Evaluation of the Real-Time Evaluation of the Real-Time Ocean Forecast System in Ocean Forecast System in

Florida Atlantic Coastal Florida Atlantic Coastal WatersWaters

June 3 to 8, 2007June 3 to 8, 2007

Matthew D. GrossiMatthew D. GrossiDepartment of Marine & Environmental Department of Marine & Environmental

SystemsSystemsFlorida Institute of TechnologyFlorida Institute of Technology

Melbourne, FloridaMelbourne, Florida

Florida Institute of TechnologyHigh Tech with a Human Touch

Department of Marine & Environmental SystemsCollege of Engineering

Florida Institute of Technology

OverviewOverview

• MissionMission

• What is RTOFS?What is RTOFS?

• Why RTOFS?Why RTOFS?

• MethodologyMethodology

• Data &Data &DiscussionDiscussion

• ConclusionsConclusions

• QuestionsQuestions

RTOFS Images: SST (bottom), SST & currents (right)

The mission…The mission…

• Evaluation of an Ocean Forecast SystemEvaluation of an Ocean Forecast System– Accuracy of model thermodynamic and Accuracy of model thermodynamic and

kinematic forecast fieldskinematic forecast fields•Temporal degradation of forecast accuracyTemporal degradation of forecast accuracy

•Spatial fidelity of forecast fieldsSpatial fidelity of forecast fields– Horizontal Horizontal – VerticalVertical

• Identification of forecast system problemsIdentification of forecast system problems– Initial conditions, boundary conditions, model physicsInitial conditions, boundary conditions, model physics

What is RTOFS?What is RTOFS?

• Real-Time Ocean Forecast SystemReal-Time Ocean Forecast System– Operational forecast model sponsored by NOAA National Operational forecast model sponsored by NOAA National

Centers for Environmental Prediction (NCEP)Centers for Environmental Prediction (NCEP)– Produces forecasts for water temperature, salinity, Produces forecasts for water temperature, salinity,

currents, sea surface heightcurrents, sea surface height– Based on HYCOM: HYbrid Coordinate Ocean ModelBased on HYCOM: HYbrid Coordinate Ocean Model

• Curvilinear horizontal coordinatesCurvilinear horizontal coordinates• Hybrid vertical coordinatesHybrid vertical coordinates• 5 km resolution near Florida5 km resolution near Florida• 26 vertical (depth) coordinates26 vertical (depth) coordinates

(21 isopycnal, 5 z-level)(21 isopycnal, 5 z-level) (NOAA 2007, HYCOM 2007, Lozano 2007)(NOAA 2007, HYCOM 2007, Lozano 2007)

RTOFSRTOFS

• Model InputsModel Inputs– Initial fields: RTOFS Global Ocean Data Initial fields: RTOFS Global Ocean Data

Assimilation Experiment (GODAE) Assimilation Experiment (GODAE) •Satellite & In-situ (e.g. QuikSCAT, buoys, ships, Satellite & In-situ (e.g. QuikSCAT, buoys, ships,

etcetc.) .) – Forcing fields: Forcing fields:

•3-hour NCEP (GDAS/GFS) meteorological model: 3-hour NCEP (GDAS/GFS) meteorological model: Wind stress, radiative heat fluxes, turbulent heat Wind stress, radiative heat fluxes, turbulent heat fluxes, precipitation, evaporation, & atmospheric fluxes, precipitation, evaporation, & atmospheric pressurepressure

•Tides & river inputTides & river input•Climatological boundary conditionsClimatological boundary conditions

(Topfer 2006)(Topfer 2006)

Why RTOFS?Why RTOFS?

