Judul: Analisis Variabilitas Konsentrasi Klorofil-a terhadap Hasil Tangkapan Ikan Tongkol di Perairan Selat Bali Menggunakan Citra Aqua MODIS
Abstrak: Selat Bali merupakan perairan yang kaya akan sumberdaya perikanan, salah satunya adalah ikan tongkol yang tergolong sebagai ikan pelagis besar dan memiliki potensi ekonomi tinggi. Hasil tangkapan ikan tongkol dipengaruhi oleh beberapa faktor oseanografi seperti konsentrasi klorofil-a. Penelitian ini bertujuan menganalisis sebaran dan variabilitas konsentrasi klorofil-a menggunakan citra Aqua MODIS dan hubungannya dengan produksi tangkapan ikan tongkol di perairan Selat Bali. Data produksi diperoleh dari hasil tangkapan ikan tongkol yang didaratkan di PPN Pengambengan dan PPP Muncar pada tahun 2018 – 2022. Data klorofil-a dan SPL menggunakan data citra Aqua MODIS level-3 dengan resolusi 4 x 4 km. Data angin menggunakan data re-analisis dari Marine Copernicus dengan resolusi 0,25 x 0,25° pada Januari (musim barat) dan Juli (musim timur) 2018 – 2022. Pengolahan data klorofil-a diolah menggunakan metode interpolasi Inverse Distance Weight (IDW), kemudian dilakukan analisis korelasi silang (crosscorellation) untuk mengetahui hubungan antara konsentrasi klorofil-a terhadap hasil tangkapan ikan tongkol. Hasil variabilitas klorofil-a dan SPL di perairan Selat Bali pada tahun 2018 – 2022 menunjukan rata-rata SPL sebesar 25,4 – 31°C, dan konsentrasi klorofil-a sebesar 0,21 – 2,9 mg/m³. Hasil pola kecepatan dan arah angin menunjukan pada musim timur sebesar 2,44 m/s dengan arah 94,97°, sedangkan pada musim barat 4,21 m/s dengan arah 250,35°. Korelasi antara klorofil-a dan hasil tangkapan ikan tongkol menunjukan hubungan positif cukup kuat dengan jeda waktu 0 – 2 bulan., The Bali Strait is rich in fishery resources, including bullet tuna, a large pelagic fish with high economic potential. The catch of bullet tuna is influenced by various oceanographic factors, including chlorophyll-a concentration. The objective of this study was to analyze the distribution and variations in chlorophyll-a concentration by using Aqua MODIS imagery. Furthermore, the study aimed to investigate how the distribution and changes in chlorophyll-a concentration are associated with the production of bullet tuna in the Bali Strait waters. The production data was collected from the catch of bullet tuna landed at PPN Pengambengan and PPP Muncar from 2018 to 2022. The chlorophyll-a and sea surface temperature (SST) data were derived from Aqua MODIS level-3 image data with a 4 x 4 resolution. The wind data uses reanalysis data from Marine Copernicus with a resolution of 0.25 x 0.25° in January (northeast monsoon) and July (southwest monsoon) between 2018 - 2022. The Inverse Distance Weight (IDW) interpolation method processed the chlorophyll-a data. After that, cross-correlation analysis was conducted to determine the relationship between chlorophyll-a concentrations and bullet tuna catch. The results showed that the average SST in the waters of the Bali Strait from 2018 to 2022 was 25.4 to 31°C, and chlorophyll-a concentrations ranged from 0.21 to 2.9 mg/m³. The results of wind speed and direction patterns show that in the east season, it is 2.44 m/s with a direction of 94.97°, while in the west season, it is 4.21 m/s with a direction of 250.35°. The correlation between chlorophyll-a and bullet tuna catch indicated a strong positive relationship with a time lag of 0-2 months.
