북서태평양 식물성플랑크톤 변동성에 미치는 태풍의 영향

Abstract

Tropical cyclones (also known as typhoons or hurricanes; TCs) are acknowledged to be an important determinant of ocean primary production. It is because TCs can cause pumping of nutrient-rich deep water to the euphotic zone and blooming of phytoplankton on the upper ocean, as well as the cooling of sea surface temperature. Despite this nutrient supply mechanism by TCs, much of research in the relationship between TCs and ocean phytoplankton are confined to case studies in which the biological responses to a certain tropical cyclone are examined in a specific region. In this study, large-scale variability of phytoplankton influenced by overall variability of tropical cyclones has been investigated. The area of interest is the western North Pacific (WNP) where the strong tropical cyclone activity can be found. The decadal-long accumulation of satellite-derived chlorophyll data, which is regarded as the representative of ocean phytoplankton amount, allows the large-scale analysis of the relationship between the two variables. The result based on statistical analyses indicates that the passage frequency of TCs averaged in the WNP region is significantly correlated with the amount of phytoplankton in the same region. In particular, co-variability of tropical cyclones and phytoplankton in the WNP is related to the Pacific decadal oscillation (PDO), a prominent climatic phenomenon in the North Pacific. This result may imply that the PDO-driven TCs activity can significantly influence the ocean primary production in the overall region of the WNP.