The improvement of ultrasonic sensor-based device for direct ocean wave measurement program at Western Java Sea – Indonesia

Sea wave measurement program in the Western Java Sea has been carried out comprehensively over a full one-year period. This activity requires tools that can work robustly and accurately in the long run in the open ocean environment; one of which is the result of modified tidal gauges based on ultrasonic sensors. Testing of modified device has been carried out simultaneously with the RBRduo wave recorder which is installed close to one another. The test was conducted at Ancol beach, Jakarta Bay, with a sampling frequency of 6 Hz, and the measurement time was carried out for 15 days. Measurement data were analyzed by applying the harmonic sea level elevation method, single wave evaluation, and statistical correlation methods. The results of the harmonic analysis show similar types of daily sea level elevations, as well as 9 (nine) daily elevation constituents that are mutually compatible with each other. Results of the wave analysis from the modified device show Hav = 11.9 cm, Hs = 15.4 cm, and Hmax = 41.1 cm, while the RBRduo instrument shows Hav = 11.8 cm, Hs = 18.1 cm, and Hmax = 39.9 cm. Statistical analysis of the wave data shows that the values produced indicate the results of measurements with the two devices have a high correlation. Therefore, it can be concluded that the modified instrument will be ready and reliable to be used for long-term wave measurements. A sample of measurements from the wave station at the Western Java Sea is shown by the end of this paper.