Jeffrey D. Paduan

Naval Postgraduate School

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Leslie K. Rosenfeld

Monterey Bay Aquarium Research Institute

J.F. Vesecky

University of California, Santa Cruz

C.C. Teague

Codar Ocean Sensors (United States)

Kenneth Laws

University of California, Santa Cruz

Igor Shulman

Stennis Space Center

J. Drake

Colorado State University

D.M. Fernandez

Universidad Complutense de Madrid

Newell Garfield

NOAA National Marine Fisheries Service Southwest Fisheries Science Center

Francisco P. Chávez

Monterey Bay Aquarium Research Institute

Michael S. Cook

Naval Postgraduate School

Cooperative Institutions

Naval Postgraduate School

Monterey Bay Aquarium Research Institute

Woods Hole Oceanographic Institution

Stennis Space Center

National Oceanic and Atmospheric Administration

Oceanography Society

United States Naval Research Laboratory

University of California, Santa Cruz

Scripps Institution of Oceanography

California Institute of Technology

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Surface circulation patterns at the southeastern Bay of Biscay: new observations from HF radar data

AGUFM (2012)

Lohitzune Solabarrieta Anna Rubio Raúl Medina Jeffrey D. Paduan Sonia Castanedo

Circulation (fluid dynamics)

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Inner shelf response to Tropical Storm Floyd

Journal of Geophysical Research Atmospheres (2006)

Josh Kohut Scott Glenn Jeffrey D. Paduan

A continuously operated coastal observatory off the southern coast of New Jersey provides an opportunity to study both long‐term trends and episodic events. On the evening of 16 September 1999, Tropical Storm Floyd moved up the New Jersey coast directly over the observatory. The response of the inner shelf is characterized using a depth‐averaged (DA) and surface layer (SL) model in conjunction with direct observations. During the storm, the DA model was more representative of the observed response. While there was a peak in the near‐inertial band of the depth average current, the response was not the typical clockwise ringing response seen in deepwater stratified regions. Instead the shallow, well‐mixed inner shelf responded with an alongshore current oscillation balanced by the alongshore pressure gradient and bottom stress. The increased influence of bottom friction damps the typical inertial tail seen in deeper ocean responses and shortens the relaxation phase from several days to hours. Immediately following the storm, the surface layer model better represents the observed currents. It appears that the excessive rainfall associated with the storm and the resulting freshening of the inner shelf isolate the surface layer from the effect of bottom friction. The large waves and currents associated with the storm increase the potential for a sediment resuspension and transport event. Unlike the typical nor'easter in which the transport in this location is alongshore toward the south and onshore, the currents coinciding with the largest waves are alongshore toward the south but with an offshore component.

Mixed layer

Mooring

10.1029/2003jc002173

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Citations (33)

Variability of the near‐surface eddy kinetic energy in the California Current based on altimetric, drifter, and moored current data

Journal of Geophysical Research Atmospheres (1998)

Kathryn A. Kelly Robert C. Beardsley Richard Limeburner K. H. Brink Jeffrey D. Paduan

Low‐pass‐filtered velocities obtained from World Ocean Circulation Experiment (WOCE) surface drifters deployed in the California Current off northern California during 1993–1995 have been compared with surface geostrophic velocity estimates made along subtracks of the TOPEX/POSEIDON altimeter and with moored acoustic Doppler current profiler (ADCP) data. To obtain absolute geostrophic velocities, a mean sea surface height (SSH) field was estimated using the mean drifter velocities and historical hydrographic data and was added to the altimetric SSH anomalies. The correlation between collocated drifter and altimetric velocities is 0.73, significant at the 95% level. The component of the drifter velocity which was uncorrelated with the altimetric velocity was correlated with the wind in the Ekman transport sense. Monthly averages of eddy kinetic energy (EKE), estimated using all drifter and altimeter data within the domain (124°–132°W, 33°–40.5°N), show energy levels for the drifters that are about 13% greater than those for the altimeter. Drifter, altimeter, and ADCP measurements all exhibit similar seasonal cycles in EKE, with the altimeter data reaching maximum values of about 0.03 m 2 s −2 in late summer/fall. Wavenumber spectra of the altimeter velocity indicate that the velocity fluctuations were dominated by features with wavelengths of 240–370 km, while the ADCP data suggest that the temporal scales of these fluctuations are at least several months. Between 36° and 40.5°N, the region of monthly maximum EKE migrates westward to about 128°W on a seasonal timescale. This region of maximum EKE coincides with the maximum zonal SSH gradient, with increased EKE associated with increased southward flow. A simple model shows that much of the seasonal cycle of the SSH anomalies can be produced by linear processes forced by the curl of the wind stress, although the model cannot explain the offshore movement of the front.

