LONG TERM GOALS: Long-term goals of this project are to improve high-resolution numerical models of the ocean circulation for the regions with complex bottom topography, coastlines and multi-scale physical fields using enhanced grid technology, nested open boundary and, ultimately, data assimilation of new observational data type like current maps from High Frequency (HF) radar installations.Award number: N0001497WR30065TER

Ly, Le Ngoc

Paduan, Jeffrey D.

English

Calhoun, Institutional Archive of the Naval Postgraduate School

Calhoun: The NPS Institutional ArchiveDSpace RepositoryFaculty and Researchers Faculty and Researchers' Publications1997-09Modeling the Response of Monterey Bay to DiurnalLy, Le Ngoc; Paduan, Jeffrey D.http://hdl.handle.net/10945/68963This 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 THE RESPONSE OF MONTEREY BAY TO DIURNAL WINDAND TIDAL FORCINGLe Ngoc LyDepartment of OceanographyNaval Postgraduate SchoolMonterey, CA 93943phone: (408) 656-1003; fax: (408) 656-2712; e-mail: lely@oc.nps.navy.milJeffrey D. PaduanDepartment of OceanographyNaval Postgraduate SchoolMonterey, CA 93943phone: (408) 656-3350; fax: (408) 656-2712; e-mail: paduan@nps.navy.milAward number: N0001497WR30065TERMLONG TERM GOALSLong-term goals of this project are to improve high-resolution numerical models of the ocean circulationfor the regions with complex bottom topography, coastlines and multi-scale physical fields usingenhanced grid technology, nested open boundary and, ultimately, data assimilation of new observationaldata type like current maps from High Frequency (HF) radar installations.OBJECTIVESThe program seeks to apply new technologies to Navy coastal ocean modeling activities. This includesvalidation of the Monterey Bay (MOB) curvilinear, nearly-orthogonal multi-block grid coastal oceanmodel developed at the NPS (Ly and Luong, 1997a,b,c,d,e) and Princeton Ocean Model (POM,Blumberg and Mellor, 1988) against observed diurnal current variations in Monterey Bay.APPROACHIn order to validate MOB and POM (or other models) in a comprehensive high-resolution domain, it isnecessary to focus on robust processes with high frequency signals that are relatively unaffected by theconditions prescribed on the open boundaries.  To this end, strong current fluctuations in Monterey Bayforced by diurnal sea breeze winds and semi-diurnal tidal oscillations are being used. Monterey Bay isalso the site of unique radar measurements of two-dimensional surface current patterns. The MOBmodel includes data routines, grid generation routines, a grid-model coupling package, and visualizationroutines. Its curvilinear, coastline-following (coastline fitted) orthogonal and nearly-orthogonal, multiblock grid options represent a new advance in coastal ocean modeling (Ly and Luong, 1977a,b,c,d,e).The system also includes a hybrid vertical grid that combines aspects of z-level and sigma-coordinategrids to better model surface and bottom boundary layers.WORK COMPLETEDThe MOB curvilinear nearly-orthogonal grid model (multi-block grid code version with 131 x 131 x 25grid points) for a single-block grid has been newly initialized. The summer diurnal observed andmesoscale model (NCAR MM5, Koracin et al., 1997) winds have been analyzed.  A new threedimensional MOB temperature and salinity fields of all available observational data has been generated.They are ready for use in the following stage. The model has been run with winds of station M42, heatand salinity fluxes to study the model output. A map of seasonal CODAR surface currents has beengenerated for studying CODAR data applications to the MOB model. Some numerical experiments haveReport 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 1997 2. REPORT TYPE 3. DATES COVERED   00-00-1997 to 00-00-1997  4. TITLE AND SUBTITLE Modeling the Response of Monterey Bay to Diurnal Wind and Tidal Forcing 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,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 5 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 been carried out using nudging to study the propagation of the information contained in the CODARdata.Extensive work has been done on the HF radar (CODAR) data for Monterey Bay to produce mapssurface current variability at diurnal and semidiurnal periods. The data set is most for the period ofAugust through December, 1994. Harmonic analyses have been conducted month-by-month for thatperiod (Paduan and Cook, 1997; Paduan and Graber, 1977). The rotated Monterey Bay POM domainhas been produced so that simulations of sea breeze and forcing can be accomplished using the offshoreand along shore open boundary conditions produced by E. Petruncio in his dissertation work (NavalPostgraduate School, Sept. 1996).RESULTSThe preliminary results of 90-day run show the some physics of the MOB summer circulation such asupwelling locations, magnitudes of current, temperature and salinity fields. Fig. 1 shows the modelsurface temperature field.  