Role of eddies in ocean circulation TOPEX e.g. vanishing of Deacon Cell What can we infer from observations? Doos and Webb Danabasoglu, McWilliams Models suggest eddies play major role in tracer, momentum and vorticity budgets But Ocean is full of geostrophic turbulence WOCE SR3 Schematic: Sverdrup Tracer distributions Salinity Residual mean Eulerian mean Bolus transport Rhines Rintoul Circulation inferred from tracers is the residual flow Antarctica What is the role of eddy transfer in setting up ? Infer Eddy transport from observations Winds Surface buoyancy fluxes Momentum balance Buoyancy transport Eddy diffusivity, Compare eddy stress to wind stress How can we estimate a K from observations? Diabatic Deacon Cell Speer,Rintoul & Sloyan Buoyancy Transport Rewrite buoyancy budget: Stream-wise average 2d (i) (ii) y z + dia Andrews and McIntyre Held & Schneider 1 Residual mean theory Gent and McWilliamsIf eddies are adiabatic Cross-stream transport inferred from air-sea fluxes from winds Speer, Rintoul & Sloyan from air-sea buoyancy fluxes Neglecting diffusion & diabatic eddy fluxes David Marshall Cross-stream transport implied by the wind is not the same as that implied by air-sea buoyancy fluxes Air-sea buoyancy fluxWind Stress NCEP SOCDaSilva Pole 0 NCEP In to ocean Out of ocean Cross-Stream transports Buoyancy fluxes Can eddies achieve such a large transport? Sv Ekman Inferred bolus transport Taka Ito Pole WOCE SAC climatology Gouretski and Jancke Eddy mixing If so, how large is the K? 2 Use idealized tracer driven by observed surface geostrophic flow to yield K Can we characterize eddies with a diffusivity, K? Device to yield diffusivity from observations idealized tracer altimetry Large-scale v drives small scale mixing Advection-diffusion in 2-d Nakamura small-scale diffusion In area coordinates problem can be rephrased as: where Haynes and Shuckburgh dissipation rate of q Theory intersects with observations very nicely Drive tracer with altimetric data Assumption: large-scale K is independent of small-scale Topex data every 10 days Emily Shuckburgh (DAMPT) Helen Jones (MIT) Planning to repeat at Resolution with Eddy diffusivity Latitude Near surface Phillips km SCM3 mooring 1500 Implications for parameterization Deducing from isopycnal slope at mixed layer base WOCE SAC climatology Sv Gouretski and Jancke Pole PV mixing PV front Momentum balance surface 0 Johnson and Bryden if at 150m 3 Eddy stress Eddy PV flux Mapping down to depth salinity No bottom water Karsten, Marshall Upper Circumpolar Deep Water (Sv) Intermediate Water Salinity Conclusions d mixing of idealized tracer 3 must be large and oppose Estimated from altimetry yields near-surface Eddy stresses are as large as wind stress 4 Eddies are hugely important in ACC and elsewhere to 2000 Transport implied by and are very different 30 Sv and consistent pattern of Estimate of global eddy stress assuming K = 1000 using WOCE SAC climatology At 300m Parameterized in our global climate models! Observations Theory Modeling Reviews