scholarly journals Quantifying changes of wind speed distributions in the historical record of Atlantic tropical cyclones

2009 ◽  
Vol 9 (5) ◽  
pp. 1749-1757 ◽  
Author(s):  
K. Chen ◽  
J. McAneney ◽  
K. Cheung
Keyword(s):  
Wind Speed ◽  
Insurance Industry ◽  
Global Climate ◽  
Historical Record ◽  
Systematic Change ◽  
Atlantic Basin ◽  
Wind Speeds ◽  
The Us ◽  
Single Category ◽  
The Stability

Abstract. Here we re-examine the official Atlantic basin tropical cyclone (hurricane) database HURDAT (1851–2008) and quantify differences between wind speed distributions in the early historical (1851–1943) record and more recent observations. Analyses were performed at three different geographical levels: for all six-hourly track segments of all Atlantic basin events, all segments of all events that crossed the US mainland, and US landfalling segments alone. At all three geographical levels of study, distributions of windspeeds over the last two, four and six decades display negligible dispersion or systematic change over time. On the other hand and relative to wind speed frequencies for subsequent years, the 1851–1943 record has a marked and statistically significant over-representation of wind speeds largely corresponding to Saffir-Simpson Categories 1 and 2 and under-representation of Categories 4 and 5 events; importantly, no single Category 5 event is recorded prior to 1924. The stability of the distribution of windspeeds at landfall over the last six decades, the dataset in which we can have most confidence, suggests that the differences in the earlier record are most likely explained by well-known measurement and observational deficiencies. Moreover by disaggregating the Power Dissipation Index (PDI), we demonstrate that the upward trend in Atlantic basin PDI since 1970s does not imply stronger and longer duration Category 5 windspeeds despite a warming climate. These results have implications for hurricane catastrophe loss modeling for the insurance industry and long-term trend analyses of the historical wind speed record, especially those related to the attribution of the role of Global Climate Change.

Global Trends in Extreme Wind Speed and Wave Height

2013 ◽  
Author(s):  
I. R. Young ◽  
S. Zieger ◽  
J. Vinoth ◽  
A. V. Babanin
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
Global Climate ◽  
Extreme Value ◽  
Global Perspective ◽  
Ocean Engineering ◽  
Change Analysis ◽  
Data Set ◽  
Wind Speeds ◽  
Extreme Wind

Satellite observations of the ocean surface provide a powerful method for acquiring global data on wind speed and wave height. Radar altimeters have now been in operation for more than 25 years, providing a reasonably long term data set with global coverage. This paper presents data from a fully calibrated and validated altimeter dataset. The dataset provides the basis for obtaining a global perspective of a number of parameters critical to ocean engineering design, ship operations and global climate change. Analysis of the data provides ocean climatology of mean monthly values of wind speed and wave height useful for ship operations. The data set is also sufficiently long to provide extreme value (i.e. 100-year return period) estimates of wind speed and wave height. The paper presents such values and describes the approaches most appropriate to obtain statistically significant extreme value estimates from such satellite data. With a data set of this length, it is possible to investigate whether there have been statistically significant changes in the wind and wave climates over the period. Careful trend analysis of the extensive data set shows that there has been a statistically significant increasing trend in mean wind speed over the period. The corresponding increase in wave height is less clear. There is also evidence to suggest that extreme wind speeds and wave heights are increasing and the data set is analysed to investigate these trends. The paper clearly shows the value of this dataset and its application to a range of engineering problems.

scholarly journals History and Data Records of the Automatic Weather Station on Denali Pass (5715 m), 1990–2007

2020 ◽  
Vol 59 (12) ◽  
pp. 2113-2127
Author(s):  
Lea Hartl ◽  
Martin Stuefer ◽  
Tohru Saito ◽  
Yoshitomi Okura
Keyword(s):  
Wind Speed ◽  
Historical Record ◽  
Reanalysis Data ◽  
Meteorological Conditions ◽  
Weather Station ◽  
Automatic Weather Station ◽  
Wind Speeds ◽  
Air Temperatures ◽  
History Of ◽  
Summit Region

