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Research Interests
Two kinds of oceanographic problems have most motivated my research. One is the interaction between fluid flows and topographic features such as continental margins. The other is how turbulence and stratified dynamics affect the distribution of constituents such as sediment and nutrients. These dynamics can have profound effects on coastal ecosystems, and many of my research projects are interdisciplinary and span the bridge between physical oceanography and biological oceanography and ecology. Most of my work has been observational, however a large part of my Ph.D. research involved theory and laboratory experiments. In graduate school I tended to fall between the physical oceanography and sediment transport communities; now I also find myself bridging coastal oceanography and ecology. My primary research focus has been the idea that intrusions, forced by internal-wave-driven mixing near a sloping boundary, might be manifest as intermediate nepheloid layers (INLs) near continental margins. Because the water in INLs has recently been in contact with the seabed and is thus relatively rich in nutrients, suspended sediment, dissolved organic carbon, silica, and lithogenic minerals such as iron, INL dispersal might also be an important means of cross-margin transport of these constituents. The primary result from the laboratory experiments was a demonstration that the growth of such intrusions is directly related to the energy lost to a net irreversible buoyancy flux near the sloping boundary layer. This work, done in collaboration with Eric Kunze (McPhee-Shaw and Kunze, 2002), also resulted in a predictive relationship between the divergence of energy density flux within an internal wave beam and horizontal intrusion growth rate. This relationship may prove useful in predicting the spreading rate of intermediate nepheloid layers (and resulting sediment flux) from continental slopes and shelves.
I have been involved in field projects examining both internal waves and INLs on the continental slope off northern California (through the STRATAForm project) and Central California (see NSF-funded projects described below), and on margins of lakes (Mono Lake and Lake Tahoe, California). Involvement with the Santa Barbara Coastal Long Term Ecological Research (SBC-LTER) project has led me to investigate the dynamics responsible for nutrient delivery to inner-shelf kelp forests. Cross-margin transport via upwelling or higher-frequency mechanisms such as internal waves and bores, was found to be the primary source of nutrients to SBC kelp, and we are currently investigating the causes for temporal variability in these mechanisms. This study is described in (McPhee-Shaw et al., 2007, Limnology and Oceanography)
Recent and Current Projects.
Benthic Exchange Events and Near-Boundary Mixing on the Continental Shelf.
Funded by the National Science Foundation. Lead PI: Dr. McPhee-Shaw. CoPIs: W. J. Shaw and T. Stanton, US Naval Postgraduate School, and J. Bellingham, Monterey Bay Aquarium Research Institute. The objective of this field program is to investigate the role of surface waves and nonlinear internal waves on forcing events of exchange between the benthos and upper water column on the continental shelf. Field operations start in spring 2011 on the Monterey shelf. Technological goals include development of a microstructure turbulence package (by NPS) on the payload of MBARI's long-ranging autonomous underwater vehicles. Dr. Olivia Cheriton joined our this project as a postdoctoral researcher at MLML in January 2011.
The Role of Canyons and Boundary Mixing and Exchange with the Ocean Interior.
This project is funded by the National Science Foundation, and Dr. McPhee-Shaw's collaborators are Dr. James Girton, from the University of Washington Applied Physics Lab, and Dr. Eric Kunze, from the University of Victoria. This experiment examines transfer of semidiurnal internal wave energy to high wavenumber upon reflection in the Monterey Canyon (~300 to 2000-m depth) and assesses resulting exchange of boundary mixed fluid with interior stratified basins. A motivation is understanding the importance of canyon mixing "hotspots" for net exchange and abyssal mixing at intermediate ocean depths. Field operations were completed in August and October 2008. MLML student Katie Morrice is currently working on an MS thesis examining temporal and along-canyon variability of bottom mixed layer thickness.
Technology Transfer: Monitoring and Maintenance of the MBARI Land-Ocean Biogeochemical Observation. This project, which was funded under the auspices of the Elkhorn Slough National Estuarine Research Reserve, involved a collaboration between MLML and Dr. Ken Johnson's research group at the Monterey Bay Aquarium Institute (MBARI). We worked to transfer the knowledge and skills of running a sophisticated set of water quality moorings from the engineers who built the system (the MBARI group) to a group of new users (the MLML group). During this project we also worked with MBARI to deploy a 20-m deep coastal mooring, which included real-time in-situ measurements of optical nitrate. MLM student Tanya Novak is currently working on an MS thesis examining the supply of terrestrial nutrients from Elkhorn Slough and the Old Salinas River Channel (mostly nitrate and phosphate from agricultural-runoff) to coastal waters.
Please see the webpage of Ken Johnson and the MBARI LOBO group for access to real-time data and a description of the LOBO mooring system.
Central and Northern California Coastal Ocean Observing System (CeNCOOS)
At MLML we are heavily involved in ongoing efforts in Coastal Ocean Observing Systems. We have instruments deployed locally and along the coast through the CSU-observing system CICORE. These instruments monitor weather conditions and water quality, and graduate student Dustin Carroll completed a masters degree using our Carmel Bay mooring to understand circulation, transport rates, and nutrient fluxes in Carmel Bay and along the Central California coast.
