U.S. GODAE: Global U.S. GODAE: Global Ocean Prediction with Ocean Prediction with

Community Effort:Community Effort: NRL, FSU, U. of Miami, NASA-GISS, NOAA/NCEP, NOAA/AOML, NOAA/PMEL, PSI, FNMOC, NAVOCEANO, SHOM, LEGI, OPeNDAP, UNC, Rutgers, USF, Fugro-GEOS, Orbimage, Shell, ExxonMobil

Global Ocean Data Assimilation Global Ocean Data Assimilation Experiment (GODAE)Experiment (GODAE)

The vision:

"A global system of observations, communications, modeling and assimilation,

that will deliver regular, comprehensive information on the state of the oceans in a way that will promote and engender wide utility and availability of this resource for

maximum benefit to society."

• Australia : (BLUELINK): Regional Australian seas to Global Ocean

• Japan : N. Pacific to Global Ocean• US (HYCOM-US and ECCO projects): N.

Atlantic to Global Ocean• Europe (Mersea/MyOcean Consortium)

– Italy (MFS) : Mediterranean Sea– France (MERCATOR) : N. Atlantic and

Mediterranean Sea to Global Ocean– Norway (TOPAZ) : North Atlantic to Arctic– UK (FOAM) : N. Atlantic / Global ocean

GODAE GODAE Modeling/Assimilation CentersModeling/Assimilation Centers

Objectives and GoalsObjectives and Goals

• A broad partnership of institutions that collaborate in developing and demonstrating the performance and application of eddy-resolving, real-time global and basin-scale ocean prediction systems using HYCOM.

• Transition for operational use by the U.S. Navy at NAVOCEANO (2008) and by NOAA at NCEP (N. Atlantic - 2007).

• Strong participation of the coastal ocean modeling community in using and evaluating boundary conditions from the global and basin-scale ocean modeling prediction systems

• Efficient data distribution (100 Terabytes Storage Area Network)

The data are available to the community at large within 24 hours via Live Access Server (LAS), ftp, and OPeNDAP at http://www.hycom.org

Objectives and GoalsObjectives and Goals

1/25° East Asian Seas HYCOM (nested inside 1/6° Pacific HYCOM)

North-south velocity cross-section along 124.5°E, upper 400 m

red=eastward flow

blue=westward flow

Snapshot on 14 October

density frontassociated with

sharp topographic feature(cannot be easily resolved withfixed z- or sigma- coordinates)

East China Sea

Yellow Sea flowreversal with depth

Isopycnals overshelf region

z-levels and sigma-levelsover shelf and in mixed layer

Snapshot on 12 April

Yellow Sea

The hybrid coordinate in HYCOM is one that is isopycnal in the open, stratified ocean, but smoothly reverts to a terrain-following

coordinate in shallow coastal regions, and to pressure coordinate in the mixed layer and/or unstratified seas

1/12º Atlantic near real-time system1/12º Atlantic near real-time system- Running once a week since July 2002- Assimilation: gridded surface observations only- 10 day hindcast, 14 day forecast

1/12º Global real time system1/12º Global real time system- Running daily since December 2006- Assimilation: NCODA- 5 day hindcast, 5 day forecast

1/25º Gulf of Mexico real time system1/25º Gulf of Mexico real time system- Running daily since November 2006- Assimilation: NCODA- 5 day hindcast, 7 day forecast

Present nowcast/forecast Present nowcast/forecast systemssystems

• Horizontal grid: 1/12° equatorial resolution – 4500 x 3298 grid points, ~6.5 km spacing on average, ~3.5 km at

pole, 5 m minimum depth• Mercator 79°S to 47°N, then Arctic dipole patch• 32 σ2* vertical coordinate surfaces: • KPP mixed layer model• Thermodynamic sea-ice model (soon to be PIPS/CICE)• Surface forcing: wind stress, wind speed, thermal forcing,

precipitation, weak relaxation to climatological SSS• Monthly river runoff (986 rivers)• Initialized from January climatology (GDEM3) T and S

Global HYCOM Global HYCOM configurationconfiguration

216,000 CPU hrs/model year on 784 IBM Power 4+ CPUs

7.2 TB/model year for daily 3-D output

29 June 2006 9

Sequential Incremental Update Cycle Analysis-Forecast-Analysis

MVOI - simultaneous analysis 5 ocean variables temperature, salinity, pressure, velocity (u,v)

Ocean modelHYCOM

Ocean data QC

Ocean dataAnalysis3D MVOI &

Cooper-Haines

Ocean obs

SST: GAC/LAC MCSST, GOES, Ship, Buoy Profile: XBT, CTD, T & S profiling Floats (ARGO), Fixed Buoy, Drifting Buoy Altimeter SSHA SSM/I Sea Ice

Innovations

Increments

Forecast Fields Prediction Errors

First Guess

Data Assimilation via NCODAData Assimilation via NCODA(Cummings et al.)(Cummings et al.)

with assimilation (GLBa0.08-60.4)

without assimilation (GLBa0.08-05.8)

Overall increase in variability - largest changes occur in the western boundary currents

13

Eddy Kinetic Energy ComparisonEddy Kinetic Energy ComparisonEKE at ~700 m in the Gulf Stream

Observations fromSchmitz (1996)

HYCOM - 2004NCOM - 2004

WorldOcean Gulf Stream

NW Arabian Sea and Gulf of Oman

EquatorialPacific Kuroshio Gulf of Mexico

1.0

0.9

0.8

0.7

1.0

0.9

0.8

0.7

0.6

Med

ian

SS

H a

no

mal

y co

rrel

atio

n

0 10 20 30 0 10 20 30 0 10 20 30

Forecast length (days)

Forecast verification statistics Forecast verification statistics from .08from .08 global HYCOM global HYCOM

4 Forecasts included in statistics

Product evaluationProduct evaluation

– Assessment of the outputs by comparison to independent observations

– Comparison with other GODAE products (i.e. MERSEA collaboration)

– Strong involvement of coastal ocean modeling groups to use and evaluate boundary conditions provided by the global and basin HYCOM real time prediction system outputs

West Florida Shelf ModelingWest Florida Shelf Modeling

Barth et al. (USFBarth et al. (USF))

WFS ROMS SST and surface velocity is

shown inside the dashed line and outside of this

area is the North Atlantic HYCOM.

Warm water is detached from the Loop Current

and transported northward as mesoscale

eddies and filaments.

HYCOM RMS errors for M2 tide vs satellite altimetry

.72 resolution .08 resolution

Adding tidal capability to global HYCOMAdding tidal capability to global HYCOM

Collaboration with Brian Arbic (U. Texas)

0 5 10 15 20 25

RMS error = 9.9 cm RMS error = 6.7 cm

Average RMS error over all 102 pelagic tide guages = 12.3 cm

HYCOM with 8-component tide vs tide gauge

.72 HYCOM tide

model tide gaugeExample with typical error:89.6% of variance explained

Future DirectionsFuture Directions

• 1/25 global HYCOM prediction system with tides and wetting and drying

• More advanced data assimilation• Nested coastal ocean prediction with grid

resolution < 1 km • Range dependent acoustic prediction• Coupled atmosphere – ocean prediction• Bio – geo – chemical – optical and

tracer/contaminant prediction• Ecosystem analysis and prediction• Earth system prediction: coupled

atmosphere-ocean-ice-land