AbstractWe present the data records and station history of an automatic weather station (AWS) on Denali Pass (5715 m MSL), Alaska. The station was installed by a team of climbers from the Japanese Alpine Club after a fatal accident involving Japanese climbers in 1989 and was operational intermittently between 1990 and 2007, measuring primarily air temperature and wind speed. In later years, the AWS was operated by the International Arctic Research Center of the University of Alaska Fairbanks. Station history is reconstructed from available documentation as archived by the expedition teams. To extract and preserve data records, the original datalogger files were processed. We highlight numerous challenges and sources of uncertainty resulting from the location of the station and the circumstances of its operation. The data records exemplify the harsh meteorological conditions at the site: air temperatures down to approximately −60°C were recorded, and wind speeds reached values in excess of 60 m s−1. Measured temperatures correlate strongly with reanalysis data at the 500-hPa level. An approximation of critical wind speed thresholds and a reanalysis-based reconstruction of the meteorological conditions during the 1989 accident confirm that the climbers faced extremely hazardous wind speeds and very low temperatures. The data from the Denali Pass AWS represent a unique historical record that can, we hope, serve as a basis for further monitoring efforts in the summit region of Denali.

Nonlinear Systems Analysis and Control of Variable Speed Wind Turbines for Multiregime Operation

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
Greg Semrau ◽  
Sigitas Rimkus ◽  
Tuhin Das
Keyword(s):  
Wind Speed ◽  
Nonlinear Systems ◽  
Wind Turbines ◽  
Control Input ◽  
Variable Speed ◽  
Wind Speeds ◽  
Speed Regulation ◽  
The Stability ◽  
Control Feedback ◽  
Operating Regimes

The key control problems associated with variable speed wind turbines are maximization of extracted energy when operating below the rated wind speed, and power and speed regulation when operating above the rated wind speed. In this paper, we develop a nonlinear systems framework to address these problems. The framework is used to visualize and analyze the equilibria of the wind turbine as its operating regimes and controllers change. For both below rated and above rated wind speeds, we adopt nonlinear controllers, analyze the stability property of the resulting equilibria, and establish the criterion for switching between control regimes. Further, the regions of attraction of the resulting equilibria are determined, and the existence of a common region of attraction, which allows stable switching between operating regimes, is shown. The control input maintains continuity at the point of switching. We next provide a method for blade pitch modulation to control rotor speed at high wind speeds. Through Lyapunov stability analysis, we prove stability of the equilibria in the presence of the two independently functioning torque- and pitch-control feedback loops. Simulation results are presented and the controller is compared with existing works from the literature.

scholarly journals PENGATURAN SUDUT AZIMUTH ROKET RUM UNTUK OPERASI PELUNCURAN PADA KECEPATAN ANGIN DI ATAS 10 KNOT

2016 ◽  
Vol 14 (1) ◽  
pp. 9
Author(s):  
Heri Budi Wibowo ◽  
Ahmad Riyadl ◽  
Yudha Agung Nugroho
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Azimuth Angle ◽  
Rocket Motor ◽  
Extreme Conditions ◽  
Wind Speeds ◽  
Flight Direction ◽  
Maximum Payload ◽  
Left And Right ◽  
The Stability

RUM rocket is a rocket used in the payload competition among university students. The rocket is designed to bring a maximum payload of 1 kg to altitude of 600-1000 m and  falls safely on a 500 m radius of the left and right rear of the center point of the launching pad of the conditions of wind speeds below 10 knots. In extreme circumstances where the wind speed is above 10 knots, the effect of speed and direction of wind to the stability of the rocket flight direction large enough  to cause it to fall beyond the defined safety radius. The research aims to adjust azimuth setting of the rocket so that the fall of  the rocket motor remains secure within the radius of the launch area. The study was conducted by testing a rocket RUM in extreme conditions (wind speed of 10-20 knots) with variations in shear-pin and azimuth angle. The test variables are the position of the fallen rocket motor. The results show that the wind direction and speed significantly affecting direction of rockets flight. The results show that rocket azimuth angle of 60 degrees with the direction of 90 degrees from the wind direction can make thea rocket falls on a secure area (within 500 m). Abstrak Roket RUM adalah roket untuk lomba muatan antar mahasiswa. Roket didisain membawa beban maksimum 1 kg dengan ketinggian 600-1000 m dan jatuh pada radius 500 m dari titik pusat peluncuran dengan kondisi kecepatan angin di bawah 10 knot. Dalam keadaan ekstrim dimana kecepatan angin di atas 10 knot, pengaruh kecepatan angin terhadap arah terbang roket menjadi besar sehingga dapat menyebabkan jatuhnya roket meleset di luar radius aman yang telah diitetapkan. Penelitian ini bertujuan mengatur sudut azimuth roket untuk mengatur jatuhnya motor roket sehingga tetap aman dalam radius area peluncuran. Penelitian dilakukan dengan melakukan pengujian roket RUM pada kondisi ekstrim (kecepatan angin 10-20 knot) dengan variasi penahan beban dan sudut azimuth. Hasil optimasi menunjukkan bahwa dengan menggunakan penahan beban dan pengaturan sudut azimuth roket 60 derajat dengan arah 90 derajat dari arah angin dapat membuat roket jatuh pada daerah aman peluncuran (500 m).

