Seasonal Variation in the Correlation Between Anomalies of Sea Level and Chlorophyll in the Antarctic Circumpolar Current

The Antarctic Circumpolar Current has highly energetic mesoscale phenomena, but their impacts on phytoplankton biomass, productivity, and biogeochemical cycling are not understood well. We analyze satellite observations and an eddy‐rich ocean model to show that they drive chlorophyll anomalies of opposite sign in winter versus summer. In winter, deeper mixed layers in positive sea surface height (SSH) anomalies reduce light availability, leading to anomalously low chlorophyll concentrations. In summer with abundant light, however, positive SSH anomalies show elevated chlorophyll concentration due to higher iron level, and an iron budget analysis reveals that anomalously strong vertical mixing enhances iron supply to the mixed layer. Features with negative SSH anomalies exhibit the opposite tendencies: higher chlorophyll concentration in winter and lower in summer. Our results suggest that mesoscale modulation of iron supply, light availability, and vertical mixing plays an important role in causing systematic variations in primary productivity over the seasonal cycle.

[1]  A. Piola,et al.  Wind modulation of upwelling at the shelf-break front off Patagonia: Observational evidence , 2017 .

[2]  Matthew J. Smith,et al.  Transient dynamics of terrestrial carbon storage: Mathematical foundation and numeric examples , 2016 .

[3]  P. Heimbach,et al.  Biogeochemical versus ecological consequences of modeled ocean physics , 2016 .

[4]  K. Sasaoka,et al.  Mesoscale eddy effects on temporal variability of surface chlorophyll a in the Kuroshio Extension , 2016, Journal of Oceanography.

[5]  Anthony J Richardson,et al.  Anticyclonic eddies are more productive than cyclonic eddies in subtropical gyres because of winter mixing , 2016, Science Advances.

[6]  D. McGillicuddy,et al.  Mechanisms of Physical-Biological-Biogeochemical Interaction at the Oceanic Mesoscale. , 2016, Annual review of marine science.

[7]  Reto Knutti,et al.  Southern Ocean eddy phenomenology , 2015 .

[8]  Michael J. Behrenfeld,et al.  Regional variations in the influence of mesoscale eddies on near‐surface chlorophyll , 2014 .

[9]  J. Greenwood,et al.  Impact of eddies on surface chlorophyll in the South Indian Ocean , 2014 .

[10]  X. Shang,et al.  Horizontal eddy energy flux in the world oceans diagnosed from altimetry data , 2014, Scientific Reports.

[11]  P. Boyd,et al.  Surface-water iron supplies in the Southern Ocean sustained by deep winter mixing , 2014 .

[12]  D. Chelton,et al.  Satellite observations of chlorophyll, phytoplankton biomass, and Ekman pumping in nonlinear mesoscale eddies , 2013 .

[13]  Scott C. Doney,et al.  Marine Ecosystem Dynamics and Biogeochemical Cycling in the Community Earth System Model [CESM1(BGC)]: Comparison of the 1990s with the 2090s under the RCP4.5 and RCP8.5 Scenarios , 2013 .

[14]  O. Aumont,et al.  A global compilation of dissolved iron measurements: focus on distributions and processes in the Southern Ocean , 2011 .

[15]  D. Chelton,et al.  The Influence of Nonlinear Mesoscale Eddies on Near-Surface Oceanic Chlorophyll , 2011, Science.

[16]  D. Chelton,et al.  Global observations of nonlinear mesoscale eddies , 2011 .

[17]  L. Bopp,et al.  The response of phytoplankton biomass to transient mixing events in the Southern Ocean , 2011 .

[18]  P. Boyd,et al.  The biogeochemical cycle of iron in the ocean , 2010 .

[19]  C. Moore,et al.  Phytoplankton and light limitation in the Southern Ocean: Learning from high‐nutrient, high‐chlorophyll areas , 2010 .

[20]  Janet Sprintall,et al.  Southern Ocean mixed-layer depth from Argo float profiles , 2008 .

[21]  Nicholas R. Bates,et al.  Eddy/Wind Interactions Stimulate Extraordinary Mid-Ocean Plankton Blooms , 2007, Science.

[22]  N. Mahowald,et al.  Combustion iron distribution and deposition , 2007 .

[23]  Keith Lindsay,et al.  Upper ocean ecosystem dynamics and iron cycling in a global three‐dimensional model , 2004 .

[24]  Dennis A. Hansell,et al.  Global distribution and dynamics of colored dissolved and detrital organic materials , 2002 .

[25]  Stéphane Maritorena,et al.  Optimization of a semianalytical ocean color model for global-scale applications. , 2002, Applied optics.

[26]  P. Worsfold,et al.  Biogeochemistry of Fe and other trace elements (Al, Co, Ni) in the upper Atlantic Ocean , 2002 .

[27]  Joaquín Tintoré,et al.  Mesoscale vertical motion and the size structure of phytoplankton in the ocean , 2001, Nature.

[28]  Carl Wunsch,et al.  Where do ocean eddy heat fluxes matter , 1999 .

[29]  Richard J. Geider,et al.  A dynamic regulatory model of phytoplanktonic acclimation to light, nutrients, and temperature , 1998 .

[30]  D. Siegel,et al.  Inherent optical property inversion of ocean color spectra and its biogeochemical interpretation: 1. Time series from the Sargasso Sea , 1997 .

[31]  Janet W. Campbell,et al.  The lognormal distribution as a model for bio‐optical variability in the sea , 1995 .

[32]  W. Large,et al.  Oceanic vertical mixing: a review and a model with a nonlocal boundary layer parameterization , 1994 .

[33]  D. M. Nelson,et al.  Sverdrup revisited: Critical depths, maximum chlorophyll levels, and the control of Southern Ocean productivity by the irradiance‐mixing regime , 1991 .

[34]  J. Marshall,et al.  Observed mesoscale eddy signatures in Southern Ocean surface mixedlayer depth , 2017 .

[35]  S. Gille,et al.  Southern Ocean wind‐driven entrainment enhances satellite chlorophyll‐a through the summer , 2015 .

[36]  I. Frenger.  On Southern Ocean eddies and their impacts on biology and the atmosphere , 2013 .

[37]  J.,et al.  Marine EcosystemDynamics and Biogeochemical Cycling in the Community Earth System Model [ CESM 1 ( BGC ) ] : Comparison of the 1990 s with the 2090 s under the RCP 4 . 5 and RCP 8 . 5 Scenarios , 2013 .

[38]  C. Wunsch,et al.  Ocean Circulation Kinetic Energy: Reservoirs, Sources, and Sinks , 2009 .

[39]  P. Boyd.  The role of iron in the biogeochemistry of the Southern Ocean and equatorial Pacific: a comparison of in situ iron enrichments , 2002 .

[40]  S. Doney,et al.  An intermediate complexity marine ecosystem model for the global domain , 2001 .