A persisting problem in ocean modeling around coastal areas has been the adequate imposition of open boundary conditions,especially in the presence of complex bathymetric features commonly found in shelf seas.Ocean mo...A persisting problem in ocean modeling around coastal areas has been the adequate imposition of open boundary conditions,especially in the presence of complex bathymetric features commonly found in shelf seas.Ocean models with horizontal resolutions of O(1 km)can generate submesoscale current variability not captured by coarser regional models which resolve mesoscale flows approximately in geostrophic and thermal-wind balance.In practice,higher-resolution systems will provide analyses with enhanced spatial detail but may be less skillful at predicting the evolution of mesoscale eddies.This study aims at assessing the role of open boundary conditions,tidal forcing and tide filtering techniques in a coastal ocean model using a split-explicit time marching scheme with horizontal resolutions of O(1 km)and its effect in coastal sea level dynamics and ocean currents.Numerical experiments have been performed using the Regional Ocean Modeling System(ROMS)with different uniform horizontal resolution:3.6km,1.2km and 740m.Initial and lateral boundary conditions are derived from the U.S.Naval Oceanographic Office(NAVOCEANO)operational AmSeas model forecast,a 3.6-km resolution application of the regional Navy Coastal Ocean Model(NCOM)that encompasses the Gulf of Mexico and Caribbean Sea.Meteorological conditions are interpolated from the Navy’s Coastal Ocean-Atmosphere Mesoscale Prediction System(COAMPS)model with the exception of surface stresses,which are computed from a 2-km application of the Weather Research and Forecasting(WRF)model used by National Center for Environmental Protection’s(NCEP)National Digital Forecast Database(NDFD).Tidal variability is imposed in two ways:1)by specifying the time evolution of sea level at the open boundaries and 2)spectrally by specifying the harmonic phases and amplitudes from the TPXO global inverse tide solutions at the boundaries.Sub-tidal low frequency conditions are imposed by filtering high frequencies out of the regional NCOM solution.A spectral analysis of the sea surface height and barotropic velocity is performed via Fourier’s transform,showing significant differences at higher frequencies.Tide signals are then reconstructed and removed from the open boundary condition’s(OBC’s)in 2 ways:1)using Rich Pawlowicz’s t_tide package(i.e.,classic harmonic analysis)(Pawlowicz,2002[1])and 2)with traditional low-pass filters.The spectral analysis provides a comprehensive characterization of the response in coastal sea level dynamics,which is difficult to elucidate in the time domain.Modeled results of sea surface height and ocean currents are validated with NOAA tide gauges and Acoustic Doppler Current Profilers.The tide filtering approach with the low-pass filter yields significant improvement of water levels in coastal areas,and similar performance in the modeled currents.The grid sensitivity analysis shows significant reduction of error when increasing the resolution from 3.6km to 1.2km,but no further improvement is found at higher resolution.Power spectra shows that further increasing the resolution yields better agreement for higher frequencies but no significant reduction in error.展开更多
An ocean forecasting system has been developed for the coastal area of Puerto Rico and the U.S.Virgin Islands.This paper presents the development and validation of the Puerto Rico Operational Regional Ocean Modeling S...An ocean forecasting system has been developed for the coastal area of Puerto Rico and the U.S.Virgin Islands.This paper presents the development and validation of the Puerto Rico Operational Regional Ocean Modeling System(PRO-ROMS)developed by the Caribbean Coastal Ocean Observing System(CARICOOS),which aims at improving currently available short-term forecasts of ocean currents for this region,and to resolve sub-mesoscale variability absent from the currently operational regional systems.The coastal ocean forecasting system is based on the Regional Ocean Modeling System(ROMS),and provides a 3-day forecast of ocean currents,water levels,temperature and salinity.Initial and lateral boundary conditions are derived from the U.S.Naval Oceanographic Office(NAVOCEANO)operational AmSeas forecasting system,a 3.6-km resolution application of the regional Navy Coastal Ocean Model(NCOM)that encompasses the Gulf of Mexico and Caribbean Sea.Meteorological conditions are interpolated from the Navy’s Coupled Ocean-Atmosphere Mesoscale Prediction System(COAMPS)with the exception of surface stresses,which are computed from a 2-km application of the Weather Research and Forecasting(WRF)model used by National Centers for Environmental Protection’s(NCEP)National Digital Forecast Database(NDFD).Tidal variability is imposed using ROMS spectral forcing by specifying the harmonic phases and amplitudes from the TPXO global inverse tide solutions at the boundaries and sub-tidal conditions are imposed by filtering out high frequencies of barotropic variables from the lateral boundary conditions interpolated from AmSeas.Modeled results of sea surface height are validated with NOAA tide gauges,ocean currents are validated with Acoustic Doppler Current Profilers(ADCP)and High Frequency Radars(HFR).Computed statistics show improvement of the ocean current forecast in PRO-ROMS compared to AmSeas,especially at higher frequencies dominated by the tides and in small channels where the bathymetry is better represented by the higher resolution coastal ocean forecasting system.展开更多
基金This work was funded by CARICOOS(NOAA IOOS Grant NA11NOS0120035).
