scholarly journals Comparative Study of the Near-Surface Typhoon Wind Profile Fitting between Offshore and Onshore Areas

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Kai Wang ◽  
Yun Guo ◽  
Xu Wang
Keyword(s):  
Wind Speed ◽  
Wind Profile ◽  
Roughness Length ◽  
Power Exponent ◽  
Near Surface ◽  
Super Typhoon ◽  
Mean Wind Speed ◽  
Log Law ◽  
Wind Profiles ◽  
Typhoon Wind

The study of typhoon wind profiles, especially offshore typhoon wind profiles, has been constrained by the scarcity of observational data. In this study, the Doppler wind lidar was used to observe the offshore wind profiles during Super Typhoon Mangkhut and onshore wind profiles during Super Typhoon Lekima. Four wind profile models, including the power law, logarithmic law, Deaves–Harris (D-H), and Gryning, were selected in the height range of 0–300 m to fit the wind profile. The variations in the power exponent with the mean wind speed and roughness length were also analyzed. The results showed that the wind profiles fitted by the four models were generally in good agreement with the observed wind profiles with correlation coefficients greater than 0.98 and root mean square deviations less than 0.5 m s−1. For the offshore case, the fitting degree of all wind profile models improved with increasing mean wind speed. Specifically, the D-H model had the highest fitting degree when the horizontal mean wind speed at 40 m was in the range of 8–25 m s−1, while the log-law model had the highest fitting degree when the wind speed exceeded 30 m s−1. For the onshore case, the fitting degree of the four wind profile models deteriorated with increasing mean wind speed, and the log-law model had the highest fitting degree in all wind speed intervals from 8 to 30 m s−1. For both offshore and onshore cases, the power exponent was less affected by mean wind speed and increased with increasing roughness length, and the logarithmic empirical model proposed in this study could well characterize the relationship between the power exponent and roughness length.

scholarly journals Atmospheric boundary layer wind profile at a flat coastal site – wind speed lidar measurements and mesoscale modeling results

2011 ◽  
Vol 6 (1) ◽  
pp. 155-159 ◽  
Author(s):  
R. Floors ◽  
E. Batchvarova ◽  
S.-E. Gryning ◽  
A. N. Hahmann ◽  
A. Peña ◽  
...  
Keyword(s):  
Wind Speed ◽  
Wind Profile ◽  
Mesoscale Model ◽  
Stable Conditions ◽  
Lidar Measurements ◽  
Mean Wind Speed ◽  
Wind Lidar ◽  
The Mean ◽  
Wind Profiles ◽  
The Individual

Abstract. Wind profiles up to 600 m height are investigated. Measurements of mean wind speed profiles were obtained from a novel wind lidar and compared to model simulations from a mesoscale model (WRF-ARW v3.1). It is found that WRF is able to predict the mean wind profile rather well and typically within 1–2 m s−1 to the individual measured values. WRF underpredicts the normalized wind profile, especially for stable conditions. The effect of baroclinicity on the upper part of the wind profile is discussed.

scholarly journals Validation of Dual-Doppler Wind Profiles with in situ Anemometry

2015 ◽  
Vol 32 (5) ◽  
pp. 943-960 ◽  
Author(s):  
W. Scott Gunter ◽  
John L. Schroeder ◽  
Brian D. Hirth
Keyword(s):  
High Resolution ◽  
Wind Speed ◽  
Doppler Radar ◽  
Heavy Precipitation ◽  
Atmospheric Conditions ◽  
Wind Speeds ◽  
Time Histories ◽  
Mean Wind Speed ◽  
Wind Profiles

