Ly, Le Ngoc

Paduan, Jeffrey D.

Calhoun, Institutional Archive of the Naval Postgraduate School

Calhoun: The NPS Institutional ArchiveDSpace RepositoryFaculty and Researchers Faculty and Researchers' Publications1999-09Modeling and Observations of Surface Wavesin Monterey BayPaduan, Jeffrey D.; Ly, Le NgocNaval Postgraduate Schoolhttp://hdl.handle.net/10945/69394This publication is a work of the U.S. Government as defined in Title 17, UnitedStates Code, Section 101. Copyright protection is not available for this work in theUnited States.Downloaded from NPS Archive: CalhounModeling and Observations of Surface Waves in Monterey BayJeffrey D. PaduanDepartment of Oceanography, Code OC/PdNaval Postgraduate SchoolMonterey, CA  93943phone: (831) 656-3350; fax: (831) 656-2712; email: paduan@nps.navy.milLe Ngoc LyDepartment of Oceanography, Code OC/LeNaval Postgraduate SchoolMonterey, CA  93943phone: (831) 656-3257; fax: (831) 656-2712; email: lely@oc.nps.navy.milAward #: N0001499WR30183http://www.oc.nps.navy.mil/~icon/LONG-TERM GOALSThe long-range goals of this project are to develop an improved turbulence closure model that takesexplicit account of surface wave effects and to quantify the effect of Stokes drift on the surface currentsignature of High Frequency (HF) radar systems.OBJECTIVESThe objectives of this project are to: 1) deploy a surface buoy with turbulent flux and surface wavemeasurement capabilities within the footprint of the HF radar network in Monterey Bay and 2)formulate a new turbulence closure scheme based on surface wave dynamics that can be evaluatedusing data from the flux buoy.APPROACHThis project is extending the measurement and modeling efforts already underway in the Monterey Bayregion to include the direct measurement and modeling of surface waves.WORK COMPLETEDAssembly and deployment of the NPS Flux Buoy has taken place, a sixty-day record has been collectedso far, and a buoy recovery and turn-around has been scheduled for November 1999.  The initialformulation of a new turbulence closure scheme based on surface wave dynamics has been completedalong with preliminary validation experiments.RESULTSAn instrumented toroid buoy was assembled, checked out and deployed in Monterey Bay to provide insitu measurements of surface waves and atmospheric forcing by K. Davidson of the NPS MeteorologyReport Documentation Page Form ApprovedOMB No. 0704-0188Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering andmaintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information,including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, ArlingtonVA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if itdoes not display a currently valid OMB control number. 1. REPORT DATE 30 SEP 1999 2. REPORT TYPE 3. DATES COVERED   00-00-1999 to 00-00-1999  4. TITLE AND SUBTITLE Modeling and Observations of Surface Waves in Monterey Bay 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Postgraduate School,Department of Oceanography,Code OC/Pd,Monterey,CA,93943 8. PERFORMING ORGANIZATIONREPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT  15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same asReport (SAR) 18. NUMBEROF PAGES 6 19a. NAME OFRESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Department.  The parameters measured by the NPS Flux Buoy are shown in Figure 1.  The buoy wasdeployed on 2 September 1999, approximately, 9 km west of Moss Landing.  It has operatedcontinuously since then and recovery and redeployment are planned for the week of 8 November 1999.A significant effort in pre-launch preparation was made to install and evaluate onboard solar-cell powergeneration in order to extend the buoy operation period up to the limit of the available onboardmemory.  The determining factors in this case are the 20 Hz sampling rates of the sonic anemometerand buoy accelerations needed for airflow turbulence and surface wave data, respectively.  Both ofthese data streams are primary to the objectives of the project.  Mean (i.e., bulk) airflow and SST dataare stored onboard the buoy using much lower sampling rates.  The bulk data are also sent via radio(RF) link to shore where they are used in real-time diplays and as checks on the buoy operatingconditions.  Examples of this data and other mooring-related data for Monterey Bay can be seen at:http://www.oc.nps.navy.mil/~icon/moorings/ .  An example of the type of data being received for real-time instrumentation and condition assessments during one twenty-four hour period is shown in Figure2.  The diurnal and shorter period variations visible in the figure are typical of the type of informationthat will be combined with the surface wave and turbulent fluxes after the onboard data is retrieved.L. Ly has developed a primitive equation circulation model for the Monterey Bay region (MOB) basedon an adaptation of the Princeton Ocean Model (POM) and multi-block grid techniques.  The MOBresponse to mesoscale wind forcing by the NCAR atmospheric model (MM5) was investigated andcompared with a companion simulation forced by spatially constant observed winds.  Sixty-daysimulations using springtime MM5 wind forcing show the basic physics of two strong upwellingcenters around a warm anticyclone in June.  The upwelling center locations, surface cold coastalcurrents, and temperature and salinity magnitudes agree well with prior observations.  The companionrun forced by spatially constant buoy winds did not reproduce these expected features.  These resultshave been written up for the AMS Third Conference on Coastal Atmospheric and Oceanic Predictionand Processes to be held in New Orleans in November 1999.A new surface wave parameterization was developed using surface turbulence energy fluxes anddiffusion.  