Measurements of Overwater Gust Factor from Near Surface to Beyond Common Hub Height: A Case Study

In September 2020 Hurricane Sally affected the north central Gulf of Mexico. Making use of the anemometers data available at 4 oil rigs over the affected region, it is found that, when the atmospheric stability was near-neutral, the gust factor (G) decreases linearly with height from approximately 1.28 at 35m above the sea surface to 1.18 at 160 m. In other words, G decreases linearly at the rate around 8% per 100 m from the typical hub height to beyond common hub height. Based on the linear equation found in this study, the G extrapolated to the standard height of 10 m is approximately 1.3 which is also consistent with that measured at two buoys over the affected region. Therefore, a G of 1.3 at near surface may be useful for offshore wind energy R&D and O&M, particularly for those regions affected by tropical cyclones.

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SEA-SURFACE TEMPERATURE SUMMARY FOR THE NORTH CENTRAL GULF OF MEXICO, 1912–33

Monthly Weather Review ◽

10.1175/1520-0493(1935)63<174b:stsftn>2.0.co;2 ◽

1935 ◽

Vol 63 (5) ◽

pp. 174-174

Author(s):

GILES SLOCUM

Keyword(s):

Gulf Of Mexico ◽

Surface Temperature ◽

Sea Surface Temperature ◽

Sea Surface ◽

North Central ◽

The North

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Field Measurements of Surface and Near-Surface Turbulence in the Presence of Breaking Waves

Journal of Physical Oceanography ◽

10.1175/jpo-d-14-0133.1 ◽

2015 ◽

Vol 45 (4) ◽

pp. 943-965 ◽

Cited By ~ 62

Author(s):

Peter Sutherland ◽

W. Kendall Melville

Keyword(s):

Field Experiments ◽

North Pacific Ocean ◽

Large Fraction ◽

Field Measurements ◽

Breaking Waves ◽

Sea Surface ◽

Near Surface ◽

Wave Energy Dissipation ◽

Eddy Simulation ◽

The North

AbstractWave breaking removes energy from the surface wave field and injects it into the upper ocean, where it is dissipated by viscosity. This paper presents an investigation of turbulent kinetic energy (TKE) dissipation beneath breaking waves. Wind, wave, and turbulence data were collected in the North Pacific Ocean aboard R/P FLIP, during the ONR-sponsored High Resolution Air-Sea Interaction (HiRes) and Radiance in a Dynamic Ocean (RaDyO) experiments. A new method for measuring TKE dissipation at the sea surface was combined with subsurface measurements to allow estimation of TKE dissipation over the entire wave-affected surface layer. Near the surface, dissipation decayed with depth as z−1, and below approximately one significant wave height, it decayed more quickly, approaching z−2. High levels of TKE dissipation very near the sea surface were consistent with the large fraction of wave energy dissipation attributed to non-air-entraining microbreakers. Comparison of measured profiles with large-eddy simulation results in the literature suggests that dissipation is concentrated closer to the surface than previously expected, largely because the simulations did not resolve microbreaking. Total integrated dissipation in the water column agreed well with dissipation by breaking for young waves, (where cm is the mean wave frequency and is the atmospheric friction velocity), implying that breaking was the dominant source of turbulence in those conditions. The results of these extensive measurements of near-surface dissipation over three field experiments are discussed in the context of observations and ocean boundary layer modeling efforts by other groups.

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