Downscaling Wind

2019 ◽  
Author(s):  
S.C. Pryor ◽  
A.N. Hahmann
Keyword(s):  
Wind Speed ◽  
Global Climate ◽  
Ecological Impacts ◽  
Atmospheric Flow ◽  
Wind Speeds ◽  
New Approaches ◽  
Hybrid Approaches ◽  
Temperature And Precipitation ◽  
Mean Wind Speed ◽  
Wind Events

Winds within the atmospheric boundary layer (i.e., near to Earth’s surface) vary across a range of scales from a few meters and sub-second timescales (i.e., the scales of turbulent motions) to extremely large and long-period phenomena (i.e., the primary circulation patterns of the global atmosphere). Winds redistribute momentum and heat, and short- and long-term predictions of wind characteristics have applications to a number of socioeconomic sectors (e.g., engineering infrastructure). Despite its importance, atmospheric flow (i.e., wind) has been subject to less research within the climate downscaling community than variables such as air temperature and precipitation. However, there is a growing comprehension that wind storms are the single biggest source of “weather-related” insurance losses in Europe and North America in the contemporary climate, and that possible changes in wind regimes and intense wind events as a result of global climate non-stationarity are of importance to a variety of potential climate change feedbacks (e.g., emission of sea spray into the atmosphere), ecological impacts (such as wind throw of trees), and a number of other socioeconomic sectors (e.g., transportation infrastructure and operation, electricity generation and distribution, and structural design codes for buildings). There are a number of specific challenges inherent in downscaling wind including, but not limited to, the fact that it has both magnitude (wind speed) and orientation (wind direction). Further, for most applications, it is necessary to accurately downscale the full probability distribution of values at short timescales (e.g., hourly), including extremes, while the mean wind speed averaged over a month or year is of little utility. Dynamical, statistical, and hybrid approaches have been developed to downscale different aspects of the wind climate, but have large uncertainties in terms of high-impact aspects of the wind (e.g., extreme wind speeds and gusts). The wind energy industry is a key application for right-scaled wind parameters and has been a major driver of new techniques to increase fidelity. Many opportunities remain to refine existing downscaling methods, to develop new approaches to improve the skill with which the spatiotemporal scales of wind variability are represented, and for new approaches to evaluate skill in the context of wind climates.

scholarly journals The Stability of Passenger Vehicles at Tornado Wind Intensities of the (Enhanced) Fujita Scale

2016 ◽  
Vol 8 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Marius J. Paulikas ◽  
Thomas W. Schmidlin ◽  
Timothy P. Marshall
Keyword(s):  
Wind Speed ◽  
Field Survey ◽  
Total N ◽  
Wind Speeds ◽  
Passenger Vehicles ◽  
Damage Indicators ◽  
Intensity Category ◽  
The Stability ◽  
Wind Intensity ◽  
Vehicle Movement

Abstract Two independent datasets (total n = 959) of tornado-stricken passenger vehicles collected from 12 tornado events over a 15-yr time span are combined and tested to determine whether vehicle movement and/or upset are consistent at various wind speed intensities. Impacted vehicles are classified into three categories of upset motions (no movement, lateral shifting, rolling and lofting motions) for each wind intensity category of the Fujita and Enhanced Fujita scales. Vehicles observed by Schmidlin exposed to F1 and F2 winds are statistically assessed to determine if upset distribution values are consistent with those assessed by Marshall at these respective wind speeds; this same approach is subsequently conducted for vehicles at F3/EF3 and F4/EF4 winds. No statistical differences are found between the two sets of field survey data, which are therefore considered to be of the same population. Passenger vehicles are currently not utilized as damage indicators for rating tornado wind intensities, although the results of this study suggest that only 10% of vehicles are typically shifted at EF0 wind speeds, 36% are displaced at EF1 and EF2 winds (5% are rolled or lofted), 63% are displaced at EF3 and EF4 winds (15% are rolled and lofted), and all vehicles exhibit some form of movement or upset at the EF5 wind speed. The results of this study may potentially serve as a basis for providing better tornado safety protocols, designing safer vehicles and infrastructure, and estimating tornado wind speeds where few EF-scale damage indicators are available.

scholarly journals Calibration of the 2007–2017 record of ARM Cloud Radar Observations using CloudSat

