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An Assessment of the Physiographical Impacts in the Mid-Atlantic Region on the Marine Boundary Layer Wind Profile

Lynn Sparling, Department of Physics
Edward Strobach, Department of Physics

 

It is well understood that a need for continuously operating profiling instruments is critical for offshore regions. As of yet an observational network of this kind has not been established in the United States. Since offshore wind farm construction is expected within the next few years along the east coast, it becomes more important than ever to examine the spatiotemporal characteristics of the wind profile, and to determine the role that the broader meteorology and nearby physiography has on wind evolution. This is particularly evident when assessing both the wind profile and turbulence generation on power output.

A two-month study during the summer of 2013 provides a unique opportunity to analyze offshore wind in Maryland’s Wind Energy Area (MDWEA). Several case studies have been selected to understand how the physiography, like the Appalachian Mountains and land-sea coastal transitions, as well as large-scale systems, such as frontal boundaries, impacts wind in the marine boundary layer. In order to get a relative assessment of offshore shore v. onshore response, a broader network of instrumentation, which includes several onshore profiling platforms, are used for a spatial context of wind systems moving across the region. In addition, several models are also considered, such as North American Regional Reanalysis (NARR), Weather Research and Forecasting (WRF), and various trajectory models, to observe the timing of wind regimes entering MDWEA as well as to understand the properties of an air parcel as moves from on- to offshore.

Two main case studies are considered: July 19th – July 21st, 2013, and July 27th. The first involves the role of the Appalachian Mountains, with the first day occurring under ‘light synoptic’ conditions, while the second two days occur under ‘strong synoptic’ conditions. The second case study centers around a sea breeze event during the late afternoon. A Doppler LIDAR and radiometer is used to capture the small scale changes, both along the vertical and with turbulent generation, as the new wind regime crosses MDWEA. It is found that each case results in significant changes in the wind profile that would substantially impact power output and possibly turbine integrity.