IDENTIFIKASI WILAYAH UPWELLING BERDASARKAN VORTISITAS DAN DIVERGENSI DI PERAIRAN SELATAN JAWA HINGGA NUSA TENGGARA BARAT
Abstract
Abstrak
Salah satu perairan di Indonesia yang telah teridentifikasi sebagai lokasi upwelling adalah perairan selatan Jawa hingga Nusa Tenggara Barat. Identifikasi daerah upwelling berdasarkan hasil model HAMSOM Baroklinik 3D menunjukkan bahwa upwelling paling kuat terjadi di perairan selatan Jawa Timur pada saat musim timur. Hasil model menunjukkan bahwa Arlindo yang melalui Selat Lombok berperan terhadap penguatan arus ke arah barat (arus zonal) di lepas pantai selatan Jawa Timur. Penguatan arus ke arah barat di lepas pantai menyebabkan kecepatan geser (shear velocity) ke arah pantai selatan Jawa Timur. Kecepatan geser ke arah pantai menimbulkan vortisitas negatif dan terjadinya zona divergensi sehingga mengakibatkan kekosongan massa air di permukaan yang dapat meningkatkan intensitas upwelling di pantai selatan Jawa Timur. Transpor Arlindo maksimum terjadi pada bulan Agustus sebesar 1,30 Sv. Analisis statistik menunjukkan bahwa transpor Arlindo memiliki korelasi yang kuat terhadap arus zonal di perairan selatan Jawa Timur dengan koefisien korelasi sebesar 0,78. Vortisitas maksimum terdapat pada bulan Agustus sebesar -8,82 x 10-6 s-1 dan divergensi horizontal sebesar +3,60 x 10-6 s-1.
Kata-kata kunci: Arlindo, arus zonal, kecepatan geser, vortisitas, divergensi.
Abstract
One of the Indonesia waters that have been identified as the location of upwelling are southern waters of Java to West Nusa Tenggara. Identification of upwelling area based on the simulation results of the HAMburg Shelf Ocean Model (HAMSOM) 3D Baroclinic showed that a stronger intensity in the southern waters of East Java in the shoutheast monsoon. The results showed that the ITF through the Lombok Strait contributes to the strengthening of the westward flow (zonal flow) off the south coast of East Java. The Strengthening of westward flows off the coast caused a shear velocity towards the southern coast of East Java. Shear velocity towards onshore caused negative vorticity and occurred the horizontally divergence zone which resulted vacancy of water masses in the surface so as to increase the intensity of upwelling. The maximum ITF was occurred in August with value 1.30 Sv and which caused westward flows to be stronger. The statistical analysis showed that the ITF transport has a strong correlation with the zonal currents in the southern waters of East Java with a correlation coefficient 0.78. The maximum vorticity was found in August with value -8.82 x 10-6 s-1 and the maximum horizontally divergence +3.60 x 10-6 s-1.
Keywords: ITF, zonal flow, shear velocity, vorticity, divergence.
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