scholarly journals Extreme value analysis of Fiji's wind records

2005 ◽  
Vol 23 (1) ◽  
pp. 1 ◽  
Author(s):  
S P Rattan ◽  
R N Sharma
Keyword(s):  
Tropical Cyclones ◽  
Extreme Value ◽  
Wind Loading ◽  
Extreme Value Analysis ◽  
Value Analysis ◽  
Analysis Techniques ◽  
Wind Speeds ◽  
Extreme Wind ◽  
Modern Methods ◽  
Extreme Wind Speeds

A number of extreme value analysis techniques are utilised to predict basic design gust wind speeds for Fiji, which lies in a tropical cyclone prone region. The study shows that a number of modern methods tend to highly under-predict extreme wind speeds in regions of Fiji severely affected by tropical cyclones, although their skills improve in less severely affected regions. The reference for comparison was Dorman?s method, which has been previously used as a guidance for development of Region D wind speeds in the Australian wind loading code ? the AS1170.2-1989. In the case of Fiji, this study recommends the AS1170.2-1989 Region C provisions for Suva and the eastern coasts of the main island of Viti Levu only, and the AS1170.2-1989 Region D provisions elsewhere. This is significantly different to the provisions of the current National Building Code of Fiji (1990) which allow for the use of AS1170.2-1989 Region C provisions for all of Fiji. This difference is attributed to differences in the frequency and intensity of tropical cyclones visiting Fiji as compared with those for Australian Region C.

Extreme-value analysis of canadian wind speeds

1987 ◽  
Vol 15 (4) ◽  
pp. 312-316 ◽  
Author(s):  
G. A. Whitmore ◽  
Jane F. Gentleman
Keyword(s):  
Extreme Value ◽  
Extreme Value Analysis ◽  
Value Analysis ◽  
Wind Speeds

scholarly journals The Global Wind Resource Observed by Scatterometer

2020 ◽  
Vol 12 (18) ◽  
pp. 2920 ◽  
Author(s):  
Ian R. Young ◽  
Ebru Kirezci ◽  
Agustinus Ribal
Keyword(s):  
North Atlantic ◽  
Extreme Value Analysis ◽  
Data Set ◽  
Value Analysis ◽  
Wind Speeds ◽  
The North ◽  
Extreme Wind ◽  
Basin Scale ◽  
The North Atlantic ◽  
Wind Resource

A 27-year-long calibrated multi-mission scatterometer data set is used to determine the global basin-scale and near-coastal wind resource. In addition to mean and percentile values, the analysis also determines the global values of both 50- and 100-year return period wind speeds. The analysis clearly shows the seasonal variability of wind speeds and the differing response of the two hemispheres. The maximum wind speeds in each hemisphere are comparable but there is a much larger seasonal cycle in the northern hemisphere. As a result, the southern hemisphere has a more consistent year-round wind climate. Hence, coastal regions of southern Africa, southern Australia, New Zealand and southern South America appear particularly suited to coastal and offshore wind energy projects. The extreme value analysis shows that the highest extreme wind speeds occur in the North Atlantic Ocean with extreme wind regions concentrated along the western boundaries of the North Atlantic and North Pacific Oceans and the Indian Ocean sector of the Southern Ocean. The signature of tropical cyclones is clearly observed in each of the well-known tropical cyclone basins.

Extreme Value Analyses of Dynamic Response Parameters of a Wind Tower Structure Under Short-Term Nonlinear Irregular Seastate

2017 ◽  
Author(s):  
Leonardo Nascimento ◽  
Luis Sagrilo ◽  
Gilberto Ellwanger
Keyword(s):  
Nonlinear Behavior ◽  
Nonlinear Effects ◽  
Extreme Value ◽  
Irregular Waves ◽  
Wind Loading ◽  
Extreme Value Analysis ◽  
Short Term ◽  
Gaussian Stochastic Process ◽  
Value Analysis ◽  
Non Gaussian

In the assessment of marine structures in shallow waters domain it is important to take into account the nonlinear (or non-Gaussian) nature of the irregular waves when predicting short and long-term responses of such structures. Other sources of nonlinearities in the response are also present due to some nonlinear effects such as: wet-dry surface effects, wind force on dry parts of the structure, drag term in Morison hydrodynamic force equation, etc. The estimation of the characteristic short-term extreme responses requires the extreme value analysis of a non-Gaussian stochastic process. There are many approaches available in literature which can be employed, such as: Hermite-based model, Weibull-fitting model, etc. In this paper two distinct Weibull fitting models (one based on the first two and other based on the first three moments of the response peaks sample) and Hermite-based models using both conventional and linear moments (L-moments) are investigated for the prediction of extreme short-term response of mono-column wind tower installed in a water depth of 20m and subject to wave, current and wind loading. The tower responses (load effects) time-histories are obtained by means of a time-domain finite element-based program using 3-D geometric nonlinear beam elements developed for the dynamic analysis of this type of structure. In this program, the nonlinear behavior of the irregular waves is modelled by means of the second order Sharma and Dean theory [1] and the wind forces are represented by a very simplified load model based on wind velocity simulated time-series and the obstruction area of the tower and blades.

