1, O1, P1, Q1, J1, OO1], semidiurnal [M2, S2, K2, N2, L2, 2N2], and shallow water [M4, and MS4], so that the dominance of diurnal components (P1 and K1) at Surabaya and Kalianget measurement stations and semidiurnal components (N2 and L2) at Probolinggo measurement station is known. Meanwhile, the results of the FFT analysis show that the tidal type in the Madura Strait is classified as a mixed double-semidiurnal tidal type with sea level elevation values not much different at the three measurement locations. The highest HHWL value at Probolinggo station (3.3455 m), the lowest LLWL value at Kalianget station (0.5493 m). The MSL values of Surabaya station, Kalianget station, and Probolinggo station are 1.4262 m; 1.2616 m; and 1.8541 m, respectively. The difference in MSL values between altimetry and tide gauge data is caused by the location which is a coastal area, where SSH altimetry data is loss data in the area. It is expected thatt the use of the FFT method can be used as an alternative in knowing the tidal characteristics of measurement stations spread in the Madura Straits.Submitted: 2024-02-28 Revisions:  2024-09-11 Accepted: 2024-09-25 Published: 2024-09-25