Local stratification control of marine productivity in the subtropical North Pacific

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Strengthened stratification of the upper ocean due to global warming is generally expected to inhibit marine primary productivity in the subtropics, based on the supposition that increased water column stability will decrease vertical mixing and consequently the entrainment of deep nutrients into the euphotic zone. A recent analysis of observational data from the subtropical North Atlantic, however, demonstrates that productivity in this region is not correlated with stratification on interannual time scales over the modern observational record, but is instead impacted by other dynamics that affect vertical mixing and nutrient supply. Herein, we examine data from the Hawaiian Ocean Time series program's Station ALOHA (A Long-Term Oligotrophic Habitat Assessment) in the subtropical North Pacific. We find that stratification and productivity are not strongly correlated at this location over the observational record. In contrast to the North Atlantic, the weakness of correlation observed at ALOHA may reflect the strongly stratified ecosystem of the eastern subtropical North Pacific and a lack of sufficiently strong interannual forcing in this region. Although basin-wide climate processes (namely El Nio-Southern Oscillation and Pacific Decadel Oscillation) have previously been suggested to impact local stratification and vertical nutrient supply at ALOHA, we find no evidence of a strong or consistent linkage. Comparing local ecosystem variability to the recently identified North Pacific Gyre Oscillation, however, we observe a correlation with local subsurface productivity and salinity. The correlations have similar structure in both space (i.e., depth) and time and are possibly linked to dynamics associated with the formation and advection of water masses in the central gyre. © 2010 by the American Geophysical Union.






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Dave, AC, and MS Lozier (2010). Local stratification control of marine productivity in the subtropical North Pacific. Journal of Geophysical Research: Oceans, 115(12). p. C12032. 10.1029/2010JC006507 Retrieved from https://hdl.handle.net/10161/4201.

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M. Susan Lozier

Ronie-Richele Garcia-Johnson Emerita Professor of Earth and Ocean Sciences

Susan Lozier is a physical oceanographer with interests in large-scale ocean circulation. Upon completion of her PhD at the University of Washington, she was a postdoctoral scholar at Woods Hole Oceanographic Institution. She has been a member of the Duke faculty since 1992. Professor Lozier was the recipient of an NSF Early Career Award in 1996, was awarded a Bass Chair for Excellence in Research and Teaching in 2000, received a Duke University Award for Excellence in Mentoring in 2007, was named an American Meteorological Society Fellow in 2008, a Distinguished Professor in 2012, a Fellow of the American Geophysical Union in 2014 where she has been elected as president elect. She begins her two-year term as president-elect on Jan. 1, 2019, and then will serve a two-year term as AGU president beginning in 2021. She was named a Fellow of the American Association for the Advancement of Science in 2015. She currently serves as the past-president of The Oceanography Society and is the international lead for the OSNAP (Overturning in the Subpolar North Atlantic Program) observing system.

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