UPWELLING CHARACTERISTICS IN THE SOUTHERN JAVA WATERS DURING STRONG LA NINA 2010 AND SUPER EL NINO 2015

Seasonal coastal upwelling in the Southern Java waters is considered to be modulated by interannual ocean-atmosphere variability of El Nino Southern Oscillation (ENSO).  This study aims to investigate a contrast in seasonal upwelling characteristics during the La Nina 2010 and El Nino 2015 events, by using multi-datasets from INDESO model output and satellite-derived datasets. Distinct characteristics of seasonal upwelling was clearly seen. In La Nina, surface ocean-atmosphere variables were much lower than that observed in El Nino, except for precipitation rate, sea surface temperature, and sea surface height.  In La Nina, warmer (27-28°C) and a very freshwater (<33.80psu) were predominant in the upper 45m depth, concealing upwelling cooler water at subsurface. In contrast, in the El Nino, a drastic upwelled subsurface water of isotherms of 25-26°C and isohalines of 34.24-34.44psu were outcropped at the sea surface. Temperature-based upwelling index is -2°C and +4°C, demonstrating the ENSO has strongly modulated the upwelling intensity. A strong eastward South Java Coastal Current (SJCC) was found only in La Nina event.  Persistent westward Indonesian Throughflow south of 9.5°S were visible both in different ENSO events.  Estimate of Ekman transport derived from model meridional current was intervened strongly by the presence of the SJCC and the ITF.Upwelling pantai musiman di perairan Selatan Jawa diduga dapat dimodulasi oleh variabilitas antar-tahunan laut-atmosfer El Nino Southern Oscillation (ENSO). Penelitian ini bertujuan untuk menganalisis perbedaan karakteristik upwelling musiman selama kejadian La Nina 2010 dan El Nino 2015, berdasarkan multi-dataset dari keluaran model INDESO dan dari data satelit. Karakteristik yang berbeda dari upwelling musiman terlihat jelas. Di La Nina, variabel laut-atmosfer permukaan jauh lebih rendah daripada yang diamati di El Nino, kecuali untuk tingkat curah hujan, suhu permukaan laut, dan tinggi permukaan laut. Di La Nina, air laut yang lebih hangat (27-28°C) dan lebih tawar (<33,80psu) mendominasi di atas lapisan kedalaman 45m, yang menahan air dingin upwelling tetap di bawah permukaan. Sebaliknya, di El Nino, air bawah permukaan naik secara drastis dari isoterm 25-26°C dan isohalin dari 34,24-34,44psu tersingkapkan di permukaan laut. Indeks upwelling berbasis suhu adalah -2°C dan +4°C, menunjukkan ENSO telah sangat memodulasi intensitas upwelling. Arus Pantai Selatan Jawa (SJCC) yang kuat mengalir kearah timur hanya ditemukan pada kejadian La Nina. Aliran Arlindo yang persisten di selatan 9,5°S terlihat pada ENSO berbeda. Perkiraan angkutan Ekman yang diturunkan dari model arus meridional telah diintervensi secara kuat oleh kehadiran SJCC dan Arlindo

Sebaran nutrien, intensitas cahaya, klorofil-a dan kualitas air di Selat Badung, Bali pada Monsun Timur

