Muhammad Helmi
Department of Oceanography, Universitas Diponegoro, Jl. Prof. Sudarto, SH, Tembalang, Semarang, Indonesia 50275

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Pola Sebaran Material Padatan Tersuspensi Berdasarkan Pemodelan Hidrodinamika 2D Saat Pasang dan Surut di Perairan Pulau Menjangan Besar, Kepulauan Karimunjawa Danang Imaddudin Mahardika; Muhammad Helmi; Agus Anugroho Dwi Suryoputro
Indonesian Journal of Oceanography Vol 4, No 3 (2022): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v4i3.14383

Abstract

Perairan Karimunjawa khususnya pada perairan Pulau Menjangan Besar memiliki fungsi yang penting bagi masyarakatnya seperti jalur pelayaran kapal, perikanan, dan wisata. Oleh karena itu harus adanya pengawasan terkait kualitas air salah satunya adalah material padatan tersuspensi. Sampel material padatan tersuspensi diambil secara langsung dilapangan dengan beberapa parameter lainnya seperti batimetri dan arus. Untuk mengetauhi pola sebaran material padatan tersuspensi dilakukan dengan pendekatan model hidrodinamika 2D menggunakan perangkat lunak Mike 21 dengan beberapa modul seperti modul Hidrodinamika untuk pemodelan arus dan Mud Transport untuk pemodelan material padatan tersuspensi.  Model ini mensimulasikan sebaran material padatan tersuspensi selama periode 1 bulan. Verifikasi hasil model untuk arus dalam arah u dan v mendapat besaran 7,9% dan 6,1 % untuk arus. Hasil pemodelan didapatkan bahwa material padatan tersuspensi tersebar mengikuti pola arus pasang surut. Saat kondisi pasang material padatan tersuspensi akan bergerak mendekati daratan dan berkumpul sementara, sebaliknya pada saat surut material padatan tersuspensi akan tersebar diperairan dan bergerak kearah perairan terbuka.Kata kunci: Material Padatan Tersuspensi, Karimunjawa, Pola Sebaran, Mud Transport Abstract Karimunjawa waters have important functions for its people, such as shipping lanes, fisheries, and tourism. Therefore, there must be monitoring related to water quality, one of which is suspended solids. Suspended solid material is a very small sediment (suspended) that floats in the water column. Samples of suspended solids were taken directly in the field with several other parameters such as bathymetry and current. To find out the distribution pattern of suspended solids, a 2D hydrodynamics modeling approach was used using Mike 21 software with several modules such as the Hydrodynamics module for flow modeling and Mud Transport for suspended solids modeling. This model simulates the distribution of suspended solids over a period of 1 month. Verification of the current model in derection of u dan v results is 7.9% and 6.1% for current. The modeling results show that the suspended solids are dispersed following the current pattern in the waters and tidal currents are the main factor in the distribution of suspended solids.Keywords: Total Suspended Sediment, Karimunjawa, Distribution Pattern, Mud Transport
Analisis Mekanisme Pengaruh IOD, ENSO dan Monsun terhadap Suhu Permukaan Laut dan Curah Hujan di Perairan Kepulauan Mentawai, Sumatera Barat Yustina Wulan Millenia; Muhammad Helmi; Lilik Maslukah
Indonesian Journal of Oceanography Vol 4, No 4 (2022): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v4i4.14414

