[A-OS27] [JJ] インド洋域の物理・生物地球化学・生態系と相互連関

[AOS27-02] Intraseasonal coastal upwelling signal along the southern coast of Java observed by Indonesian tidal station data

*堀井 孝憲¹、植木 巌¹、Syamsudin Fadli²、Sofian Ibnu³、安藤 健太郎¹ (1.海洋研究開発機構　地球環境観測研究開発センター、2.インドネシア技術評価応用庁、3.インドネシア地理空間情報局)

キーワード：東部インド洋、沿岸湧昇、スマトラ・ジャワ島、潮位データ、東部インド洋湧昇イニシアティブ

Understanding coastal upwelling along the southwestern coasts of Sumatra and Java and their impacts on ocean surface heat and biogeochemical balance in the eastern Indian Ocean are the main target of international research collaboration, the Eastern Indian Ocean Upwelling Research Initiative (EIOURI). In this study, analyzing sea level data along the coasts of Sumatra and Java, we investigated the coastal upwelling signal that is linked to local sea surface temperature (SST) variability. We used Indonesian tidal station data together with satellite SST data and atmospheric reanalysis data. The sea level variations along the southern coast of Java have a significant coherence with remote wind, local wind, and local SST variations, with an intraseasonal time scale of 20–50 days. Assuming that a coastal upwelling signal would appear as a sea level drop (SLD), we focused on intraseasonal-scale SLD events in the data. Significant upwelling signals are frequently observed during both the boreal summer and winter. To evaluate the impact of the coastal upwelling on local SST, we examined statistical relationships between sea level and SST variations. The results demonstrated that events that occurred during April-August were associated with local SST cooling. The horizontal distribution of the SST cooling was analogous with annual-mean SST, suggesting the importance of intraseasonal-scale coastal upwelling in forming the climatic conditions of the southeastern tropical Indian Ocean.