Elevated turbulent and double-diffusive nutrient flux in the Kuroshio over the Izu Ridge and in the Kuroshio Extension

Autor: Fuminori Hashihama, Takeyoshi Nagai, Gandy Maria Rosales Quintana, Gloria Silvana Durán Gómez, Kosei Komatsu
Jazyk: angličtina
Rok vydání: 2021
Předmět:
沖縄トラフ・トカラ海峡で高鉛直波数近慣性波シアと乱流が卓越するメカニズム
The Kuroshio Extension
010504 meteorology & atmospheric sciences
Resolving multi-scale mixing processes and their impacts using a twin tow-yo microstructure profiling system
Nitrate flux
Geometry
Nutrient flux
Oceanography
01 natural sciences
Mechanisms of dominant vertical high wavenumber near inertial shear and strong turbulence in the Okinawa Trough and the Tokara Strait
Near-inertial wave generations and diapycnal mixing in the Kuroshio origin regions near the continental shelf
Double-Diffusion
0105 earth and related environmental sciences
Physics
二台同時自由落下曳航観測手法を用いたマルチスケール混合現象とその影響に関する研究
The Kuroshio
010505 oceanography
Turbulence
Double diffusion
Izu-Ridge
科学研究費研究成果
黒潮源流が陸棚縁で生成する近慣性内部波と躍層における鉛直混合メカニズムの解明
Ridge (meteorology)
Diffusive flux
Production (computer science)
Zdroj: Journal of Oceanography. 77:55-74
ISSN: 0916-8370
DOI: 10.1007/s10872-020-00582-2
Popis: While the Kuroshio is known to be a nutrient stream, as these nutrients are in dark subsurface layers, they are not immediately available for photosynthesis unless they are supplied to the sunlit surface layers. Recent microstructure observations have revealed that strong diapycnal mixing caused by the Kuroshio flowing over topographic features and double diffusion in the subsurface layers of the Kuroshio. However, it is still unclear how much nutrient flux can be provided by these microscale mixing processes. In this study, using an autonomous microstructure float and nutrient samplings, nutrient flux caused by the Kuroshio over the Izu Ridge, and that caused by double diffusion in the Kuroshio Extension are quantified. The nitrate diffusive flux is estimated to be $$>1 \,\hbox {mmol} \,\hbox {N}\,\hbox {m}^{-2}\hbox {day}^{-1}$$ > 1 mmol N m - 2 day - 1 over a distance, 20–30 km near the Izu Ridge and $$>0.1 \,\hbox {mmol} \,\hbox {N}\, \hbox {m}^{-2}\hbox {day}^{-1}$$ > 0.1 mmol N m - 2 day - 1 , which persists further downstream direction over 100 km along the Kuroshio, increasing the subsurface chlorophyll-a concentration in the region 200 km downstream. The double-diffusion-induced nitrate flux is estimated to be 1-$$10 \,\hbox {mmol} \,\hbox {N} \,\hbox {m}^{-2}\hbox {day}^{-1}$$ 10 mmol N m - 2 day - 1 in the pycnostad 26–$$26.5\,\hbox {kgm}^{-3}$$ 26.5 kgm - 3 of the Kuroshio Extension, suggesting that whether this double-diffusion-induced nutrient flux in the subsurface layers can ultimately contribute to surface primary production depends on additional eddy up- and northward fluxes.
Databáze: OpenAIRE
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