Austin Jay A.

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Austin
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Jay A.
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  • Technical Report
    Coastal ocean processes inner-shelf study : coastal and moored physical oceanographic measurements
    (Woods Hole Oceanographic Institution, 1996-05) Alessi, Carol A. ; Lentz, Steven J. ; Austin, Jay A.
    To improve our understanding of the physical and biological processes influencing plantonic larval distributions over the inner shelf, an interdisciplinary field program funded by the National Science Foundation's Coastal Ocean Processes program (CoOP) was conducted near Duck, North Carolina in the southern porton of the Middle Atlantic Bight. The field program took place from August to December, 1994 and included both moored and shipboard measurements of physical, biological and sedimentological variables. This report summarizes the observations from one component of this field program, a moored array of physical oceanographic and meteorological instruments. This component of the field program consisted of a cross-shelf array of three surface/subsurface mooring pairs in 13 m, 20 m and 25 m of water supporting instruments to measure currents, temperature and conductivity, a suite of meteorological instruments on surface buoys at the 20 -m and 25 -m site, and an along-shelf array of temperature, conductivity and bottom pressure sensors mounted on jetted pipes along the 5-m isobath and on moorings along the 20-m isobath. The report includes descriptions of the cross-shelf and along-shelf arrays, the four types of instruments used (VAWRs, VMCMs, SeaCats, and SeaGauges), and the data return from the field program. Statistical and graphical summaries of the atmospheric (wind, air temperature, barometric pressure, relative humidity, short- and long-wave radiation), and oceanic (current, water temperature, conductivity and bottom pressure) measurements are presented.
  • Thesis
    Wind-driven circulation on a shallow, stratified shelf
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1998-08) Austin, Jay A.
    Data from the Coastal Ocean Processes Inner Shelf Study are analyzed to determine atmospheric forcing characteristics and the heat balance of the inner shelf, and are used as motivation for a numerical study of inner shelf circulation during upwelling and downwelling. Variation in meteorological forcing on the North Carolina Inner shelf is shown to be dominated by synoptic weather systems. The structure of cold fronts, which are the dominant synoptic feature, and the local meteorological conditions they produce result in a strong correlation between the surface heat flux and the wind orientation. This has implications for the heat balance of the inner shelf, which is considered next. During stratified conditions (observed during August 1994), cross-shelf heat fluxes due to Ekman dynamics dominate variation in heat content of the inner shelf, while during weakly-stratified conditions (observed during October 1994), the surface heat flux dominated variation in heat content. Both processes are correlated with the alongshelf wind, implying that the heat balance of the inner shelf can be modeled largely in terms of the alongshelf wind. The dominance of cross-shelf processes during stratified conditions motivated numerical studies of upwelling and downwelling. It was found that the feedback between mixing and stratification played a role in determining the strength of the circulation on the inner shelf, which differed between upwelling and downwelling. During upwelling, dense water is brought onto the inner shelf from below the pycnocline, producing vertical stratification, lowering eddy viscosities, and enhancing the inner shelf circulation. In contrast, during downwelling, circulation was weakened by the presence of stratification. These circulation patterns are discussed in the context of coastal observations, and the implications for cross-shelf transport and exchange processes are considered.