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12.22.10: Notes on “Net community production in the deep euphotic zone of the subtropical North Pacific gyre from glider surveys” by Nicholson et al. (2008)

“Rossby waves and eddies in the region cause a vertical displacement of isopycnal depth of ,650 m at the base of the euphotic zone. Shoaling of isopycnals is demonstrated to drive productivity in the deep euphotic zone. Four mesoscale shoaling events were observed between February and November in 2005. During each event when isopycnals shoaled, oxygen concentrations on isopycnals increased, fluorescence in the deep euphotic zone was higher, and net community production was elevated. Productivity in the deep euphotic zone was strongly influenced by Rossby waves and eddies, but this influence was not observed to extend into the mixed layer.”

“In this paper, we focus on NCP in the deep euphotic zone because this zone is most directly influenced by nutrient injections from below. In the mixed layer, nutrients are more likely to be supplied by other sources, such as nitrogen fixation. [...] Mixed-layer NCP was not observed to correlate with the timing of mesoscale shoaling events.”

But submesoscale dynamics may be able to bring nutrient shallow enough into the mixed layer.

Note that these data were taken during WHOTS-1 and WHOTS-2. It would be nice to get them to support our conclusion of the WHOTS data.