Spectral characteristics of turbulence in the hurricane boundary layer over the ocean between the outer rain bands

Zhang, Jun A.

doi:10.1002/qj.610

Cited by 31 publications

(27 citation statements)

References 52 publications

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“…Compared to the Kaimal and von Kármán curves, the frequency of peak power in the S10 power-spectral-density curves is also shifted to higher frequencies for all three storm examples, in agreement with Zhang (2010a). The normalized frequency of the peak powerspectral-density curve for all storm examples (blue lines in Fig.…”

Section: Comparison Of Les-derived Power Spectral Density To Establissupporting

confidence: 80%

“…The sample time series comprises approximately 6 min of velocity observations ( Fig. 3) collected during the Coupled Boundary Layer Air-Sea Transfer (CBLAST) -Hurricane experiment (Black et al 2007;Zhang et al 2009;Zhang 2010a). The length of this dataset is one-of-a-kind, because the other CBLAST measurements were taken for a duration of 3 min or less.…”

Section: Observationsmentioning

confidence: 99%

“…Investigations of turbulent spectra in the HBL (Yu et al 2008;Zhang 2010a;Zhang et al 2010;Li et al 2015) have relied on observations from less intense hurricanes (undergoing landfall), without an emphasis on turbine loads. Zhang (2010a) compared normalized spectra and cospectra of wind velocity, temperature, and humidity fluctuations to theoretical spectral curves over the land and ocean based on Monin-Obukhov similarity theory.…”

Section: Introductionmentioning

confidence: 99%

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Using Large-Eddy Simulations to Define Spectral and Coherence Characteristics of the Hurricane Boundary Layer for Wind-Energy Applications

Worsnop

Bryan

Lundquist

et al. 2017

Boundary-Layer Meteorol

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Offshore wind-energy development is planned for regions where hurricanes commonly occur, such as the USA Atlantic Coast. Even the most robust wind-turbine design (IEC Class I) may be unable to withstand a Category-2 hurricane (hub-height wind speeds >50 m s −1 ). Characteristics of the hurricane boundary layer that affect the structural integrity of turbines, especially in major hurricanes, are poorly understood, primarily due to a lack of adequate observations that span typical turbine heights (<200 m above sea level). To provide these data, we use large-eddy simulations to produce wind profiles of an idealized Category-5 hurricane at high spatial (10 m) and temporal (0.1 s) resolution. By comparison with unique flight-level observations from a field project, we find that a relatively simple configuration of the Cloud Model I model accurately represents the properties of Hurricane Isabel (2003) in terms of mean wind speeds, wind-speed variances, and power spectra. Comparisons of power spectra and coherence curves derived from our hurricane simulations to those used in current turbine design standards suggest that adjustments to these standards may be needed to capture characteristics of turbulence seen within the simulated hurricane boundary layer. To enable improved design standards for wind turbines to withstand hurricanes, we suggest modifications to account for shifts in peak power to higher frequencies and greater spectral coherence at large separations.

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Section: Comparison Of Les-derived Power Spectral Density To Establissupporting

confidence: 80%

Section: Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Using Large-Eddy Simulations to Define Spectral and Coherence Characteristics of the Hurricane Boundary Layer for Wind-Energy Applications

Worsnop

Bryan

Lundquist

et al. 2017

Boundary-Layer Meteorol

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“…However, since then, many studies have shown that the structure of turbulent boundary layers at high wind speeds can be very different from the standard von Karman spectrum, especially in the large wavenumber range; the peak of the normalized spectrum nS u (z, n)/σ 2 u either shifted to a low frequency or a high frequency range (e.g. Kaimal and Finnigan 1994;Högström et al 2002;Schroeder and Smith 2003;Caracoglia and Jones 2009;Zhang 2010). The variance of wind fluctuations in tropical cyclones also exceeds those observed in extratropical storm boundary-layer flows that are largely shear driven near the surface.…”

Section: Introductionmentioning

confidence: 98%

Turbulence Spectra for Boundary-Layer Winds in Tropical Cyclones: A Conceptual Framework and Field Measurements at Coastlines

Kareem

Hunt

et al. 2014

Boundary-Layer Meteorol

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A conceptual model is proposed for the characteristic sub-ranges in the velocity and temperature spectra in the boundary layer of tropical cyclones (hurricanes or typhoons). The model is based on observations and computation of radial and vertical profiles of the mean flow and turbulence, and on the interpretation of eddy mechanisms determined by shear (namely roll and streak structures near the surface), convection, rotation, blocking and sheltering effects at the ground/sea surface and in internal shear layers. The significant subranges, as the frequency increases, are associated with larger energy containing eddies, shear and blocking, inertial transfer between large and small scales, and intense small-scale eddies generated near the surface caused by waves, coastal roughness change, and the buoyancy force associated with the evaporation of spray droplets. These sub-ranges vary with the locations at which the spectra are measured, i.e. the level z in relation to the height z max of the peak mean velocity and the depth h of the boundary layer, and the radius r in relation to the eyewall radius R ew and the outer-vortex radius R ov . For two tropical cyclones (Nuri and Hagupit), experimental data were analyzed. Spectra were measured where r is near to R ew and R ov using four 1-h long datasets at coastal towers, at 10-and 60-m heights for tropical cyclone Nuri, and at 60-m height for tropical cyclone Hagupit at the south China coast. The field measurements of spectra within the boundary layer show significant sub-ranges of self-similar energy spectra (lying between the length scale 1,000 m and the smallest scales less than 40 m) that are consistent with the above conceptual model of the surface layer. However, with very high wind speeds near the eyewall, the energy of the independently 123 L. Li et al. generated intense surface eddy motions, associated with surface waves and water droplets in the airflow, greatly exceeds the energies of the small scales in the inertial sub-range of the boundary layer, over scales less than about 3-40 m depending on the height z and the radius r . This rise in the small-scale frequency weighted spectra (nS u (n), where n is natural frequency, and S u (n) is the energy spectrum of the longitudinal wind component) is consistent with the hypothesis that these processes are only weakly correlated with the main boundary-layer turbulence.

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“…A majority of these measurements found that tropical wind spectra matched von Karman spectrum (Karman, 1948). However, some measured results noted that the energy distribution did not exactly follow the empirical spectra and the frequency associated with the peak value of the normalized spectrum nS u (z,n)/s u 2 either shifted to a low frequency or a high frequency range (Schroeder and Smith, 2003;Yu et al, 2008;Caracoglia and Jones, 2009;Zhang, 2010). The variance of fluctuations in tropical cyclones also exceeds those observed in extratropical storm boundary layer flows modeled in terms of the surface shear wind speeds.…”

Section: Introductionmentioning

confidence: 87%

Modeling typhoon wind power spectra near sea surface based on measurements in the South China sea

Xiao

Kareem

et al. 2012

Journal of Wind Engineering and Industrial Aerodynamics

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Spectral characteristics of turbulence in the hurricane boundary layer over the ocean between the outer rain bands

Cited by 31 publications

References 52 publications

Using Large-Eddy Simulations to Define Spectral and Coherence Characteristics of the Hurricane Boundary Layer for Wind-Energy Applications

Using Large-Eddy Simulations to Define Spectral and Coherence Characteristics of the Hurricane Boundary Layer for Wind-Energy Applications

Turbulence Spectra for Boundary-Layer Winds in Tropical Cyclones: A Conceptual Framework and Field Measurements at Coastlines

Modeling typhoon wind power spectra near sea surface based on measurements in the South China sea

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