VIMS Events
This calendar presented by
Virginia Institute of Marine Science
[PAST EVENT] Physical controls on hypoxia in Chesapeake Bay
October 21, 2011
3:30pm - 4:30pm
Location
VIMS - Watermen's Hall, McHugh Auditorium1375 Greate Road
Gloucester Point, VA 23062Map this location
"Physical controls on hypoxia in Chesapeake Bay"
Reception at 3:00 p.m. in Watermen's Hall Lobby
Seminar from 3:30 p.m. to 4:30 p.m. in McHugh Auditorium
Presenter: Malcolm Scully, Assistant Professor, Center for Coastal Physical Oceanography, Old Dominion University
Title: "Physical controls on hypoxia in Chesapeake Bay"
Background
Dr. Scully received his B.A. in Environmental Science in 1993 from the University of Virginia and his M.S. and Ph.D. from VIMS, the College of William & Mary. He was a post-doc at Woods Hole Oceanographic Institution, Department of Applied Physics and Engineering, from 2005 to 2008 and has since been at Old Dominion University. His research interests include the dynamics of coastal and estuarine circulation, the interactions between density stratification and turbulence mixing, and how these interactions impact the transport and fate of sediment and biologically relevant constituents.
Abstract
The seasonal depletion of oxygen (hypoxia) is a significant water quality issue in the Chesapeake Bay. Billions of dollars have been spent on nutrient reduction with the goal of decreasing the extent and severity of summer hypoxia. However, assessing the effectiveness of these efforts is often confounded by the complexity and variability of the physical processes that control the distribution of dissolved oxygen in the Bay. In his presentation, Dr. Scully will assess the importance of the variations in physical forcing on modulating dissolved oxygen in the Chesapeake Bay using a 3-D circulation model with a simple formulation for oxygen dynamics. The model uses a depth-dependent oxygen utilization (respiration) that is constant in time and exchanges oxygen with the atmosphere via a surface flux. Despite the simplicity of the approach, this model can accurately simulate the observed seasonal cycle of hypoxia in the Bay. Further, because the biological utilization of oxygen is constant in time, the model effectively isolates the role of physical processes in modulating dissolved oxygen in this system. In model runs, variations in wind speed and direction are the most important physical variables in controlling seasonal hypoxia, with secondary effects attributed to variations in water temperature. The model suggests that the magnitude of river discharge has little impact on the extent and severity of seasonal hypoxia in the Bay. A 15-year model simulation demonstrates some skill, but fails to capture much of the observed inter-annual variability in hypoxic volume. Model residuals are correlated with integrated nitrogen loading, emphasizing the importance of biological processes in controlling the inter-annual variability.
Reception at 3:00 p.m. in Watermen's Hall Lobby
Seminar from 3:30 p.m. to 4:30 p.m. in McHugh Auditorium
Presenter: Malcolm Scully, Assistant Professor, Center for Coastal Physical Oceanography, Old Dominion University
Title: "Physical controls on hypoxia in Chesapeake Bay"
Background
Dr. Scully received his B.A. in Environmental Science in 1993 from the University of Virginia and his M.S. and Ph.D. from VIMS, the College of William & Mary. He was a post-doc at Woods Hole Oceanographic Institution, Department of Applied Physics and Engineering, from 2005 to 2008 and has since been at Old Dominion University. His research interests include the dynamics of coastal and estuarine circulation, the interactions between density stratification and turbulence mixing, and how these interactions impact the transport and fate of sediment and biologically relevant constituents.
Abstract
The seasonal depletion of oxygen (hypoxia) is a significant water quality issue in the Chesapeake Bay. Billions of dollars have been spent on nutrient reduction with the goal of decreasing the extent and severity of summer hypoxia. However, assessing the effectiveness of these efforts is often confounded by the complexity and variability of the physical processes that control the distribution of dissolved oxygen in the Bay. In his presentation, Dr. Scully will assess the importance of the variations in physical forcing on modulating dissolved oxygen in the Chesapeake Bay using a 3-D circulation model with a simple formulation for oxygen dynamics. The model uses a depth-dependent oxygen utilization (respiration) that is constant in time and exchanges oxygen with the atmosphere via a surface flux. Despite the simplicity of the approach, this model can accurately simulate the observed seasonal cycle of hypoxia in the Bay. Further, because the biological utilization of oxygen is constant in time, the model effectively isolates the role of physical processes in modulating dissolved oxygen in this system. In model runs, variations in wind speed and direction are the most important physical variables in controlling seasonal hypoxia, with secondary effects attributed to variations in water temperature. The model suggests that the magnitude of river discharge has little impact on the extent and severity of seasonal hypoxia in the Bay. A 15-year model simulation demonstrates some skill, but fails to capture much of the observed inter-annual variability in hypoxic volume. Model residuals are correlated with integrated nitrogen loading, emphasizing the importance of biological processes in controlling the inter-annual variability.
Contact
[[seitz,Rochelle Seitz]] at 804-684-7698