Abstract. Badung Strait generally have nutrient distribution patterns influenced by Sea-atmosphere interactions. The waters of the Lombok Strait is also branching traversed by Indonesian Throughflow (ARLINDO), which will be followed by Indonesian Throughflow variability of sea surface temperature changes. The distribution of nutrients is closely related to light intensity to produce primary productivity. The purpose of this research was conducted to determine the distribution of nutrient concentration and light intensity and chlorophyll-a in Badung Strait during Southeast Monsoon (June 2014). The variables investigated are the concentration of nitrate, phosphate, ammonia, light intensity and chlorophyll-a. The results showed the average value of the concentration of nitrate, phosphate and ammonia at 0.01106 mg/L, 0.01 mg/L and 0.13475 mg/L. The average value of the light intensity at 272.8775 W/m2 and the average value of chlorophyll-a concentration of 0.40925 mg/L. The visualitation images show that there is homogeneus pattern for the phosphate concertration and konvergen patterns for the other paramaters. It is cause of physical parameters influence when obtain the waters sample. Based on the result, it can be conclude that the waters productivity of Badung Strait, Bali is in good condition. The role of other water quality parameters such as temperature, salinity and dissolved oxygen also supports fertility waters.Keywords: nutrients; light intensity; chlorophyll-a; water quality; Badung StraitAbstrak. Perairan Selat Badung secara umum merupakan perairan yang memiliki pola sebaran nutrien yang dipengaruhi oleh interaksi Laut-Atmosfer. Perairan tersebut juga merupakan percabangan Selat Lombok yang dilalui oleh ARLINDO (Arus Lintas Indonesia), dimana variabilitas ARLINDO akan diikuti oleh perubahan suhu permukaan laut. Sebaran nutrien tersebut berkaitan erat dengan intensitas cahaya untuk menghasilkan produktivitas primer. Penelitian ini bertujuan untuk mengetahui sebaran konsentrasi nutrien, intensitas cahaya dan klorofil-a di perairan Selat Badung pada Monsun Timur (Juni 2014). Variabel yang diamati berupa konsentrasi nitrat, fosfat, ammonia, intensitas cahaya dan klorofil-a. Hasil penelitian menunjukkan nilai rata-rata konsentrasi nitrat, fosfat dan ammonia sebesar 0,01106 mg/L, 0,01 mg/L dan 0,13475 mg/L. Nilai rata-rata intensitas cahaya sebesar 272,8775 W/m2 dan nilai rata-rata konsentrasi klorofil-a sebesar 0,40925 mg/L. Hasil visualisasi menunjukkan adanya pola yang homogen untuk konsentrasi fosfat dan pola konvergen untuk parameter lainnya. Hal ini diduga karena adanya pengaruh parameter fisika pada saat pengambilan sampel air. Namun secara umum, berdasarkan data yang diperoleh dapat dikatakan bahwa tingkat kesuburan perairan Selat Badung, Bali dalam kondisi yang baik. Peranan parameter kualitas perairan lainnya seperti suhu, salinitas dan oksigen terlarut juga mendukung tingkat kesuburan perairan.Kata kunci: nutrient; intensitas cahaya; klorofil-a; kualitas air; Selat Badun

DISTRIBUTION OF HEAVY METALS IN NATUNA COASTAL WATERS

ABSTRACTThe study of Pb, Cd, Cu, Hg, and As and Fe in Natuna coastal waters, Riau Islands was conducted in November 2012. Water and sediment samples were collected from 35 stations by purposive sampling method and those heavy metals were analysed using Atomic Absorption Spectrophotometer, flame type (FAAS). The results showed that concentrations of total Pb, Cd, Cu, Hg, and As in surface water were below instrument detection limit (2 µg/L for Pb, Cd, and Cu; 0.02 µg/L for Hg and As). Moreover, the concentration of metal Fe in surface water was 0.021-0.054 mg/L. Concentrations of Pb and Cu in sediment were 0.05-22.67 mg/kg and 3.77-11.00 mg/kg, respectively, at which the highest concentrations were found near Binjai Estuary. Those concentrations were significantly below the standard levels set by CCME (2002) and ANZECC/ARMCANZ (2000). Concentration of Fe in sediment varied from 751.13-2309.12 mg/kg and showed similar spatial distribution to Cu-in-sediment. No standard level for Fe in waters was available. Generally, it can be concluded that Natuna coastal water was still uncontaminated.  Keywords: heavy metals, iron metal, Natuna coastal waters

Variabilitas Lapisan Termoklin Terhadap Kenaikan Mixed Layer Depth (MLD) di Selat Makassar

