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• 11. [Article] Offshore wind forcing in the Gulf of Tehuantepec, Mexico: the asymmetric circulation

  Since the early surveys carried out by the Eastern Tropical Pacific (EASTROPIC) and Scripps Tuna Oceanographic Research (STOR) projects in the tropical Pacific off Mexico, the northerly winds which blow ...

  Citation × Citation Citation Abstract Copy Title: Offshore wind forcing in the Gulf of Tehuantepec, Mexico: the asymmetric circulation Author: Velez, H.S., Kosro, P. Michael, 1951-, Brown, J., Smith, Robert L. (Robert Lloyd), 1935-, Barton, E.D., Trasvina, A. Since the early surveys carried out by the Eastern Tropical Pacific (EASTROPIC) and Scripps Tuna Oceanographic Research (STOR) projects in the tropical Pacific off Mexico, the northerly winds which blow over the Gulf of Tehuantepec were described as an Important factor controlling the dynamics of this coastal ocean. In January-February 1989 an international team carried out the experiment Tehuano, designed to study the response of the gulf to these wind pulses. The complete evolution of the coastal ocean after an event of moderate intensity was observed. The forcing is characterized by a mostly symmetric, fanshaped, offshore wind jet, which in turn produces a remarkably asymmetric upper ocean response. While analytical results based on Ekman theory forced by a symmetric offshore wind predict the formation of a symmetric dipolar circulation, the observed flow consists mainly of a large (200 km in diameter) anticyclonic warm-core eddy in the western gulf, with only a weak cyclonic counterpart in the eastern gulf. Intense surface cooling under the wind jet is caused by entrainment of subsurface water into the upper layer. The thermocline in the west deepens with the development of the eddy, which is formed initially by the advection of warm surface waters from west of the gulf. East of the axis of the wind, the mixed layer deepens due to wind-induced entrainment, while, at the same time, shoaling and compression of the deeper isotherms by curl-induced upwelling (Ekman pumping) strengthen the thermocline. Title: Offshore wind forcing in the Gulf of Tehuantepec, Mexico: the asymmetric circulation Author: Velez, H.S., Kosro, P. Michael, 1951-, Brown, J., Smith, Robert L. (Robert Lloyd), 1935-, Barton, E.D., Trasvina, A. Since the early surveys carried out by the Eastern Tropical Pacific (EASTROPIC) and Scripps Tuna Oceanographic Research (STOR) projects in the tropical Pacific off Mexico, the northerly winds which blow over the Gulf of Tehuantepec were described as an Important factor controlling the dynamics of this coastal ocean. In January-February 1989 an international team carried out the experiment Tehuano, designed to study the response of the gulf to these wind pulses. The complete evolution of the coastal ocean after an event of moderate intensity was observed. The forcing is characterized by a mostly symmetric, fanshaped, offshore wind jet, which in turn produces a remarkably asymmetric upper ocean response. While analytical results based on Ekman theory forced by a symmetric offshore wind predict the formation of a symmetric dipolar circulation, the observed flow consists mainly of a large (200 km in diameter) anticyclonic warm-core eddy in the western gulf, with only a weak cyclonic counterpart in the eastern gulf. Intense surface cooling under the wind jet is caused by entrainment of subsurface water into the upper layer. The thermocline in the west deepens with the development of the eddy, which is formed initially by the advection of warm surface waters from west of the gulf. East of the axis of the wind, the mixed layer deepens due to wind-induced entrainment, while, at the same time, shoaling and compression of the deeper isotherms by curl-induced upwelling (Ekman pumping) strengthen the thermocline. Close

• 12. [Article] Tidal currents on the central Oregon shelf : models, data, and assimilation

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Tidal currents on the central Oregon shelf : models, data, and assimilation Author: Kosro, P. Michael, 1951-, Erofeeva, Svetlana Y., Egbert, Gary D. copyrighted by American Geophysical Union Title: Tidal currents on the central Oregon shelf : models, data, and assimilation Author: Kosro, P. Michael, 1951-, Erofeeva, Svetlana Y., Egbert, Gary D. copyrighted by American Geophysical Union Close

• 13. [Article] On the spatial structure of coastal circulation off Newport, Oregon, during spring and summer 2001 in a region of varying shelf width

  A time series of hourly surface current maps in the shelf waters off Newport, Oregon, was made during April–September 2001 using five SeaSonde HF current mappers, during Coastal Advances in Shelf Transport ...

  Citation × Citation Citation Abstract Copy Title: On the spatial structure of coastal circulation off Newport, Oregon, during spring and summer 2001 in a region of varying shelf width Author: Kosro, P. Michael, 1951- A time series of hourly surface current maps in the shelf waters off Newport, Oregon, was made during April–September 2001 using five SeaSonde HF current mappers, during Coastal Advances in Shelf Transport (COAST). The surface currents responded rapidly to the changing winds, in repeated patterns that were strongly affected by bottom topography. An equatorward current jet repeatedly formed in response to upwelling winds, its strength, but not its trajectory, covarying with the meridional wind stress. Near Cape Foulweather (44.8°N), where the shelf begins to widen, the jet rotates, weakens, and trends offshore to the south first along, then across, the isobaths. Below Cape Foulweather, inshore of the jet, a lee region of generally weak currents was commonly observed. The equatorward jet core was most commonly observed near the 80-m isobath between 45.0°N and 44.4°N, but transited offshore between spring and summer over Heceta Bank. At Newport (44.6°N), it was rarely observed less than 8 km from the coast. A second, inshore, equatorward jet, previously unknown, was observed repeatedly south of Waldport (44.4°N). Sustained downwelling wind episodes produced poleward currents, though less responsively north of Cape Foulweather. Strongest poleward flow was generally trapped near the coast. Surface currents were correlated with the northward wind, except regionally far from shore over Heceta Bank, responding within half a day. Response to the wind varies spatially, being intensified in the narrow shelf (northern) region. The equatorward jet persists through periods of zero wind forcing. Coastal sea level covaries with the meridional wind and the primary mode of ocean current response. Title: On the spatial structure of coastal circulation off Newport, Oregon, during spring and summer 2001 in a region of varying shelf width Author: Kosro, P. Michael, 1951- A time series of hourly surface current maps in the shelf waters off Newport, Oregon, was made during April–September 2001 using five SeaSonde HF current mappers, during Coastal Advances in Shelf Transport (COAST). The surface currents responded rapidly to the changing winds, in repeated patterns that were strongly affected by bottom topography. An equatorward current jet repeatedly formed in response to upwelling winds, its strength, but not its trajectory, covarying with the meridional wind stress. Near Cape Foulweather (44.8°N), where the shelf begins to widen, the jet rotates, weakens, and trends offshore to the south first along, then across, the isobaths. Below Cape Foulweather, inshore of the jet, a lee region of generally weak currents was commonly observed. The equatorward jet core was most commonly observed near the 80-m isobath between 45.0°N and 44.4°N, but transited offshore between spring and summer over Heceta Bank. At Newport (44.6°N), it was rarely observed less than 8 km from the coast. A second, inshore, equatorward jet, previously unknown, was observed repeatedly south of Waldport (44.4°N). Sustained downwelling wind episodes produced poleward currents, though less responsively north of Cape Foulweather. Strongest poleward flow was generally trapped near the coast. Surface currents were correlated with the northward wind, except regionally far from shore over Heceta Bank, responding within half a day. Response to the wind varies spatially, being intensified in the narrow shelf (northern) region. The equatorward jet persists through periods of zero wind forcing. Coastal sea level covaries with the meridional wind and the primary mode of ocean current response. Close