Distribusi Suhu, Salinitas dan Densitas di Lapisan Homogen dan Termoklin Perairan Selat Makassar

Abstract

Selat Makassar merupakan salah satu celah penghubung antara Samudera Pasifik dan Samudera Hindia dengan karakteristik oseanografi lebih dipengaruhi oleh Samudera Pasifik melalui sirkulasi Arlindo. Sirkulasi Arlindo bersama dengan variasi pergerakan angin muson akan berpengaruh terhadap distribusi suhu, salinitas dan densitas di lapisan homogen dan termoklin. Penelitian ini bertujuan mengkaji distribusi suhu, salinitas dan densitas di lapisan homogen dan termoklin perairan Selat Makassar. Penelitian ini dilaksanakan pada bulan Oktober 2015. Data diperoleh dari Pusat Penelitian dan Pengembangan Sumber Daya Laut dan Pesisir (P3SDLP) dengan data primer berupa data suhu, salinitas, densitas dan kedalaman menggunakan instrumen CTD. Stasiun pengambilan data terdiri dari 18 stasiun pengambilan data berdasarkan metode purposive sampling. Data yang diperoleh kemudian dianalisis menggunakan metode analisis statistik deskriptif. Hasil menunjukkan bahwa ketebalan lapisan homogen antara 19,5-68,5 m. Ketebalan lapisan termoklin bervariasi antara 50-220 m. Variabilitas ketebalan lapisan homogen dan lapisan termoklin disebabkan beberapa  faktor seperti tekanan angin, pemanasan matahari, transpor massa air, dan aktivitas gelombang internal.  Sebaran nilai suhu di lapisan homogen bervariasi antara 25,35-29,94 ^oC. Suhu permukaan laut cenderung lebih tinggi di bagian utara Selat Makassar. Suhu di lapisan termoklin berkisar antara 12,09-29,22 ^oC. Salinitas di lapisan homogen bervariasi antara 33,91-34,59 ‰. Nilai salinitas permukaan laut cenderung lebih tinggi di selatan Selat Makassar. Hal ini diduga disebabkan pengaruh dari Laut Jawa dan Laut Flores. Salinitas di lapisan termoklin bervariasi antara 34,18-34,88 ‰. Nilai densitas di lapisan homogen bervariasi antara 20,93-22,93 kg/m³. Nilai densitas di lapisan termoklin bervariasi antara 21,47-26,13 kg/m³. Gradien rata – rata temperatur lapisan termoklin antara 0,07-0,14 ^oC/m. Gradien rata – rata temperatur berbanding terbalik dengan ketebalan lapisan termoklin.

Makassar Strait is a pathway that connected the Pacific Ocean and the Indian Ocean with oceanographic characteristics  more influenced by the Pacific Ocean through Arlindo. Arlindo circulation and movement variations of the monsoon will affect the distribution of temperature, salinity and density in homogeneous and thermocline layer. The aims of this study is were to assess the distribution of temperature, salinity and density in homogeneous and thermocline layer of Makassar Strait. This research was conducted in October 2015. Data were obtained from the Pusat Penelitian dan Pengembangan Sumber Daya Laut dan Pesisir (P3SDLP) with the primary data that were temperature, salinity, density and depth by using CTD instruments. Data measurement station consists of 18 stations based on purposive sampling method. Data were analyzed using descriptive statistical analysis method. The results showed that the homogeneous layer thickness were vary with range from 19.5 m to 68.5 m. Thermocline layer thickness between 50-220 m. Variability homogeneous layer thickness and the thermocline were caused by several factors such as air pressure, solar heating, water mass transport, and internal wave activity. The distribution of temperature in a homogeneous layer were vary with range from 25.35 ° C to 29.94 ° C. Sea-surface temperatures tend to be higher in the northern of Makassar Strait. Temperatures in the thermocline layer ranged from 12.09 °C to 29.22 °C. Salinity in a homogeneous layer werer vary with range from 33.91 ‰ to 34.59 ‰. Sea surface salinity were higher in the southern of Makassar Strait. This was assumed due to the influence of the Java Sea and Flores Sea. Salinity in the thermocline layer were vary with range from 34.18 ‰ to 34.88 ‰. The density in a homogeneous layer vary among 20.93-22.93 kg/m³. The density in the thermocline layer were vary with range from 21.47 kg/m³ to 26.13 kg/m³. Average gradient temperature of the thermocline layer were vary with range from 0.07 °C/m  to 0.14 °C/m. Average gradient of temperature was inversely proportional to the thickness of the thermocline layer.