Extreme Wind Research Articles

Extreme wind events responsible for an outsized role in shelf-basin exchange around the southern tip of Greenland

The coastal circulation around Southern Greenland transports fresh, buoyant water masses from the Arctic and Greenland Ice Sheet near regions of convection, sinking, and deep-water formation in the Irminger and Labrador Seas. Here, we track the pathways and fate of these fresh water masses by initializing synthetic particles in the East Greenland Coastal Current on the Southeast Greenland shelf and running them through altimetry-derived surface currents from 1993 to 2021. We report that the majority of waters (83%) remain on the shelf around the southern tip of Greenland. Variability in the shelf-basin exchange of the remaining particles closely follows the number of tip jet wind events on seasonal and interannual timescales. The probability of a particle exiting the shelf increases almost fivefold during a tip jet event. These results indicate that the number of tip jets is a close proxy of the shelf-basin exchange around Southern Greenland.

Impact of Surface Turbulent Fluxes on the Formation of Roll Vortices in a Mediterranean Windstorm

AbstractRoll vortices can have a significant influence on the exchanges of momentum, sensible heat and moisture throughout the boundary layer. They have been shown to reinforce air‐sea interactions under strong wind conditions. This raises the question of how air‐sea exchanges can, in turn, affect the roll vortices. However, representing surface turbulent fluxes during extreme wind conditions is a major challenge in numerical weather prediction and can lead to large uncertainties in surface wind speed. The sensitivity of rolls to different representations of surface fluxes is investigated using large eddy simulations. The study focuses on Mediterranean windstorm Adrian, where rolls are responsible for the transport of strong winds to the surface. Considering the effects of sea spray increases surface heat fluxes and significantly influences the roll morphology. The rolls become narrower and extend over a greater height, while the downward transport of momentum is intensified and results in higher wind speed near the surface. Roll vortices vanish within a few minutes in the absence of momentum fluxes, which maintain the wind shear necessary for their organization. They also quickly weaken without sensible heat fluxes, which sustain the near‐neutral stratification required for their development. In contrast, latent heat fluxes play a minor role. These findings emphasize the necessity of precisely representing the processes occurring at the air‐sea interface, which do not only affect the thermodynamic surface conditions but also the vertical transport of momentum within the windstorm.

The anomalous state of Uranus’s magnetosphere during the Voyager 2 flyby

AbstractThe Voyager 2 flyby of Uranus in 1986 revealed an unusually oblique and off-centred magnetic field. This single in situ measurement has been the basis of our interpretation of Uranus’s magnetosphere as the canonical extreme magnetosphere of the solar system; with inexplicably intense electron radiation belts and a severely plasma-depleted magnetosphere. However, the role of external forcing by the solar wind has rarely been considered in explaining these observations. Here we revisit the Voyager 2 dataset to show that Voyager 2 observed Uranus’s magnetosphere in an anomalous, compressed state that we estimate to be present less than 5% of the time. If the spacecraft had arrived only a few days earlier, the upstream solar wind dynamic pressure would have been ~20 times lower, resulting in a dramatically different magnetospheric configuration. We postulate that such a compression of the magnetosphere could increase energetic electron fluxes within the radiation belts and empty the magnetosphere of its plasma temporarily. Therefore, the interpretation of Uranus’s magnetosphere as being extreme may simply be a product of a flyby that occurred under extreme upstream solar wind conditions.

Refining a Multidisciplinary “Vasculo-plastic” Approach to Limb Salvage: An Institutional Review Examining 300 Lower Extremity Free Flaps

Background: The use of free tissue transfer (FTT) is effective for chronic, non-healing lower extremity (LE) wounds, requiring collaboration across plastic, vascular, podiatric, orthopedic, and infectious disease disciplines for comprehensive treatment plants to optimize limb salvage. This study aims to describe our vasculo-pathic approach with 300 LE FTTs, comparing outcomes between the first 200 LE FTT and the most recent 100 procedures performed. Methods: A single-institution, retrospective review of 300 LE FTTs from July 2011 to January 2023 was performed. Patients were compared between the first 200 (Group 1, July 2011 – February 2020) and last 100 flaps (Group 2, February 2020 – January 2023) performed. Patient characteristics, preoperative management, intraoperative details, and outcomes were collected. Results: Group 2 patients had significantly higher rates of diabetes (67.0% vs. 48.5%, p=0.002), peripheral vascular disease (56.0% vs. 24.5%, p<0.001), history of venous thromboembolisms (13.0% vs. 6.0%, p=0.039), venous reflux (81.9% vs. 67.8%; p=0.028), and preoperative venous thromboses on venous testing (25.5% vs. 10.5%; p=0.003) compared to Group 1. Group 2 underwent more pre-FTT endovascular interventions (23.0% vs. 16.5%, p=0.039) and vascular bypasses (4.0% vs. 0.0%, p =0.012). While immediate flap success and amputation rates were similar between the groups, Group 2 had higher rates of partial flap necrosis (7% vs. 3%; p=0.012). Conclusions: The adoption of a vasculo-plastic approach allows LE FTT to remain successful and achieve long-term limb salvage despite a highly comorbid population.