AbstractTypical methods used to acquire wind profiles from Doppler radar measurements rely on plan position indicator (PPI) scans being performed at multiple elevation angles to utilize the velocity–azimuth display technique or to construct dual-Doppler synthesis. These techniques, as well as those employed by wind profilers, often produce wind profiles that lack the spatial or temporal resolution to resolve finescale features. If two radars perform range–height indicator (RHI) scans (constant azimuth, multiple elevations) along azimuths separated by approximately 90°, then the intersection of the coordinated RHI planes represents a vertical set of points where dual-Doppler wind syntheses are possible and wind speed and direction profiles can be retrieved. This method also allows for the generation of high-resolution wind time histories that can be compared to anemometer time histories. This study focuses on the use of the coordinated RHI scanning strategy by two high-resolution mobile Doppler radars in close proximity to a 200-m instrumented tower. In one of the first high-resolution, long-duration comparisons of dual-Doppler wind synthesis with in situ anemometry, the mean and turbulence states of the wind measured by each platform were compared in varying atmospheric conditions. Examination of mean wind speed and direction profiles in both clear-air (nonprecipitating) and precipitating environments revealed excellent agreement above approximately 50 m. Below this level, dual-Doppler wind speeds were still good but slightly overestimated as compared to the anemometer-measured wind speeds in heavy precipitation. Bulk turbulence parameters were also slightly underestimated by the dual-Doppler syntheses.

scholarly journals Design and Implementation of a Low Power Wind Turbine Emulator Through the Induction Motor-Permanent Magnet Generator Arrangement

2020 ◽  
Vol 29 (54) ◽  
pp. e10530
Author(s):  
David Felipe Bajonero-Sandoval ◽  
Jeyson Sanabria-Vargas ◽  
César Leonardo Trujillo-Rodriguez
Keyword(s):  
Wind Speed ◽  
Low Power ◽  
Wind Turbine ◽  
Permanent Magnet ◽  
Induction Motor ◽  
Wind Profile ◽  
Labview Software ◽  
Three Phase ◽  
Wind Profiles ◽  
Permanent Magnet Generator

This paper presents the design and construction stage of a low power wind turbine emulator, which is used at the laboratory level, to reproduce different wind profiles. There are several types of wind emulators, among which the wind tunnel emulators stand out. These emulators use a motor with a propeller on their axis to obtain the desired wind speed. However, in the present work -and done from a computer- speed control is developed for a three-phase induction motor, thus driving a permanent magnet generator. The motor-generator group is controlled through a program developed in the Labview software. Also, it has the particularity of operating automatically, being able to load different speed data. Such data is associated with a particular power that takes into account the selected wind profile and can operate through manual control of the wind speed. However, this depends on the frequency given. The emulator operation is validated experimentally through two scenarios: the first one emulates the curve presented by the Eolos turbine and subsequently compares the results obtained, whereas the second one loads the wind profile of Uribía-Guajira -a region in Colombia-  achieving that the emulated wind profile can be accurately seen in the loaded wind profile.

scholarly journals Is There a “Tipping Point” between Simulated Nontornadic and Tornadic Supercells in VORTEX2 Environments?

2018 ◽  
Vol 146 (8) ◽  
pp. 2667-2693 ◽  
Author(s):  
Brice E. Coffer ◽  
Matthew D. Parker
Keyword(s):  
Wind Profile ◽  
Tipping Point ◽  
Near Surface ◽  
Vertical Vorticity ◽  
Low Level ◽  
Surface Circulation ◽  
Wind Profiles ◽  
Tornadic Storms ◽  
Tropospheric Wind

Abstract Previous work has suggested that the lower-tropospheric wind profile may partly determine whether supercells become tornadic. If tornadogenesis within the VORTEX2 composite environments is more sensitive to the lower-tropospheric winds than to either the upper-tropospheric winds or the thermodynamic profile, then systematically varying the lower-tropospheric wind profile might reveal a “tipping point” between nontornadic and tornadic supercells. As a test, simulated supercells are initiated in environments that have been gradually interpolated between the low-level wind profiles of the nontornadic and tornadic VORTEX2 supercell composites while also interchanging the upper-tropospheric winds and thermodynamic profile. Simulated supercells become tornadic when the low-level wind profile incorporates at least 40% of the structure from the tornadic VORTEX2 composite environment. Both the nontornadic and tornadic storms have similar outflow temperatures and availability of surface vertical vorticity near their updrafts. Most distinctly, a robust low-level mesocyclone and updraft immediately overlie the intensifying near-surface circulation in each of the tornadic supercells. The nontornadic supercells have low-level updrafts that are disorganized, with pockets of descent throughout the region where surface vertical vorticity resides. The lower-tropospheric wind profile drives these distinct configurations of the low-level mesocyclone and updraft, regardless of the VORTEX2 composite upper-tropospheric wind profile or thermodynamic profile. This study therefore supports a potentially useful, robust link between the probability of supercell tornadogenesis and the lower-tropospheric wind profile, with tornadogenesis more (less) likely when the orientation of horizontal vorticity in the lowest few hundred meters is streamwise (crosswise).