Keyword: Chlorophyll-a, Cross-Correlation, Bali Strait, Sea Surface Temperature (SST), Bullet Tuna

Judul: Variability of Sea Surface Temperature and Chlorophyll-a and Its Relationship with Bullet Tuna (Auxis rochei) Production in Southern West Java Waters
Abstrak: Perairan Selatan Jawa Barat merupakan perairan dengan dinamika oseanografi yang kompleks yang dipengaruhi variabilitas iklim, seperti angin monsun dan Indian Ocean Dipole (IOD). Perairan ini memiliki potensi perikanan tongkol lisong (Auxis rochei) yang tinggi sehingga perlu dikaji agar dapat dimanfaatkan secara optimal. Dinamika perairan akan mempengaruhi kondisi perikanan tongkol lisong. Penelitian ini bertujuan menganalisis variabilitas suhu permukaan laut (SPL) dan konsentrasi klorofil-a dari citra Aqua-MODIS serta hubungannya dengan produksi tongkol lisong di perairan selatan Jawa Barat. Data yang digunakan berupa data produksi tongkol lisong dari logbook Pelabuhan Perikanan Nusantara Palabuhanratu, Dipole Mode Index, dan citra Aqua-MODIS level 3. Analisis korelasi silang digunakan untuk menganalisis pengaruh dan jeda waktu pengaruh konsentrasi klorofil-a sebagai indikator kelimpahan fitoplankton terhadap produksi ikan tongkol lisong. Hasil estimasi SPL rata-rata bulanan pada tahun 2016 – 2020 berkisar 25,35 – 30,93 °C dan konsentrasi klorofil-a rata-rata bulanan berkisar 0,09 – 1,38 mg/m3. SPL bernilai tinggi dan konsentrasi klorofil-a rendah pada periode musim barat, sedangkan SPL bernilai rendah dan konsentrasi klorofil-a tinggi pada periode musim timur. Pada fase IOD negatif SPL tinggi dan konsentrasi klorofil-a rendah, sementara pada fase IOD positif SPL rendah dan konsentrasi klorofil-a tinggi. Produksi tongkol lisong (Auxis rochei) yang tinggi terjadi pada musim timur – musim peralihan 2 dengan SPL daerah penangkapan berkisar 26,46 – 29,02 °C dan konsentrasi klorofil-a berkisar 0,3 – 3,75 mg/m3. Terdapat pengaruh yang signifikan konsentrasi klorofil-a terhadap produksi tongkol lisong dengan jeda waktu 1 bulan., Southern West Java waters have complex oceanographical dynamics waters that are influenced by climate variabilities, such as monsoon and Indian Ocean Dipole (IOD). These waters have a high potential for bullet tuna (Auxis rochei) production so it needs to be studied to be utilized optimally. The dynamics of the waters will affect the condition of the bullet tuna fishery. This study aims to analyze the variability of sea surface temperature (SST) and chlorophyll-a concentration from Aqua-MODIS imagery and its relationship with bullet tuna production in southern West Java waters. The data used in this study were bullet tuna production from Palabuhanratu National Fishing Port logbook, Dipole Mode Index, and Aqua-MODIS level 3 imagery. Cross-correlation analysis was used to analyze the effect and time lag influence of chlorophyll-a as an indicator of the phytoplankton abundance on the bullet tuna production. The results of estimated monthly average SST in 2016 – 2020 ranges from 25,35 – 30,93 °C and monthly average chlorophyll-a concentration ranges from 0,09 – 1,38 mg/m3. SST was high and chlorophyll-a concentration was low in the west monsoon period, while the SST was low and chlorophyll-a concentration was high in the east monsoon period. Negative IOD causes high SST and low chlorophyll-a concentration, while positive IOD causes low SST and high chlorophyll-a concentration. The high production of bullet tuna (Auxis rochei) occurred in the east monsoon – second transition season with SST in the fishing ground ranges from 26,46 – 29,02 °C and chlorophyll-a concentration ranges from 0,3 – 3,75 mg/m3. There is a significant effect of chlorophyll-a concentration on bullet tuna production with a time lag of 1 month.
Keyword: Aqua-MODIS, Klorofil-a, Tongkol lisong, SPL, Bullet tuna, Chlorophyll-a, SST

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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