LONG-TERM GOALSOur long-term goal is to better understand ocean interactions at various space and time scales by quantifying submesoscale processes. We focus on the following four areas:•Understanding small-scale coastal ocean processes;• Understanding small-scale advective exchange and stirring;APPROACH 1We use a spectral technique called normal mode analysis (NMA), a generalization of a method first described by Rao and Schwab (1981) in an analysis of currents in Lake Ontario. Numerically Report Documentation PageForm Approved OMB 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 and maintaining 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, Arlington VA 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 it does not display a currently valid OMB control number 1. REPORT DATE

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The long-term goal of ODDAS is to develop strategies for the deployment of drifting sensors that maximize the amount of environmental information collected with the fewest sensors. Two critical concerns in these deployments are: the advection of the array out of the region of interest during the operational period, and the distortion of the array with subsequent loss of information. Mesoscale and submesoscale advective processes are responsible for array translation and distortion. Our primary long-term research goal is to quantify submesoscale stirring process. Calculating the origin and fate of representative parcels is an essential part of our analysis. Thus, the long-term research and ODDAS goals are complementary. The methodology is directly applicable to deployment planning and the data from the deployments are useful in our assessments of stirring.

This letter constitutes the revised final report for ONR contract N00014-88-K-0203 awarded to Old Dominion University for the period October 1, 1987 though January 31, 1989. The original final report was submitted to the Office of Naval Research as part of a renewal proposal.The bulk of the research activities conducted under this contract consisted of basic research on ocean flow dynamics as it pertains to the prediction of ocean motion. During the contract period, three papers describing aspects of the research were published in the adjudicated scientific literature. These papers are:1. "Genesis of the Gulf of Mexico Ring as Determined from Kinematic Analysis," J. Geophys. Res., 92(Cll), 11727-11740, 1987. 2. "Observed and Simulated Kinematic Properties of Loop Current Rings," J. Geophys. Res., 93(C2), 1189-1198, 1988 3. "Notes on the Cluster Method for Interpreting Relative Motions," J. Gcophys. Res., 93(C8), C '7-9339, 1988.In addition to these pap..rs, the results of the research were reported at the 1988 Liege Colloquium on Ocean Hydrodynamics, Mesoscale/Synoptic Coherence in Geophysical Turbulence..As a part of the research effort, the funds were used to support William Indest, a Ph.D. graduate student in the Department of Oceanography.I am grateful to the Office of Naval Research for continued support for this research. The rcwlt% of the analynk sugget a pbocm by shidi Loop Current rings can be generated. Apparently. ibis mechaikam can cause the Loop Current to become reconfigured in 2-3 months for beginning the prcs torringsparsltion. I. I~tU)(I(h)NThefollowing analysis is obtained from the movement of Thte shedding of Loop Current rings has a major impact on drifters 3354 and 3378 as well as concurrent sea surface ternprocescs itt the central and'western Gulf of Mexico. These lieratUre (SST) data and XDT data. These. along with the latrge atnticyclones transport a tremendous amount of momen-presence and location of Ghost Eddy. suggest a new process turn, heat. and salt across the gulf. all the way to the Mexican by which an anticyclorlic vortex is formed that ca 'n eventually coast Whatn. 1982 A detailed description of the kinematic characteristics of the D~uring June 1985. an attempt was made to put atn Argos Loop Current and the ring is provided by an analysis of the drifter into the Loop Cutrrent as a ring was pinching off. How -drifter paths. This analysis gives us the time histories of the ever. the ring did not totatlly disconnecct from thc Loop Cur-rotation rate, eccentricity and orientation of the ellipses of the rent. and the drifter ended tip spending approximately 3 trajectories swirl velocities. and movement of the centers of nionth% iti thc Loop Current proper. The drifter exited the rotation. A comparison is made of the kinematics of the Loop Gulf of Mexico ((JONI) through the Florida Straits in Scptem-Current as deterniined by drifter 3354 during the time it coher 1985 (Figure 1. drifter 3354). Fortunatcly, a second drifter existed with a ring. The latter is designated by drifter 3378...

LONG-TERM GOALSThe long term goal of our research is to quantify submesoscale dynamical processes and understand their interactions with motions at larger scales. In particular, we focus on the following three areas:Use of high resolution disparate (HRD) data sets to develop dynamically consistent nowcasts of a flow field; Application of HRD observations to dynamical systems studies of the mixing properties of the surface flow field; Use of HRD surface observations to infer subsurface flow conditions. OBJECTIVESOur objective is to combine disparate surface current observations from sources like HF radar, Lagrangian drifters, passive remote sensing and ADCPs with open boundary flow information from any available source (numerical model, observations, climatology, etc.) to develop dynamically consistent nowcasts of the surface flow field. These nowcasts can then be analyzed using existing dynamical systems templates to study the mixing characteristics of the surface flow field. Also, because our formulation is exactly three-dimensionally incompressible, the nowcast can be used to infer some features of the subsurface flow field and may be readily assimilated into a numerical model. APPROACHOur nowcast approach uses normal mode analysis (NMA), a spectral technique that is a generalization of a method first described by Rao and Schwab (1981) in an analysis of currents in Lake Ontario. The