Xiaochun WangXiaochun Wang

Influence of Stratification on Semidiurnal Tides in Monterey Bay, California

& Coastal Barotropic Tide Solutions

Contributions from: JPL Yi Chao OSU C.K. Shum, Yuchan Yi UCLA Changming Dong, James McWillams NPS Leslie Rosenfeld, Jeffery Paduan NAO Koji Matsumoto, Tadahiro Sato Newcastle Xiaoli Deng; Hong Kong PolyTech Baki Iz

OSTST 2006

a b

a: Jet Propulsion Lab/California Institute of Technologyb: Raytheon, ITSS

. Validation of tidal solution

. Influence of stratification

Comparison with TOPEX Barotropic Tide

Away from the coastRoot of Summed Square 3.45cm<6% of M2 amplitude

cm

Tidal BC from TPXO6.0

Baroclinic Tides Derived from Altimetry and ROMS

Satellite Sample # Mean Amp Std Amp Corr (Amp) Corr (Pha) TOPEX 1013 0.52 0.30 0.195 0.103T/P-Tandem 1070 0.76 0.41 0.009 0.072 GFO 1855 0.81 0.46 0.101 0.087 ROMS 1013 0.25 0.15 1.000 1.000

Significant at 99% level by Monte Carlo simulation.

cm cm

* Cycles used, TOPEX: 4-364, Tandem: 369-479, GFO: 37-168 Envisat: ~250 data points.

Baroclinic Tides Derived from Altimetry

TOPEX T/P-Tandem GFO

TOPEX 1.0 0.124 0.351

T/P-Tandem 84.3% 1.0 0.298

GFO 99.2% 99.5% 1.0

TOPEX T/P-Tandem GFOTOPEX 1.0 0.157 0.206 T/P-Tandem 90.3% 1.0 0.079GFO 99.6% 85.1% 1.0

Correlation coefficients and their significant level, 99% highlighted.

Amplitude

Phase

Surface Tidal Currents with Different Stratification

Experiment 1: Levitus climatology + Hourly forcing Experiment 2 1-year spin-up run from Levitus climatology + Hourly forcing Experiment 3 Data-assimilated initial condition of August 2003 + Hourly forcing Experiment 4 Data-assimilated initial condition of Aug. 2003 + Monthly forcing

Tidal Current Improved

Barotropic and Surface Baroclinic Tidal Currents

Barotropic Tidal Current Surface Baroclinic Tidal Current

Both barotropic and baroclinic tidal current are changed with stratification

Subtle Stratification Change

can make a difference.*Barolinic tidal forcing term, Baines (1982) F(N**2, Grad. h, Ub)

Comparison of 8 Short Period Tides

Empirical Solutions and FES 2004 Tide Model

TOPEX+JASON Along-track Solution – FES 04: 2.4 cm RMSTOPEX+Tandem Mission Crossovers – FES 04: 3.5 cm RMS (squares)

OSTST, Hobart, 3/07; OSU, JPL, NAO, Newcastle U., HK Polytech U.

TOPEX-only Along-track Solution – FES 04: 2.6 cm RMS

TOPEX+JASON Along-track Solution – FES 04: 2.4 cm RMS

Tides TOPEX only TOPEX+JASON Change/Amplitude

M2

K1

O1

S2

N2

P1

1.01

1.16

0.83

1.61

0.57

0.54

0.95

1.16

0.71

1.53

0.52

0.53

-0.1% of 49 cm

0.0 % of 26 cm

-0.7 % of 16 cm

-0.5 % of 16 cm

-0.5 % of 10 cm

-0.1 % of 9 cm

Total 2.6 cm 2.4 cm -0.2% of 61 cm

Comparison of 8 Short Period Tides

Empirical Solutions and FES 2004 Tide Model (Alaska)

OSTST, Hobart, 3/07; OSU, JPL, NAO, Newcastle U., HK Polytech U.

