1. Turbulence and Mixing in Shelf Seas John Simpson, Tom Rippeth, Neil Fisher,Mattias Green Eirwen Williams, Phil Wiles, Matthew Palmer Funded by the NERC, EU (OAERRE, MABENE, C2C) and Dstl With technical support from Ray Wilton, Ben Powell & the officers and crew of the Prince Madog. School of Ocean Sciences, University of Wales Bangor, Menai Bridge, LL59 5EY, UK Ysgol Gwyddorau Eigion, Prifysgol Cymru Bangor, Porthaethwy Visit our web site at: www.sos.bangor.ac.uk/research/tmiss/index.html

2. Menu Motivation Measurement capabilities Mapping ε in shelf regimes with FLY ADCP variance method for Production Mixing in the pycnocline of the shelf seas

3. Turbulent processes in shelf seas Motivation ? Key environmental control of: Fluxes of nutrients/ particles etc. (Mixing) Particle aggregation/disaggregation Predator-prey encounter rates Tests of Turbulence Closure schemes for models

4. Which Properties ? Diffusion TKE production Buoyancy Dissipation ADCP Variance method

5. FLY Dissipation Profiler

6. S1 M1

7. Mixed station M1 observed ε ε Model MY2.2 (with diffusion) Model MY2.0 (no diffusion) Time(days)

8. Stratified station S1 T°C ε (Wm -3 )

9. ε Model MY2.2 ε observed

10. Model – Observation Inter-comparison BIG discrepancy between the predicted (using MY2.2 closure scheme) and observed levels of  (Simpson et al., 1996). ie. The model fails to reproduce the critical dissipation and thus mixing within the thermocline. Bottom Boundary Layer Log 10 [  0 (Wm -3 )] Model Obs. Missing physical processes within the model? S1

11. The velocity shear in a boundary layer forced by an oscillating pressure gradient X=A cos ωt is given by (Lamb p.622): The corresponding TKE production will be : which increase with height above bed at a rate So that the production (and hence ε ) will exhibit an M 4 phase lag of : The phase of TKE production ?

12. Phase lag (hours) Mixed Nz=0.4m 2 s -1 Stratified Nz=0.025m 2 s -1 PHASE AMPLITUDE Mixed Nz=0.13m 2 s -1

13. Liverpool Bay ROFI

17. LB2 Temperature Salinity

18. Cycle of epsilon with density JPO 31,2458-2471 (2001) Log W/m 3

20. GOT Model k-epsilon +Canuto Hans Burchard Karsten Bolding

21. P/ε B/ε

22. ADCP Variance Method z w4w4 v4v4 b4b4 43  y