Update on hydrodynamic model comparisons Marjy Friedrichs and Carl Friedrichs Aaron Bever (post-doc) Leslie Bland (summer undergraduate student)

Methods: Target diagrams (Jolliff et al., 2009) 1 1 Unbiased RMSD Bias Total RMSD 2 = Bias 2 + unbiased RMSD 2 meanseasonal variability x > 0 overestimates variability y > 0: overestimates mean

Methods: Target diagrams (Jolliff et al., 2009) 1 1 Unbiased RMSD Bias Total RMSD 2 = Bias 2 + unbiased RMSD 2 meanvariability x > 0 overestimates variability y > 0: overestimates mean

Methods: Target diagrams (Jolliff et al., 2009) 1 1 Unbiased RMSD/stdev(obs) Bias/stdev(obs) Normalization by standard deviation of observations outer circle: Model-data misfit = variability in data x > 0 overestimates variability y > 0: overestimates mean

Methods: Target diagrams (Jolliff et al., 2009) 1 1 Unbiased RMSD/stdev(obs) Bias/stdev(obs) Normalization by standard deviation of observations outer circle: Model-data misfit = variability in data x > 0 overestimates variability y > 0: overestimates mean

Methods: Target diagrams (Jolliff et al., 2009) 1 1 Unbiased RMSD/stdev(obs) Bias/stdev(obs) Normalization by standard deviation of observations outer circle: Model-data misfit = variability in data x > 0 overestimates variability y > 0: overestimates mean model does worse than the mean of the data

Model simulations Original simulations (summer ‘10) ◦ CH3D (P. Wang) ◦ EFDC (J. Shen) ◦ ChesROMS (W. Long) ◦ CBOFS2 (L. Lanerolle) New ‘consistent forcing’ simulations (this week!) ◦ EFDC (J. Shen) ◦ CBOFS2 (L. Lanerolle) ◦ UMCES ROMS (Y. Li)

Preliminary model comparisons (Summer ‘10) Initially examined salinity at the halocline (max dS/dz) as a function of bathymetric error, latitude, salinity, oxygen, bottom depth Conclusion: For all four models, model skill (total RMSD) is primarily a function of mean salinity and/or latitude

New model comparisons (Fall ‘10) Best match over ±12 hour time window Additional variables: dS/dz at max dS/dz z of max dS/dz S at max dS/dz New ‘consistent forcing’ simulations

New model comparisons (Fall ‘10) Best match over ±12 hour time window Additional variables: dS/dz at max dS/dz z of max dS/dz S at max dS/dz New ‘consistent forcing’ simulations

= inst match = best match (over 24h) = inst match = best match (over 24h) Surface Salinity

New model comparisons (Fall ‘10) Best match over ±12 hour time window Additional variables: dS/dz at max dS/dz z of max dS/dz S at max dS/dz New ‘consistent forcing’ simulations

Salinity (psu) Stratification = max dS/dz Stratification = max dS/dz

depth of max dS/dz Salinity (psu)

Salinity at max dS/dz Salinity at max dS/dz Salinity (psu)

New model comparisons (Fall ‘10) Best match over ±12 hour time window Additional variables: dS/dz at max dS/dz z of max dS/dz S at max dS/dz New ‘consistent forcing’ simulations

Surface Salinity EFDC CBOFS2 New forcing: Slight improvement in CBOFS2 results Slight degradation in EFDC results Red = First runs Black = New or consistent forcing runs. The EFDC results here are without showing the far outliers. = old results = new results = old results = new results

max dS/dz old forcing new forcing Salinity (psu)

max dS/dz new forcing Salinity (psu)

depth of max dS/dz old forcing new forcing Salinity (psu)

depth of max dS/dz new forcing Salinity (psu)

Salinity at max dS/dz old forcing new forcing Salinity (psu)

Salinity at max dS/dz new forcing Salinity (psu)

Next steps for hydrodynamic comparisons? Why does CH3D produce superior stratification? ◦ Vertical grid structure? C&D canal? Bathymetry? ◦ other? Next model runs ◦ Atmospheric forcing? ◦ Boundary conditions on shelf? Additional metrics