The corresponding surface currents have magnitudes up to 0.5 m/s in thenortheastern part of the model domain and MOB. An anticyclonic eddy is located off Monterey Bay(south part of the model domain). There is a band of cold and saline water with a surface temperature ofless than 10˚ C and a salinity of greater than 33.7‰. This cold and saline water flows equatorward,which can be seen from Fig. 1. This indicates an upwelling center at the northeastern corner of the modeldomain and the northern part of MOB. The above upwelling location, magnitudes of surface temperatureand salinity are observed features (Rosenfeld et al., 1994).The model generated CODAR data is shown in Fig. 2. Our preliminary results of simulations bynudging show that the model six-hour interval CODAR data reduce rms of the two velocitycomponents. It is expected that the two-hour interval CODAR data will reduce the rms faster. The model(NCAR MM5) wind speeds and directions at the NPS-Fort Ord point for June 22 and 23 are presentedin Figs 3 and 4. These winds show a clear diurnal (sea breeze) signal in the model wind forcing.The observed CODAR data show distinct differences on the physical processes responsible for diurnaland semidiurnal fluctuations in Monterey Bay. The former is largely driven by diurnal (sea breeze)variations in the wind forcing, while the latter is a highly spatially dependent response to tidal forcing.Initial POM simulations on the realistic Monterey Bay grid using observed diurnal wind variations showa reversing surface similar to that observed in CODAR maps (Fig. 5). Now that the model domain isconfigured, detailed comparisons can be made under various wind and stratification conditions. POMresults on this rotated, rectangular domain can also be compared with those from MOB.IMPACT/APPLICATIONSThe coastal ocean system is used to study the model forecast capability using surface current data(CODAR) for regions with complicated coastlines and bottom topography. The system can be used insea-wave coupling study. Application of numerical grid generation is a new advance in coastal oceanmodeling. The technique and our grid routines are interested by various research groups.TRANSITIONSOur works are closely in-cooperated with NAVO (Dr. Phu Luong). Our model development efforts andcoastal ocean modeling products are shared with NAVO.RELATED PROJECTSThis program is related to Ly’s air-wave-sea interaction project in efforts of sea-wave interaction study.This program is also closely related to the ONR project on coastal atmospheric mesoscale modeling forthe northern California coasts using NCAR MM5 by Prof. Koracin of the Desert Research Institute(Reno, NV) regarding high-resolution model surface wind fields for the northern California andMonterey Bay regions.REFERENCESBlumberg, A.F. and G.L. Mellor (1987) A description of a three-dimensional coastal ocean circulationmodel.    Three     Dimensional     Coastal     Ocean      Models   . American Geophysical Union. 1-13.Koracin, D., J. Frye, V. Isakov, and P. Saha, 1977. Observations and simulations of the coastal jetduring the coast wave program in June 1996.  12-th Symposium on Boundary Layer and Turbulence.AMS, Vancouver, Canada, August, 1977, 352-353.Ly, L.N. and P. Luong (1997a). A mathematical coastal ocean circulation system with breaking waveeffects and numerical grid generation.     Applied      Mathematical      Modeling   . (To be appeared).Ly, L.N and P. Luong (1997b).  Numerical multi-block grids in coastal ocean modeling.     Computational   Physics   . (In review).Ly, L.N. and P. Luong (1997c). A coastal ocean circulation system and application to the South ChinaSea.     VACETS    Technical    Journal  , vol. 2,6-16.Ly, L.N. and P. Luong (1997d). On numerical grids used in a ocean circulation model with breakingwaves.     The    second    Pan-American      Workshop    in     Applied    and     Computational      Mathematics   . September,97, Gramado, Brazil. (Invited).Ly, L.N. and P. Luong (1997e). On numerical multi-block grids in coastal circulation modeling.     The   Fourth    SIAM     Conference    on       Mathematical     &   Issues   in   the     Geosciences   . June, 1997. Albuquerque, NewMexico.Paduan, J.D., and M.S. Cook, 1997.  Mapping surface current in Monterey Bay with CODAR-type HPradar. Oceanogranphy, 10, In Press.Paduan, J.D., and H.C. Graber, 1997.  Introduction to high frequency radar: Reality and myth.Oceanography, 10, In Press.Paduan, J.D., M.S. Cook, and D.M. Fernandez, 1997.  Two-dimensional diurnal to monthly periodsurface currents in Monterey Bay from CODAR-type HF radar.  Proceedings, IEEE Inter. Geosciencesand Remote Sensing Symposium, Singapore, August 1977, pp. 1814-1816.Rosenfeld, L.K., Schwing, N. Garfield and D.E. Tracy, 1994: Bifurcated flow from an upwelling center:a cold water for Monterey Bay.     Cont.    Shelf     Res   ., 14, 931-964.Http://www.oc.nps.navy.mil/~radlab/…NPS’ Radar and Drifter Laboratory Home PageFig. 1. Surface temperature field produced by 90 day MOB model run.Fig. 2. MOB model-generated CODAR data.0 5 10 15 20 25200210220230240250260270NPS−Fort Ord−wd22jun(o),wd23jun(+)Time (hr)Wind direction (deg)0 5 10 15 20 251.522.533.544.555.566.5NPS−Fort Ord−ws22jun(o),ws23jun(+)Time (hr)Wind speed (m/s)Fig. 3. Atmospheric model (MM5) wind speed Fig. 4. Atmospheric model (MM5) wind directionat NPS-Fort Ord on 22 (o) and 23 (+) June 1996. at NPS-Fort Ord on 22 (o) and 23 (+) June 1996.123 122.5 1223636.236.436.636.83737.2Uo,Vo (max:0.09m/s) Hr:8LongitudeLatitude123 122.5 1223636.236.436.636.83737.2Uo,Vo (max:0.08m/s) Hr:16LongitudeLatitude123 122.5 1223636.236.436.636.83737.2Uo,Vo (max:0.36m/s) Hr:24LongitudeLatitude0 10 20 30 4042024HoursWind [m/s]Wind fluctuation (from M1)(Usolid)(Vdashed)Figure 5. Surface currents at three phases of the diurnal wind forcing from initial POM simulations ofMonterey Bay together with observed wind fluctuations from center of the bay. Horizontal modelresolution is 1 km; every third vector is plotted.

Modeling the Response of Monterey Bay to Diurnal

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Modeling the Response of Monterey Bay to Diurnal

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