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All Journal Jurnal Silvikultur Tropika (JST) Jurnal Ilmu dan Teknologi Kelautan Tropis Indonesian Journal of Geography JOURNAL OF COASTAL DEVELOPMENT Jurnal Matematika & Sains Journal of Mathematical and Fundamental Sciences International Journal of Advances in Intelligent Informatics JURNAL ILMIAH PENDIDIKAN FISIKA AL BIRUNI Science and Technology Indonesia Jurnal Penelitian Sains Jurnal Penelitian Pendidikan IPA (JPPIPA) Marine Research in Indonesia Jurnal Kelautan Nasional International Journal of Remote Sensing and Earth Sciences (IJReSES) Jurnal Teori dan Aplikasi Fisika Indobiosains SRIWIJAYA JOURNAL OF ENVIRONMENT Makara Journal of Science
Iskhaq Iskandar
University Of Sriwijaya
Agriculture, Biological Sciences & Forestry Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Computer Science & IT Decision Sciences, Operations Research & Management Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Environmental Science Immunology & microbiology Library & Information Science Materials Science & Nanotechnology Mathematics Physics Public Health Social Sciences

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Journal : Jurnal Matematika

 1 
Dynamics of Intraseasonal Sea Level Variations Observed at Gan Island and Sibolga Iskhaq Iskandar
Jurnal Matematika & Sains Vol 14, No 3 (2009)
Publisher : Institut Teknologi Bandung

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Dynamics of intraseasonal sea level variability in the central and eastern equatorial Indian Ocean is examined using 66 months (1 January 1993 to 30 June 1998) of the observed sea level at Gan Island (0°41S, 73°E) and Sibolga (1°45N, 98°46E). The analysis shows that the intraseasonal signals of 20-100-day at those two tidal stations are coherent and exhibit eastward energy propagation. These intraseasonal variations are associated with the propagation of equatorial Kelvin waves generated by the zonal winds along the equator. The lag-correlation analysis reveals that their phase speed is closed to the theoretical phase speed of the first and second baroclinic modes of the Kelvin waves.
30–75-day Sea Level Variations in The Equatorial Indian Ocean as Observed by Satellite Altimeter Iskhaq Iskandar
Jurnal Matematika & Sains Vol 16, No 1 (2011)
Publisher : Institut Teknologi Bandung

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Abstract

Basin-wide structure of intraseasonal sea level variations in the equatorial Indian Ocean is investigated using satellite altimeter data. The spectral analysis reveals that the intraseasonal sea level variations are dominated by the 30-75-day oscillations. The spatial amplitude structures of the intraseasonal sea level inferred from the complex empirical orthogonal function (CEOF) analysis show a typical structure of equatorial Kelvin and off-equatorial Rossby waves. Moreover, the spatial phase structures of the CEOF mode reveal eastward propagating signal. The estimated phase speed does not correspond exactly to that of one particular baroclinic modes though it falls within the range expected for the first three baroclinic modes in the Indian Ocean. This may suggest that the propagating signals do not involve a single baroclinic mode, but instead the first, second and possibly higher baroclinic modes.
Spatial and Temporal Variability of Sea Surface Height in the Southeastern Tropical Indian Ocean Based on the Satellite Altimeter Data Iskandar, Iskhaq; Mardiansyah, Wijaya; Setiabudidaya, Dedi
Jurnal Matematika dan Sains Vol 19 No 2 (2014)
Publisher : Institut Teknologi Bandung

