The Makassar Strait throughflow of ~12–13 Sv, representing ~77% of the total Indonesian Throughflow, displays fluctuations over a broad range of time scales, from intraseasonal to seasonal (monsoonal) and interannual scales. We now have 13.3 years of Makassar throughflow observations: November 1996 to early July 1998; January 2004 to August 2011; and August 2013 to August 2017. Strong southward transport is evident during boreal summer, modulated by an ENSO interannual signal, with weaker southward flow and a deeper subsurface velocity maximum during El Niño; stronger southward flow with a shallower velocity maximum during La Niña. Accordingly, the southward heat flux, a product of the along‐channel current and temperature profiles, is significantly larger in summer and slightly larger during La Niña. The southward flow relaxed in 2014 and more so in 2015/2016, similar though not as extreme as during the strong El Niño event of 1997. In 2017, the throughflow increased to ~20 Sv. Since 2016, the deep layer, 300‐ to 760‐m southward transport increases, almost doubling to ~7.5 Sv. From mid‐2016 into early 2017, the transports above 300 m and below 300 m are about equal, whereas previously, the ratio was about 2.7:1. Near zero or northward flow occurs in the upper 100 m during boreal winter, albeit with interannual variability. Particularly strong winter reversals were observed in 2014/2015 and 2016/2017, the latter being the strongest winter reversal revealed in the entire Makassar time series.

No abstract

No abstract

Volume, heat and freshwater transports from the South China Sea (SCS) to the Java Sea through the Karimata Strait are estimated based on direct measurements of current, temperature, salinity, and satellite observations. Subject to strong seasonal variability, the volume, heat, freshwater transports

Two distinct CO2 sink/source characteristics are found in the tropical Indonesian seas from the compilation of observed data for the period 1984–2013. The western region persistently emits CO2 to the atmosphere, whereas the eastern region is dynamic and acts either as a small source or sink of CO2 to the atmosphere, depending on sites. The segregation is proximal to the Makassar Strait, which is located over the continental shelf and is one of the main routes of the Indonesian Throughflow (ITF). Lower salinity and higher silicate were found in the western region, suggesting a terrestrial influence in this area. Temperature has a limited influence in controlling different CO2 sink/source characteristics in the west and east. However, an SST change of −2.0°C during La Niña events effectively reduces the pCO2 difference between the atmosphere and surface seawater by 50% compared to normal year conditions. During La Niña events, higher wind speeds double the CO2 flux from the ocean to the atmosphere compared to that of a normal year. In the continental shelf area where the CO2 sink area was found, data of over 29 years show that the seawater pCO2 increased by 0.6–3.8 μatm yr−1. Overall, the seawater pCO2 of the Indonesian seas is supersaturated relative to the atmosphere by 15.9 ± 8.6 μatm and thus acts as a source of CO2 to the atmosphere.

No abstract

No abstract

ABSTRAKMeningkatnya kandungan karbondioksida (CO 2 ) serta berkurangnya luas hutan sebagai penyerap CO 2 di atmosfer merupakan penyebab pemanasan global. Salah satu solusi untuk menurunkan kandungan CO 2 di atmosfer adalah melalui pembangunan atau perbaikan vegetasi hutan. Hutan mangrove dianggap dapat menyerap karbon cukup baik melalui proses fotosintesis. Tujuan penelitian ini yaitumengestimasi simpanan karbon tegakan dan seresah hutan mangrove di Desa Margasari Kecamatan Labuhan Maringgai Kabupaten Lampung Timur. Penelitian ini dilakukan dengan metode jalur berpetak. Jalur dan petak awal ditentukan secara acak kemudian jalur dan petak diambil secara sistematis. Petak pengamatan pohon dibuat berukuran 20 m x 20 m dengan jarak antar petak pada jalur 20 m dengan jumlah 20 petak. Setiap petak dilakukan pengukuran diameter pohon≥ 5 cm. Masing-masing petak dibuat sub petak pengamatan serasah berukuran 0,5 m x 0,5 m. Perhitungan jumlah biomassa tersimpan pada pohon menggunakan persamaan allometrikB = 0,1848D 2.3624 dan pada seresah menggunakan total berat kering. Konsentrasi karbon dalam bahan organik biasanya sekitar 46% sehingga mengalikan biomassa masing-masing dengan46%. Hasil penelitian diperoleh rata-rata biomassa hutan mangrove sebesar 431,78 ton/ha. Estimasi karbon tegakan mangrove 197,36 ton/ha dan estimasi karbon serasah 1,25 ton/ha, sehingga berdasarkan hasil penelitian jumlah estimasi total karbon tersimpan hutan mangrove 198,61 ton/ha.