Recent reversal of mean wind speed and gusts across the Iberian Peninsula and its relationship with modes of climate variability, 1961-2019

2021 ◽  
Author(s):  
Eduardo Utrabo-Carazo ◽  
Cesar Azorin-Molina ◽  
Encarna Serrano ◽  
Enric Aguilar ◽  
Manola Brunet
Keyword(s):  
Wind Speed ◽  
Iberian Peninsula ◽  
Atmospheric Circulation ◽  
Weather Forecasting ◽  
Surface Wind ◽  
Wind Gust ◽  
Near Surface ◽  
Modes Of Variability ◽  
Mean Wind Speed ◽  
Mediterranean Oscillation

<p>In a context of climate change, near-surface wind speed (SWS) has received less attention than other variables such as air temperature or precipitation, despite its undeniable environmental and socio-economic impacts. Studies suggest a generalized decrease of SWS in continental surfaces located in the middle latitudes from 1979 to 2010, the so-called stilling phenomenon, and an increase in it thereafter, which has been termed reversal or recovery phenomenon. Recent studies indicate that multidecade oscillations produced by the internal variability of the climate system are responsible for both phenomena. The aim of this work is to advance in the evaluation of the multidecadal variability and causes of the stilling and reversal in the observed SWS, covering the complete 2010s decade and focusing on the Iberian Peninsula region (IP). More specifically, the particular objectives of this study are: (i) to determine for the first time the occurrence of the reversal phenomenon in the IP over the last decade(s), identifying its onset year and its magnitude; (ii) to deepen into the relation between atmospheric teleconnection indices and observed trends in SWS; and (iii) to link atmospheric circulation changes to observed SWS variability. For that purpose, homogenized series of mean wind speed and gusts will be used, as well as data from the ERA5 reanalysis (European Centre for Medium-Range Weather Forecasting). Three SWS parameters will be analysed: monthly mean SWS anomaly; monthly mean daily peak wind gust (DPWG) anomaly; and number of days in which the value of DPWG exceeds the 90th percentile of the series considered. Trends of these parameters will be calculated, as well as the correlation between them and the modes of variability that govern in the region: North Atlantic Oscillation (NAO), Mediterranean Oscillation (MO) and Western Mediterranean Oscillation. Finally, trends of these modes of variability and of other parameters dependent on atmospheric circulation (e.g., geostrophic wind) will be calculated to try to clarify the drivers of the observed changes in the SWS.</p>

A comparison of the high-frequency (>1 Hz) surface and subsurface noise environment at three sites in the United States

1996 ◽  
Vol 86 (5) ◽  
pp. 1516-1528 ◽  
Author(s):  
Christopher J. Young ◽  
Eric P. Chael ◽  
Mitchell M. Withers ◽  
Richard C. Aster
Keyword(s):  
United States ◽  
Wind Speed ◽  
High Frequency ◽  
Wind Profile ◽  
The United States ◽  
Noise Levels ◽  
Wind Noise ◽  
Near Surface ◽  
Unconsolidated Material ◽  
Noise Data

