Judul: Dinamika populasi ikan lemuru, Sardinella Lemuru Bleeker 1853 (Pisces: Clupeidae) di perairan Selat Bali dan alternatif pengelolaannya
Abstrak: Perairan Selat Bali merupakan suatu bentuk perairan yang relatif sempit, berbentuk corong dengan luas kira-kira 2.500 km2 , produktivitasnya tinggi karena ter jadi proses penaikan air mulai kira-kira bulan April sampai Oktober. Ikan lemuru merupakan jenis ikan yang dominan yang tertangkap di perairan tersebut, produksinya berkisar antara 1.583-21.363 ton (32,85-97,9%) atau rata-rata 10.708 ton (78,46%) per tahun, sedangkan setiap bulannya berkisar antara 501-1.441 ton (65,86-92,89%) atau rata-rata 894 ton (76,07%) dalam periode 1984 sampai dengan 1989 (Data hanya dari KUD Mina Karya, Pengambengan, Bali).
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Judul: Tingkat Pemanfaatan dan Pola Musim Penangkapan Ikan Lemuru (Sardinella lemuru) di Perairan Selat Bali
Abstrak: Ikan lemuru (Sardinella lemuru) merupakan salah satu sumberdaya ikan di Perairan Selat Bali yang mempunyai potensi dan nilai ekonomis yang cukup tinggi. Produksi hasil tangkapan yang diperoleh saat ini sudah mengalami penurunan sebagai akibat terjadinya penangkapan berlebih (overfishing). Penelitian ini bertujuan untuk mengestimasi potensi lestari, tingkat pemanfaatan dan pengupayaan, serta pola musim penangkapan sumberdaya ikan lemuru di Perairan Selat Bali berdasarkan hasil tangkapan yang didaratkan di Pelabuhan Perikanan Pantai Muncar. Metode dalam penelitian ini menggunakan metode surplus produksi untuk mencari potensi lestari (maximum sustainable yield), upaya optimum serta tingkat pemanfaatan dengan menggunakan model Schaefer. Sedangkan pola musim penangkapan ikan menggunakan analisis deret waktu (time series data) dan metode rata-rata bergerak (moving average). Hasil analisis menunjukkan bahwa nilai potensi lestari dan upaya optimumnya sebesar 33.576 ton per tahun dan 26.696 trip per tahun. Adapun untuk tingkat pemanfaatan selama 2004-2008 telah melebihi nilai potensi lestari pada tahun 2006 dan 2007 yaitu sebesar 153% dan 161%, dan tingkat pengupayaan selama lima tahun terakhir telah melebihi upaya optimumnya sudah diatas 100%. Bulan Desember sampai Februari sangat baik untuk melakukan operasi penangkapan ikan lemuru karena sumberdaya ikan melimpah dan sudah layak tangkap. Sebaliknya, pada bulan Maret sampai Nopember merupakan waktu yang kurang baik dalam mengupayakan operasi penangkapan ikan lemuru karena sumberdaya ikan sedikit dan ukuran ikan belum layak tangkap.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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