Abstract

Fenomena El-Niño Southern Oscillation (ENSO) dan Indian Ocean Dipole (IOD) berkaitan erat dengan suhu permukaan laut dan variabilitas curah hujan. Monsun Asia sering menyebabkan hujan lebat termasuk di Sumatera bagian utara sedangkan monsun Australia umumnya menyebabkan kemarau. Perairan Kepulauan Mentawai berada di dekat Samudra Hindia dan dilalui oleh garis khatulistiwa. Hal ini menyebabkan kondisi iklim curah hujan dipengaruhi oleh beberapa faktor seperti suhu muka laut, dipole mode, angin dan Niño 3.4. Data yang digunakan pada penelitian ini adalah data curah hujan (GSMaP), data suhu permukaan laut MUR Level 4 (GHRSST), data angin (ASCAT) yang diolah menggunakan metode komposit serta analisa koefisien korelasi dan koefisien determinasi. Saat fenomena IOD positif, sebesar 60,6% indeks IOD mempengaruhi suhu permukaan laut, sedangkan curah hujan sebesar 21,8%. Saat fenomena ENSO terutama saat La-Niña, indeks ENSO mempengaruhi SPL sebesar 15,8% dan mempengaruhi curah hujan sebesar 6,1%. Monsun asia mempengaruhi SPL sebesar 50,2% sedangkan monsun Australia sebesar 36,7%. Fenomena IOD lebih berpengaruh terhadap SPL dan curah hujan di Perairan Kepulauan Mentawai dibandingkan dengan fenomena ENSO. Saat fenomena El-Niño dan IOD positif suhu permukaan laut menurun diikuti dengan curah hujan rendah. Saat La-Niña dan IOD negatif SPL meningkat diikuti dengan curah hujan yang meningkat. Kecepatan angin yang tinggi menyebabkan SPL merendah.Kata kunci: Curah Hujan, ENSO, IOD, Monsun, SPL Abstract Analysis of Mechanisms of Influence of IOD, ENSO and Monsoon on Sea Surface Temperature and Rainfall in Mentawai Islands Waters, West Sumatra The El-Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are closely related to sea surface temperature and rainfall variability. The Asian monsoon often causes heavy rains, including in northern Sumatra, while the Australian monsoon generally causes dryness. The sea of the Mentawai Islands are near the Indian Ocean and are traversed by the equator. This causes the climatic conditions of rainfall to be influenced by several factors such as sea surface temperature, dipole mode, wind and Niño 3.4. This research uses rainfall data (GSMaP), sea surface temperature data from MUR Level 4 (GHRSST), wind data (ASCAT) which is processed using the composite method and analysis of correlation coefficients and coefficients of determination. When the IOD is positive, 60.6% of the IOD index affects sea surface temperature, while rainfall is 21.8%. During the ENSO phenomenon, especially during La-Niña, the ENSO index affects SST by 15.8% and affects rainfall by 6.1%. The Asian monsoon affects SST by 50.2% while the Australian monsoon affects 36.7%. The IOD phenomenon has more influence on SST and rainfall in the Mentawai Islands waters compared to the ENSO phenomenon. When the El-Niño and IOD are positive, the sea surface temperature decreases, followed by low rainfall. When La-Niña and IOD are negative the SST increases followed by an increase in rainfall. The high wind speed causes the SST to decrease.Keywords: Rainfall, ENSO, IOD, Monsoon, SST
Studi Karakteristik Geospasial Daerah Senyap (Shadow Zone) Menggunakan Pendekatan MMPE (Monterrey-Miami Parabolic Equation) di Perairan Selat Sunda Bagian Selatan Khalif Keninggan; Muhammad Helmi; Azis Rifai
Indonesian Journal of Oceanography Vol 5, No 1 (2023): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v5i1.16235

Abstract

Selat Sunda merupakan selat yang berada di dalam ALKI (Alur Laut Kepulauan Indonesia) dimana kapal selam bebas melewatinya. Pada Selat Sunda terdapat daerah senyap, yaitu daerah bawah air yang tidak dapat dilalui gelombang suara. Sehingga Selat Sunda memiliki posisi strategis dalam segi militer dan keamanan negara. Penelitian ini bertujuan untuk mengetahui keberadaan daerah senyap dan karakteristik geospasialnya di perairan. Penelitian ini menggunakan metode MMPE (Monterrey-Miami Parabolic Equation) dengan data input berupa batimetri dan jenis sedimen.  Data karakteristik termoklin dan haloklin sebagai validasi. Metode MMPE menghasilkan data dan informasi visual propagasi gelombang suara di dalam kolom perairan yang dapat diinterpretasikan sebagai daerah senyap. Riset ini menunjukkan daerah senyap di Selat Sunda bagian selatan berada di kedalaman 50-200 m dan panjang bervariasi dari 20-55 km dengan luas 265.2 hektar. Keberadaan daerah senyap sesuai dengan kedalaman termoklin yaitu 50-200 meter dan kedalaman dari haloklin yaitu 30-150 meter.Kata kunci: Shadow zone, sonar, geospasial, MMPE, Selat Sunda The Sunda Strait is located within Indonesia Archipelago Sea Channel, where submarines are free to pass through. The Sunda Strait has a shadow zone, which is an underwater area where sound waves cannot propagate. So that the Sunda Strait has a strategic position in terms of military and state security. This research aims to determine geospatial characteristics of shadow zone in Sunda strait. The MMPE (Monterrey-Miami Parabolic Equation) method uses bathymetry and sediment type as inputs of the program. The Characteristics of thermocline and halocline were used to validated f the results. The MMPE method provides visual information of underwater wave propagation, which is interpreted as a shadow zone. The results showed that using 5000hz frequency and 150 m sound source depth has provided the best information about the shadow zone. This research showed that the shadow zone waslocated at a depth  ranged from 50  to 200 m and has a length that varies from 20-55 km with area wide 265,2 ha. The results also showed that the characteristics of the shadow zone directly influenced by the bathymetric condition of Sunda Strait . The location of the shadow zone corresponds to the depth of thermocline, which was 50-200 m and the depth of halocline, which was 30-150 m. It can be concluded that thermocline and halocline can  affect the depth of the shadow zone  and the characteristic as well.Keywords: Shadow Zone, Sonar, Geospatial, MMPE, Sunda Strait