Determination of near-surface velocity fields in the CTZ using combined altimetric and inverse modelling techniques. PDF
Preview Determination of near-surface velocity fields in the CTZ using combined altimetric and inverse modelling techniques.
NAVAL POSTGRADUATE SCHOOL Monterey California , THESIS DETERMINATION OF NEAR-SURFACE VELOCITY FIELDS IN THE CTZ USING COMBINED ALTIMETRIC AND INVERSE MODELLING TECHNIQUES by Douglas Michael Taggart March 1991 Thesis Advisor Steven R. Ramp Co-Advisor Newell Garfield Approved for public release; distribution is unlimited T254583 nclassified :unty classi"ication ofthis page REPORT DOCUMENTATION PAGE a Report Security Classification Unclassified lb Restrictive Markings aSecurity Classification Authority 3 Distribution Availability of Report b Declassification Downgrading Schedule Approved for public release; distribution is unlimited. Performing Organization Report Number(s) 5 Monitoring Organization Report Number(s) a Name of Performing Organization 6b Office Symbol 7a Name of Monitoring Organization \'aval Postgraduate School (ifapplicable) 35 Naval Postgraduate School c Address Icity, state, and ZIP code) 7b Address (city, state, andZIPcode) Monterey. CA 93943-5000 Monterey. CA 93943-5000 a Name ofFunding Sponsoring Organization 8b Office Symbol 9 Procurement Instrument Identification Number (ifapplicable) c Address (city, state, and ZIPcode) 10 Source of Funding Numbers Program Element No Project No Task No Work Unit Accession No :i TOitMleB(IinNclEudDeseAcuLriTtyIclMasEsiTfiRcaItiCon)ADNEDTEIRNMVIENRSAETIMOONDEOLFLNIENAGR-TSEUCRHFNAICQEUEVSELOCITY FIELDS IN THE CTZ USING 2 Personal Author(s) Douglas Michael Taggart 3aType of Report 13b Time Covered 14 Date of Report (year, month, day) 15 Page Count Master's Thesis From To March 1991 54 6 Supplementary Notation The views expressed in this thesis are those ofthe author and do not reflect the official policy or po- rtion of the Department of Defense or the U.S. Government. 7 Cosati Codes 18 Subject Terms (continue on reverseifnecessary andidentify by block number) >ieid Group Subgroup inverse model,ocean currents,AVHRR,GEOSAT,radar altimeter 9 Abstract (continue on reverse ifnecessary andidentify by block number) An inverse model involving AVHRR imagery and the heat equation with dynamical constraints on the divergence, kinetic nergy and vorticity of the solutions was used by Kelly (1989) to produce velocity fields that were in good agreement with Acoustic Doppler Current Profiler (ADCP) data. Dynamic heights derived from GEOSAT radar altimeter data have also >een used to determine near-surface geostrophic currents. Synthetic GEOSAT-derived velocity data was generated from ^DCP data collected as part ofthe Coastal Transition Zone (CTZ) Field Program. The inverse model was run with AVHRR magery that was coincident to the CTZ Field Program ADCP data and the synthetic velocity data was added as an additional onstraint on the model's solution. The resulting velocity solutions were much improved over those given by the inverse nodel alone. Refinement of this method involving a combination of different data sources should improve efforts to deter- nine near-surface velocities of the ocean entirely by remote means. Distribution Availability of Abstract 21 Abstract Security Classification 3 unclassified unlimited D same as report DT1C users Unclassified 2a Name of Responsible Individual 22b Telephone (includeArea code) 22c Office Symbol •teven R. Ramp (408) 646-3162 OC/Ra D FORM 1473,84 MAR 83 APR edition may be used until exhausted security classification ofthis page All other editions are obsolete Unclassified Approved for public release; distribution is unlimited. Determination ofNear-Surface Velocity Fields in the CTZ Using Combined Altimetric and Inverse Modelling Techniques by Douglas Michael Taggart Lieutenant Commander, United States Navy B.S., United States Naval Academy, 1979 Submitted in partial fulfillment ofthe requirements for the degree of MASTER OF SCIENCE IN METEOROLOGY AND PHYSICAL OCEANOGRAPHY from the NAVAL POSTGRADUATE SCHOOL March 1991 Curtis A. Collins, Chairman, Department of Oceanography ABSTRACT An inverse model involving AVHRR imagery and the heat equation with dynamical constraints on the divergence, kinetic energy and vorticity ofthe solutions was used by Kelly (1989) to produce velocity fields that were in good agreement with Acoustic Doppler Current Profiler (ADCP) data. Dynamic heights derived from GEOSAT radar altimeter data have also been used to determine near-surface geostrophic currents. Synthetic GEOSAT-derived velocity data was generated from ADCP data collected as part of the Coastal Transition Zone (CTZ) Field Program. The inverse model was run with AVHRR imagery that was coincident to the CTZ Field Program ADCP data and the synthetic velocity data was added as an additional constraint on the model's sol- ution. The resulting velocity solutions were much improved over those given by the in- verse model alone. Refinement ofthis method involving a combination ofdifferent data sources should improve efforts to determine near-surface velocities ofthe ocean entirely by remote means. ui t.f TABLE OF CONTENTS BACKGROUND I. 1 FEATURE TRACKING A. 1 INVERSE METHODS B. 2 RADAR ALTIMETER DERIVED NEAR-SURFACE VELOCITIES C. 3 D. RADAR ALTIMETER DERIVED VELOCITIES AS CONSTRANTS ON AN INVERSE MODEL 5 METHODS II. 6 DATA III. 9 AVHRR IMAGERY A. 9 CTZ DATA B. 10 SYNTHETIC GEOSAT-DERIVED VELOCITY DATA C. 11 THE MODEL IV. 12 V. RESULTS 13 A. THE INVERSE MODEL WITHOUT VELOCITY CONSTRAINTS 13 THE INVERSE MODEL WITH SYNTHETIC VELOCITY CON- B. STRAINTS 16 CONCLUSIONS AND RECOMMENDATIONS VI. 20 APPENDIX A. FIGURES 22 REFERENCES 42 INITIAL DISTRIBUTION LIST 44 IV
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