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Evidences of increasing primary production in the ocean by Stommel's perpetual salt fountain |
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| Authors: | Shigenao Maruyama Takashi YabukiTetsuya Sato Koutaro TsubakiAtsuki Komiya Mikihito WatanabeHiroshi Kawamura Katsumi Tsukamoto |
| Institution: | a Institute of Fluid Science, Tohoku University, Sendai 980-8577, Japan b School of Engineering, Tohoku University, Sendai 980-8579, Japan c Department of Mechanical Engineering, Saga University, Saga 840-8502, Japan d Graduate School of Science, Tohoku University, Sendai 980-8578, Japan e Ocean Research Institute, The University of Tokyo, Tokyo 164-8639, Japan |
| Abstract: | The American physical oceanographer Henry Stommel and co-workers proposed “the perpetual salt fountain” and suggested the possibility of upwelling deep seawater without an energy source. In the open ocean, deep seawater containing rich nutrients becomes a source of primary production. Previously, we have tested Stommel's hypothesis by numerical simulations and in ocean experiments, and confirmed the upwelling of a perpetual salt fountain. In the present study, we conducted an open-ocean experiment in the Philippines Sea, and succeeded to demonstrate an increase in chlorophyll concentration. The chlorophyll concentration at the pipe outlet was much greater than that in the surrounding seawater. Satellite ocean-color image around the pipe was analyzed, and the signal of artificial upwelling is investigated. Composite analysis of satellite chlorophyll image indicates an increased surface chlorophyll distribution in the vicinity of pipe position, in which the increasing signal is much larger than the expected production based on nutrient supply. Although the problem must be further discussed, this increased signal is shown to be statistically significant. This mechanism may contribute to effective utilization of fishery resources in subtropical oligotrophic region. |
| Keywords: | Perpetual salt fountain Deep seawater Artificial upwelling Remote sensing Chlorophyll concentration The North Pacific |
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