Tidal band current variability over the Northern California continental shelf

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution December 1986The focus of this dissertation is on the description and dynamical interpretation of the tidal band current fluctuations over the continental shelf off northern California. The term "tidal band" is used here to denote fluctuations with periods from about one-half to one day, including all the major diurnal and semidiurnal tidal constituents. The semidiurnal frequency is super-inertial, and the diurnal frequency sub-inertial, at this mid-latitude location. Kinetic and potential energy are strongly peaked at the diurnal and semidiurnal frequencies. Although inertial currents are occasionally observed, particularly during the winter when internal wave energy in general is elevated in this locale, they do not contribute significantly to the current variance. Consequently, the treatment here is divided into discussion of the diurnal and semidiurnal variability. Each chapter emphasizes a process which can cause the tidal currents to deviate from what would be anticipated based solely on observations of sea level. In Chapter II, the diurnal current variability is discussed, and the role played by atmospheric forcing is examined in detail. In Chapter III, the barotropic semidiurnal tidal currents over the shelf are described, and the effect of small-scale bumps in the coastline is evaluated. The baroclinic semi diurnal tidal currents, which are dependent upon the local time-varying hydrographic conditions, are examined in Chapter IV.Support from the WHOI Education Office, a NASA traineeship, and NSF grants OCE 80-14941 and OCE 84-17769

Role of Tidal Forcing in Determining the Internal Wave Spectrum in the Littoral Ocean

The long-range goals of this project are to understand the environmental factors that define the level of internal wave activity in the littoral oceans and to develop re-locatable models capable of predicting these levels. The hypothesis is that energy due to internal tides generated through interactions with complex coastal topography is both predictable, using high-resolution primitive equation numerical models, and responsible for setting energy levels of the broader-frequency internal wave spectrum.Award #: N00014–97WR–3000

Role of Tidal Forcing in Determining the Internal Wave Spectrum in the Littoral Ocean

LONG-TERM GOALS: The long-range goals of this project are to understand the environmental factors that define the level of internal wave activity in the littoral oceans and to develop re-locatable models capable of predicting these levels. The hypothesis is that energy due to internal tides generated through interactions with complex coastal topography is both predictable, using high-resolution primitive equation numerical models, and responsible for setting energy levels of the broader-frequency internal wave spectrum.Award #: N00014–97WR–3000

QuikSCAT Satellite Comparisons with Nearshore Buoy Wind Data off the U.S. West Coast

To determine the accuracy of nearshore winds from the QuikSCAT satellite, winds from three satellite datasets (scientifically processed swath, gridded near-real-time, and gridded science datasets) were compared to those from 12 nearshore and 3 offshore U.S. West Coast buoys. Satellite observations from August 1999 to December 2000 that were within 25 km and 30 min of each buoy were used. Comparisons showed that satellite–buoy wind differences near shore were larger than those offshore. Editing the satellite data by discarding observations recorded in rain and those recorded in light winds improved the accuracy of all three datasets. After removing rain-flagged data and wind speeds less than 3 m s21, root-mean-squared differences (satellite minus buoy) for swath data, the best of the three datasets, were 1.4 m s21 and 378 based on 5741 nearshore comparisons. By removing winds less than 6 m s21, these differences were reduced to 1.3 m s21 and 268. At the three offshore buoys, the root-mean-squared differences for the swath data, with both rain and winds less than 6 m s21 removed, were 1.0 m s21 and 158 based on 1920 comparisons. Although the satellite’s scientifically processed swath data near shore do not match buoy observations as closely as those offshore, they are sufficiently accurate for many coastal studies

The California Current System: A multiscale overview and the development of a feature-oriented regional modeling system (FORMS)

