WAVEFORM RETRACKING ANALYSES OF ALTIMETRY SATELLITE DATA AROUND GULF, SMALL ISLANDS, AND DEEP WATERS IN HALMAHERA SEA
| Main Authors: | Sinurat, Maya Eria Br, Nababan, Bisman, Lumban Gaol, Jonson |
|---|---|
| Format: | Article info application/pdf eJournal |
| Bahasa: | eng |
| Terbitan: |
Department of Marine Science and Technology, Faculty of Fisheries and Marine Science, IPB University
, 2019
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| Subjects: | |
| Online Access: |
http://journal.ipb.ac.id/index.php/jurnalikt/article/view/27101 http://journal.ipb.ac.id/index.php/jurnalikt/article/view/27101/18996 |
Daftar Isi:
- Akurasi estimasi tinggi muka laut (SSH) dari satelit altimeter sangat dipengaruhi oleh kondisi perairan dan daratan disekitar perairan tersebut. Estimasi SSH di laut lepas umumnya sudah akurat. Namun, pada daerah pantai, estimasi SSH kurang akurat karena gangguan pantulan sinyal dari daratan. Penelitian ini bertujuan untuk melakukan analisis retracking waveform satelit altimeter pada perairan yang kompleks di Laut Halmahera. Data yang digunakan pada penelitian ini yaitu data waveform dari Sensor Geophysical Data Record type D (SGDR-D) Jason-2 dan Jason-3 tahun 2017. Algoritma retracking yang digunakan yaitu Offset Centre of Gravity (OCOG), Iced, Threshold, dan Improved Threshold. Hasil retracking waveform menunjukkan semua retracker memberikan perbaikan data SSH yang signifikan kecuali OCOG. Retracker yang paling cocok diaplikasikan di Laut Halmahera pada teluk dangkal dan sempit yaitu Threshold 10%, pada teluk dalam dan lebar yaitu Threshold 50%, serta pada perairan dekat pulau pulau kecil yaitu Threshold 10% dan Threshold 20%. Secara umum, Non-Brown waveform lebih banyak ditemukan di perairan teluk dangkal dan sempit (rata-rata=63,49%) dibandingkan dengan teluk dalam dan lebar (rata-rata=11,51%) dan perairan pulau-pulau kecil (rata-rata=9,57%). Namun demikian, tingkat perbaikan data SSH di perairan teluk dangkal dan sempit lebih tinggi dibandingkan dengan teluk dalam dan lebar serta perairan pulau-pulau kecil dan laut dalam. Persentase peningkatan perbaikan data (IMP) tertinggi yaitu 96,71% dengan algoritma Improved Threshold 10% pada Jason-2 pass 164.
- The accuracy of sea surface height (SSH) estimation from altimeter satellites is strongly influenced by waters condition and coastal land. In general, SSH estimations in offshore are accurate. However, in coastal waters, SSH estimation are inaccurate due to the reflection of signal from land. The study purpose was to retrack the waveform of Altimeter satellites in a complex the Halmahera Sea. The data used for this study were the waveform Sensor Geophysical Data Record type D (SGDR-D) of Jason-2 and Jason-3 of 2017. To retrack waveform, we used several algorithms i.e., Offset Centre of Gravity (OCOG), Iced, Threshold, and Improved Threshold. All retrackers provided significant improvement in SSH estimations except OCOG. The best retracker used in Halmahera Sea for the shallow and narrow bay was Threshold 10%, for the deep and wide bay was Threshold 50%, and for small islands waters were Threshold 10% and Threshold 20%. In general, Non-Brown waveforms were more common in the shallow and narrow bay waters (average=63.49%) vs. the deep and wide bay waters (average=11.51%) and small island waters (average=9.57%). However, the improvement percentage of SSH estimations in the shallow and narrow bay waters was higher than the deep and wide bay waters and small islands waters. The best retrackers in the Halmahera Sea was the Threshold 10% algorithm with the IMP value of 96.71% on Jason-2 pass 164.