Extreme-value analysis of Canadian wind speeds

1994 ◽  
pp. 119-144 ◽  
Author(s):  
Jane F. Gentleman ◽  
G. A. Whitmore ◽  
F. W. Zwiers ◽  
W. H. Ross
Keyword(s):  
Extreme Value ◽  
Extreme Value Analysis ◽  
Value Analysis ◽  
Wind Speeds

scholarly journals The mechanical stability of the world’s tallest broadleaf trees

2019 ◽  
Author(s):  
T. Jackson ◽  
A. Shenkin ◽  
N. Majalap ◽  
J. bin Jami ◽  
A. bin Sailim ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
Tree Height ◽  
Wind Loading ◽  
Maximum Height ◽  
Wind Speeds ◽  
Extreme Wind ◽  
North Borneo ◽  
Relative Rarity ◽  
Extreme Wind Speeds ◽  
The Tropics

AbstractThe factors that limit the maximum height of trees, whether ecophysiological or mechanical, are the subject of longstanding debate. Here we examine the role of mechanical stability in limiting tree height and focus on trees from the tallest tropical forests on Earth, in Sabah, Malaysian Borneo, including the recently discovered tallest tropical tree, a 100.8 mShorea faguetiana. We use terrestrial laser scans,in situstrain gauge data and finite-element simulations to map the architecture of tall broadleaf trees and monitor their response to wind loading. We demonstrate that a tree’s risk of breaking due to gravity or self-weight decreases with tree height and is much more strongly affected by tree architecture than by material properties. In contrast, wind damage risk increases with tree height despite the larger diameters of tall trees, resulting in a U-shaped curve of mechanical risk with tree height. The relative rarity of extreme wind speeds in north Borneo may be the reason it is home to the tallest trees in the tropics.

scholarly journals Statistics of Extreme Synoptic-Scale Wind Speeds in Ensemble Simulations of Current and Future Climate

2004 ◽  
Vol 17 (23) ◽  
pp. 4564-4574 ◽  
Author(s):  
H. W. van den Brink ◽  
G. P. Können ◽  
J. D. Opsteegh
Keyword(s):  
Climate Model ◽  
Extreme Value Distribution ◽  
Extreme Value ◽  
Extreme Value Analysis ◽  
Jet Stream ◽  
Return Periods ◽  
Value Analysis ◽  
Wind Speeds ◽  
Westerly Jet ◽  
Extreme Wind Speed

Abstract Statistical analysis of the wind speeds, generated by a climate model of intermediate complexity, indicates the existence of areas where the extreme value distribution of extratropical winds is double populated, the second population becoming dominant for return periods of order 103 yr. Meteorological analysis of the second population shows that it is caused when extratropical cyclones merge in an extremely strong westerly jet stream such that conditions are generated that are favorable for occurrence of strong diabatic feedbacks. Doubling of the greenhouse gas concentrations changes the areas of second population and increases its frequency. If these model results apply to the real world, then in the exit areas of the jet stream the extreme wind speed with centennial-to-millennial return periods is considerably larger than extreme value analysis of observational records implies.

scholarly journals A Nonstationary Extreme Value Analysis for the Assessment of Changes in Extreme Annual Wind Speed over the Gulf of St. Lawrence, Canada

2008 ◽  
Vol 47 (11) ◽  
pp. 2745-2759 ◽  
Author(s):  
Y. Hundecha ◽  
A. St-Hilaire ◽  
T. B. M. J. Ouarda ◽  
S. El Adlouni ◽  
P. Gachon
Keyword(s):  
Wind Speed ◽  
Gumbel Distribution ◽  
Reanalysis Data ◽  
Extreme Value ◽  
Significant Trend ◽  
Generalized Extreme Value Distribution ◽  
Extreme Value Analysis ◽  
Value Analysis ◽  
Significance Level ◽  
Wind Speeds

Abstract Changes in the extreme annual wind speed in and around the Gulf of St. Lawrence (Canada) were investigated through a nonstationary extreme value analysis of the annual maximum 10-m wind speed obtained from the North American Regional Reanalysis (NARR) dataset as well as observed data from selected stations of Environment Canada. A generalized extreme value distribution with time-dependent location and scale parameters was used to estimate quantiles of interest as functions of time at locations where significant trend was detected. A Bayesian method, the generalized maximum likelihood approach, is implemented to estimate the parameters. The analysis yielded shape parameters very close to 0, suggesting that the distribution can be modeled using the Gumbel distribution. A similar analysis using a nonstationary Gumbel model yielded similar quantiles with narrower credibility intervals. Overall, little change was detected over the period 1979–2004. Only 7% of the investigated grids exhibited trends at the 5% significant level, and the analysis performed on the reanalysis data at locations of significant trend indicated a rise in the median extreme annual wind speed by up to 2 m s−1 per decade in the southern coastal areas with a corresponding increase in the 90% and 99% quantiles of the extreme annual wind speeds by up to 5 m s−1 per decade. Also in the northern part of the gulf and some offshore areas in the south, the 50%, 90%, and 99% quantile values of the extreme annual wind speeds are noted to drop by up to 1.5, 3, and 5 m s−1, respectively. While the directions of the changes in the annual extremes at the selected stations are similar to those of the reanalysis data at nearby grid cells, the magnitudes and significance levels of the changes are generally inconsistent. Change at the same significance level over the same period of the NARR dataset was noted only at 2 stations out of 13.

Extreme value analysis for estimating 50 year return wind speeds from reanalysis data

Wind Energy ◽  
2013 ◽  
Vol 17 (8) ◽  
pp. 1231-1245 ◽  
Author(s):  
G. Anastasiades ◽  
P. E. McSharry
Keyword(s):  
Reanalysis Data ◽  
Extreme Value ◽  
Extreme Value Analysis ◽  
Value Analysis ◽  
Wind Speeds
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