2019 ◽  
Author(s):  
Pavlos Kollias ◽  
Bernat Puigdomènech Treserras ◽  
Alain Protat
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Operating Mode ◽  
Historical Record ◽  
Department Of Energy ◽  
Radar Observations ◽  
Cloud Radar ◽  
Radar Network ◽  
The Us

Abstract. The US Department of Energy (DOE) Atmospheric Radiation Measurements (ARM) program has been at the forefront of millimeter wavelength radar development and operations since the late 90’s. The operational performance of the ARM cloud radar network is very high; however, the calibration of the historical record is not well established. Here, we use a well-characterized spaceborne 94-GHz cloud profiling radar (CloudSat) to characterize the calibration of the different generations of the ARM cloud radars from 2007 to 2017 over a variety of climatological regimes and for fixed and mobile deployments. Over 43 years of ARM profiling cloud radar observations are compared to CloudSat and the calibration offsets are reported as a function of time using a sliding window of 6 months. The study also provides the calibration offsets for each operating mode of the ARM cloud radars. Overall, significant calibration offsets are found that exceed the uncertainty of the technique (1–2 dB). The findings of this study are critical to past, on-going and planned studies of cloud and precipitation and should assist the DOE ARM to build a legacy decadal ground-based cloud radar dataset for global climate model validation.

scholarly journals PENGATURAN SUDUT AZIMUTH ROKET RUM UNTUK OPERASI PELUNCURAN PADA KECEPATAN ANGIN DI ATAS 10 KNOT (AZIMUTH ANGLE’S SETTING OF ROCKET RUM FOR LAUNCH OPERATION AT WIND SPEED MORE THAN 10 KNOT)

2018 ◽  
Vol 14 (1) ◽  
pp. 9
Author(s):  
Heri Budi Wibowo ◽  
Ahmad Riyadl ◽  
Yudha Agung Nugroho
Keyword(s):  
Wind Speed ◽  
Wind Direction ◽  
Azimuth Angle ◽  
Rocket Motor ◽  
Extreme Conditions ◽  
Wind Speeds ◽  
Flight Direction ◽  
Maximum Payload ◽  
Left And Right ◽  
The Stability

RUM rocket is a rocket used in the payload competition among university students. The rocket is designed to bring a maximum payload of 1 kg to altitude of 600-1000 m and falls safely on a 500 m radius of the left and right rear of the center point of the launching pad of the conditions of wind speeds below 10 knots. In extreme circumstances where the wind speed is above 10 knots, the effect of speed and direction of wind to the stability of the rocket flight direction large enough to cause it to fall beyond the defined safety radius. The research aims to adjust azimuth setting of the rocket so that the fall of the rocket motor remains secure within the radius of the launch area. The study was conducted by testing a rocket RUM in extreme conditions (wind speed of 10-20 knots) with variations in shear-pin and azimuth angle. The test variables are the position of the fallen rocket motor. The results show that the wind direction and speed significantly affecting direction of rockets flight. The results show that rocket azimuth angle of 60 degrees with the direction of 90 degrees from the wind direction can make thea rocket falls on a secure area (within 500 m). ABSTRAKRoket RUM adalah roket untuk lomba muatan antar mahasiswa. Roket didisain membawa beban maksimum 1 kg dengan ketinggian 600-1000 m dan jatuh pada radius 500 m dari titik pusat peluncuran dengan kondisi kecepatan angin di bawah 10 knot. Dalam keadaan ekstrim dimana kecepatan angin di atas 10 knot, pengaruh kecepatan angin terhadap arah terbang roket menjadi besar sehingga dapat menyebabkan jatuhnya roket meleset di luar radius aman yang telah diitetapkan. Penelitian ini bertujuan mengatur sudut azimuth roket untuk mengatur jatuhnya motor roket sehingga tetap aman dalam radius area peluncuran. Penelitian dilakukan dengan melakukan pengujian roket RUM pada kondisi ekstrim (kecepatan angin 10-20 knot) dengan variasi penahan beban dan sudut azimuth. Hasil optimasi menunjukkan bahwa dengan menggunakan penahan beban dan pengaturan sudut azimuth roket 60 derajat dengan arah 90 derajat dari arah angin dapat membuat roket jatuh pada daerah aman peluncuran (500 m).

scholarly journals The Quantification and Correction of Wind-Induced Precipitation Measurement Errors

2016 ◽  
Author(s):  
John Kochendorfer ◽  
Roy Rasmussen ◽  
Mareile Wolff ◽  
Bruce Baker ◽  
Mark E. Hall ◽  
...  
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Measurement Errors ◽  
Transfer Functions ◽  
Universal Function ◽  
Climate Change Research ◽  
Wind Speeds ◽  
Solid Precipitation ◽  
The Us ◽  
Precipitation Gauge