Penelitian ini bertujuan untuk mengkaji kondisi suhu, MLD, variabilitas ENSO, dan arus yang mempengaruhi lapisan termoklin di Selat Makassar. Metode yang digunakan dalam penelitian ini adalah analisis temporal dan spasial serta deskriptif komparatif sehingga menghasilkan output berupa profil suhu vertikal. Suhu rata-rata pada kedalaman 0-500 m mencapai 25,8 dengan kisaran suhu 6,64-33,81. Pada tahun 2015 lapisan termoklin terbentuk pada kedalaman 50-400 m dengan kisaran suhu 9-28. Pada tahun 2016 lapisan termoklin mulai terbentuk pada kedalaman 50-300 m dengan kisaran suhu 9-27. Kedalaman MLD pada daerah tenggara Selat Makassar lebih tinggi. Kekuatan arus terkuat terjadi selama musim Barat dengan kecepatan rata-rata 0,06 m/s kearah selatan dan barat. El Nino terjadi pada November 2014 sampai Mei 2016 dengan El Nino terkuat pada 2015 menyebabkan nilai MLD kecil yaitu sebesar 50,30 m. Pada Agustus sampai Desember 2016 terjadi La Nina yang menyebabkan nilai MLD meningkat

Detecting change in the Indonesian Seas

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Sprintall, J., Gordon, A. L., Wijffels, S. E., Feng, M., Hu, S., Koch-Larrouy, A., Phillips, H., Nugroho, D., Napitu, A., Pujiana, K., Susanto, R. D., Sloyan, B., Yuan, D., Riama, N. F., Siswanto, S., Kuswardani, A., Arifin, Z., Wahyudi, A. J., Zhou, H., Nagai, T., Ansong, J. K., Bourdalle-Badie, R., Chanuts, J., Lyard, F., Arbic, B. K., Ramdhani, A., & Setiawan, A. Detecting change in the Indonesian Seas. Frontiers in Marine Science, 6, (2019):257, doi:10.3389/fmars.2019.00257.The Indonesian seas play a fundamental role in the coupled ocean and climate system with the Indonesian Throughflow (ITF) providing the only tropical pathway connecting the global oceans. Pacific warm pool waters passing through the Indonesian seas are cooled and freshened by strong air-sea fluxes and mixing from internal tides to form a unique water mass that can be tracked across the Indian Ocean basin and beyond. The Indonesian seas lie at the climatological center of the atmospheric deep convection associated with the ascending branch of the Walker Circulation. Regional SST variations cause changes in the surface winds that can shift the center of atmospheric deep convection, subsequently altering the precipitation and ocean circulation patterns within the entire Indo-Pacific region. Recent multi-decadal changes in the wind and buoyancy forcing over the tropical Indo-Pacific have directly affected the vertical profile, strength, and the heat and freshwater transports of the ITF. These changes influence the large-scale sea level, SST, precipitation and wind patterns. Observing long-term changes in mass, heat and freshwater within the Indonesian seas is central to understanding the variability and predictability of the global coupled climate system. Although substantial progress has been made over the past decade in measuring and modeling the physical and biogeochemical variability within the Indonesian seas, large uncertainties remain. A comprehensive strategy is needed for measuring the temporal and spatial scales of variability that govern the various water mass transport streams of the ITF, its connection with the circulation and heat and freshwater inventories and associated air-sea fluxes of the regional and global oceans. This white paper puts forward the design of an observational array using multi-platforms combined with high-resolution models aimed at increasing our quantitative understanding of water mass transformation rates and advection within the Indonesian seas and their impacts on the air-sea climate system. IntroductionJS acknowledges funding to support her effort by the National Science Foundation under Grant Number OCE-1736285 and NOAA’s Climate Program Office, Climate Variability and Predictability Program under Award Number NA17OAR4310257. SH was supported by the National Natural Science Foundation of China (Grant 41776018) and the Key Research Program of Frontier Sciences, CAS (QYZDB-SSW-SYS023). HP acknowledges support from the Australian Government’s National Environmental Science Programme. HZ acknowledges support from National Science Foundation under Grant No. 41876009. RS was supported by National Science Foundation Grant No. OCE-07-25935; Office of Naval Research Grant No. N00014-08-01-0618 and National Aeronautics and Space Administration Grant No. 80NSSC18K0777. SW, MF, and BS were supported by Center for Southern Hemisphere Oceans Research (CSHOR), which is a joint initiative between the Qingdao National Laboratory for Marine Science and Technology (QNLM), CSIRO, University of New South Wales and University of Tasmania