Link to Carmel Bay mooring time series: CICORE / Stillwater Cove mooring
Connectivity of West Coast Sanctuaries: Tracking Sooty Shearwaters throughout Upwelling Ecosystems in the California Current System. MLML colleagues James Harvey, Josh Adams, Larry Breaker, and I are completing a CA SeaGrant-funded study examining how the movement of sooty shearwaters relates to oceanographic fronts and divergences in wind and current fields. MLML student Melinda Nakagawa is working on her MS thesis interpreting how tagged sooty shearwater movements around coastal California through Oregon and Washington are related to varying patterns in wind fields along the coast.
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Publications:
McPhee-Shaw, E., T. Maurer, and K. Johnson. The ocean response to fertilizer nitrate pollution during a “first-flush” runoff event on the Central California Coast. Manuscript in preparation.
Kunze, E., C. MacKay, E. McPhee-Shaw, K. Morrice, J. Girton, and S. Terker. 2012. On the efficiency of mixing in bottom boundary layers over sloping topography. Journal of Physical Oceanography, DOI:10.1175/JPO-D-11-075.1. In press.
Booth*, J.A.T, E.E. McPhee-Shaw, P. Chua, E. Kingsley, M. Denny, R. Phillips, S. J. Bograd, L. D. Zeidberg, W. F.Gilly, 2012. Natural intrusions of hypoxic, low pH water into nearshore marine environments on the California coast (Submitted to Continental Shelf Research) *graduate student first author
Cazenave*, F., Y. Zhang, E. McPhee-Shaw, J. Bellingham, and T. Stanton, 2011. High-resolution surveys of internal tidal waves in Monterey Bay, California, using an autonomous underwater vehicle. Limnology and Oceanography: Methods, 9, 2011, 571-581*graduate student first author
Oliver, J.S., K.K Hammerstrom, E. E. McPhee-Shaw, P. N. Slattery, J. M. Oakden, S. L. Kim, S. I. Hartwell, 2011. High species density patterns in macrofaunal invertebrate communities in the marine benthos. (Marine Ecology, DOI: 10.1111/j.1439-0485.2011.00461.x)
McPhee-Shaw, E. E. K. J. Nielsen, J. L. Largier, and B. A. Menge, 2011. Nearshore chlorophyll-a events and wave-driven transport. Geophysical Research Letters, 38, doi:10.1029/2010GL045810. (pdf)
Gough, M., N. Garfield, and E. McPhee-Shaw, 2010. An analysis of HF-radar measured surface currents to determine tidal, wind-forced and seasonal circulation in the Gulf of the Farallones, California, United States. Journal of Geophysical Research, 115, C04019, doi:10.1029/2009JC005644.
Cudaback, C. and E. McPhee-Shaw. 2009. Diurnal period internal waves near Point Conception, California. Estuarine, Coastal, and Shelf Sciences, 83, 349-359.
McPhee-Shaw, E.E., D. Siegel, L. Washburn, M. Brzezinski, J. Jones, A. Leydecker, and J. Melack 2007 ‘Mechanisms for nutrient delivery to the inner shelf: observations from the Santa Barbara Channel’ Limnology and Oceanography, 52(5), 1748-1766. (pdf)
McPhee-Shaw, E. E., 2006. ‘Boundary- Interior Interactions: Reviewing the idea that internal-wave mixing enhances lateral dispersion near continental margins.’ Deep-Sea Research II, 53, 42-59.(pdf)
Bassin, C. J., L. Washburn, M. Brzezinski, and E. McPhee-Shaw, 2005, Sub-mesoscale coastal eddies observed by high frequency radar: a new mechanism for delivering nutrients to kelp forests in the Southern California Bight. Geophysical Research Letters, 32, L12604 doi:10.1029/2005GL023017.
McPhee-Shaw, E. E., R.W. Sternberg, B. Mullenbach, and A. S. Ogston, 2004, ‘Observations of intermediate nepheloid layers on the northern California margin.’ Continental Shelf Research. 24, 693-720.
McPhee-Shaw, E. E. and E. Kunze, 2002, ‘Boundary-layer intrusions from a sloping bottom: A mechanism for generating intermediate nepheloid layers.’ Journal of Geophysical Research. 10.1029/2001JC000801. (pdf)
McPhee, E. E., A. R. M. Nowell, and R. W. Sternberg, 1998, ‘Boundary layer measurements and their implications for sediment transport on the Eastern Norwegian Sea Continental Slope.’ Deep-Sea Research I, 45, 719-743.
Manuscripts in revision
Cheriton, O., M. A. McManus, E. McPhee-Shaw, J. Sevadjian, and D. Carroll. 2011, Insights into the hydrography of a coastal embayment from a decade of observational data (in revision)
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