1. Sensitivity Analysis of SST along NJ coast with ADROMS Weifeng (Gordon) Zhang John Wilkin Julia Levin Hernan Arango Institute of Marine and Coastal Sciences, Rutgers University Oct. 2005

2. Background  Plenty of measurement in New Jersey shore area;  Ocean forecast and hind-cast with forward ROMS has been running;  To use data assimilation in these area to improve the forecast and measurement;  Adjoint sensitivity analysis with ADROMS is applied first to test the model based on our understanding of the physics in this area.  Adjoint sensitivity analysis: What causes the event?

3. Forward Model – Background for Adjoint model Three idealized cases (steady low river discharge, no tide, no surface exchange): No wind Southwestward wind Northeastward wind

4. Adjoint sensitivity set-up For upwelling event: Background state: 5 days bi-hourly forward model output. Event time: Adjoint forcing: Adjoint variable: FORWARD_MIXING: Adjoint model reads mixing coefficients from forward output

5. No wind case

6. Nowind case (cont’d) Adjoint variableMagnitude of adjoint variable Standard deviation of variable ad_SST(0, 0.02)50.1 ad_SSS(-0.002, 0.002)50.01 ad_u/ad_v(-0.05, 0.05)0.50.025 ad_Akv(-100, 100)10 -4 10 -2 ad_Akt(0, 60)10 -5 10 -4 ad_Aks(-3, 3)10 -5

7. Southward wind case

8. Southward wind case (cont’d) Adjoint variableMagnitude of adjoint variable Standard deviation of variable ad_SST(0, 0.02)50.1 ad_SSS(-0.005, 0.005)50.025 ad_sustr/ad_svstr (-100, 100)0.0020.2 ad_u/ad_v(-0.05, 0.05)0.50.025 ad_Akv(-150, 150)10 -4 0.015 ad_Akt(0, 15)10 -5 10 -4 ad_Aks(-10, 5)10 -5 10 -4

9. Northward wind case

10. Northward wind case (cont’d)

11. Summary  ADROMS gives physically reasonable results for sensitivity analysis on idealized application in NJ shore area  Users need to think about the definition of the measure of certain event, J  The validity of linearization to the nonlinear model has to be considered carefully and proved first ______________________________________________________ Great appreciation goes to John Wilkin, Hernan Arango, Julia Levin, Andrew Moore and B-J Choi!