Agus S. Atmadipoera

Contrasted turbulence intensities in the Indonesian Throughflow: a challenge for parameterizing energy dissipation rate

Microstructure measurements were performed along two sections through the Halmahera Sea and the Ombai Strait and at a station in the deep Banda Sea. Contrasting dissipation rates (𝜖) and vertical eddy diffusivities (Kz) were obtained with depth-averaged ranges of ∼[9×10−10−10−5]

RANCANG BANGUN DAN UJI KINERJA WAVE BUOY SEBAGAI ALAT PENGUKUR TINGGI GELOMBANG PESISIR

\sim [9 \times 10^{-10}-10^{-5}]

Sedimentation in lagoon waters (Case study on Segara Anakan Lagoon)

W kg− 1 and of ∼[1×10−5−2×10−3]

Physical processes contributing to the water mass transformation of the Indonesian Throughflow

\sim [1 \times 10^{-5}-2 \times 10^{-3}]

Observed features of the Halmahera and Mindanao Eddies

m2 s− 1, respectively. Similarly, turbulence intensity, I=𝜖/(νN2)

Characteristics and variability of the Indonesian throughflow water at the outflow straits

I={\epsilon }/(\nu N^{2})

Estimates of tidal mixing in the Indonesian archipelago from multidisciplinary INDOMIX in-situ data

with ν the kinematic viscosity and N the buoyancy frequency, was found to vary seven orders of magnitude with values up to 107

Deep circulation driven by strong vertical mixing in the Timor Basin

10^{7}

Struktur Arus dan Variasi Spasial Arlindo di Selat Makassar dari EWIN 2013

. These large ranges of variations were correlated with the internal tide energy level, which highlights the contrast between regions close and far from internal tide generations. Finescale parameterizations of 𝜖 induced by the breaking of weakly nonlinear internal waves were only relevant in regions located far from any generation area (“far field”), at the deep Banda Sea station. Closer to generation areas, at the “intermediate field” station of the Halmahera Sea, a modified formulation of MacKinnon and Gregg (2005) was validated for moderately turbulent regimes with 100 < I < 1000. Near generation areas marked by strong turbulent regimes such as “near field” stations within strait and passages, 𝜖 is most adequately inferred from horizontal velocities provided that part of the inertial subrange is resolved, according to Kolmogorov scaling.

REKAM SEDIMEN INTI UNTUK MEMPERKIRAKAN PERUBAHAN LINGKUNGAN DI PERAIRAN LERENG KANGEAN

Gelombang di laut memiliki pergerakan yang acak dan komplek, sehingga tinggi dan periode gelombang sulit untuk diukur dan dirumuskan secara akurat. Wahana terapung seperti wave buoy dengan sensor percepatan telah banyak digunakan untuk mengukur gelombang permukaan. Penelitian ini bertujuan merancang dan membuat wave buoy sederhana sebagai pengukur tinggi gelombang di perairan pantai serta menguji coba kinerja alat yang dihasilkan pada skala laboratorium dan skala lapang, sehingga alat yang dihasilkan mampu bekerja dengan baik. Hasil perhitungan terhadap dimensi atau ukuran buoy diperoleh nilai metasentrum sebesar 2,5 dimana hal ini menunjukkan bahwa wahana pelampung stabil. Selain itu, perbedaan kecepatan pada uji coba di laboratorium berhasil diperoleh gelombang yang memiliki dua frekuensi yang berbeda, dengan galat pengukuran yang diperoleh sebesar 0,01-0,07 m dengan periode yang terukur sebesar. Kinerja alat yang dilakukan di Teluk Palabuhan Ratu diperoleh beberapa tipe gelombang yang dihasilkan. Pengujian selama 24 jam diperoleh 4 periode yang signifikan yang terbagi ke dalam tiga kelompok gelombang yakni periode 1 detik, 3,37 detik kelompok gelombang angin, 1,20 jam kelompok gelombang variasi angin dan 12 jam kelompok gelombang pasang surut. Alat yang dihasilkan dapat berfungsi dengan baik mampu menyimpan data, memiliki nilai akurasi yang tinggi dapat merekam gelombang dengan periode kecil hingga periode besar.Ocean wave has complex and random characteristics that makes, which may cause the wave height and period are difficult to measure and to predict. In this paper we describe the development of wave buoy instrument was made using the acceleration sensor to monitor of buoys position in 3 axes (xyz). The measurement results shown metasentrum value is 2.5 which means that the buoy is stable. In addition, the difference in speed during the test successfully illustrated by means of the presence of two different frequencies with error is 0.01-0.07 m for a periode of 2.91 s and 4.95 s. Field measurement in the Palabuhan Ratu bay was succesfully obtaining some type of generated waves. The field trial that was done for 24 hours showed 4 significant period, clasisifield into 1 second and 3.37 second (wind wave), 1.20 hour (anomaly wave), and 12 hour (tidal wave). In conclusion, the wave buoy developed was successfully tested and performed well at sea trial, where the wave buoy capable of recording various wave spectrum.