Pola dan Karakteristik Arus Laut pada Berbagai Kedalaman Di Selat Badung, Bali

Selat Badung merupakan percabangan outlet dari Selat Lombok yang berada di antara Pulau Bali dan Pulau Nusa Penida. Kecepatan arus di Selat Badung berkisar dari 0,2 cm/s - 204,3 cm/s. Kajian arus di lokasi ini diperlukan untuk mengetahui pola dan karakteristik arus berdasarkan komponen harmonik pasang surut. Pengukuran data di perairan lokasi penelitian dilaksanakan pada tanggal 20 Juni 2014 - 5 Juli 2014 dengan interval perekaman 30 menit. Metode yang digunakan dalam penelitian ini menggunakan software Matlab dengan toolbox t_tide yang dapat memisahkan data arus perekaman menjadi data arus harmonik dan non-harmonik dengan mengeluarkan komponen pasang surut yang berpengaruh terhadap keberlangsungan arus harmoniknya. Ketiga data arus ini akan dianalisis untuk mengetahui pola dan karakteristiknya. Berdasarkan hasil penelitian, pola arus didominasi oleh arus non harmonik ke arah tenggara. Komponen harmonik yang berpengaruh besar pada lokasi tersebut adalah Msf, M2 dan S2

Karakteristik Upwelling di Perairan Selatan Jawa pada Tahun Strong La Nina 2010 dan Super El Nino 2015

Upwelling pantai musiman di perairan Selatan Jawa diduga dapat dimodulasi oleh variabilitas antar-tahunan laut-atmosfer El Nino Southern Oscillation (ENSO). Penelitian ini bertujuan untuk menganalisis perbedaan karakteristik upwelling musiman selama kejadian La Nina 2010 dan El Nino 2015, berdasarkan multi-dataset dari keluaran model INDESO dan dari data satelit. Karakteristik yang berbeda dari upwelling musiman terlihat jelas. Di La Nina, variabel laut-atmosfer permukaan jauh lebih rendah daripada yang diamati di El Nino, kecuali untuk tingkat curah hujan, suhu permukaan laut, dan tinggi permukaan laut. Di La Nina, air laut yang lebih hangat (27-28°C) dan lebih tawar (<33,80psu) mendominasi di atas lapisan kedalaman 45m, yang menahan air dingin upwelling tetap di bawah permukaan. Sebaliknya, di El Nino, air bawah permukaan naik secara drastis dari isoterm 25-26°C dan isohalin dari 34,24-34,44psu tersingkapkan di permukaan laut. Indeks upwelling berbasis suhu adalah -2°C dan +4°C, menunjukkan ENSO telah sangat memodulasi intensitas upwelling. Arus Pantai Selatan Jawa (SJCC) yang kuat mengalir kearah timur hanya ditemukan pada kejadian La Nina. Aliran Arlindo yang persisten di selatan 9,5°S terlihat pada ENSO berbeda. Perkiraan angkutan Ekman yang diturunkan dari model arus meridional telah diintervensi secara kuat oleh kehadiran SJCC dan Arlindo

Satellite-Observed Multi-Scale Variability of Sea Surface Chlorophyll-a Concentration along the South Coast of the Sumatra-Java Islands

The southern coast of Java is known as one of the most productive fishing grounds for tuna, feeding by nutrient-rich water along the coast caused by the subsurface water upwelling. This primary productivity can be evidenced by the high sea surface chlorophyll-a concentration (SSC). Based on satellite remote sensing products, we investigate the multi-scale variability in SSC along the Sumatra-Java coast. The results show that seasonal variability of SSCs is primarily due to monsoon-driven upwelling and rainfall in the Indian Ocean and Indonesian seas sides of the Sumatra and Java Islands, respectively. Local Ekman pumping plays a secondary role, while rainfall input to the ocean has little effect. Coastally trapped Kelvin waves and mesoscale eddies are responsible for the intraseasonal SSC anomalies in regions along the south coast of Java and off the Sunda and Lombok Straits, respectively. The interannual variability in SSC is caused by the anomalous upwelling related to the Indian Ocean Dipole. There was a weak increasing trend of ~0.1–0.2 mg/m3 per decade, above the global averaged trend, which may be related to enhanced local Ekman pumping. These analyses provide an overall description of SSC variations based on satellite observations; however, further investigations based on in situ observations are needed to achieve better quantification