[A-OS19] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS19-12] Impact of the deviation of phytoplankton stoichiometry from Redfield ratio on global oceanic net primary production

*増田 良帆¹、山中 康裕¹、平田 貴文²、中野 英之³ (1.北海道大学地球環境科学研究院、2.北海道大学北極域研究センター、3.気象研究所)

キーワード：全球一次生産、CN比、海洋大循環モデル

The deviation of the carbon to nitrogen ratio (C:N) of oceanic phytoplankton from Redfield ratio is well known in field observations; however almost all marine ecosystem models are based on Redfield ratio. Incubation experiments show that C:N increases with an increase in the chlorophyll a to carbon ratio (chl:C) of phytoplankton. Recently developed FlexPFT (Flexible phytoplankton Functional Type) model proposed in Smith et al. (2016) can naturally represent the observed relation between chl:C and C:N. We introduced the FlexPFT model into a 3D ecosystem model combined with an OGCM (Oceanic General Circulation Model). We found that the global oceanic net primary production in a variable C:N case is 1.5 times larger than that in the fixed Redfield C:N case. Higher C:N in equatorial regions mainly contributes to the increase in global primary production.