Drifter

Sea-surface height

Geostrophic current

Ocean surface topography

Mooring

Dynamic height

Buoy

10.1029/97jc03760

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Citations (104)

Surface current measurements by HF radar in freshwater lakes

IEEE Journal of Oceanic Engineering (2000)

D.M. Fernandez Lorelle Meadows J.F. Vesecky C.C. Teague Jeffrey D. Paduan

HF radar has become an increasingly important tool for mapping surface currents in the coastal ocean. However, the limited range, due to much higher propagation loss and smaller wave heights (relative to the saltwater ocean), has discouraged HF radar use over fresh water, Nevertheless, the potential usefulness of HF radar in measuring circulation patterns in freshwater lakes has stimulated pilot experiments to explore HF radar capabilities over fresh water. The Episodic Events Great Lakes Experiment (EEGLE), which studied the impact of intermittent strong wind events on the resuspension of pollutants from lake-bottom sediments, provided an excellent venue for a pilot experiment. A Multifrequency Coastal HF Radar (MCR) was deployed for 10 days at two sites on the shore of Lake Michigan near St. Joseph, MI. Similarly, a single-frequency CODAR SeaSonde instrument was deployed on the California shore of Lake Tahoe. These two experiments showed that when sufficiently strong surface winds (2 about 7 m/s) exist for an hour or more, a single HE radar can be effective in measuring the radial component of surface currents out to ranges of 10-15 km. We also show the effectiveness of using HF radar in concert with acoustic Doppler current profilers (ADCPs) for measuring a radial component of the current profile to depths as shallow as 50 cm and thus potentially extending the vertical coverage of an ADCP array.

Wave radar

10.1109/48.895353

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Citations (19)

Observations of upwelling and relaxation events in the northern Monterey Bay during August 2000

Journal of Geophysical Research Atmospheres (2005)

Steven R. Ramp Jeffrey D. Paduan Igor Shulman John C. Kindle Frederick L. Bahr

The interplay between the Point Año Nuevo upwelling center, an offshore anticyclonic mesoscale eddy, and the waters of the Monterey Bay was studied during a series of up‐ and downwelling favorable wind events during August 2000. The upwelling events were characterized by the appearance of cold, salty water at Point Año Nuevo at the north end of the bay that subsequently spread southward across the mouth of the bay as the winds continued. During the downwelling/relaxation events, the surface current and temperature response was dominated by the onshore translation of the offshore eddy and by local surface heating in the bay itself. The circulation within the bay was cyclonic during both wind regimes but slightly more barotropic under poleward forcing. The ICON model, a nested, data assimilating, sigma coordinate model, was used to simulate the upwelling and relaxation events and calculate the subsurface current and density fields. The model reproduced the dominant current and temperature patterns outside the bay, including the southward flowing upwelling filament, the movement of the offshore eddy, the poleward flow off Point Sur, and the circulation within the bay. The model salinity fields at the surface and 100 m levels show that during upwelling, the bay was filled with higher‐salinity water stemming from the Point Año Nuevo upwelling center to the north. During downwelling, the source water for both the surface and 100 m levels was the colder, fresher California Current water offshore, which had advected southward well past Point Piños during the previous upwelling event.

