[A-OS12] Physical, biogeochemical, and ecological processes and variability in the Indian Ocean

[AOS12-03] Intraseasonal variation of surface Chlorophyll-a associated with coastal upwelling along the southern coast of Java

*Takanori Horii¹, Eko Siswanto², Iskhaq Iskandar³, Iwao Ueki¹ (1.Global Ocean Observation Research Center, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2.Earth Surface System Research Center, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3.Faculty of Mathematics and Natural Sciences, Sriwijaya University, Indonesia)

Keywords:Surface Chlorophyll-a, Java island, Indian Ocean Dipole

Coastal upwelling along the southern coast of Java brings cold and nutrient-rich subsurface water upward and plays an important role in controlling ocean surface heat balance, biogeochemical balance, coastal ecosystem, and regional fisheries. To understand the coastal upwelling, we investigated satellite-based Chlorophyll-a data south of Java, with a focus on the seasonal and intraseasonal-scale variability. We first interpolated the data and produced daily timeseries. The spectrum analysis showed that annual, semi-annual, and intraseasonal (20-60-day) variations were significant in the Chlorophyll-a variations. The Chlorophyll-a peaks were accompanied with decreases in the local sea level and sea surface temperature, suggesting a coastal upwelling of cold and nutrient-rich subsurface water at the intraseasonal timescale. A relationship between the intraseasonal Chlorophyll-a variations and the Indian Ocean Dipole will be discussed.