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Biogeochemistry in oligotrophic ocean gyres
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Particulate carbon and silica export meditated by cyclonic eddies at Station ALOHA
Tuesday 8th @ 1450-1510, Multifunction Hall
Kuanbo Zhou* , State Key Lab of Marine Environmental Science, Xiamen University
Jie Huang, Ministry of Education Key Laboratory for Earth System Modeling, and Department of Earth System Science, Tsinghua University
Peng Xiu, State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology
Claudia Benitez-Nelson, School of the Earth, Ocean & Environment, University of South Carolina
Zhenyu Sun, State Key Lab of Marine Environmental Science, Xiamen University
Minhan Dai, State Key Lab of Marine Environmental Science, Xiamen University
Presenter Email: kbzhou@xmu.edu.cn |
| Mesoscale eddies may mediate the influx of nutrients into the photic zone and ultimately the downward export of particles to depth. In this study, we diagnosed all cyclonic eddies during 1989-2014 that passed by the Station ALOHA using satellite altimetry, and export fluxes measured by floating traps were found to be documented in 24 eddies. The seasonality of the eddy export followed a similar pattern with that of the climatology. Significant submesoscale variability of export fluxes anomaly (eddy flux minus monthly average) was observed within those eddies if they were normalized into a standard eddy. Higher particle fluxes are tended to be occurred at the edge region when eddies are under their maturity. However, if we combine all eddy flux together and compare to corresponding references, modest enhancement of carbon fluxes (1.1-1.3-fold) is found while that of silica flux was more elevated (1.2-3.8-fold). Such estimate of the flux enhancement was believed to be more robust as it included a 4-D spatial and temporal variability. It thus may be implied that eddy-induced carbon flux might not be as significant as previously thought. Instead, eddies may exert as a more significant silica pump. Further examination revealed a mean of 6±3% of the export efficiency (e-ratios) within the eddies, similar to those in typical oligotrophic settings. |
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