Downwelling

Temperature salinity diagrams

Anticyclone

Wind Stress

10.1029/2004jc002538

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Citations (57)

Modeling and Observations of Surface Waves in Monterey Bay

Le Ngoc Ly Jeffrey D. Paduan

Abstract : The long-range goals of this project are to develop an improved turbulence closure model that takes explicit account of surface wave effects and to quantify the effect of Stokes drift on the surface current signature of High Frequency (HF) radar systems. The objectives of this project are to: 1) deploy a surface buoy with turbulent flux and surface wave measurement capabilities within the footprint of the HF radar network in Monterey Bay and 2) formulate a new turbulence closure scheme based on surface wave dynamics that can be evaluated using data from the flux buoy. This project is extending the measurement and modeling efforts already underway in the Monterey Bay region to include the direct measurement and modeling of surface waves. It is combining three efforts to assemble a better surface flux parameterization: 1) the Ly et al. wave modeling, 2) the Davidson et al. meteorological flux observations, and 3) the NOPP/ICON coastal modeling.

10.21236/ada609832

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High-frequency radar simulations

D.M. Fernandez Kenneth Laws Jeffrey D. Paduan

A simulation of the University of Michigan's Multifrequency Coastal Radar (MCR) has been applied under various scenarios to compare the performance of beam forming and direction finding techniques for bearing determination. The MCR system is a phased array radar that operates at four distinct frequencies in the high frequency (HF) range in order to measure ocean surface currents at several depths. These simulations indicate a decrease in performance of the system using either algorithm for lower frequencies. The simulations also demonstrate an empirical means of generating improved estimates based on the MUSIC algorithm, and indicate advantages of applying the MUSIC algorithm in regions of large horizontal divergence.

Divergence (linguistics)

3D radar

10.1109/ccm.1999.755205

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Citations (1)

Aerial Surveys of the Ocean and Atmosphere off Central California

Steven R. Ramp Jeffrey D. Paduan Curtis A. Collins Wendell A. Nuss

Abstract : The long-term goal is to enhance our understanding of air/sea interaction in the littoral zone by means of applying simple dynamical theories to high-quality observations obtained in the field. The Monterey Bay serves as our natural laboratory for these purposes. The grant is one of a continuing series of programs to study the bay funded by the National Ocean Partnership Program (NOPP) and the ONR Naval Ocean Modeling and Prediction (NOMP) Program.

10.21236/ada626593

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GLOBEC Mapping the Evolution of Mesoscale Jets and Eddies in the Upwelling Ecosystem off Cape Blanco, Oregon, using Long-Range High-Frequency Radar

Jeffrey D. Paduan P. Michael Kosro

Cape

Eddy

Source

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Inertial oscillations in the upper ocean during the Mixed Layer Dynamics Experiment (MILDEX)

Journal of Geophysical Research Atmospheres (1989)

Jeffrey D. Paduan Roland A. de Szoeke Robert A. Weller

Surface currents in the near‐inertial frequency band were analyzed from 18‐day‐long measurements taken in October/November 1983 as part of the Mixed Layer Dynamics Experiment. The currents below two drifting platforms separated by 55 km were found to have differed in their inertial response to a frontal passage on November 1 by 10 cm s −1 . Wind records from the two platforms were used to compute the predicted inertial currents with a simple slab model of the wind‐driven flow. The model currents reproduced most of the features of the observed inertial currents, including the disparity between the two locations following the November 1 frontal passage. The disparity was due to differences in the weak winds preceding the frontal passage which account for inertial currents of ∼5 cm s −1 in opposing directions at the two platforms at the time of the front. These differences, or small‐scale (∼50 km) structure in the wind field, were responsible for the disparity rather than the slight difference in the arrival time (∼2 hours) of the front at the two locations.

Inertial wave

Slab

Mixed layer

Dynamics

10.1029/jc094ic04p04835

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Citations (21)