Noir Primadona Purba

Eddies spatial variability at Makassar Strait – Flores Sea

This study was aimed to get the distribution of eddies spatially and temporally from Makassar Waters (MW) to Flores Sea (FS), as well as its relations with the upwelling, the downwelling, and chlorophyll-a concentration. The study area extends from 115o–125o E to 2.5o–8o S. The datasets were consisted of monthly geostrophic currents, sea surface heights, sea surface temperatures, and chlorophyll-a from 2008 – 2012. The results showed that eddies which found at Makassar Strait (MS) has the highest diameter and speed of 255.3 km and 21.4 cm/s respectively, while at the southern MW has 266.4 km and 15.6 cm/s, and at FS has 182.04 km and 11.4 cm/s. From a total of 51 eddies found, the majority of eddies type was anticyclonic. At MS and FS, eddies formed along the year, whereas at southern MW were found missing in West Season. Moreover, the chlorophyll-a concentration was consistently higher at the eddies area. Even though, the correlation among eddies and the upwelling downwelling phenomena was not significantly as shown by sea surface temperatures value.

Building up the database of the Level-2 Java Sea Ecoregion based on physical oceanographic parameters

The Java Sea (JS) is one of the sea with unique characteristic with especially in biodiversity and oceanographic condition. The purpose of this research is to identify the EL into level 2 in Java Sea based on oceanographic condition. The Java Sea, which covers an area of 467,000 Km2 with an average depth of 50m, is located on the Southeastern part of the Sunda Shelf. This research uses the temperature and salinity data provided by the INDESO, the sea surface height (SSH) data downloaded from the HYCOM website, and the level 2 Java Sea ecoregion shape file data from the Indonesian seas delineation team. The physical oceanographic conditions of the level 2 Java Sea ecoregions are influenced by the moonsun and their respective geographical positions. The results showed that the distribution of temperature, sea current, salinity, and Sea Surface Height differed in each Java Sea Ecoregion level 2 because it is influenced by the geographical and astronomical location of each Java Sea Ecoregion level and influenced by the monsoon that exists over Indonesia. In the east of Java Sea influence from Makassar Strait and in the west affected by Karimata Strait. Within the region, EL 6.1. (Sunda Strait), the physical oceanography condition is slightly different from other Java EL because it is strongly influenced by the Indian Ocean.

Influence of El Ni?o Southern Oscillation (ENSO) phenomena on Eddies Variability in the Western Pacific Ocean

Sea Surface Height (SSH), seawater temperature, and ocean currents are an important oceanographic variables that were used to identify the ocean eddies variability. This research aims to investigate the influence of ENSO on eddies variability in Western Pacific Ocean (WPO), by using the Automated Eddy Detection (AED). The results showed that cyclonic eddies are mostly formed in WPO from a total of 2024 eddies. Eddies total increases within the amount of the seas depth, at 200 m has the highest of eddy total. The temperature in eddy center mostly started changing at a depth of 150 m, which is at the cyclonic eddy has a lower value and at anticyclonic has a higher value. That has the large effect of changes SSH. During El Nino, sea level anomaly decreases down to -0.3 m, while sea level anomaly minimum decrease down to -0.1 m during La Ni?a. At the WPO, Mindanao Eddies formed along the year, whereas Halmahera Eddies were weakened in West Season. A periodic ENSO affects eddies variability, in general, the diameter, total and temperature center of eddies are smaller during El Ni?o, and greater during La Ni?a than normal condition.

Overview of physical oceanographic condition at Biawak Island: past achievement and future challenge

Biawak Islands is one of Marine Protected Areas (MPA) in Java Seas and categorized as remote area. The purpose of this research is to assess datas from 2011-2017 and to understand about these island from oceanographic point of view. Due to its location in the center of Java Sea (JS), variations of oceanographic condition at Biawak Island is supposed to be similarity with JS. Seasonal variations in this shallow-flat topography of JS are mostly influenced by the monsoon due to the sea level difference between Pacific and Indian Ocean. Water masses from the South China Sea (SCS) and Pacific Ocean (PO) take turns to enter JS at two distinct monsoon seasons. The results showed that temperature ranges 26.28 - 34.3 ?C, salinity ranges 27.5 - 34.5 psu, transparency ranges 0.7 - 20 m, dissolved oxygen ranges 4.1 - 6.5 mg/L, and pH 6.30-8.5. Tides with mixed tide prevailing diurnal. The wind pattern with monsunal variation and the surface current is about 0.2-0.8 m/sec. The dominant substrat in the Biawak is sand and coral. Further, there is a need long-term programs concentrate on delivering quantification data related to environmental issues.

