1. Bangor, 10-12/04/06Simpson Retirement Conference1 Numerical Modelling of SImPSon Hans Burchard Baltic Sea Research Institute Warnemünde Bolding & Burchard Hyrodynamics hans.burchard@io-warnemuende.de

2. Bangor, 10-12/04/06Simpson Retirement Conference2 What is SIPS ? Google says: Social Inclusion Partnerships Structural Insulated Panels Signal Processing Systems Secure Internet Processing Services Statistically Improbable Phrases Schweizerische Interessengemeinschaft für Polio-Spätfolgen Società Italiana di Psicologia Side Impact Protection System Student Intellectual Property Society... Strain Induced Periodic Stratification (search for 'sips john simpson bangor')

3. Bangor, 10-12/04/06Simpson Retirement Conference3 Tidal straining during ebb tide Simpson et al. 1990

4. Bangor, 10-12/04/06Simpson Retirement Conference4 Tidal asymmetry (schematically) Jay and Musiak 1994

5. Bangor, 10-12/04/06Simpson Retirement Conference5 Tidal asymmetry (numerically) Burchard and Baumert, 1998

6. Bangor, 10-12/04/06Simpson Retirement Conference6 Tidal straining and estuarine turbidity maxima Burchard et al. 2004 Animation by Manuel Ruiz

7. Bangor, 10-12/04/06Simpson Retirement Conference7 Strain-induced periodic stratification (SIPS) (in Liverpool Bay, temperature & salinity) Rippeth et al. (2001), Burchard (2002), Simpson et al. (2002)

8. Bangor, 10-12/04/06Simpson Retirement Conference8 Rippeth et al. (2001), Burchard (2002), Simpson et al. (2002) Strain induced periodic stratification (SIPS) (in Liverpool Bay, dissipation rate)

9. Bangor, 10-12/04/06Simpson Retirement Conference9 A simple model for SIPS See also Sharples and Simpson (1995)

10. Bangor, 10-12/04/06Simpson Retirement Conference10 Scaling of SIPS equations See also Baumert and Radach (1992)

11. Bangor, 10-12/04/06Simpson Retirement Conference11 Two independent SIPS parameters

12. Bangor, 10-12/04/06Simpson Retirement Conference12 Non-dimensional SIPS equations

13. Bangor, 10-12/04/06Simpson Retirement Conference13 Measure for SIPS intensity See also Simpson and Bowers (1981)

14. Bangor, 10-12/04/06Simpson Retirement Conference14 Example calculation for idealised SIPS Dimensionless relative buoyancy Potential energy anomaly (dimless) Dimensionless time (P g =0.2, S i =0.01)

15. Bangor, 10-12/04/06Simpson Retirement Conference15 SiSi PgPg red: P g · S i = 0.002 No SIPS  ~ Maximum potential density anomaly as function of S i and P g

16. Bangor, 10-12/04/06Simpson Retirement Conference16 Suggested condition for SIPS:

17. Bangor, 10-12/04/06Simpson Retirement Conference17 What we have ignored: Varying sea level elevation Non-zero mean surface slope Varying horizontal density gradient Bottom roughness to depth ratio Earth rotation Surface heat flux Solar radiation Surface momentum flux Surface waves Internal waves Each of these processes would give us at least one more dimensionless number Conclusion: The real world is too complex for us to understand.