日本地球惑星科学連合2019年大会

講演情報

[E] 口頭発表

セッション記号 A (大気水圏科学) » A-OS 海洋科学・海洋環境

[A-OS12] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

2019年5月27日(月) 10:45 〜 12:15 302 (3F)

コンビーナ:伊藤 進一(東京大学大気海洋研究所)、平田 貴文(北海道大学地球環境科学研究院)、Enrique N Curchitser(Rutgers University New Brunswick)、Eileen E Hofmann(Old Dominion University)、座長:松村 義正(東京大学大気海洋研究所)

10:45 〜 11:05

[AOS12-06] A Lagrangian view of spring phytoplankton blooms

★Invited Papers

*木田 新一郎1伊藤 貴充2 (1.九州大学・応用力学研究所、2.ジョージア工科大学)

キーワード:春季ブルーム、粒子追跡モデル

The basic mechanism behind spring phytoplankton blooms is investigated using a 1-dimensional Lagrangian NPZD model, where the movement and transfers of nutrient parcels are solved by tracking a nitrogen parcel. The Lagrangian framework is useful for understanding how the nitrogen cycle works in the ocean since it naturally follows the movement of materials through the turbulent ocean environment. The model reveals that the onset of spring blooms depends on the cumulative euphotic age, which is the total time that inorganic nutrient is exposed to light before the photosynthetic conversion to phytoplankton biomass. This is regardless of the underlying mechanism, such as critical depth hypothesis or critical turbulence hypothesis. The difference between the two modes lies in how cumulative euphotic age is accumulated and this can be distinguished by examining the cumulative euphotic age spectrum. We further examined the impact of mortality by comparing the model experiments with and without mortality. The cumulative euphotic age necessary for a spring bloom is found to increase, as expected, but the spectral shapes remained similar.