HR: 1330h
AN: OS32B-0244    [PDF]
TI: Impact of Stratification on Summer Hypoxia in Narragansett Bay, RI: Time-Series Observations and Numerical Modeling
AU: * Bergondo, D L
EM: dbergondo@gso.uri.edu
AF: University of Rhode Island Graduate School of Oceanography, South Ferry Road, Narragansett, RI 02882 United States
AU: Kincaid, C R
EM: ckincaid@gso.uri.edu
AF: University of Rhode Island Graduate School of Oceanography, South Ferry Road, Narragansett, RI 02882 United States
AU: Kester, D R
AF: University of Rhode Island Graduate School of Oceanography, South Ferry Road, Narragansett, RI 02882 United States
AB: Determining water column structure in a partially-mixed estuary, such as Narragansett Bay, is important for understanding the impact stratification has on phytoplankton productivity and dissolved oxygen concentrations. Stratification reduces vertical mixing and influences the vertical flux of ecologically important variables such as phytoplankton, heat, oxygen, and nutrients. We utilize a combination of buoy data and numerical modeling to better understand processes surrounding the evolution and breakdown in stratification in Narragansett Bay for a range of environmental conditions. Autonomous sensors have been deployed in Narragansett Bay to collect continuous high temporal resolution chemical and hydrographic data. Data were collected every fifteen minutes 0.5 m below the surface and 1 m from the bottom from July 2001 to December 2001 and from July 2002 to December 2002 at two locations in Narragansett Bay and the Providence River, RI. The suite of water column variables measured were surface and bottom temperature, salinity, dissolved oxygen and pH, and surface chlorophyll. Results show that stratification events occur intermittently in the Providence River and Narragansett Bay and that increased phytoplankton productivity and hypoxia were associated with summertime stratification events. The Regional Ocean Modeling System (ROMS) model, a three-dimensional hydrodynamic model developed by Rutgers University, New Jersey, has been applied to Narragansett Bay to determine how the basic layered flow can be perturbed by runoff events and variable winds. For instance, in the basic stratified flow pattern in Narragansett Bay there is an outward flow of fresher water at the surface and an inward flow of deep denser water within the channel, however, strong south winds shutdown the deep return flow. Time series observations combined with model relationships have been able to enhance the understanding of the development and breakdown of stratification and the impact stratification has on phytoplankton blooms and dissolved oxygen conditions in Narragansett Bay.
DE: 4235 Estuarine processes
DE: 4255 Numerical modeling
DE: 4834 Hypoxic environments
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting