Evaluation of the Real-Time Ocean Forecast System in Florida Atlantic Coastal Waters June 3 to 8, 2007 Matthew D. Grossi Department of Marine & Environmental Systems Florida Institute of Technology Melbourne, Florida Florida Institute of Technology High Tech with a Human Touch Department of Marine & Environmental Systems College of Engineering Florida Institute of Technology

Overview Mission Mission What is RTOFS? What is RTOFS? Why RTOFS? Why RTOFS? Methodology Methodology Data & Discussion Data & Discussion Conclusions Conclusions Questions Questions RTOFS Images: SST (bottom), SST & currents (right)

The mission… Evaluation of an Ocean Forecast System Evaluation of an Ocean Forecast System –Accuracy of model thermodynamic and kinematic forecast fields Temporal degradation of forecast accuracy Temporal degradation of forecast accuracy Spatial fidelity of forecast fields Spatial fidelity of forecast fields –Horizontal –Vertical Identification of forecast system problems Identification of forecast system problems –Initial conditions, boundary conditions, model physics

What is RTOFS? Real-Time Ocean Forecast System Real-Time Ocean Forecast System –Operational forecast model sponsored by NOAA National Centers for Environmental Prediction (NCEP) –Produces forecasts for water temperature, salinity, currents, sea surface height –Based on HYCOM: HYbrid Coordinate Ocean Model Curvilinear horizontal coordinates Curvilinear horizontal coordinates Hybrid vertical coordinates Hybrid vertical coordinates 5 km resolution near Florida 5 km resolution near Florida 26 vertical (depth) coordinates 26 vertical (depth) coordinates (21 isopycnal, 5 z-level) (NOAA 2007, HYCOM 2007, Lozano 2007) (NOAA 2007, HYCOM 2007, Lozano 2007)

RTOFS Model Inputs Model Inputs –Initial fields: RTOFS Global Ocean Data Assimilation Experiment (GODAE) Satellite & In-situ (e.g. QuikSCAT, buoys, ships, etc.) Satellite & In-situ (e.g. QuikSCAT, buoys, ships, etc.) –Forcing fields: 3-hour NCEP (GDAS/GFS) meteorological model: Wind stress, radiative heat fluxes, turbulent heat fluxes, precipitation, evaporation, & atmospheric pressure 3-hour NCEP (GDAS/GFS) meteorological model: Wind stress, radiative heat fluxes, turbulent heat fluxes, precipitation, evaporation, & atmospheric pressure Tides & river input Tides & river input Climatological boundary conditions Climatological boundary conditions (Topfer 2006) (Topfer 2006)

Why RTOFS? Provide boundary & initial conditions for regional ocean physical & biogeochemical models Provide boundary & initial conditions for regional ocean physical & biogeochemical models Coupled Model Systems Coupled Model Systems –Circulation-wave ocean models with 1- & 2- way interactions –Ocean-atmosphere hurricane forecast Seasonal outlooks, ocean forecasting Seasonal outlooks, ocean forecasting (NOAA 2007 & Toepfer 2006)

Methodology One of several projects carried out during Field Projects summer cruises One of several projects carried out during Field Projects summer cruises (2 Jun – 8 Jun 2007) Gulf Stream Eagle Gulf Stream Eagle Interdisciplinary project: Interdisciplinary project: –Oceanography –Meteorology –Environmental Science –Ocean Engineering

Methodology Field Data Acquisition Field Data Acquisition –Conductivity-Temperature-Depth (CTD) –Acoustic Doppler Current Profiler (ADCP) Collection of Daily RTOFS Forecasts Collection of Daily RTOFS Forecasts –Issued at 00Z out to 120 hours 24-hr 3-D forecast 24-hr 3-D forecast Hourly surface forecasts Hourly surface forecasts 3-D 24hr48hr72hr96hr surface 120hr surface 3-D 00hr: Initialized

CTD sample (cast) sites overlaying SST infrared image valid for 05 June CTD Cast Sites

1-day Forecast vs. Observed 1-day Forecast vs. Observed –Forecast ~1°C lower –Mean Error: -0.89°C –RMS Error: 0.96°C 5-day Forecast vs. Observed 5-day Forecast vs. Observed –Cooler in cool waters Mean error -1.86°C –Warmer in warm waters Mean Error: +2.01°C –RMS Error: 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 StreamWarm waters in Gulf Stream Surface Temperature Cast Number (various locations) Cool watersWarm waters

Regional SST Bias Is the cool bias in shelf waters a systemic problem in RTOFS forecast? GOES image vs. RTOFS 16-hr forecast valid July 16, 2007 GOES Image: Lazarus, et. al GOES Image: Lazarus, et. al. 2007

1-day Forecast vs. Observed 1-day Forecast vs. Observed –Forecast ~0.4 ppt higher –Mean Error: 0.43 ppt –RMS Error: 0.66 ppt 5-day Forecast vs. Observed 5-day Forecast vs. Observed –Difference of ppt ( % difference) –Mean Error: 0.34 ppt –RMS Error 0.58 ppt Improvement 5- vs. 1- day? Improvement 5- vs. 1- day? –MAE: 0.29 ppt & 0.36 ppt (respectively)  NO Surface Salinity Cast Number (various locations) Cool waters west of Gulf Stream Warm waters in Gulf Stream Cool watersWarm waters

3-D Temperature Temperature (°C) Depth (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 day Forecast for 00Z 2 June 2007  Surface (10 m) Wind Vectors & Precipitation Rate from GFS Model Error due to atmospheric model input Error due to atmospheric model input Wind impact on thermocline? Wind impact on thermocline?

Conclusions Temperature Temperature –RTOFS SST cool in shelf waters & warm in Gulf Stream May indicate problems with model initial conditions, boundary conditions, or model physics May indicate problems with model initial conditions, boundary conditions, or model physics –RTOFS had a tendency to produce thermoclines that were unobserved May be related to surface wind forecast errors May be related to surface wind forecast errors Salinity Salinity –Forecasted higher than measured at all times & locations May be related to precipitation forecast errors May be related to precipitation forecast errors

Questions? Next: Michelle Tyson

HYCOM Consortium for Data Assimilated Modeling. Center for Ocean-Atmospheric Prediction Studies (COAPS) Last accessed 12 July 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 Last accessed 11 July NOAA Real-Time Ocean Forecast System (Atlantic). NOAA/ National Weather Service Toepfer, Fred. NOAA Operational Basin Scale Ocean Modeling for Research and Operations. November Last accessed 11 July References 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 Strehle Photographs: Eduardo Gonzalez Ship Crew: Gulf Stream Eagle captains & crew Acknowledgements

3-D Salinity RTOFS 1-day & 5-day Forecasts & Observed 3-D Salinity (ppt) Depth (m) Salinity (ppt) June 3 June 4 June 5 June 6 June 7 June 8 CTD 1-day 5-day