17 USC 105 interim-entered record; under review.Over the past decade, the feature-oriented regional modeling methodology has been developed and applied in several ocean domains, including the western North Atlantic and tropical North Atlantic. This methodology is model-independent and can be utilized with or without satellite and/or in situ observations. Here we develop new feature-oriented models for the eastern North Pacific from 36◦ to 48◦N – essentially, most of the regional eastern boundary current. This is the firsttime feature-modeling has been applied to a complex eastern boundary current system. As a prerequisite to feature modeling, prevalent features that comprise the multiscale and complex circulation in the California Current system (CCS) are first overviewed. This description is based on contemporary understanding ofthe features and their dominant space and time scales of variability. A synergistic configuration of circulation features interacting with one another on multiple and sometimes overlapping space and time scales as a meander-eddy-upwelling system is presented. The second step is to define the feature-oriented regional modeling system (FORMS). The major multiscale circulation features include the mean flow and southeastward meandering jet(s) of the California Current (CC), the poleward flowing California Undercurrent (CUC), and six upwelling regions along the coastline. Next, the typical synoptic width, location, vertical extent, and core characteristics of these features and their dominant scales of variability are identified from past observational, theoretical and modeling studies. The parameterized features are then melded with the climatology, in situ and remotely sensed data, as available. The methodology is exemplified here for initialization of primitiveequation models. Dynamical simulations are run as nowcasts and short-term (4–6 weeks) forecasts using these feature models (FM) as initial fields and the Princeton Ocean Model (POM) for dynamics. The set of simulations over a 40-day period illustrate the applicability of FORMS to a transient eastern boundary current region such as the CCS. Comparisons are made with simulations initialized from climatology only. The FORMS approach increases skill in severalfactors, including the: (i) maintenance of the low-salinity pool in the core of the CC; (ii) representation of eddy activity inshore of the coastal transition zone; (iii) realistic eddy kinetic energy evolution; (iv) subsurface (intermediate depth) mesoscale feature evolution; and (v) deep poleward flow evolution.This work was funded by the Office of Naval Research grants N00014-03-1-0411 and N00014-03-1-0206 at the University of Massachusetts at Dartmouth. Leslie Rosenfeld’s participation was supported by ONR grant N00014-03-WR-20009. PFJL, PJH and WGL are grateful to ONR for support under grant N00014-08-1-1097, N00014-08-1-0680 and MURI-ASAP to the Massachusetts Institute of Technology

The circulation and water masses in the Gulf of the Farallones

Six ADCP and CTD ship surveys of the continental shelf and slope in the vicinity of the Gulf of the Farallones, CA, were conducted in 1990}1992. ADCP data provide much more detail on the structure of the currents over the slope and shelf in the Gulf and reveal a persistent, largely barotropic poleward #ow with a complex mesoscale #ow "eld superimposed. The directly measured currents are not well represented by the geostrophic velocity "elds derived from hydrographic casts. Important upper-ocean circulation features include: a Slope Countercurrent (SCC), variable shelf circulation, and submesoscale eddy-like features. The SCC was present in all seasons and is believed due to a strong year-round positive wind-stress curl enhanced by Point Reyes. Its #ow was poleward throughout the upper 300 m, and often surface intensi"ed. Poleward transport in the upper 400 m was 1}3 Sv, much greater than previous geostrophic estimates for the California Current System constrained to a 500 dbar reference level. The shelf circulation was much more variable than the SCC and generally exhibited a pattern consistent with classic Ekman dynamics, responding to synoptic wind forcing. Submesoscale vortices, or eddies, often dominated the general #ow "eld. These eddies are thought to be generated by the frictional torque associated with current}topography interactions. Their centers typically have a distinct water type associated with either the SCC or the southward-#owing California Current. Higher spiciness anomalies, representing a higher percentage of Paci"c Equatorial Water (PEW), were typically found in the core of the SCC or within anticyclonic eddies. Lower (bland) spiciness anomalies, characteristic of a higher percentage of Paci"c Subarctic Water (PSAW), were associated with cyclonic eddies. While these circulation features were largely barotropic, the #ow also adjusted baroclinically to changes in the density "eld, as di!erent water types were advected by the general #ow "eld or by mesoscale instabilities in the large-scale boundary currents as they interacted with topography. Despite a seasonal cycle in regional wind and ocean temperature time series, there is no obvious seasonal pattern in the circulation. Most of the temporal variability in the current appears to be due to synoptic and interannual variations in atmospheric forcing. Because of the very dynamic three-dimensional nature of the regional circulation, the Gulf of the Farallones is likely to be a center for active mixing and exchange between the coastal and California Current waters, relative to most US west coast locales

Observations of the Internal Tide in Monterey Canyon

Data from two shipboard experiments in 1994, designed to observe the semidiurnal internal tide in Monterey Canyon, reveal semidiurnal currents of about 20 cm s−1, which is an order of magnitude larger than the estimated barotropic tidal currents. The kinetic and potential energy (evidenced by isopycnal displacements of about 50 m) was greatest along paths following the characteristics calculated from linear theory. These energy ray paths are oriented nearly parallel to the canyon floor and may originate from large bathymetric features beyond the mouth of Monterey Bay. Energy propagated shoreward during the April experiment (ITEX1), whereas a standing wave, that is, an internal seiche, was observed in October (ITEX2). The difference is attributed to changes in stratification between the two experiments. Higher energy levels were present during ITEX1, which took place near the spring phase of the fortnightly (14.8 days) cycle in sea level, while ITEX2 occurred close to the neap phase. Further evidence of phase-locking between the surface and internal tides comes from monthlong current and temperature records obtained near the canyon head in 1991. The measured ratio of kinetic to potential energy during both ITEX1 and ITEX2 was only half that predicted by linear theory for freely propagating internal waves, probably a result of the constraining effects of topography. Internal tidal energy dissipation rate estimates for ITEX1 range from 1.3 × 10−4 to 2.3 × 10−3 W m−3, depending on assumptions made about the effect of canyon shape on dissipation. Cross-canyon measurements made during ITEX2 reveal vertical transport of denser water from within the canyon up onto the adjacent continental shelf.ONR N0001495WR30022ONR N000149310403ONR N0001497WR3000

