5:15 PM - 7:15 PM
[MAG32-P03] Land–Sea Contrast of Nearshore Wind and Thermal Conditions at the Mutsu-Ogawara Test Site
Keywords:Offshore Wind Energy, Wind resource assessment, Doppler lidar, Atmospheric stability, Mutsu-Ogawara Offshore Wind Observation Test Site
Abstract:
Understanding the surrounding thermal environment is essential for assessing nearshore wind conditions, which is crucial for offshore wind power development. This study investigates the differences in wind characteristics and atmospheric stability between onshore and offshore environments at the Mutsu-Ogawara Test Site in Aomori, Japan. Year-round wind observations were conducted at two locations: an onshore site (St.L) and an offshore site (St.S, 1.5 km offshore), using fixed and floating vertical wind lidars to measure wind conditions up to approximately 200 m in height.
The results indicate that at a reference height of 120 m, corresponding to typical wind turbine hub heights, the annual mean wind speed at St.S was approximately 6.4% higher than at St.L, demonstrating offshore wind acceleration. A stronger wind speed trend at St.S was observed not only for land-sector winds blowing offshore but also for sea-sector winds blowing from the ocean toward the land. Furthermore, significant differences in vertical wind speed profiles were observed, with land-sector winds accelerating by 19% over 1.5 km offshore at a low height of 63 m. Consequently, the power-law exponent α, representing vertical wind shear, was larger at St.L (α = 0.32) than at St.S (α = 0.19), highlighting the importance of terrain effects on wind formation in nearshore areas.
Atmospheric stability exhibited both diurnal and seasonal variations. At St.L, solar radiation had a strong influence, leading to unstable conditions during the day and stable conditions at night. In contrast, at St.S, diurnal variations were less distinct, and stability was more strongly influenced by seasonal variations in sea surface temperature. This study confirms that wind and thermal conditions differ significantly between land and sea, even over a short 1.5 km distance, emphasizing the importance of on-site offshore wind condition assessments.
Acknowledgements:
This paper is based on results obtained from project JPNP07015 commissioned by the New Energy and Industrial Technology Development Organization (NEDO).
Understanding the surrounding thermal environment is essential for assessing nearshore wind conditions, which is crucial for offshore wind power development. This study investigates the differences in wind characteristics and atmospheric stability between onshore and offshore environments at the Mutsu-Ogawara Test Site in Aomori, Japan. Year-round wind observations were conducted at two locations: an onshore site (St.L) and an offshore site (St.S, 1.5 km offshore), using fixed and floating vertical wind lidars to measure wind conditions up to approximately 200 m in height.
The results indicate that at a reference height of 120 m, corresponding to typical wind turbine hub heights, the annual mean wind speed at St.S was approximately 6.4% higher than at St.L, demonstrating offshore wind acceleration. A stronger wind speed trend at St.S was observed not only for land-sector winds blowing offshore but also for sea-sector winds blowing from the ocean toward the land. Furthermore, significant differences in vertical wind speed profiles were observed, with land-sector winds accelerating by 19% over 1.5 km offshore at a low height of 63 m. Consequently, the power-law exponent α, representing vertical wind shear, was larger at St.L (α = 0.32) than at St.S (α = 0.19), highlighting the importance of terrain effects on wind formation in nearshore areas.
Atmospheric stability exhibited both diurnal and seasonal variations. At St.L, solar radiation had a strong influence, leading to unstable conditions during the day and stable conditions at night. In contrast, at St.S, diurnal variations were less distinct, and stability was more strongly influenced by seasonal variations in sea surface temperature. This study confirms that wind and thermal conditions differ significantly between land and sea, even over a short 1.5 km distance, emphasizing the importance of on-site offshore wind condition assessments.
Acknowledgements:
This paper is based on results obtained from project JPNP07015 commissioned by the New Energy and Industrial Technology Development Organization (NEDO).