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Surface Circulation Associated with the Mindanao and Halmahera Eddies

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Surface Circulation Associated with the Mindanao and Halmahera Eddies Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection 1989-06 Surface circulation associated with the Mindanao and Halmahera Eddies Carpenter, Glen H. Monterey, California. Naval Postgraduate School http://hdl.handle.net/10945/27297 - TTtTOX TJBBAB?^^ NPS-68-89-005 NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS Surface Circulation Associated with the Mindanao and Halmahera Eddies by Glen H. Carpenter June 1989 Thesis Ad-zisor: Curtis Collins Approved for public release; distribution is unlimited Prepared for: Chief of Office of Naval Research 800 North Quincy Arlington, VA 22217-5000 T 244047 NAVAL POSTGRADUATE SCHX)L Monterey, California Pear Admiral R.C. Austin Harrison Shull Superintendent Provost This report was prepared in cxmjunction with Cliief Office of Naval Research, Arlington, VA and funded by the Naval Postgraduate School. Unclassified KiiroKi 0(K imi:maii()\ i'aci: la Repori Security ClasMlic 3 Distribution .\\ailability ul Keport 2b Declassificauon Downgrading Schedule Aj^piovcd for public release; dislribulion is unlimited. ing Organization Report Nuniber(s) NPS-68-89-005 I Report Numbcr(s) .anie of Performing Organizati 6b Office Symbol a Name of .\!oniioriii<: Or^'anlzation \a\al Posteruduate School (ijafplkabie) 52 Office of Naval Research 6c Address (dry. siaie. and ZIP code) 7b Address (dry. state, and ZIP code) Monterey, CA 93943-5000 800 Ouencv, Arlington. VA 22217-5000 8a Name of Funding Sponsoring Organization t Instrument IdciUirication Number Naval Pos1-gr;=<rhi;=i1-p .q<-hnn1 0^3MN, nirerrh. Fiirif^ing Sc Address (dry. state, and ZIP code) Monterey, CA 93943-5000 ^ itie (include security classification) SURFACE ClRCULAllON ASSOCIAIUD Willi I HE MINDANAO AND IIALMAIIERA EDDIES mai Author(s) Glen 11. Carpenter 13a 1 )p« of Report 13b Time Covered 14 Date of Report {year, month, day) 5 Page Count Master's 1 hesis June 19S9 121 16 Supplementary Notation 1 hc vieus expressed in tliis thesis are tho.se of the author and do not reflect the olTicial policy or po- sition of the Department of Defense or the U.S. Govenunent. 18 Subject terms ( ij iiixcssary and Identify by block /luntbtir) word processing, Script, G.ML, text processing. 9 Abstract (conitmie on reverse if necessary and identify by block number) During June and July, 1988, an AXBT SUr\ey was conducted southeast of Mindanao, I'liilippines in conjunction with C ID sections completed along the coast of Mindanao. Simultane- ously, six Lagranjiian drifters are launched iji tlie Mindanao Current. yVnalysis of the data indicate a liigldy dynamic and complicated circulation which forms the origin of the North Equatorial Countercuirent. Strong shears are obser\ed across the Mmdanao current and across a cuirent located on the noilheast coast of Borneo, and based on v\aler mass characteristics and Lagrangian data, the general positions and siiengths of the Mindanao and Ilalinahera Eddies. 