Transitions: Linking People to Jobs in an Age of Welfare Reform: A Carolina Planning Forum

Editors' Note: As a result of the recent federal welfare reform legislation, welfare recipients are being forced to find jobs. At the same time, the strong growth of the economy is leaving many Americans behind. Planners need to consider new ways to connect unemployed and underemployed people to jobs. The editors of Carolina Planning hosted a forum to discuss how people in North Carolina are dealing with these issues. We brought together a panel that includes varied perspectives, from private training programs to community development corporations to state agencies. The text of this article is an edited version of the discussion, which took place at the University of North Carolina-Chapel Hill on November 10, 1997

Advancing coastal ocean modelling, analysis, and prediction for the US Integrated Ocean Observing System

Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here by permission of Taylor & Francis for personal use, not for redistribution. The definitive version was published in Journal of Operational Oceanography 10 (2017): 115-126, doi:10.1080/1755876X.2017.1322026.This paper outlines strategies that would advance coastal ocean modeling, analysis and prediction as a complement to the observing and data management activities of the coastal components of the U.S. Integrated Ocean Observing System (IOOS®) and the Global Ocean Observing System (GOOS). The views presented are the consensus of a group of U.S. based researchers with a cross-section of coastal oceanography and ocean modeling expertise and community representation drawn from Regional and U.S. Federal partners in IOOS. Priorities for research and development are suggested that would enhance the value of IOOS observations through model-based synthesis, deliver better model-based information products, and assist the design, evaluation and operation of the observing system itself. The proposed priorities are: model coupling, data assimilation, nearshore processes, cyberinfrastructure and model skill assessment, modeling for observing system design, evaluation and operation, ensemble prediction, and fast predictors. Approaches are suggested to accomplish substantial progress in a 3-8 year timeframe. In addition, the group proposes steps to promote collaboration between research and operations groups in Regional Associations, U.S. Federal Agencies, and the international ocean research community in general that would foster coordination on scientific and technical issues, and strengthen federal-academic partnerships benefiting IOOS stakeholders and end users.2018-05-2

CODE-1 : moored array and large-scale data report

The Coastal Ocean Dynamics Experiment (CODE) was undertaken to identify and study the important dynamical processes which govern the wind-driven motion of coastal water over the continental shelf. The initial effort in this multi-year, multi-institutional research program was to obtain high-quality data sets of all the relevant physical variables needed to construct accurate kinematic and dynamic descriptions of the response of shelf water to strong wind forcing in the 2 to 10 day band. A series of two small-scale, densely-instrumented field experiments of approximately four months duration (called CODE-1 and CODE-2) were designed to explore and to determine the kinematics and momentum and heat balances of the local wind-driven flow over a region of the northern California shelf which is characterized by both relatively simple bottom topography and large wind stress events in both winter and summer. A more lightly instrumented, long-term, large-scale component was designed to help separate the local wind-driven response in the region of the small-scale experiments from motions generated either offshore by the California Current system or in some distant region along the coast, and also to help determine the seasonal cycles of the atmospheric forcing, water structure, and coastal currents over the northern California shelf. The first small-scale experiment (CODE-1) was conducted between April and August, 1981 as a pilot study in which primary emphasis was placed on characterizing the wind-driven "signal" and the "noise" from which this signal must be extracted. In particular, CODE-1 was designed to identify the key features of the circulation and its variability over the northern California shelf and to determine the important time and length scales of the wind-driven response. This report presents a basic description of the moored array data and some other Eulerian data collected during CODE-1. A brief description of the CODE-1 field program is presented first, followed by a description of the common data analysis procedures used to produce the various data sets presented here. Then basic descriptions of the following data sets are presented: (a) the coastal and moored meteorological measurements, (b) the moored current measurements, (c) the moored temperature and conductivity observations, (d) the bottom pressure measurements, and (e) the wind and adjusted coastal sea level observations obtained as part of the CODE-1 large-scale component.Prepared for the National Science Foundation under Grant OCE 80-14941