Judul: Variability of Chlorophyll-a Concentration and Sea Surface Temperature in the Western Java Sea Using MODIS Satellite Data on Fish Catches
Abstrak: Konsentrasi klorofil-a (Chl-a) dan Suhu Permukaan Laut (SPL) adalah parameter penting yang berpengaruh terhadap keberadaan sumberdaya ikan. Tujuan penelitian ini adalah menganalisis variabilitas konsentrasi klorofil-a dan SPL dari satelit Moderate Resolution Maging Spectroradiometer (MODIS), serta hasil tangkapan ikan di Perairan Laut Jawa bagian barat. Selain itu data pendukung lainnya berupa El Nino Southern Oscillation (ENSO) bulanan dan Indeks Dipole Mode (DMI) bulanan juga digunakan dalam peneltiian ini. Penelitian ini dilaksanakan pada bulan Desember 2021-Juli 2022 di Perairan Laut Jawa bagian barat. Data SPL dan klorofil-a dianalisis berdasarkan data rata-rata bulanan dari hasil estimasi satelitMODIS selama 12 tahun (Januari 2010-Desember 2021). Hasil penelitian menunjukkan nilai konsentrasi klorofil-a berada dikisaran 0.42 mg/m³–1.55 mg/m³ yang mengalami peningkatan pada musim barat dan timur serta mengalami penurunan pada musim peralihan 1 dan 2. Nilai SPL berada dikisaran 29.05°C-30.71°C dan mengalami peningkatan saat musim peralihan 1 dan 2 yang dipengaruhi oleh peningkatan intensitas radiasi matahari dan pergerakkan massa air dari Timur Laut menuju Barat Daya. Variabilitas SPL dan klorofil-a memiliki kecenderungan terhadap hasil tangkapan ikan tembang di Perairan Laut Jawa bagian barat dan sekitarnya. Pada saat fenomena La Nina (ENSO Indeks positif) dan Dipole Mode Index bernilai negatif terjadi secara bersamaan, nilai klorofil-a relatif lebih tinggi dari normalnya dan nilai SPL relatif lebih rendah dari normalnya., Concentration of chlorophyll-a (Chl-a) and sea surface temperature (SST) are important parameters that affect the existence of fish resources. The purpose of this study was to analyze the variability of chlorophyll-a concentrations and SST from the Moderate Resolution Maging Spectroradiometer (MODIS) satellite, as well as fish catches in the western Java Sea. In addition, other supporting data in the form of monthly El Nino Southern Oscillation (ENSO) and monthly Dipole Mode Index (DMI) are also used in this study. This research was carried out in December 2021-July 2022 in the western part of the Java Sea. SST and chlorophyll-a data were analyzed based on monthly average data from the estimation results of the MODIS satellite for 12 years (January 2010-December 2021). The results showed that the concentration of chlorophyll-a was in the range of 0.42 mg/m³–1.55 mg/m³ which increased in the west and east monsoons and decreased in transition seasons 1 and 2. SST values were in the range of 29.05°C-30.71°C and experienced increase during transitional seasons 1 and 2 which are influenced by increased intensity of solar radiation and movement of water masses from the Northeast to the Southwest. The variability of SST and chlorophyll-a has a tendency to catch tembang fish in the western Java Sea and its surroundings. When the La Nina phenomenon (positive ENSO Index) and negative Dipole Mode Index occur simultaneously, the chlorophyll-a value is relatively higher than normal and the SST value is relatively lower than normal.
Keyword: Klorofil-a, Musim, Suhu Permukaan Laut, Chlorophyll-a, Season, Sea Surface Temperature

Judul: Analisis Sebaran Klorofil-a dan Suhu Permukaan Laut Menggunakan Data Satelit Aqua Modis di Laut Jawa
Abstrak: Laut Jawa memiliki potensi sumber daya ikan yang besar. Suhu permukaan laut dan konsentrasi klorofil-a merupakan parameter oseanografi yang dapat mempengaruhi persebaran ikan. Penggunaan parameter ini dapat menganalisis sebaran suhu permukaan laut dan kloofil-a dengan memanfaatan teknologi penginderaan jauh. Tujuan penelitian ini untuk menganalisis sebaran klorofil-a dan suhu permukaan laut menggunakan sensor satelit Aqua Modis di Laut Jawa pada Tahun 2020.Penelitian ini berlokasi di perairan Laut Jawa menggunakan data citra Aqua MODIS bulanan selama tahun 2020. Penentuan nilai konsentrasi klorofil-a dan suhu permukaan laut yang sebelumnya telah diolah menggunakan interpolasi Inverse Distance Weighted (IDW). Analisis sebaran SPL rata-rata bulanan di Laut Jawa dari citra satelit Aqua MODIS tahun 2020 berkisar antara 28.5°C – 30.9°C. Penyebaran SPL di Laut Jawa mengikuti pola angin musim yang terjadi di perairan Indonesia dimana SPL cenderung turun pada musim barat dan timur serta naik pada musim peralihan 1 dan peralihan 2. Konsentrasi klorofil-a berkisar antara 0.54-4 mg/m³. Nilai konsentrasi klorofil-a setiap bulannya berfluktuasi mengikuti musim angin yang sedang berlangsung. Kata kunci: IDW, klorofil-a, Laut Jawa, suhu permukaan laut, The Java Sea has great potential for fish resources. Sea surface temperature and chlorophyll-a concentration are oceanographic parameters that can affect the distribution of fish. The use of this parameter can analyze the distribution of sea surface temperature and chlorophyll-a by utilizing remote sensing technology. The purpose of this study was to analyze the distribution of chlorophyll-a and sea surface temperature using the Aqua Modis satellite sensor in the Java Sea in 2020. This study was located in the waters of the Java Sea using monthly Aqua MODIS image data during 2020. Determination of the value of chlorophyll-a concentration and sea surface temperature which had previously been processed using Inverse Distance Weighted (IDW) interpolation. Analysis of the monthly average SST distribution in the Java Sea from Aqua MODIS satellite imagery in 2020 ranges from 28.5°C – 30.9°C. The distribution of SST in the Java Sea follows the pattern of monsoons that occur in Indonesian waters where SST tends to decrease in the west and east seasons and rises in transitional season 1 and transition 2. The concentration of chlorophyll-a ranges from 0.54-4 mg/m³. The value of the concentration of chlorophyll-a fluctuates every month following the ongoing wind season. Keywords: chlorophyll-a, IDW, Java Sea, sea surface temperature
Keyword: chlorophyll-a, IDW, Java Sea, sea surface temperature

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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