1. Numerical Simulation of an Upwelling Event in the Southern California Bight (SCB) Changming “Charles” Dong IGPP, UCLA Collaborators: J. McWilliams, M. Hughes, A. Hall and E. Idica

2. Outline 1.Introduction 2.Model Configuration 3.Model Validation (seasonal and longer scales) 4.Upwelling Event (synoptic scale) 5.Sensitivity 6.Summary

3. (Strub and James, 2000, DSR) Seasonal SST (AVHRR) and SSH (TOPEX) Southern California Bight (SCB) California Current:

4. (Digiacomo and Holt, 2001)

5. Regional Oceanic Model System (ROMS) 3-level One-way nested grids (~20km  ~6.7km, online) (~6.7km  1km offline) Surface Forcing (MM5 54km 18km, 6km, 2 km) Open Boundary Data (SODA, Carton et al, 2000a,b, JPO) SODA (IC) Integration from 1996-2003 20km 6.7km 1km

6. (Dong et al, 2009)

7. (Dong et al, 2008)

8. (Adapted from Dong et al, 2008)

12. Synoptic-scale Simulation: An Upwelling Event in March, 2002

22. Sensitivities 1.Wind Resolution 2.Tidal Forcing 3.Surface Heat Flux Function

28. (adapted from Dong et al, 2009)

30. Surface heat flux and freshwater flux choices : 1.MM5 heat/freshwater flux 2.COADS Heat/freshwater flux + analytical diurnal heat flux

32. SUMMARY 1.The ROMS forward model is applied to study the oceanic circulation system in the Southern California Bight using three-level nesting grids (20km,6.8km, and 1km) forced by reanalyzed MM5 product. 2. Model results are validated with observational data in terms of seasonal and longer scales. And the synoptical-scale performance is tested. 3.An upwelling event in March, 2002 is well reproduced using the ROMS forward model. The sensitivity study shows it is sensitive to the wind forcing resolution and its results converge when the wind resolution moves to 2km. The tidal forcing plays important role in the relaxation of the upwelling. The different heat flux functions are tested. THANKS. ENJOY YOUR STAY AT SYDNEY!