• Provide boundary & initial conditions Provide boundary & initial conditions for regional ocean physical & for regional ocean physical & biogeochemical modelsbiogeochemical models

• Coupled Model SystemsCoupled Model Systems– Circulation-wave ocean models with 1- & Circulation-wave ocean models with 1- &

2- way interactions2- way interactions– Ocean-atmosphere hurricane forecastOcean-atmosphere hurricane forecast

• Seasonal outlooks, ocean forecastingSeasonal outlooks, ocean forecasting(NOAA 2007 & Toepfer 2006)(NOAA 2007 & Toepfer 2006)

MethodologyMethodology

• One of several One of several projects carried out projects carried out during Field Projects during Field Projects summer cruisessummer cruises(2 Jun – 8 Jun 2007)(2 Jun – 8 Jun 2007)

• Gulf Stream EagleGulf Stream Eagle• Interdisciplinary Interdisciplinary

project:project:– OceanographyOceanography– MeteorologyMeteorology– Environmental Environmental

ScienceScience– Ocean EngineeringOcean Engineering

MethodologyMethodology

• Field Data AcquisitionField Data Acquisition– Conductivity-Temperature-Depth Conductivity-Temperature-Depth

(CTD)(CTD)– Acoustic Doppler Current Profiler Acoustic Doppler Current Profiler

(ADCP)(ADCP)

• Collection of Daily RTOFS ForecastsCollection of Daily RTOFS Forecasts– Issued at 00Z out to 120 hoursIssued at 00Z out to 120 hours

• 24-hr 3-D forecast24-hr 3-D forecast

• Hourly surface forecastsHourly surface forecasts

3-D 3-D 3-D 3-D 3-D

24hr

48hr

72hr

96hr

surface 120hr

surface surface surfacesurface3-D

00hr:Initialized

CTD sample (cast) sites overlaying SST infrared image valid for 05 CTD sample (cast) sites overlaying SST infrared image valid for 05 June 07.June 07.

8

CTD Cast SitesCTD Cast Sites

RTOFS 5-day Forecast & Observed SST (°C)

23

25

27

29

31

9 11 13 15 17 19 21 23 25

Cast Number

Tem

per

atu

re (

°C)

RTOFS Forecast Observed

• 1-day Forecast vs. Observed1-day Forecast vs. Observed– Forecast ~1°C lowerForecast ~1°C lower– Mean Error: Mean Error: -0.89°C-0.89°C– RMS Error: RMS Error: 0.96°C0.96°C

• 5-day Forecast vs. Observed5-day Forecast vs. Observed– Cooler in cool watersCooler in cool waters

Mean error Mean error -1.86°C-1.86°C– Warmer in warm watersWarmer in warm waters

Mean Error: Mean Error: +2.01°C+2.01°C– RMS Error:RMS Error: 2.06°C 2.06°C

• Improvement 5- vs. 1- day?Improvement 5- vs. 1- day?– MAE: 1.96°C vs. 0.91°C

(respectively) YES

Cool waters west of Gulf Stream Warm waters in Gulf Stream

Surface Surface TemperatureTemperature

Cast Number (various locations)

Cast Number (various locations)

RTOFS 1-day Forecast & Observed SST (°C)

23

25

27

29

31

1 3 5 7 9 11

Cast Number (various locations)

Tem

per

atu

re (

°C)

RTOFS Forecast Observed

Cool watersWarm waters

Regional SST BiasRegional SST Bias

Is the cool bias in shelf waters a systemic problem in RTOFS forecast?Is the cool bias in shelf waters a systemic problem in RTOFS forecast?

GOES image vs. RTOFS 16-hr forecast valid July 16, 2007GOES image vs. RTOFS 16-hr forecast valid July 16, 2007

GOES Image: Lazarus, GOES Image: Lazarus, et. al. et. al. 2007 2007

• 1-day Forecast vs. 1-day Forecast vs. ObservedObserved– Forecast ~0.4 ppt higherForecast ~0.4 ppt higher– Mean Error: Mean Error: 0.43 ppt0.43 ppt– RMS Error: RMS Error: 0.66 ppt0.66 ppt

• 5-day Forecast vs. 5-day Forecast vs. ObservedObserved– Difference of 0.18-0.73 Difference of 0.18-0.73

ppt (0.49-1.96% ppt (0.49-1.96% difference)difference)

– Mean Error: Mean Error: 0.34 ppt0.34 ppt– RMS Error RMS Error 0.58 ppt0.58 ppt

• Improvement 5- vs. 1- Improvement 5- vs. 1- day?day?– MAE: 0.29 ppt & 0.36 ppt MAE: 0.29 ppt & 0.36 ppt