Abstract Surface and subsurface high-frequency (>1 Hz) noise data were recorded using nearly identical instrumentation at three widely separated sites in the United States (Amarillo, Texas; Datil, New Mexico; and Pinedale, Wyoming) for extended periods of time under varying wind conditions. While the sites are geologically distinct, the near-surface noise environments have many common features that we believe may be due in large part to the presence of a surficial layer of highly attenuative unconsolidated material at each site. Noise levels seen at or near the surface (5 m or less) are much higher (up to 30 dB) and much more variable (power range up to 44 dB) than those seen at depth (the smallest range was 9 dB for 1951 m at Amarillo). The greatest gains in noise level reduction are realized within the first 100 m and probably much shallower (< ∼ 10 m). Regardless of the wind profile or local lithology, all sites show an excellent correlation between increased noise levels and higher wind speed, even at significant depths (367 m at Amarillo). Wind-generated noise is broadband (at least 15 to 60 Hz) and apparently nonlinear, increasing dramatically when a wind speed threshold is exceeded (3 to 4 m/sec within a few meters of the surface; as high as 8 m/sec at a depth of a few hundred meters). It is possible to be essentially completely shielded from the wind-generated component of seismic noise by deploying instruments at sufficient depth, but we observed this only for the two deepest deployments (1219 and 1951 m, both at Amarillo). Reducing the wind profile at the surface, however, can yield similar reductions for a much smaller cost. Cultural or “workday” noise, if present (depending on the remoteness of the site), is typically much weaker (10 dB or less) than wind noise but may propagate very effectively to great depths and therefore could be of concern for very deep deployments where wind is not a factor.

scholarly journals Modelling Wind Damage to Southeastern U.S. Trees: Effects of Wind Profile, Gaps, Neighborhood Interactions, and Wind Direction

2021 ◽  
Vol 4 ◽  
Author(s):  
Chris J. Peterson ◽  
Jeffery B. Cannon
Keyword(s):  
Wind Speed ◽  
Wind Profile ◽  
Wind Damage ◽  
Area Measurement ◽  
Storm Damage ◽  
Gap Formation ◽  
Extinction Coefficients ◽  
Wind Speeds ◽  
Direct Damage ◽  
Wind Profiles

Tree damage from a variety of types of wind events is widespread and of great ecological and economic importance. In terms of areas impacted, tropical storms have the most widespread effects on tropical and temperate forests, with southeastern U.S. forests particularly prone to tropical storm damage. This impact motivates attempts to understand the tree and forest characteristics that influence levels of damage. This study presents initial findings from a spatially explicit, individual-based mechanistic wind severity model, ForSTORM, parameterized from winching research on trees in southeastern U.S. This model allows independent control of six wind and neighborhood parameters likely to influence the patterns of wind damage, such as gap formation, the shape of the vertical wind profile, indirect damage, and support from neighbors. We arranged the subject trees in two virtual stands orientations with identical positions relative to each other, but with one virtual stand rotated 90 degrees from the other virtual stand – to explore the effect of wind coming from two alternative directions. The model reproduces several trends observed in field damage surveys, as well as analogous CWS models developed for other forests, and reveals unexpected insights. Wind profiles with higher extinction coefficients, or steeper decrease in wind speed from canopy top to lower levels, resulted in significantly higher critical wind speeds, thus reducing level of damage for a given wind speed. Three alternative formulations of wind profiles also led to significant differences in critical wind speed (CWS), although the effect of profile was less than effect of different extinction coefficients. The CWS differed little between the two alternative stand orientations. Support from neighboring trees resulted in significantly higher critical wind speeds, regardless of type of wind profile or spatial arrangement of trees. The presence or absence of gaps caused marginally significant different in CWS, while inclusion of indirect damage along with direct damage did not significantly change CWS from those caused by direct damage alone. Empirical research that could most benefit this modelling approach includes improving crown area measurement, refining drag coefficients, and development of a biomechanical framework for neighbor support.

scholarly journals A decline of observed daily peak wind gusts with distinct seasonality in Australia, 1941-2016

2021 ◽  
pp. 1-63
Author(s):  
Cesar Azorin-Molina ◽  
Tim R. McVicar ◽  
Jose A. Guijarro ◽  
Blair Trewin ◽  
Andrew J. Frost ◽  
...  
Keyword(s):  
Wind Speed ◽  
Decadal Variability ◽  
Southern Annular Mode ◽  
Near Surface ◽  
Wind Gusts ◽  
Decadal Scale ◽  
Mean Wind Speed ◽  
Long Term Trends ◽  
The Indian Ocean

