Intraseasonal flow and its impact on the chlorophyll-a concentration in the Sunda Strait and its vicinity

Xu, Tengfei; Li, Shujiang; Hamzah, Faisal; Setiawan, Agus; Susanto, R. Dwi; Cao, Guojiao; Wei, Zexun

doi:10.1016/j.dsr.2018.04.003

Cited by 18 publications

(25 citation statements)

References 30 publications

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“…At deeper layers with a relatively constant σ θ of ~27.5 kg m −3 , salinity and temperature were ~34.7 PSU and ~6°C, respectively, indicative of upper Indian Ocean Deep Water. The similarity in water mass structure with that of the major ITF outflow passages of the Lombok Strait and the southern coast of Java‐Bali (Atmadipoera et al, ), along with time‐series measurements of velocity in the Sunda Strait (Susanto et al, ), confirm that the Sunda Strait is one of the exit passages of the ITF into the Indian Ocean, as previously reported (Susanto et al, ; Xu et al, ).…”

Section: Resultssupporting

confidence: 61%

“…This is attributed to enhanced biological consumption stimulated by rich nutrient supply via water displacement in the western Indonesian Seas, which is generated by westward wind stress persistently pushing waters from the Java Sea into the Indian Ocean via the Sunda Strait (blue pathway in Figure b; Susanto et al, ). Indeed, high chlorophyll‐a induced by nutrient‐rich water was previously reported in the Sunda Strait during the southeast monsoon season (Xu et al, ). The net removal of DIC appears diminished at high salinities (>33.5 PSU) in the Sunda Strait.…”

Section: Discussionmentioning

confidence: 53%

“…In the shallower regions, mixing between different water masses showed a reverse transport pattern between surface and subsurface waters in the Karimata Strait and strong intraseasonal and seasonal variability in the Sunda Strait (Fang et al, ; Susanto et al, , ; Xu et al, ). In the Karimata Strait, the plume waters had low DIC and TAlk concentrations, with higher concentrations beneath (30–45 m, Figure a).…”

Section: Discussionmentioning

confidence: 99%

“…18 where DIC and TAlk values showed higher values beneath 35 m depth (Figure b). Indeed, these fresher waters intrude into the Indian Ocean via the Sunda Strait due to continuous wind stress in the western Java Sea, resulting in a different sea level gradient between the Java Sea and southern Sunda Strait (Li et al, ; Susanto et al, ; Xu et al, ). The throughflow would be strongest during the peak of the southeast monsoon, bringing waters with low DIC, TAlk, and salinity into the Indian Ocean (Figure ).…”

Section: Discussionmentioning

confidence: 99%

“…During this period, JSW intrudes into the Indian Ocean with current speeds between 0.2 and 0.4 m s ‐1 (Figure b). During the southeast monsoon (June to August)‚ the wind blows northwesterly, drawing waters from the Makassar Strait and Flores Sea into the Java Sea; the low salinity, low‐density JSWs flow both into the Indian Ocean and the SCS (Hendiarti et al, ; Hendiarti et al, ; Potemra et al, ; Susanto et al, ; Xu et al, ). However, in the Karimata Strait, the upper water layer flows towards the SCS while the lower layer current remains flowing south into the Sunda Strait (Figure c).…”

Section: Methodsmentioning

confidence: 99%

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Dynamics of the Carbonate System in the Western Indonesian Seas During the Southeast Monsoon

et al. 2020

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We present a unique water column data set of dissolved inorganic carbon (DIC) and total alkalinity (TAlk) from a cruise to the western Indonesian Seas during the southeast monsoon, covering the Karimata Strait, western Java Sea, and Sunda Strait. Salinity-normalized TAlk (NTAlk) in the surface water ranged 2,297-2,348 μmol kg −1 , very close to typical values observed in the tropical ocean. In the Karimata Strait, the Kapuas River plume was observed, featuring low salinity, DIC, and TAlk. In the western Java Sea, where waters were well mixed, we observed relatively homogeneous distributions of salinity, DIC, and TAlk. In the Sunda Strait, waters intruding from the Java Sea occupied the upper layer, and below was the Indian Ocean water with lower values of salinity, DIC, and TAlk. In its deep portion, depth profiles of normalized DIC and NTAlk were very similar to those observed in the Indian Ocean. Physical processes and air-sea gas exchange exerted predominant controls on the carbonate system in the Karimata Strait and western Java Sea. While both processes play large roles in the Sunda Strait, a net DIC removal of 31 ± 23 μmol kg −1 in the surface mixed layer were revealed. The drawdown of DIC is consistent with an overall supersaturation of dissolved oxygen (102-107%), suggesting significant organic carbon production. In the subsurface-intermediate waters of the Sunda Strait mainly influenced by the advection of Indian Ocean water, a net DIC consumption of 54 ± 45 μmol kg −1 was distinct, likely stimulated by the nutrients supplied from the Indian Ocean. Plain Language SummaryResearch on the carbonate system in the tropical regime of the Indonesian Seas is minimal, which hampers our understanding to its essential role in interbasin exchanges of material and energy via the Indonesian throughflow. Here we present a unique data set to examine the dynamics of the carbonate system in the western Indonesian Seas. Based on DIC and TAlk relationships, we show that water mass mixing in the western Indonesian Seas during the southeast monsoon is dominated by zonal wind-mixed waters from the plume of the Kapuas River, the Java Sea and South China Sea mixed water, and the subsurface Indian Ocean water. These processes resulted in homogenous distributions of physical properties and carbonate system parameters. However, biologically mediated DIC consumption occurred in the surface mixed layer of the Sunda Strait, which led to an increase in dissolved oxygen saturation, the saturation state of aragonite (Ω arag ), and pH. Overall, our region was a source of atmospheric CO 2 as previously reported, although the controlling processes may vary with respect to time at both seasonal and interannual timescales.

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Section: Resultssupporting

confidence: 61%

Section: Discussionmentioning

confidence: 53%