Mean gust factors in complex terrain

Ágústsson, Hálfdán; Ólafsson, Haraldur

doi:10.1127/0941-2948/2004/0013-0149

Cited by 37 publications

(28 citation statements)

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“…For the 2661 gust observations in this study, the mode and median GF 5 1.5 and the mean 5 1.57 (Fig. Prognostic gust forecasting, although of high potential utility, is extremely challenging (Thorarinsdottir and Johnson 2012), in part because the relationship between GF and U is highly nonlinear and is a function of measurement height (Agustsson and Olafsson 2004;Cheng et al 2012;Krayer and Marshall 1992;Paulsen and Schroeder 2005). Although differences in averaging period confound detailed comparisons with prior studies, these values are in reasonable accord with previous estimates of GF for extratropical cyclones (Table 1) and corroborate research that has suggested that GF from extratropical cyclones may exceed those from tropical systems (Paulsen and Schroeder 2005).…”

Section: B Resultsmentioning

confidence: 88%

Intense and Extreme Wind Speeds Observed by Anemometer and Seismic Networks: An Eastern U.S. Case Study

Pryor

Conrick

Miller

et al. 2014

Journal of Applied Meteorology and Climatology

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The scale and intensity of extreme wind events have tremendous relevance to determining the impact on infrastructure and natural and managed ecosystems. Analyses presented herein show the following. 1) Wind speeds in excess of the station-specific 95th percentile are coherent over distances of up to 1000 km over the eastern United States, which implies that the drivers of high wind speeds are manifest at the synoptic scale. 2) Although cold fronts associated with extratropical cyclones are a major cause of high-wind speed events, maximum sustained and gust wind speeds are only weakly dependent on the near-surface horizontal temperature gradient across the front. 3) Gust factors (GF) over the eastern United States have a mean value of 1.57 and conform to a lognormal probability distribution, and the relationship between maximum observed GF and sustained wind speed conforms to a power law with coefficients of 5.91 and 20.499. Even though there is coherence in the occurrence of intense wind speeds at the synoptic scale, the intensity and spatial extent of extreme wind events are not fully characterized even by the dense meteorological networks deployed by the National Weather Service. Seismic data from the USArray, a program within the Earthscope initiative, may be suitable for use in mapping high-wind and gust events, however. It is shown that the seismic channels exhibit well-defined spectral signatures under conditions of high wind, with a variance peak at frequencies of ;0.04 s 21 and an amplitude that appears to scale with the magnitude of observed wind gusts.

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Section: B Resultsmentioning

confidence: 88%

Intense and Extreme Wind Speeds Observed by Anemometer and Seismic Networks: An Eastern U.S. Case Study

Pryor

Conrick

Miller

et al. 2014

Journal of Applied Meteorology and Climatology

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“…Mountain waves, induced by stable tropospheric flow over terrain, are a well-known source of aviation hazards, such as strong up-and down-drafts, downslope windstorms [1][2][3][4], clear air turbulence (CAT) associated with tropospheric wave breaking [5][6][7][8][9][10], low-level turbulence and 'rotors' associated with wave-induced boundary layer separation [11][12][13][14][15][16][17] and hydraulic jump-like flows [12,18], as well as hazards to surface transport [19], such as very strong or gusty winds [20].…”

Section: Introductionmentioning

confidence: 99%

Mountain Waves in High Resolution Forecast Models: Automated Diagnostics of Wave Severity and Impact on Surface Winds

Sheridan

Brown

2017

Atmosphere

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An automated method producing a diagnostic of the severity of lee waves and their impacts on surface winds as represented in output from a high resolution linear numerical model (3D velocities over mountains (3DVOM)) covering several areas of the U.K. is discussed. Lee waves involving turbulent rotor activity or downslope windstorms represent a hazard to aviation and ground transport, and summary information of this kind is highly valuable as an efficient 'heads-up' for forecasters, for automated products or to feed into impact models. Automated diagnosis of lee wave surface effects presents a particular challenge due to the complexity of turbulent zones in the lee of irregular terrain. The method proposed quantifies modelled wind perturbations relative to those that would occur in the absence of lee waves for a given background wind, and diagnoses using it are found to be quite consistent between cases and for different ranges of U.K. hills. A recent upgrade of the operational U.K. limited area model, the U.K. Variable Resolution Model (UKV) used for general forecasting at the Met Office means that it now resolves lee waves, and its performance is here demonstrated using comparisons with aircraft-and surface-based observations and the linear model. In the future, automated diagnostics may be adapted to use its output to routinely produce contiguous mesoscale maps of lee wave activity and surface impacts over the whole U.K.

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“…Furthermore, it is situated on the northeast fringes of the study area where strong mid-latitude cyclones (e.g., northeasters) are more frequent. Roanoke and Asheville's high frequency is also anticipated, because of their higher elevations and proximity to irregular mountain landscapes that induce more numerous gusts (Kondo et al, 2002;Agustsson and Olafsson, 2004). The lowest incidence of gusts is reported at Wilmington, NC, and Chattanooga, TN.…”

Section: Resultsmentioning

confidence: 88%

Directional Characteristics of Potentially Damaging Wind Gusts in the Southeast United States

Martin

Konrad

2006

Physical Geography

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Annual estimated storm damage in the United States is seven billion dollars. Much of that damage is caused by tree blowover that is induced by high wind gusts. The prevailing directions of these wind gusts dictate the zones around structures in which trees may potentially fall and cause damage. To gain a better understanding of hazardous wind gusts, this research examines the directional component of wind gusts in the Southeast United States. Regional patterns of wind gusts are identified and tied to atmospheric and terrestrial patterns. Results indicate the following: (1) gusts along the northeast coast of the study area are bidirectional, being from the northeast and southwest; (2) the southeast coast has a predominantly westerly component to the gusts with little impact from the east; (3) the Piedmont is strongly influenced by westerly gusts, but an easterly component increases gradually to the northeast; and (4) high gusts in the mountains demonstrate a strong relationship with the regional and local topographic characteristics. [

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Mean gust factors in complex terrain

Cited by 37 publications

References 0 publications

Intense and Extreme Wind Speeds Observed by Anemometer and Seismic Networks: An Eastern U.S. Case Study

Intense and Extreme Wind Speeds Observed by Anemometer and Seismic Networks: An Eastern U.S. Case Study

Mountain Waves in High Resolution Forecast Models: Automated Diagnostics of Wave Severity and Impact on Surface Winds

Directional Characteristics of Potentially Damaging Wind Gusts in the Southeast United States

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