AbstractWind gusts represent one of the main natural hazards due to their increasing socioeconomic and environmental impacts on, as examples: human safety; maritime-terrestrial-aviation activities; engineering and insurance applications; and energy production. However, the existing scientific studies focused on observed wind gusts are relatively few compared to those on mean wind speed. In Australia, previous studies found a slowdown of near-surface mean wind speed, termed “stilling”, but a lack of knowledge on the multi-decadal variability and trends in the magnitude (wind speed maxima) and frequency (exceeding the 90th percentile) of wind gusts exists. A new homogenized daily peak wind gusts (DPWG) dataset containing 548 time series across Australia for the period 1941-2016 is analyzed to determine long-term trends in wind gusts. Here we show that both the magnitude and frequency of DPWG declined across much of the continent, with a distinct seasonality: negative trends in summer-spring-autumn and weak negative or non-trending (even positive) trends in winter. We demonstrate that ocean-atmosphere oscillations such as the Indian Ocean Dipole and the Southern Annular Mode partly modulate decadal-scale variations of DPWG. The long-term declining trend of DPWG is consistent with the “stilling” phenomenon, suggesting that global warming may have reduced Australian wind gusts.

scholarly journals Estimates of tropical cyclone geometry parameters based on best track data

2019 ◽  
Author(s):  
Kees Nederhoff ◽  
Alessio Giardino ◽  
Maarten van Ormondt ◽  
Deepak Vatvani
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Wind Profile ◽  
Wind Fields ◽  
Engineering Applications ◽  
Wind Speeds ◽  
Pressure Fields ◽  
Ne Pacific ◽  
Wind Profiles

Abstract. Parametric wind profiles are commonly applied in a number of engineering applications for the generation of tropical cyclone (TC) wind and pressure fields. Nevertheless, existing formulations for computing wind fields often lack the required accuracy when the TC geometry is not known. This may affect the accuracy of the computed impacts generated by these winds. In this paper, empirical stochastic relationships are derived to describe two important parameters affecting the TC geometry: radius of maximum winds (RMW) and the radius of gale force winds (∆AR35). These relationships are formulated using best track data (BTD) for all seven ocean basins (Atlantic, S/NW/NE Pacific, N/SW/SE Indian Oceans). This makes it possible to a) estimate RMW and ∆AR35 when these properties are not known and b) generate improved parametric wind fields for all oceanic basins. Validation results show how the proposed relationships allow the TC geometry to be represented with higher accuracy than when using relationships available from the literature. Outer wind speeds can be well reproduced by the commonly used Holland wind profile when calibrated using information either from best-track-data or from the proposed relationships. The scripts to compute the TC geometry and the outer wind speed are freely available via Delft Dashboard.

scholarly journals Estimates of tropical cyclone geometry parameters based on best-track data

2019 ◽  
Vol 19 (11) ◽  
pp. 2359-2370 ◽  
Author(s):  
Kees Nederhoff ◽  
Alessio Giardino ◽  
Maarten van Ormondt ◽  
Deepak Vatvani
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Wind Profile ◽  
Wind Fields ◽  
Engineering Applications ◽  
Wind Speeds ◽  
Pressure Fields ◽  
Ne Pacific ◽  
Wind Profiles

Abstract. Parametric wind profiles are commonly applied in a number of engineering applications for the generation of tropical cyclone (TC) wind and pressure fields. Nevertheless, existing formulations for computing wind fields often lack the required accuracy when the TC geometry is not known. This may affect the accuracy of the computed impacts generated by these winds. In this paper, empirical stochastic relationships are derived to describe two important parameters affecting the TC geometry: radius of maximum winds (RMW) and the radius of gale-force winds (ΔAR35). These relationships are formulated using best-track data (BTD) for all seven ocean basins (Atlantic; S, NW, and NE Pacific; and N, SW, and SE Indian oceans). This makes it possible to (a) estimate RMW and ΔAR35 when these properties are not known and (b) generate improved parametric wind fields for all oceanic basins. Validation results show how the proposed relationships allow the TC geometry to be represented with higher accuracy than when using relationships available from literature. Outer wind speeds can be reproduced well by the commonly used Holland wind profile when calibrated using information either from best-track data or from the proposed relationships. The scripts to compute the TC geometry and the outer wind speed are freely available via the following URL: https://bit.ly/2k9py1J (last access: October 2019).

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