Comparison of 8 Short Period Tides

Empirical Solutions and FES 2004 Tide Model

Multi-satellite Empirical Solution – FES 04: 2.2 cm RMS along T/P tracks (T/P, Tandem, Jason, GFO, ENIVSAT) 3.3 cm RMS at crossovers

4.6 cm RMS at all grid points

OSTST, Hobart, 3/07; OSU, JPL, NAO, Newcastle U., HK Polytech U.

TOPEX: 2.6, TOPEX+Jason: 2.4 (Along T/P tracks)

Comparison of 8 Short Period Tides

Empirical Solutions and FES 2004 Tide Model

OSTST, Hobart, 3/07; OSU, JPL, NAO, Newcastle U., HK Polytech U.

Patagonia Shelf East China Sea

Changes of RMS Difference due to increased TOPEX data span in the coastal study regions

Alaska area: 2.6 cm to 2.4 cm (61 cm)

California (MB): 1.6 cm to 1.5 cm (44 cm) Patagonia: 5.2 cm to 5.0 cm (66 cm) East China Sea: 9.3 cm to 9.2 cm (56 cm) NW Atlantic: 3.1 cm to 2.9 cm (41 cm)

Preliminary Conclusions Improved agreements with FES 2004 by increasing TOPEX data span (O1, K1, P1, S2, and N2 tides) Multi-satellite solution agrees with FES 2004 model better than Dual-satellite solution of TOPEX+JASON along T/P and JASON tracks

Comparison of 8 Short Period Tides

Empirical Solutions and FES 2004 Tide Model

OSTST, Hobart, 3/07; OSU, JPL, NAO, Newcastle U., HK Polytech U.

SummarySummary•Barotropic and baroclinic tidal solutions from Barotropic and baroclinic tidal solutions from altimeter observations prove to be useful to validate altimeter observations prove to be useful to validate regional OGCMs. Marginal improvement observed regional OGCMs. Marginal improvement observed in using multi-satellite altimetry in study regions.in using multi-satellite altimetry in study regions.

•Baroclinic tide amplitude and phase generated by Baroclinic tide amplitude and phase generated by model have significant correlation coefficients with model have significant correlation coefficients with TOPEX and GFO observations. Magnitude is TOPEX and GFO observations. Magnitude is smaller by a factor of 2-3.smaller by a factor of 2-3.

•Subtle changes in stratification can cause changes Subtle changes in stratification can cause changes in tidal current in coast regions, which poses a in tidal current in coast regions, which poses a challenge for tide-permitting forecasting systems.challenge for tide-permitting forecasting systems.Future work: Regional model for Alaska, Improve tidal solutions

Three Level Nested ROMS

3-Level Nested Model Grid Size Time Step Res. L0: 85*170*32 900s 16.5km L1: 95*191*32 300s 5.3km L2: 83*179*32 100s 1.6km

16 Processors on SGI Altix 3000 1 hour integration takes 1min cpu time.

Los AngelesSan Francisco

Monterey Bay

Monterey Bay

Baroclinic Tide around Mendocino Escarpment

Baroclinic Tide Energy Energy Flux

J/m^2

Consistent with observation (Althaus et al. 2003)

J/m*m

Comparison with Tide Gauges

Monterey Domain3 Gauges

US SW Coast Domain 10 Gauges

RSS 3.51cm

RSS 5.41cm

Along the coast<10% of M2 amplitude

Barotropic Tidal Current Comparison

0

10

20

30

40

50

60

M2 K1

SSH

Major Axis

ROMS vs. TPXO.6

RM

S/M

ean

(%

)

0

10

20

30

40

50

60

M2 K1

SSH

Major Axis

RM

S/M

ean

(%

)

ROMS vs. ADCIRC

Baroclinic Tide Theory

ggz

p

tw iii

0

1

00

1

DGEEt C g

eh

hziNg tiV

)1

()(1

2

0

1

Generation

Energetics

Baroclinic Tide Forcing Subscript i : Baroclinic Subscript 1: Barotropic

G: ForcingD: Dissipation

E: Baroclinic tide energy CgE: Baroclinic tide energy flux

N2

V 1

hz

Baines (1982), Gill(1982)

Stratification, Bathymetry, Barotropic tide flux