Composite Three‐Dimensional Biogeochemical Responses to Tropical Cyclones in the Northwest Pacific

We innovatively investigated three‐dimensional biogeochemical responses to tropical cyclones (TCs) in the Northwest Pacific using a composite analysis of simulations from a coupled physical‐biogeochemical model. TC‐induced upwelling and vertical mixing cause a vertical redistribution of chlorophyll a concentration (Chl ‐a ), increasing surface Chl‐ a while decreasing subsurface Chl ‐a , within a 100‐km radius of the TC center. Simultaneously, these processes bring nutrient‐rich deep waters into the upper layer. Following the TC passage, the significant increases in both Chl ‐a and nutrients lead to a high Chl ‐a anomaly in the subsurface layer that persists for over 30 days. Westward geostrophic advection, driven by the meridional density gradient, tends to shift the subsurface nutrients and Chl ‐a anomalies toward the left side of the generally northwestward TC track. The total biomass in the upper ocean, as indicated by integrated Chl ‐a , decreases shortly after the TC passage and subsequently starts to rise, ultimately resulting in a net increase.