VERIFICATION STRATEGYFOR OCEANS, WAVES & SEA-ICE

Robert Grumbine, Avichal Mehra and Arun ChawlaNWS/NCEP/EMC

• Ocean – Daily/Weekly monitoring of fields using GODAE Class Metrics:

• Class 1 (analysis of surface fields, e.g. SST, SSH, Sea Ice Cover)

• Class 2 (vertical sections, e.g. ARGO profiles, WOCE sections)• Class 3 (derived products, e.g. Florida Current transports, GS

North Wall location)• Class 4 (forecast skill metrics, e.g. SST, SSH, profiles)

– Daily metrics/stats made available at: http://polar.ncep.noaa.gov/global/monitor/

• Waves– Monitoring of Class 1 and Class 4 metrics – Metrics based on bulk spectral parameters (Significant wave height,

Peak Period etc.)– Skill scores typically developed over month long (or more) – Use collocated buoys and altimeters – No consensus on metrics in frequency space yet

VERIFICATION

• First order variables defining Sea Ice– Sea Ice Concentrations

• Moderately well observed• Poorly predicted• In need of metrics

– Sea Ice Drift Speeds• Well observed (buoys, SSMI)• Established metrics

– Sea Ice thickness• Poorly observed• In need of metrics

• Work in progress but much to do

SEA ICE VERIFICATION

Class 1: Sea Ice Cover in the polar regions

OCEAN-ICE VERIFICATION

Class 2 & 4: Global RTOFS profiles vs ARGO data

OCEAN VERIFICATION

Class 4: Global wave model skill scores for 72 hour forecast

Monthly skill scores Seasonal skill scoresSkill scores based on comparisons at all available NDBC buoys, time in MM/YY

New Physics introduced

WAVES VERIFICATION

Class 1: Wave hindcast Significant wave height bias maps (in m) using collocated altimeter tracks

WAVES VERIFICATION

• RTOFS Verification and Metrics– Garraffo et al., 2014. Modeling of 137Cs as a tracer in a regional model for

the Western Pacific, after the Fukushima Daiichi Nuclear power plant accident of March 2011. Weather and Forecasting. doi: http://dx.doi.org/10.1175/WAF-D-13-00101.1

– Ryan et al., 2015. GODAE Ocean View Class 4 forecast verification framework: Global ocean inter-comparison. J Oper Oceanogr. 7(3)

– Divakaran et al., 2015. GODAE OceanView Inter-comparison for the Australian Region. J Oper Oceanogr. doi:10.1080/1755876X.2015.1022333.

– Hernandez et al., 2015.Recent progress in performance evaluations and near real-time assessment of operational ocean products. J. Oper. Oceanogr. (accepted)

• Waves– Chawla et al. 2013. A multigrid wave forecasting model: A new paradigm in

operational wave forecasting. Wea. & Forecasting, 28, 1057 – 1078 – Chawla et al 2012. Validation of a thirty year wave hindcast using the

Climate Forecast System Reanalysis winds.Ocean Mod.http://dx.doi.org/10.1016/j.ocemod.2012.07.005

RECENT PUBLICATIONS

• Waves (contd)– Alves et al. 2014. The Operational Implementation of a Great Lakes Wave

Forecasting System at NOAA/NCEP. Wea. & Forecasting, 29.6: 1473-1497.– Alves et al. 2013. The NCEP-FNMOC Combined Wave Ensemble Product:

Expanding Benefits of Interagency Probabilistic Forecasts to the Oceanic Environment. Bull. American Meteo. Soc., 94(12), 1893-1905.

– Van der Westhuysen, et al. 2013: Development and validation of the Nearshore Wave Prediction System. Proc. 93rd AMS Annual Meeting, Austin, TX.

• Sea Ice– Robert Grumbine: 2013: Keeping Ice'S Simplicity -- A Modeling Start, MMAB

Tech Note 314, 32 pp–  Robert Grumbine: 2013: Long Range Sea Ice Drift Model Verification, MMAB

Tech Note 315, 22 pp..

RECENT PUBLICATIONS (CONTD)

System coupling metrics immature

Not that there are no measures, but ….

Examples :– Coupled ocean – waves

• Mixed layer depths • Stokes drift estimates (3rd moments of spectra,

Ardhuin et al 2009)– Coupled ice – ocean

• Heat flux modulations– Coupled wave – ice

• Scattering & damping

COUPLED SYSTEMS VERIFICATION