20 Distribution Availability of .Abstract 21 Abstract Security Classificatio H unclassiTied unlimited D same a UncIassiJied !2a Name of Responsible Individual 22b 1 elephoiie (include Area code) Cunis A. Collins (40S) M6-276S DD FOR.M 1473,84 .MAR Unclassified Approved for public release; distribution is unlimited. Surface Ciiculation Associated with the Mindaiiau and llahnahcra l.ddies by Glen H. Carpenter Lieutenant Commander, United Slates Nunt B.S., University of Washington, 1977 Submitted in partial fulliUmcnt ol" the requirements for tiie degree of MASTER OF SCIENCE IN OCEANOGII.APHY AND METEOROEOGY from the NAVAL POSTGR.ADUATE SCHOOL June 1989 ABSTRACT During June and July, 19bS, an AXBT burvey was conducted southeast of Mindanao, Philippines in conjunction with C'lD sections completed along the coast of Mindanao. Simuhaneously, six Lagrangian drilters are launched in the Mindanao Current. Analysis of the data indicate a highly dynamic and compUcaied circulation which forms the origin of the North Equatorial Countercurrent. Strong shears are observed across the Mindanao current and across a current located on the northeast coast of Borneo, and based on water mass characteristics and Lagrangian data, the general positions and streneths of the Mmdaiiao and llalmaliera IZddies. CI TABLE OF CONTEN1S I. INTRODUCTION 1 II. BATHYMETRY 5 III. LAGRANGIAN DRIFTER MEASUREMENTS 8 A. MINI-TRISTAR DRIFTER 8 B. DRIFTER MEASUREMENTS 8 C. LAGRANGIAN TR.\JECTORIES 9 1. Buoys launched along 7°N 11 a. Buoy 52 11 b. Buoy 51 13 c. Buoy 55 13 2. Buoys launched along 8°N 18 a. Buoy 50 18 b. Buoy 54 20 c. Buoy 53 20 D. LAGR.ANGIAN VELOCITY CORRELATIONS 21 1. Philippine Sea 23 2. Celebes Sea 25 E. LAGR.ANGIAN TEMPER.ATURES 26 F. SUMMARY 30 IV. AXBT AND CTD MEASUREMENTS 38 A. VERTICAL PROFILES 38 B. VERTICAL SECTIONS 39 C. HORIZONTAL TEMPER.\TURE STRUCTURE 42 D. DYNAMIC STRUC'IURE 43 V. SUMMARY AND RECO.MMENDATIONS 50 A. SU.M.MARY 50 B. RECOMMENDATIONS 51 mi')J APPENDIX A. AXBT TnMPiiR.MLRC PPkOFILCS 52 APPENDIX B. LAGll.\NGiAN lEMPhRAIl Rl riMi; SlRll.S 110 LIST OF REFERENCES 124 INITIAL DISTRIBUTION LIST 125 LIST OF TABLES Table 1. DRIFTER NTCROLOGY 13 ^7 Table 2. TIME AVERAGED LAGR/WGIAN MEAN VELOCITIES Table 3. LAGRANGIAX VARIANCES AND EDDY KINETIC ENERG^' ... 37 Table A. DYNAMIC HEIGHT COMPARISONS 43 LIST OF FIGURES Figu 1. Baihymeiiic Chart of the Survey Region 7 Figui 2. MINI-TRISTAR Drogue and Surlacc Float Configuration 10 Figu: 3. Schematic of the Observed Motion of TRISTAR in Surface Waves ... 11 Figui 4. Geometry of Location Calculations 12 Figui 5. Lagrangian Trajectory of Buoy 52 14 Figui e 6. Buoy 52 Velocity Time Series 15 Figu e 7. Lagrangian Trajectory of Buoy 51 16 Figui S. Buoy 51 Velocity Time Series 17 Figui 9. Lagrangian 1 rajcctor\' of Buoy 55 18 Figu e 10. Buoy 55 Velocity Time Scries 19 Figui e 11. Lagrangian Trajcctor}" ol" Buoy 50 21 Figu e 12. Buoy 50 Velocity Time Series 22 Figui 13. Lagrangian Trajectory of Buoy 54 23 Figui e 14. Buoy 54 Velocity Time Series 24 Figui e 15. Lagrangian Trajectory of Buoy 53 25 Figui e 16. Buoy 53 Velocity fime Series Day 206-270 26 Figui e 17. Lagrangian Trajecton ol" Buoy 53 27 Figui e IS. Buoy 53 Velocity lime Series Day 270-35U 28 Figui e 19.. Buoy 53 Velocity Time Series Day 340-430 29 Figu :0. Buoy 51 Lagrangian N'elocity Correlations 30 Figui e 21. Buoy 52 Lagrangian Velocity Correlations 31 Figui e 22. Buoy 52 Lagrangian Velocity Correlations 32 Figu] •e 23. Buoy 53 Lagrangian Velocity Correlations 33 Figui 4. Buoy 53 Lagrangian Velocity Correlations 33 FigUi e 25. Buoy 50 Lagrangian Velocity Correlations 34 Figu; e 26. Buoy 54 Lagrangian Velocity Correlations 34 Figu; 7. Buoy 55 Lagrangian Velocity Correlations 35 Figu e 2S. Lagrangian Daily Minimum Sea Surface Temperature 36 Figu e 29. AXBT and CTD Station Locations 39 Figu; e 30. Vertical Profiles of Temperature, Salinity, and Density Anomaly 40 Figu; e 31. Vertical Profile of Temperature, Salinity, and Density y\nomaly 41 Figure 32. Vertical Temperature Cross-section A 44 Figure 33. Vertical Temperature Cross-section B 45 I'igure 34. Vertical Tempcratuic (j-oss-seciion C 40 Figure 35. 