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Sea surface height (SSH) data from merged-satellite observations (e.g. TOPEX/Poseidon, JASON and ERS) were used to evaluate the spatial and temporal variations of sea surface circulations in the southeastern tropical Indian Ocean (SETIO). A Complex Empirical Orthogonal Function (CEOF) was used to extract the dominant mode of variability in the SETIO region. The results show that the first mode accounts for 41.2% of the total variance dominates the variation. The second mode accounts for 18.2% of the total variance, while the third and the fourth modes explain 6.5% and 2.6% of the total variance, respectively. The spectrum analysis indicates that the 35-day variations is a prominent feature in all CEOF modes. Furthermore, semiannual variation at period of about 180-day was observed in the first third modes, while the annual variation of about 300-day was only observed in the first two modes. A relatively strong variation at period of around 500-day was observed in the first, second and fourth modes. It is suggested that the spatial and phase pattern of the first and third modes are related to the propagation of the Kelvin waves generated by wind stress over the equatorial Indian Ocean. On the other hand, the second was likely related to the local upwelling and downwelling generated by the seasonal changes in the alongshore winds. Furthermore, the fourth mode represents the oceanic eddy generated from the downstream straits of the Indonesian Throughflow.Variasi Spasial dan Temporal Tinggi Muka Laut di Wilayah Tropis Samudera India Bagian Tenggara Berdasarkan Data Satelit AltimetriAbstrak Data tinggi permukaan laut hasil observasi dari beberapa satelit (yaitu: TOPEX/Poseidon, JASON dan ERS) digunakan untuk evaluasi variasi spasial dan variasi temporal sirkulasi permukaan laut di wilayah tropis Samudera Hindia bagian tenggara. Analysis dilakukan menggunakan metode Complex Empirical Orthogonal Function (CEOF) untuk mendapatkan mode variasi yang dominan di wilayah ini. Hasil analisis menunjukkan bahwa mode CEOF pertama menjelaskan 41,2% dari variasi total dan merupakan mode yang paling dominan. Mode CEOF kedua mengandung 18,2% dari variasi total, sedangkan mode ketiga dan keempat menjelaskan masing-masing 6,5% dan 2,6% dari variasi total. Analisis spektrum terhadap deret waktu masing-masing mode CEOF menunjukkan bahwa variasi dalam skala 35 hari merupakan variasi yang signifikan untuk setiap mode. Selanjutnya, variasi setengah-tahunan dengan periode osilasi sekitar 180 hari terekam pada tiga mode pertama, sementara variasi tahunan dengan periode osilasi sekitar 300 hari hanya terekam pada mode pertama dan mode kedua. Variasi yang cukup kuat pada periode osilasi sekitar 500 hari terekam pada mode pertama, mode kedua dan mode keempat. Hasil analisis ini juga menunjukkan bahwa pola spasial dan fase gelombang pada mode pertama dan mode ketiga adalah terkait dengan penjalaran gelombang Kelvin yang dibangkitkan oleh stres angin di wilayah ekuator Samudera Hindia. Sementara itu, mode kedua terkait dengan proses upwelling dan downwelling yang dibangkitkan oleh angin muson di sepanjang pantai. Selanjutnya, mode keempat merepresentasikan oceanic eddy yang terbentuk dari selat-selat arus lintas Indonesia (ARLINDO).  Kata kunci: Complex empirical orthogonal function, Analisis Fourier, Samudera Hindia, Tinggi permukaan laut. 
Co-Authors Aan Johan Wahyudi Adam Darmawan Afdal Agus Dwi Saputra Akmal Johan ANDY MULYANA Anna IS Purwiyanto Apriani, Yosi Arsali Arsali Azhar Affandi Azhar Kholiq Affandi Dedi Setiabudidaya Deni Okta Lestari Deni Okta Lestari Dominikus Krisna Herlambang Dwi Setyawan Eddy, Syaiful Edy Sutriyono Edy Sutriyono Fadli Syamsuddin Fena Siska Putriyani Hamdi akhsan, Hamdi Hilda Zulkifli Hilda Zulkifli Ian Mochamad Sofian Indra Yustian Keisuke Mizuno Khakim, Mokhamad Yusup Nur Kusuma, Willy Anta Lestrai, Deni Okta Melly Ariska Moh. Rasyid Ridho Mokhamad Yusup Nur Khakim Muhammad Hendri Muhammad Irfan Muhammad Irfan Muhammad Nur Nuril Azhar Pradanto Poerwono Puad Maulana Mandailing Qurnia Wulan Sari Raden Putra Rezi Apri Rozirwan . Sabaruddin Kadir Sabaruddin Sabaruddin SABARUDDIN, . Septi Hermialingga Supari Supari Supari Supari Syaiful Eddy Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah Wijaya Mardiansyah, Wijaya Yukio Masumoto Zulfikhar Zulfikhar Zulfikhar, Zulfikhar Zulkifli Dahlan