1. MODELLING THE FEEDBACKS BETWEEN PHYTOPLANKTON AND GLOBAL OCEAN PHYSICS 1 Max-Planck-Institut für Biogeochemie, Jena, Germany. 2 University of East Anglia, Norwich, United Kingdom. Manfredi Manizza 1,2, C. Le Quéré 1, A. J. Watson 2, E. Buitenhuis 1

2. PHYTOPLANKTON-LIGHT- HEAT INTERACTION Ocean Surface Sun Absorption & Warming IoIo Shading & Cooling I (z) Phytoplankton

3. FROM TROPICAL TO GLOBAL 1) An OGCM (OPA) on global configuration: 0.5 ° - 1.5 ° x 2.0 ° (Lat x Lon) 1.5 order TKE Model. Gent-McWilliams eddy-mixing. 2) An ocean biogeochemistry model (Dynamic Green Ocean Model) : Diatoms and Coccolithophores and Nanophytoplankton. Micro and Mesozooplankton. Co-limitation of light,P, Si and Fe. 3) A Sea-Ice model (LIM) Tropical Studies : Nakamoto et al. (2000, 2001); Murtugudde et al. (2002) OGCM + Satellite derived Chlorophyll “Off-line” forcing  NO FEEDBACKS !! Ocean Surface IoIo I (z)

4. INCLUDING THE BIOLOGY K ( ) = kw ( ) + χ ( ) * [Chl] tot e( ) K ( ) = LIGHT EXTINCTION COEFFICIENT I (z) = I 0 *( R*e (-z/  1 ) + (1-R)*(e -(kr * z) +e -(kg * z) ) _____________ 2 RED BLUE/GREEN INFRARED I (z) = I o * (R*e (-z/  1 ) + (1-R)*e (-z/  2 ) ) Paulson & Simpson Model (JPO,1977) Morel Model (JGR,1988) [Chl] tot = [Chl] diatom + [Chl] cocco + [Chl] nano

5. Monthly Maximum 2.5 0 THE MODELLED “BIO-FORCING” ( mg m-3) Monthly Average SURFACE [Chl]

6. Δ PENETRATION DEPTH (Z pen ) IoIo Z pen Z pen = ( ez ∫ I (z) dz)/I o -6-0.5 Average (m) Z pen Visible Light = 23 m

7. TROPICS

8. Average 2 Δ SEA SURFACE TEMPERATURE °C Δ TEMPERATURE 0.4 -1.4 °C

9. Δ MLD & Δ u (surf) Average 200 - -20 - 0.3 m/s - (m)

10. TROPICS TO SUB-TROPICS

11. TROPICS/SUBTROPICS INTERACTION -3080 Equator Subtropics +ΔPO 4 -ΔMLD +Δu+Δu +ΔTPP Δ TOTAL PRIMARY PRODUCTION gC m -2 yr -1 MONTHLY AVERAGE DEPTH

12. HIGH LATITUDES

13. Δ SEA SURFACE TEMPERATURE Monthly Maximum 2 °C

14. EFFECTS ON SEA-ICE (AVERAGE) Δ %ICE N = -0.17 * [Chl] surf Δ %ICE S = -1.3 * [Chl] surf %( Δ Ice fraction) 80 -80 Sea-ice Ocean Sun Phytoplankton

15. GLOBAL

16. ECOSYSTEM RESPONSE ΔTotal Chl (mg m -3 ) ΔDiatoms (%) ΔCoccolithophores (%) ΔNanophyto (%) AVERAGE + 30 -30 +0.35-0.35

17. IMPACT ON OCEAN CARBON CYCLE DiagnosticHow much ?Why ? ΔTOTAL PRIMARY PRODUCTION +0.6 PgC yr -1 Increased stratification and extra lateral supply of PO 4 in the subtropics. ΔEXPORT PRODUCTION -0.3 PgC yr -1 Greater stratification & higher remineralization of organic matter. ΔCO 2 FLUX-0.1 PgC yr -1 Surface warming, reduced vertical mixing, enhanced equatorial upwelling.

18. CONCLUSIONS Different and Regional Modifications: SST, MLD, CURRENTS, SEA-ICE. OCEAN PHYSICS  ECOSYSTEM & OCEAN BIOGEOCHEMISTRY  OCEAN CARBON CYCLE. Global OBGCM  Tropics and Interaction Tropics/Subtropics & High Latitudes. Phytoplankton presence affects light and heat penetration in the ocean.

19. Dynamic Green Ocean Model N 2 fixers DMS producers coccolith. Nano phytoplankton Fe NO 3 Si CaCO 3 PO 4 NH 4 DOM diatoms (Buitenhuis et al.,in prep.)