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| Abstract Submission No. | ABS-2022-03-0331 |
| Title of Abstract | Coastal upwelling events along the southern coasts of Sumatra and Java and its relation to Indian Ocean Dipole |
| Authors | Takanori Horii*, Iwao Ueki, Eko Siswanto, Iskhaq Iskandar, Kentaro Ando |
| Organisation | JAMSTEC |
| Address | 2-15 Natsushima Yokosuka, Kanagawa, Japan Pincode: 2350033 Mobile: 468679844 E-mail: horiit@jamstec.go.jp |
| Country | Japan |
| Presentation | Oral |
| Abstract | Coastal upwelling occurs along the southern coasts of Sumatra and Java due to southeasterly wind during the boreal summer monsoon and plays an important role in the ocean surface heat balance, biogeochemical balance, coastal ecosystem and fisheries in the southeastern tropical Indian Ocean. To understand the coastal upwelling system, we investigated ocean temperature and salinity variations obtained from Argo floats. During 2005-2017, several Argo floats successfully observed vertical structure of temperature and salinity near the coasts of Sumatra and Java. During the 2008 positive Indian Ocean Dipole (IOD) event, an Argo float approached Java and observed intraseasonal-scale temperature cooling events in July and August, with significant upward movements of thermocline. During 2013-2017, two Argo floats observed temperature and salinity variations within 100 km from the southwestern coast of Sumatra. These data indicate that the Argo floats observed coastal upwelling signals along the southern coasts of Sumatra and Java. On the observational data south of Java, we found that the coastal upwelling signal can be quantitatively explained by local southwesterly alongshore winds. In case southwest of Sumatra, the upwelling signals were frequently accompanied by surface low salinity and subsurface density stratification associated with local precipitation. The relationship of the local precipitation, surface-to-subsurface salinity stratification, barrier layer thickness, and mixed layer temperature variation observed during the coastal upwelling events are further presented. In the presentation, we also present our recent results on the coastal upwelling signal estimated from the satellite-observed Chlorophyll-a data. A relationship between the coastal upwelling variations and the Indian Ocean Dipole will be discussed. |