These promising results are theoretical. The pictures are stills from a upwelling calculator built with xcode and cocoa on Apple OS 10.5 (Leopard) which is available on the reference page for download (Mac only). The source code is available on request. The calculator displays the results (upwelling rate, exit temperatures, heat transfer coefficients, Reynolds numbers, etc.) when the parameters are varied (temperature profile, conduit sizes, conduit positions,wave height).
Pacific Results
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Notice that there is an upwelling even at a wave-height of zero. This phenomenon was predicted and known as the "perpetual salt fountain". See "Artificial Upwelling of Deep Seawater Using the Perpetual Salt Fountain for Cultivation of Ocean Desert" by Maruyama, S. Tsubaki, K. Taira, K. Sakai, S. in JOURNAL OF OCEANOGRAPHY Vol. 60 pp. 563-568 (2004).
Notice also the hysteresis, which is a result of the heat conductance for turbulent flow (the up-flow) being more conductive than that for laminar flow. The white line is the performance as the wave height is decreasing, and the flow is turbulent. As the wave height increases from a calm ocean, there is not enough heat transfer to reach turbulent flow until about a wave height of 0.2 meters at which point the flow increases, becoming more turbulent and more heat conductive until an upwelling flow of 1.2 cubic meters per second is reached.
Atlantic Results
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The steep slope of the temperature profile of the Atlantic made it necessary to move the position of the efflux to the deeper level of 100 meters. When the exchanger had the same dimensions as the Pacific example there was not a transition from laminar to turbulent flow, notwithstanding the higher salt concentration at the surface which helps the performance. There is not much light for the nutrient efflux at 100 meters, and photosynthesis is slow. Is it a disadvantage for the efflux to be at 100 meters and not 50 meters? It is if you want the fruits of the upwelling to be near the upwelling device. Depending on ambient conditions, the upwelled nutrient may be many miles away before it becomes a product of photosynthesis. The U.S. Marine biomass project (1972-1986) tried to contained the upwelling (in this case by power of diesel) inside a makeshift structure, which was destroyed by waves and boats. Containment is probably not a good idea.
Nutrients
In the top several hundred meters in the North Pacific, the concentration of nitrate increases approximately linearly by 6.5 μmoles per liter for every 100 meters depth, and phosphate concentration increases by 0.5 μmoles per liter for every 100 meters depth (Marine Geochemistry edited by Horst D. Schulz and Matthias Zabel, 2006, page 208). With the dimensions given for the device in the pacific, nitrate is added to the photic zone at a rate of 14.95 millimoles per cubic meter of upwelling. The amount of phosphate added is 1.15 millimoles per cubic meter of upwelling. At a rate of 1.4 cubic meters per second, a single upwelling device is delivering 112 kilograms of nitrate and 13.2 kilograms of phosphate to the photic zone each day.