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On the role of eddies for coastal productivity and carbon cycling Hartmut Frenzel 1, Nicolas Gruber 2,1, Gian-Kasper Plattner 2, Takeyoshi Nagai 3,1, James.

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Presentation on theme: "On the role of eddies for coastal productivity and carbon cycling Hartmut Frenzel 1, Nicolas Gruber 2,1, Gian-Kasper Plattner 2, Takeyoshi Nagai 3,1, James."— Presentation transcript:

1 On the role of eddies for coastal productivity and carbon cycling Hartmut Frenzel 1, Nicolas Gruber 2,1, Gian-Kasper Plattner 2, Takeyoshi Nagai 3,1, James C. McWilliams 1, Zouhair Lachkar 2 1 IGPP & DAOS, UCLA 2 Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Switzerland 3 Tokyo Institute of Fisheries, Japan

2 (gC m -2 yr -1 )

3

4

5 Horizontal resolution: 5 km Vertical resolution: 20 levels climatological forcing WOA01 for T,S; COADS for winds NPZD model Nitrogen based (no iron limitation) Upwelling system focused Fixed stoichiometric ratios of C:N US WEST COAST CONFIGURATION OF ROMS [Gruber et al., DSR I, 2006]

6 USWC-5km ROMS

7 IMPACT OF MESO-SCALE PROCESSES Standard (eddy) run: #define UV_ADV Linear run: #undef UV_ADV (VISC2 = 100 m 2 /s) Both for USWC 5 km configuration

8 (all fluxes: mol C m -2 yr -1 )

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10 Eddy induced anomalous circulation

11

12 California upwelling: highest TKE and lowest PP

13 NPP: California vs. Canary Current System [Gruber et al., in prep. 2007 ]

14 UWI: California vs. Canary Current System [Gruber et al., in prep. 2007]

15 EKE: California vs. Canary Current System [Gruber et al., in prep. 2007]

16 [Gruber et al., in prep. 2007]

17 NPP/UWI and NPP/EKE: California and Canary CS [Gruber et al., in prep. 2007]

18 SUMMARY Meso- and submesoscale processes tend to suppress primary production and air-sea fluxes of CO 2 in coastal upwelling systems. This is due to an eddy-induced "overturning" circulation that counteracts the upwelling and leads to a “leakage” of nutrients out of the upwelling region. First results indicate that the differing levels of eddy kinetic energy in the various upwelling systems are a primary reason for their large differences in primary production.

19 Eddy-partNon-eddy part EDDY CONTRIBUTION TO OFFSHORE TRANSPORT Nagai et al. (in prep. 2007) Offshore distance Total offshore transport of NO 3 & NH 4 Eddy-tracking Fraction by Eddies >60% of offshore transport by eddies

20 MECHANISMS OF OFFSHORE TRANSPORT Filament transport Subduction Westward propagating eddies Upwelling Nearshore ~200km Beyond 200 km

21 Acknowledgments Funding: NASA and NSF Computer time: NCSA


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