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Wave Forecasting at the WFO San Juan. CarICOOS Workshop on Simulation and Model Testbed March 29, 2012 University of Puerto Rico at Mayaguez. Ernesto Rodriguez Meteorologist Local Modeling Team Leader NWS San Juan. Carlos Anselmi Meteorologist Intern SWAN Team Member NWS San Juan.

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Wave forecasting at the wfo san juan

Wave Forecasting at theWFOSan Juan

CarICOOS Workshop on Simulation and Model Testbed

March 29, 2012

University of Puerto Rico at Mayaguez

Ernesto Rodriguez

Meteorologist

Local Modeling Team Leader

NWS San Juan

CarlosAnselmi

Meteorologist Intern

SWAN Team Member

NWS San Juan


Outline
Outline

  • National Weather Service Mission

  • Marine Forecast Methodology

  • Marine Products

    • Routine

    • Non-routine

  • Local Model Verification (SWAN)

    • Analysis of the Error Sources

  • Case Study (Nov. 5-11, 2011)

  • Conclusion


Mission
Mission

  • "The National Weather Service TM (NWS) provides weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas, for the protection of life and property and the enhancement of the national economy."



Marine forecast process
Marine Forecast Process

Regional

Models

Local

Models

Wind

Obs

Buoy

Obs

ANALYSIS & FORECAST

Wind

Forecast

Wave

Forecast


Marine products
Marine Products

Routine

Non-Routine

Special Marine Warning

Marine Weather Statement

Coastal Flood Watch, Advisory & Warning

High Surf Advisory

High Surf Warning

Marine Weather Message

Hazardous Weather Outlook

  • Coastal Waters Forecast

    • Synopsis

    • Waves

    • Wind

    • Weather

  • Surf Zone Forecast (Near Future)

    • Breaking Wave Height

    • Rip Current Potential

    • Wind at the coast

    • Tides




Error statistics
Error Statistics

  • Mean Error (ME) is the mean of the arithmetic differences between the observations and forecasts.

  • Mean Absolute Error (MAE) is the mean of the absolute differences between the observations and forecasts.

  • Root Mean Squared Error (RMSE) is the square root of the mean of the squared differences between the observations and forecasts.


Buoy 41053 san juan pr
BUOY 41053 – San Juan, PR

Wave Height Time Series

Wave Rose Plot

ME = 0.41 MAE = 0.62 RMSE = 0.96


Buoy 42085 ponce pr
BUOY 42085 – Ponce , PR

Wave Height Time Series

Wave Rose Plot

ME = -0.001 MAE = 0.42 RMSE = 0.57


Buoy 41115 rincon pr
BUOY 41115 – Rincon, PR

Wave Height Time Series

Wave Rose Plot

ME = 0.20 MAE = 0.50 RMSE = 0.66


Buoy 41052 st john usvi
BUOY 41052 – St. John, USVI

Wave Height Time Series

Wave Rose Plot

ME = 0.34 MAE = 0.52 RMSE = 0.69


Model accuracy year 2011
MODEL ACCURACY (Year 2011)

MEAN ERROR (ME)

MEAN ABSOLUTE ERROR

ROOT MEAN SQUARE ERROR (RMSE)

0.4084

0.6206

0.9616

0.1959

0.5017

0.6642

0.3427

0.5226

0.6927

-0.0013

0.4237

0.5671


Error sources
Error Sources

Wind Forecast Wave Height Model Error


Buoys
Buoys

41043

41053

41115

41052

42085


Buoy 41043 sw north atlantic
BUOY 41043 – SW North Atlantic

Analyzed only incoming waves from WNW to ENE

and with periods greater than 8 seconds

ME = 0.37 MAE = 0.74 RMSE = 0.96


Buoy 41053 san juan pr1
BUOY 41053 – San Juan, PR

Analyzed only incoming wave from WNW to ENE

and with periods greater than 8 seconds

ME = 0.57 MAE = 0.72 RMSE = 0.87


Errors at the buoys
Errors at the Buoys

MEAN ERROR (ME) - All Waves

MEAN ERROR (ME) - Waves with Tp<= 8

MEAN ERROR (ME) - Waves with Tp > 8

NWW3 vs. Buoy 41043

0.55

0.42

0.37

41043

SWAN vs. Buoy 41053

0.41

0.13

0.45

41053

41115

41052

42085




41047 ne bahamas
41047 - NE Bahamas

  • Swell Decay

  • Travel distance ≅ 575nm (off Rincón)

  • Travel time ≅ 30-36hr approximately

E = 0°, N = 90°, W = 180°, S=270°

Counterclockwise rotation


41046 e bahamas
41046 - E Bahamas

  • Buoy Location:

  • (23.838N, 68.333W)

  • 332nm (615km) offshore

  • Travel time ≅ 12-15hr

  • Travel Distance ≅ 274m



Nearshore verification
Nearshore Verification

  • ≈ 30 hours after the swell event was observed at 41047

  • Wave field discrepancies associated to wind forcing errors.


Summary of the mean error
Summary of the Mean Error

0.37÷ 0.45 = 0.822

Errors associated with

NWW3 82.2 %

Other 18.8 %

SWAN Wind

Forecast


Conclusion
Conclusion

  • SWAN results thus far, indicate that the model errors inside our domain are fairly low.

  • The main error source in our Local SWAN simulations is the initial boundary conditions (spectral energy) from NWW3.

  • The errors associates with the wind forecast and SWAN are minimal compared with the NWW3 boundary conditions.

  • The operational NCEP NWW3 has shown a slight high bias as compared with other global models (FNMOC WW3), buoys and satellite observations. (Stripling, et al)


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