(respectively) (respectively) NO NO

Surface Surface SalinitySalinity

Cast Number (various locations)

Cast Number (various locations)

35.6

36.0

36.4

36.8

9 11 13 15 17 19 21 23 25Cast Number (various locations)

Sa

linty

(p

pt)

RTOFS Forecast Observed

RTOFS 5-day Forecast & Observed Surface Salinity (ppt)

RTOFS 1-day Forecast & Observed Salinity (ppt)

35.6

36.0

36.4

36.8

1 3 5 7 9 11 13

Cast Number (various locations)

Sa

linit

y (

pp

t)

RTOFS Forecast Observed

Cool waters west of Gulf Stream Warm waters in Gulf Stream

Cool watersWarm waters

3-D Temperature3-D Temperature

Temperature (°C)

De

pth

(m

)

RTOFS 1-day & 5-day Forecasts & Observed 3-D Temperature (°C)

June 3

June 4

June 5

June 6

June 7

June 8

CTD

1-day

5-day

5-day Forecast for 00Z 2 June 20075-day Forecast for 00Z 2 June 2007

1-day Forecast for 00Z 2 June 2007 1-day Forecast for 00Z 2 June 2007

Surface (10 m) Wind Surface (10 m) Wind Vectors & Precipitation Vectors & Precipitation RateRatefrom GFS Modelfrom GFS Model

• Error due to Error due to atmospheric model atmospheric model inputinput

• Wind impact on Wind impact on thermocline?thermocline?

ConclusionsConclusions

• TemperatureTemperature– RTOFSRTOFS SST cool in shelf waters & warm in Gulf SST cool in shelf waters & warm in Gulf

StreamStream• May indicate problems with model initial conditions, May indicate problems with model initial conditions,

boundary conditions, or model physicsboundary conditions, or model physics– RTOFS had a tendency to produce RTOFS had a tendency to produce

thermoclines that were unobservedthermoclines that were unobserved• May be related to surface wind forecast errorsMay be related to surface wind forecast errors

• SalinitySalinity– Forecasted higher than measured at all times Forecasted higher than measured at all times

& locations& locations• May be related to precipitation forecast errorsMay be related to precipitation forecast errors

Questions?Questions?

Next: Michelle Tyson

HYCOM Consortium for Data Assimilated Modeling. Center for Ocean-Atmospheric Prediction Studies (COAPS). 2007. Last accessed 12 July 2007. http://hycom.rsmas.miami.edu.

Lazarus, S. M., C. G. Calvert, M. E. Splitt, P. Santos, D. W. Sharp, P. F. Blottman, and S. M. Spratt. “Real Time, High-Resolution, Space–Time Analysis of Sea Surface Temperatures from Multiple Platforms.” In press, Monthly Weather Review.

Lozano, Carlos. “HYCOM for Ocean Modeling at NCEP”. April 2007. Last accessed 11 July 2007.http://hycom.rsmas.miami.edu/meetings/eleven/tue/am/4_Lozano.pdf

NOAA Real-Time Ocean Forecast System (Atlantic). NOAA/ National Weather Service. http://polar.ncep.noaa.gov/ofs 2007.

Toepfer, Fred. NOAA Operational Basin Scale Ocean Modeling for Research and Operations. November 2006. Last accessed 11 July 2007. http://www.ocean.us/system/files/Basin+Scale+NCEP+IOOS+Workshop+11282006v1.ppt

ReferencesReferences

Faculty: Mr. Michael Splitt, Dr. Kevin Johnson, Dr. John Windsor, Bill Battin

Data Collection: All who assisted on both cruises

Data Analysis: Rebecca Kitto & Julie StrehlePhotographs: Eduardo GonzalezShip Crew: Gulf Stream Eagle captains &

crew

AcknowledgemenAcknowledgementsts

3-D Salinity3-D Salinity

RTOFS 1-day & 5-day Forecasts & Observed 3-D Salinity (ppt)

De

pth

(m

)

Salinity (ppt)

June 3

June 4

June 5

June 6

June 7

June 8

CTD

1-day

5-day