Analisis Pola Spasial dan Variabilitas Musiman Parameter Oseanografi di Perairan Jawa Timur

Abstract

Perairan Jawa Timur merupakan wilayah yang dipengaruhi oleh interaksi dinamika Laut Jawa dan Samudera Hindia sehingga memiliki variabilitas oseanografi yang kompleks. Penelitian ini bertujuan menganalisis pola spasial dan variabilitas musiman suhu permukaan laut, salinitas permukaan, tinggi permukaan laut, arus permukaan, dan angin, serta mengkaji pengaruh angin Musim Timur terhadap transport Ekman di Perairan Jawa Timur. Penelitian menggunakan data model oseanografi CROCO periode 2004 - 2006 yang divalidasi menggunakan data observasi satelit. Analisis dilakukan secara spasial dan temporal melalui pendekatan klimatologi musiman, Empirical Orthogonal Function (EOF), dan Power Spectral Density (PSD). Hasil penelitian menunjukkan adanya perbedaan karakteristik yang jelas antara perairan utara dan selatan Jawa Timur. Perairan utara memiliki suhu lebih hangat, salinitas lebih rendah, dan tinggi muka laut yang relatif stabil akibat pengaruh perairan dangkal dan masukan air tawar. Sebaliknya, perairan selatan menunjukkan suhu lebih rendah, salinitas lebih tinggi, dan variabilitas tinggi muka laut yang lebih dinamis akibat pengaruh Samudera Hindia dan proses upwelling. Analisis EOF menunjukkan Mode 1 mendominasi variabilitas SPL (81.72%), salinitas (65.19%), dan TPL (78.41%), yang merepresentasikan pengaruh utama sistem monsun. Penguatan angin tenggara pada Musim Timur meningkatkan wind stress dan transport Ekman menjauhi pantai sehingga memicu upwelling yang ditandai oleh penurunan suhu permukaan laut, peningkatan salinitas, dan penurunan tinggi muka laut di selatan Jawa Timur.

The waters off East Java are influenced by the interaction between the dynamics of the Java Sea and the Indian Ocean, resulting in complex oceanographic variability. This study aims to analyse the spatial patterns and seasonal variability of sea surface temperature, surface salinity, sea level, surface currents and wind, as well as to examine the influence of the East Monsoon winds on Ekman transport in the waters off East Java. The study utilised CROCO oceanographic model data from the period 2004 - 2006, validated using satellite observation data. Analyses were conducted spatially and temporally using seasonal climatology, Empirical Orthogonal Function (EOF), and Power Spectral Density (PSD) approaches. The study utilised data from the CROCO oceanographic model for the period 2004–2006, which was validated using satellite observation data. Analyses were conducted spatially and temporally using a seasonal climatology approach, Empirical Orthogonal Function (EOF), and Power Spectral Density (PSD). The results indicate clear differences in characteristics between the northern and southern waters of East Java. The northern waters have warmer temperatures, lower salinity, and relatively stable sea levels due to the influence of shallow waters and freshwater inflow. Conversely, the southern waters exhibit lower temperatures, higher salinity, and more dynamic sea level variability due to the influence of the Indian Ocean and upwelling processes. EOF analysis indicates that Mode 1 dominates the variability of SST (81.72%), salinity (65.19%), and SSH (78.41%), representing the primary influence of the monsoon system. The strengthening of the south-easterly winds during the East Monsoon increases wind stress and Ekman transport away from the coast, thereby triggering upwelling characterised by a decrease in sea surface temperature, an increase in salinity, and a decrease in sea level in the south of East Java.