Simulations show that models using the new coupled air-wave-sea scheme better reproducedissipation distributions and other physical characteristics in the ocean than models using the previousscheme (Ly, 1995; Ly and Garwood, 1999), or the classical wall-layer theory, when compared withavailable measurements as shown in Figure 3.  A description of this parameterization scheme isavailable in draft form (Ly, Garwood and Paduan, 1999) and was presented at the AMS ThirteenthInternational Symposium on Boundary Layers and Turbulence held in Dallas, TX, in January 1999.The new closure scheme has been implemented within MOB using the pivotal-condensation numericalmethod.  That implementation is being debugged now.  The next step will be to transfer subroutines forthe new scheme to the POM-based Monterey Bay model being used with local data assimilation by I.Shulman as part of the National Ocean Partnership Program’s Innovative Coastal-Ocean ObservingNetwork (NOPP/ICON).  A second turbulence closure scheme with a wave (spectral) parameterizationhas been developed using wave mean momentum and wave kinetic energy by Ly and Benilov.  Thisscheme will also be incorporated into an air-wave-sea coupled model to test the output againstobservational data.Parameter Sensor Descrip.Bulk (Sfc-Layer and Sfc)Pressure BarometerVector Wind Propeller-Vaneand CompassAir Temperature RTD SensorAir Humidity HygrometerSST Hull and FloatThermistor, IRFluctuating (Sfc-Layer and Sfc)Wind SonicAnemometerTemperature SonicAnemometer2-D Sfc Waves–swell through 2 mwind wavesAccel.-Rate GyroSystem2-D CapillaryWaves–to 3 cmCapacitanceWires (Planned) 1.  Photograph and measurement specificationsfor the NPS Flux Buoy.IMPACT/APPLICATIONSThe likely impacts of this research will include improved understanding of the effects of surface waveson the measurement of surface currents by HF radar installations along with an expanded capability toinclude the effects of surface waves within turbulence closure schemes used by primitive equationmodels.  The application of these results should lead to fundamentally improved models and moreaccurate remotely sensed surface currents.             0246810  Wind (m/s)             101510201025  Pres (mb)             8090100  RH (%)00 02 04 06 08 10 12 14 16 18 20 22 2410121416 17 October 1999 (UTC)Temp (° °°°C) Air Sea IR Sea Bulk2.  Real-time bulk data from the NPS Flux Buoy for 17 October 1999 (UTC) showing, from top tobottom: 1) wind speed (line) and direction from (barbs), 2) atmospheric pressure, 3) relativehumidity, and 4) air temperature (black), IR-derived sea surface temperature (red), and hull-mounted thermistor sea temperature (blue).TRANSITIONSThe transition opportunities are related to next-generation ocean circulation models and coupledatmosphere-wave-ocean models.  These models will require improved parameterizations of the effectsof surface waves on turbulent transport near the ocean surface.  In addition, the information about theeffects of surface waves on HF radar measurements will be needed to correct observed surface currentfields prior to assimilation into ocean circulation models.RELATED PROJECTSThis project represents and extension of the efforts underway as part of the Monterey Bay componentof the National Ocean Partnership Program (NOPP).  That project, an Innovative Coastal-OceanObserving Network (ICON) is utilizing data from six HF radar units and four deep-ocean moorings asinput to a coastal circulation model.  Information about this project and the broader ICON efforts canbe found at: http://www.oc.nps.navy.mil/~icon . 3.  Various measurements (symbols) of nondimensional dissipation, ε, as a function ofnondimensional depth adapted from Agrawal et al. (1992) along with the classic wall-layerdistribution and a range of results from the new wave parameterization.REFERENCESAgrawal Y. C., E. A. Terray, M. A. Donelan, P. A. Hwang, A. J. Williams, W. Drennan, K. K. Kahma,and S. A. Kitaigorodskii, 1992: Enhanced dissipation of kinetic energy beneath breaking waves.Nature, 359, 219-220.Ly, L.N., 1995: A Numerical Coupled Model for Studying Air-Sea-Wave Interaction. Physics ofFluids, 7 (10), 2396-2406.Ly, L.N., and  R. W. Garwood, Jr., 1999: Numerical Modeling of Wave-Enhanced Turbulence in theOceanic Upper Layer. Journal of Oceanography, Submitted.Ly, L.N., R. W. Garwood, Jr., and J.D. Paduan, 1999: Modeling of Breaking Wave Effects on theOcean Surface Turbulent Layer, in preparation.PUBLICATIONSLy, L.N., and L. Jiang, 1999: Horizontal Pressure Gradient Errors of the Monterey Bay SigmaCoordinate Ocean Model with Various Grids. Journal of  Oceanography, 55, 87-97.Ly, L.N., and R. W. Garwood, Jr., 1999: On Breaking Wave-Enhanced Turbulence in the OceanicSurface Boundary Layer. Proceedings, Thirteen International Symposium on Boundary Layers andTurbulence, 359-361.Ly, L. N., and P. Luong, 1999a: Numerical Multi-Block Grids in Coastal Ocean Circulation Modeling.Applied Mathematical Modeling, 23, 865-879.Ly, L.N., and P. Luong, 1999b: Numerical Grids Used in a Coastal Ocean Model with Breaking WaveEffects. Computational and Applied Mathematics, 103, 125-137.Ly, L.N., P. Luong, J. D. Paduan, and D. Koracin, 1999: Response of the Monterey Bay Region toWind Forcing by an Atmospheric Model. Proceedings, Third Conference on Coastal Atmospheric andOceanic Prediction and Processes, New Orleans, LA, 3-5 November.

Modeling and Observations of Surface Waves in Monterey Bay

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Modeling and Observations of Surface Waves in Monterey Bay

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