Variabilitas temperature laut pada fase IOD (Indian Ocean Dipole) di Perairan Barat Sumatera menggunakan data Argo Float

The objective of the research was to analyze the vertical variability of the water column in the West Sumatra waters. The data used to analyze the vertical variability was the temperature data sets from Argo float instruments which were operated from 2009 to 2011 in the West Sumatran sea region. The secondary data that used was the geostrophic current data sets which obtained from the Jason image satellite also sea temperature anomaly data. The method used in this research is by analyzing temporally and spatially and then describing while comparing the data. The result of the research showed that IOD formed from June to July with the peak of IOD was from September to November and the disintegration starts in December. The SST average on 2009 (Neutral IOD) during peak phase of IOD was 29.060C, in 2010 (Negative IOD) the SST mean is 28.690C, in 2011 (Positive IOD) the SST mean was 28.790C. The result from spatial analyzes showed that the strong IOD was the main reason for the movement of the mixed layer in West Sumatra waters, so the warm water cannot be found around the West Sumatra waters. The upper boundary depth of thermocline during peak phase of 2009’s neutral IOD starts from September was on 82.59 m, in October was 86.12 m and in November was 89.5 m. In Septemeber 2010 the upper thermocline boundary was found on 89.06 m deep, in October was 104.05 m, and in November was 107.36 m, the thermocline got deeper because the input of water masses from West Indian Ocean intensifies because of negative IOD event. In September 2011 the upper thermocline boundary was found on 64.16 m, in October was 75.35 m and in November was 79.88 m. The thermocline found more shallow because the mixed layer on East Indian Ocean moved westward so the thermocline lifted up to fill the water column emptiness. Penelitian ini bertujuan mengkaji variabilitas kolom air secara vertikal di perairan Barat Sumatera. Data yang digunakan yaitu data suhu dari instrumen Argo float yang beroperasi di perairan Barat Sumatera tahun 2009 – 2011. Data pendukung yaitu data arus geostropik yang diperoleh yang diperoleh dari citra Jason selain itu digunakan data suhu anomali laut. Metode yang digunakan adalah analisis temporal dan spasial serta deskriptif komparatif. Hasil penelitian menunjukkan proses pembentukan IOD terjadi pada Juni – Agustus kemudian mencapai puncak pada September – November dan proses peluruhannya pada Desember. Rata – rata SPL pada fase puncak tahun 2009 (IOD netral) yaitu 29.06 0 C; pada 2010 (IOD negatif) yaitu 28.69 0 C; dan pada 2011 (IOD positif) yaitu 28.79 0 C. Berdasarkan analisis spasial IOD dengan intensitas kuat mengakibatkan pergerakan massa air hangat melewati perairan Barat Sumatera sehingga tidak terdeteksi lagi di lokasi ini. Batas atas termoklin pada fase puncak IOD 2009 (September) yaitu 82.59 m; Oktober sekitar 86.12 m dan November mencapai 89.5 m. Selanjutnya pada 2010 yaitu pada September sekitar 89.06 m; Oktober sekitar 104.05 m dan November mencapai 107.36 m. Terlihat, termoklin semakin dalam karena massa air hangat dari Hindia Barat yang mengisi perairan Barat Sumatera menjadi semakin kuat pada fase IOD negatif. Sebaliknya, pada September 2011 termoklin berada pada kedalaman 64.16 m; Oktober pada kedalaman 75.35 m dan November sekitar 79.88 m. Pada periode ini termoklin terdeteksi lebih dangkal karena lapisan mixed layer bergerak ke Hindia Barat dan kekosongannya diisi lapisan termoklin.