Provided by Eric P. Chassignet, COAPS, Florida Provided by Eric P. Chassignet, COAPS, Florida State UniversityState University

HYCOM High HYCOM High Resolution Resolution ModelingModeling

HYCOM with TidesHYCOM with Tides Includes tidal forcing and Includes tidal forcing and

slightly increased slightly increased interfacial diffusioninterfacial diffusion

7/2003 – 06/20087/2003 – 06/2008 8 largest constituents 8 largest constituents

(M2, S2, K1, O1, N2, P1, (M2, S2, K1, O1, N2, P1, K2, Q1) forward tidesK2, Q1) forward tides

Whole domain daily Whole domain daily averaged filesaveraged files

Hourly 3-D archive files, Hourly 3-D archive files, Global: May 2004 Global: May 2004 Small subdomains: Small subdomains: 08/2005 – 06/200808/2005 – 06/2008

Twin 1/12Twin 1/12 Global HYCOM Simulations Global HYCOM Simulations HYCOM without TidesHYCOM without Tides

Climatological spin-up: Climatological spin-up: 1979-2002 21979-2002 2ndnd ECMWF ECMWF Reanalysis scaled to Reanalysis scaled to QuikSCAT wind speedQuikSCAT wind speed

Then 01/2003 – 06/2008 Then 01/2003 – 06/2008 3-hourly 3-hourly 0.50.5° ° NOGAPS NOGAPS forcing scaled to forcing scaled to QuikSCATQuikSCAT

KPP mixed layerKPP mixed layer Advect T & SAdvect T & S Daily global 3-D archive Daily global 3-D archive

filesfilesArbic, Wallcraft, and Metzger

Sea Surface Elevation Error in HYCOM with Sea Surface Elevation Error in HYCOM with Winds and TidesWinds and Tides

Constituent Signal (cm) Error (cm) % Variance

Q1 1.62 0.68 82.1

O1 7.76 2.48 89.7

P1 3.62 0.79 95.2

K1 11.26 2.48 95.1

N1 6.86 1.40 95.9

M2 33.22 8.26 93.8

S2 12.62 5.17 83.2

K2 3.43 1.65 76.9

RSS 39.04 10.63 92.6Computed with standard set of 102 pelagic tide

gauges (Shum et al. 1997)

Eddy Resolving Global Eddy Resolving Global Prediction With TidesPrediction With Tides

Hourly steric SSH Hourly non-steric SSH

Internal tidal signature seenin the steric SSH signal

Propagation of tides is consistentwith Robertson and Ffield (2008)

Eight largest tidal constituents in a 32-layer .08° global HYCOM simulation with NOGAPS atmospheric forcing

Difference in Steric SSH Over 6 Hours Difference in Steric SSH Over 6 Hours June 30 2006: 06Z – 00ZJune 30 2006: 06Z – 00Z

-10 -5 0 5 10(cm)

Climatological spin-up:Climatological spin-up:

• Start from January GDEM3 climatologyStart from January GDEM3 climatology

• 1979-2002 ERA-40 scaled to QuikSCAT wind speed1979-2002 ERA-40 scaled to QuikSCAT wind speed

• KPP mixed layerKPP mixed layer

• Improvements over earlier 1/12Improvements over earlier 1/12 simulations: simulations:

• Equation of state quadratic (vs linear) in salinityEquation of state quadratic (vs linear) in salinity

• More accurate thermobaric correctionMore accurate thermobaric correction

• More accurate vertical remapping of layersMore accurate vertical remapping of layers

• Also run a 1/12Also run a 1/12 exact twin exact twin

• Both have run for 5 model yearsBoth have run for 5 model yearsZamudio, Metzger, Wallcraft

Initial 1/25Initial 1/25° ° Global HYCOM Global HYCOM SimulationSimulation

Gulf Stream Sea Surface Height VariabilityGulf Stream Sea Surface Height Variability

a) Along-track from four satellite altimeters (Hurlburt and Hogan, 2008)

b) 1/12 global model year 3c) 1/25 global model year 3

(a)

(c)(b)