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

Outline

1. Introduction

2. Model Configuration

3. Model Validation (seasonal and longer scales)

4. Upwelling Event (synoptic scale)

5. Sensitivity

6. Summary

(Strub and James, 2000, DSR)

Seasonal SST (AVHRR)and SSH (TOPEX)

SouthernCaliforniaBight (SCB)

California Current:

(Digiacomo and Holt, 2001)

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

(Dong et al, 2009)

(Dong et al, 2008)

(Adapted from Dong et al, 2008)

(Adapted from Dong et al, 2008)

(Adapted from Dong et al, 2008)

(Adapted from Dong et al, 2008)

Synoptic-scale Simulation:

An Upwelling Event in March, 2002

Sensitivities

1. Wind Resolution

2. Tidal Forcing

3. Surface Heat Flux Function

(adapted from Dong et al, 2009)

Surface heat flux and freshwater flux choices:

1. MM5 heat/freshwater flux

2. COADS Heat/freshwater flux + analytical diurnal heat flux

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.

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