Dynamic changes of chlorophyll a and nutrients in different water layers under typhoon influence

Abstract

Global climate change and increasing extreme weather events present significant challenges to marine ecosystems, highlighting the importance of understanding the interactions between phytoplankton and nutrients during typhoons. By exploring the interactions between upwelling, mixing, and phytoplankton dynamics, we aim to provide a comprehensive understanding of how typhoons affect the distribution of nutrients and Chl-a in the ocean using BGC-Argo data and satellite data. Our findings indicate that the upwelling caused by the typhoon increased the amount of nutrients and Chl-a in 40-80 m layer. Specifically, depth-integrated nitrate levels rose by 14.76 % and depth-integrated Chl-a levels increased by 49.84 %. This shows that the new nitrogen brought to the surface during the storm was essential for phytoplankton growth. However, the typhoons also raised the subsurface Chl-a maximum layer, leading to fewer phytoplankton in their original layer. This reduction slowed down how quickly nutrients were used, resulting in more nitrate accumulating in that area. Additionally, we observed a warming phenomenon below 100 m, which is attributed to downwelling caused by the typhoon. These results enhance our understanding of nutrient dynamics changes and responses of phytoplankton to typhoons in the context of climate variability.

Keywords: Chlorophyll a; Nutrients; Typhoon; Vertical velocity.