文摘A persisting problem in ocean modeling around coastal areas has been the adequate imposition of open boundary conditions,especially in the presence of complex bathymetric features commonly found in shelf seas.Ocean models with horizontal resolutions of O(1 km)can generate submesoscale current variability not captured by coarser regional models which resolve mesoscale flows approximately in geostrophic and thermal-wind balance.In practice,higher-resolution systems will provide analyses with enhanced spatial detail but may be less skillful at predicting the evolution of mesoscale eddies.This study aims at assessing the role of open boundary conditions,tidal forcing and tide filtering techniques in a coastal ocean model using a split-explicit time marching scheme with horizontal resolutions of O(1 km)and its effect in coastal sea level dynamics and ocean currents.Numerical experiments have been performed using the Regional Ocean Modeling System(ROMS)with different uniform horizontal resolution:3.6km,1.2km and 740m.Initial and lateral boundary conditions are derived from the U.S.Naval Oceanographic Office(NAVOCEANO)operational AmSeas model forecast,a 3.6-km resolution application of the regional Navy Coastal Ocean Model(NCOM)that encompasses the Gulf of Mexico and Caribbean Sea.Meteorological conditions are interpolated from the Navy’s Coastal Ocean-Atmosphere Mesoscale Prediction System(COAMPS)model with the exception of surface stresses,which are computed from a 2-km application of the Weather Research and Forecasting(WRF)model used by National Center for Environmental Protection’s(NCEP)National Digital Forecast Database(NDFD).Tidal variability is imposed in two ways:1)by specifying the time evolution of sea level at the open boundaries and 2)spectrally by specifying the harmonic phases and amplitudes from the TPXO global inverse tide solutions at the boundaries.Sub-tidal low frequency conditions are imposed by filtering high frequencies out of the regional NCOM solution.A spectral analysis of the sea surface height and barotropic velocity is performed via Fourier’s transform,showing significant differences at higher frequencies.Tide signals are then reconstructed and removed from the open boundary condition’s(OBC’s)in 2 ways:1)using Rich Pawlowicz’s t_tide package(i.e.,classic harmonic analysis)(Pawlowicz,2002[1])and 2)with traditional low-pass filters.The spectral analysis provides a comprehensive characterization of the response in coastal sea level dynamics,which is difficult to elucidate in the time domain.Modeled results of sea surface height and ocean currents are validated with NOAA tide gauges and Acoustic Doppler Current Profilers.The tide filtering approach with the low-pass filter yields significant improvement of water levels in coastal areas,and similar performance in the modeled currents.The grid sensitivity analysis shows significant reduction of error when increasing the resolution from 3.6km to 1.2km,but no further improvement is found at higher resolution.Power spectra shows that further increasing the resolution yields better agreement for higher frequencies but no significant reduction in error.
基金This work was funded by CARICOOS(NOAA IOOS Grant NA11NOS0120035).
文摘An ocean forecasting system has been developed for the coastal area of Puerto Rico and the U.S.Virgin Islands.This paper presents the development and validation of the Puerto Rico Operational Regional Ocean Modeling System(PRO-ROMS)developed by the Caribbean Coastal Ocean Observing System(CARICOOS),which aims at improving currently available short-term forecasts of ocean currents for this region,and to resolve sub-mesoscale variability absent from the currently operational regional systems.The coastal ocean forecasting system is based on the Regional Ocean Modeling System(ROMS),and provides a 3-day forecast of ocean currents,water levels,temperature and salinity.Initial and lateral boundary conditions are derived from the U.S.Naval Oceanographic Office(NAVOCEANO)operational AmSeas forecasting system,a 3.6-km resolution application of the regional Navy Coastal Ocean Model(NCOM)that encompasses the Gulf of Mexico and Caribbean Sea.Meteorological conditions are interpolated from the Navy’s Coupled Ocean-Atmosphere Mesoscale Prediction System(COAMPS)with the exception of surface stresses,which are computed from a 2-km application of the Weather Research and Forecasting(WRF)model used by National Centers for Environmental Protection’s(NCEP)National Digital Forecast Database(NDFD).Tidal variability is imposed using ROMS spectral forcing by specifying the harmonic phases and amplitudes from the TPXO global inverse tide solutions at the boundaries and sub-tidal conditions are imposed by filtering out high frequencies of barotropic variables from the lateral boundary conditions interpolated from AmSeas.Modeled results of sea surface height are validated with NOAA tide gauges,ocean currents are validated with Acoustic Doppler Current Profilers(ADCP)and High Frequency Radars(HFR).Computed statistics show improvement of the ocean current forecast in PRO-ROMS compared to AmSeas,especially at higher frequencies dominated by the tides and in small channels where the bathymetry is better represented by the higher resolution coastal ocean forecasting system.
