COSA Committee Meeting June 22, 2017 Jennifer Draher Oceanographer Office of Renewable Energy Programs jennifer.draher@boem.gov

Hydrodynamic Modeling and Particle Tracking in the U. S Hydrodynamic Modeling and Particle Tracking in the U.S. Mid-Atlantic Bight BOEM Information Need: To understand the impact of offshore wind construction projects on regional physical and biological oceanographic processes Date Information is Required: FY 2018

Background Relationship with Previous Work/Efforts: Use of Finite-Volume Modeling and the Northeast Coastal Ocean Forecast System for OSW Planning Relationship with Concurrent/Future Efforts: None. The previous study focused on acute storm events to model oceanographic changes from the installations of an offshore wind farm in southern New England. This follow-on study would build on that by looking at more normal oceanographic conditions and adding a wind wake model and further refining the particle tracking aspects of the previous study.

Study Objectives Model the cumulative and site specific regional and local hydrodynamic changes as a result of offshore wind construction processes. Determine how hydrodynamic changes may impact the transport of juvenile fish and larvae and the susceptibility of sediment resuspension.

Methods Use of 3 models: Wind wake Ocean circulation Particle tracking Estimate surface wind velocities to account for changes in air flow due to wind facility operations Ocean circulation High resolution capable of resolving small-scale physical processes throughout the water column Particle tracking Individual based model for tracking larvae at different life phases or suspended sediment particles Careful model selection may allow for more than one aspect to be addressed by a single model (many have both circulation and particle tracking capabilities). Unstructured or nested grids allow for finer scale resolution in areas of importance, such as within the turbine field.

Methods Models should: Account for changes within the marine surface boundary layer and the benthic boundary layer Assess changes in wind and current speed and direction and their impact on vertical mixing Be ground in empirical evidence such as current profiles, bathymetry, and surficial sediment Be capable of modeling the build-out of several offshore wind projects throughout the Mid-Atlantic Bight Changes within the benthic layer should include sediment suspension and deposition. It is not anticipated that additional empirical data will need to be collected.

Relationship to Strategic Science Questions Assess cumulative effects, effect of habitat or landscape alteration, future ocean conditions and dynamics. How BOEM can better use existing or emerging technology, long term monitoring.