23° Isotherm 47 Figure 36. 14° Isotherm 47 Figure 37. 14°-23° Thickness 4S Figure 38. Buoy Trajectory composite 48 Figure 39. Dvnamic Meishts 0, 300 m 49 I. INTR0DUC110N On Jdiiuan- 1, I9S5, the international 'lOGA (Tropical Ocean Global Atmosphere) program commenced. Planning for this program had been on going since 1981 with its central focus being air-sea interaction and its elfect on the global climate. In 1982-1983, a strong El Nino event stimulated higher levels of mterest in this research. TOGA is envisioned to be a 10-year program with its efibrts centered around four major program elements. The first of these elements is modeling with an aini at fixing the predictability of the atmosphere through coupled air-ocean models. Second, empirical studies, based on historical data sets, will continue to contribute to the understanding of the processes that control the predictability of the environment. Third, process studies will be focused on those physical mechanism which are identified to be of critical importance to the understanding of large scale atmospheric - oceanographic variability. Finally, long term observations are necessary to determine the time-dependent structure of the tropical oceans and the global atmosphere. Although, global eifects of tropical air-sea interactions is central to the understand- ing of the circulation of the oceans at low latitudes along the western boundaries, yet until recently there had been few modern occcuiograpliic observations in the western equatorial Pacific. Then, between 19S5 and 1988, under the umbrella of the process studies element of TOGA, se\eral expeditions were carried out as part of a Western Equatorial Pacific Ocean Circulation Study (WEPOCS). 'fhe third of these expeditions was a survey conducted by the R I' Moana Wave called WEPOCS 111. fhe purpose of this cruise was [Lukas, et al, 1987]: 1. defining the circulation of the low-latitude western boundary currents of the west- ern Pacific, including the possible cross-equatorial transports, 2. determining the convergence of waters of northern and southern hemisphere origin in the far western equatorial Pacific, 3. determining the source water mass c' aracteristics for the Pacific to Indian Ocean Indonesian throughllow, A. defining the Origin of the Equatorial Lndercurrent, and 5. determining the circulation patterns which supply the North Equatorial Counter- current near its origin. In order to learn more about the mesoscale structure in the region, the Naval Postgraduate School (NPS) supplemented the WEPOCS 111 program by providing ad- ditional drifting buoys and an airciafi survey. Mini-TRISTAR drifting buoys were de- ployed to bracket the Mindanao Current. During three days in July, 1988, an Airborne Expendable Bathythermograph (.-WBr) survey was conducted by NPS souiheasi oC Mindanao, in which 84 temperature profiles were obtained.
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