Abstract. Hydrologic measurements are becoming increasingly important for both the short and long term management of water resources. Of all the terms in the hydrologic budget, precipitation is the typically most important input. However, measurements of precipitation are still subject to large errors and biases. For example, a high-quality but unshielded weighing precipitation gauge can collect less than 50 % of the actual amount of solid precipitation when wind speeds exceed 5 ms−1. Using results from two different precipitation testbeds, such errors have been assessed for unshielded weighing gauges and for four of the most common windshields currently in use. Functions used to correct wind-induced undercatch were developed and tested. In addition, corrections for the single Altar weighing gauge were developed using the combined results of two separate sites, one of which was in Norway and other in the US. In general the results indicate that corrections described as a function of air temperature and wind speed effectively remove the undercatch bias that affects such precipitation measurements. In addition, a single ‘universal’ function developed for the single Altar gauges effectively removed the bias at both sites, with the bias at the US site improved from −12 % to 0 %, and the bias at the Norwegian site improved from −27 % to −3 %. These correction functions require only wind speed and air temperature, and were developed for use in national and local precipitation networks, hydrological monitoring, roadway and airport safety work, and climate change research. The techniques used to develop and test these transfer functions at more than one site can also be used for other more comprehensive studies, such as the WMO Solid Precipitation Intercomparison Experiment.

scholarly journals Evaluating dust emission model performance using dichotomous satellite observations of dust emission

2022 ◽  
Author(s):  
Mark Hennen ◽  
Adrian Chappell ◽  
Nicholas Webb ◽  
Kerstin Schepanski ◽  
Matthew Baddock ◽  
...  
Keyword(s):  
Wind Speed ◽  
Dust Emission ◽  
Point Sources ◽  
Sediment Supply ◽  
Emission Model ◽  
Atmospheric Dust ◽  
Wind Speeds ◽  
Space And Time ◽  
The Us ◽  
Emission Models

Abstract. Measurements of dust in the atmosphere have long been used to calibrate dust emission models. However, there is growing recognition that atmospheric dust confounds the magnitude and frequency of emission from dust sources and hides potential weaknesses in dust emission model formulation. In the satellite era, dichotomous (presence = 1 or absence = 0) observations of dust emission point sources (DPS) provide a valuable inventory of regional dust emission. We used these DPS data to develop an open and transparent framework to routinely evaluate dust emission model (development) performance using coincidence of simulated and observed dust emission (or lack of emission). To illustrate the utility of this framework, we evaluated the recently developed albedo-based dust emission model (AEM) which included the traditional entrainment threshold (u*ts) at the grain scale, fixed over space and static over time, with sediment supply infinite everywhere. For comparison with the dichotomous DPS data, we reduced the AEM simulations to its frequency of occurrence in which soil surface wind friction velocity (us*) exceeds the u*ts, P(us* > u*ts). We used a global collation of nine DPS datasets from established studies to describe the spatio-temporal variation of dust emission frequency. A total of 37,352 unique DPS locations were aggregated into 1,945 1° grid boxes to harmonise data across the studies which identified a total of 59,688 dust emissions. The DPS data alone revealed that dust emission does not usually recur at the same location, are rare (1.8 %) even in North Africa and the Middle East, indicative of extreme, large wind speed events. The AEM over-estimated the occurrence of dust emission by between 1 and 2 orders of magnitude. More diagnostically, the AEM simulations coincided with dichotomous observations ~71 % of the time but simulated dust emission ~27 % of the time when no dust emission was observed. Our analysis indicates that u*ts was typically too small, needed to vary over space and time, and at the grain-scale u*ts is incompatible with the us* scale (MODIS 500 m). During observed dust emission, us* was too small because wind speeds were too small and/or the wind speed scale (ERA5; 11 km) is incompatible with the us* scale. The absence of any limit to sediment supply caused the AEM to simulate dust emission whenever P (us* > u*ts), producing many false positives when and where wind speeds were frequently large. Dust emission model scaling needs to be reconciled and new parameterisations are required for u*ts and to restrict sediment supply varying over space and time. Whilst u*ts remains poorly constrained and unrealistic assumptions persist about sediment supply and availability, the DPS data provide a basis for the calibration of dust emission models for operational use. As dust emission models develop, these DPS data provide a consistent, reproducible, and valid framework for their routine evaluation and potential model optimisation. This work emphasises the growing recognition that dust emission models should not be evaluated against atmospheric dust.

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