Antarctic extreme seasons under 20th and 21st century climate change

In this study, available large ensemble datasets in the Coupled Model Intercomparison Phase 6 (CMIP6) archive were used to provide the first multi-variate overview of the evolution of extreme seasons over Antarctica and the Southern Ocean during the 20th and 21st centuries following medium-to-high radiative forcing scenarios. The results show significant differences between simulated changes in background mean climate and changes in low (10th percentile) and high (90th percentile) extreme seasons. Regional winter warming is most pronounced for cold extremes. In summer, there are more pronounced increases in high extremes in precipitation and westerly wind during the ozone hole formation period (late 20th century), affecting coastal regions and, in particular, the Antarctic Peninsula. At midlatitudes, there is a reduction in the range of summer season wind extremes. Suggested mechanisms for these differences are provided relating to sea ice retreat and westerly jet position.

Trend Analysis of Extreme Wind and Wave Height at Key Port Locations Along the Indian Coastline

Trend Analysis of Extreme Wind and Wave Height at Key Port Locations Along the Indian Coastline

A novel life-cycle analysis framework to assess the performances of tall buildings considering the climate change

Structural performance against wind hazards is necessary in modern tall building design, especially for structures in the region prone to tropical cyclones. In fact, wind-related failures and building life-cycle analysis (LCA) may be impacted by climate change on the increase of frequency and intensity of tropical cyclones. In this study, a novel LCA framework considering the climate change is proposed, which includes taking into account the climate change via the serviceability failure cost for the cases where the building vibrates exceeding the corresponding thresholds. In detail, the non-stationary Poisson process is used to model the occurrence and intensity of tropical cyclones, which in turn leads to the financial loss of the coastal building. Specifically, the vulnerability of the building is derived considering both the uncertainty of the extreme wind speeds in the tropical cyclone boundary layer and the fragility curve which includes the uncertainty from the structural damping ratio. To estimate the maintenance cost, the financial values associated with maintenance-related operations and the emission of greenhouse gas are combined. In order to illustrate the proposed LCA framework, a case study targeting a 240 m high benchmark building located close to the coast of Hong Kong is conducted. In addition, the sensitivity of the damping ratio, limit threshold, and climate change are assessed via the LCA results of the benchmark building.

Vapor kinetic energy for the detection and understanding of atmospheric rivers

Poleward water vapor transport in the midlatitudes mainly occurs in meandering filaments of intense water vapor transport, spanning thousands of kilometers long and hundreds of kilometers wide and moving eastward. The water vapor filaments are known as atmospheric rivers (ARs). They can cause extreme wind gusts, intense precipitation, and flooding along densely populated coastal regions. Many recent studies about ARs focused on the statistical analyses of ARs, but a process-level understanding of ARs remains elusive. Here we show that ARs are streams of air with enhanced vapor kinetic energy (VKE) and derive a governing equation for Integrated VKE to understand what contributes to the evolution of ARs. We find that ARs grow mainly because of potential energy conversion to kinetic energy, decay largely owing to condensation and turbulence, and the eastward movement is primarily due to horizontal advection of VKE. Our VKE framework complements the integrated vapor transport framework, which is popular for identifying ARs but lacks a prognostic equation for understanding the physical processes.

Non-Gaussian properties and their effects on extreme wind pressure of a 4:1 rectangular cylinder

This paper investigates the wind pressure characteristics of a 4:1 rectangular cylinder under 19 wind angles using a rigid model wind tunnel test, focusing on non-Gaussian properties and extreme wind pressure. The wind angle (α) varies from 0° to 90° and the Reynolds number (Re) ranges from 0.32 × 105 to 2.14 × 105. The spatial and statistical distributions of wind pressure, along with its non-Gaussian properties, are presented. Detailed analyses of these characteristics are provided. The peak factor of wind pressure was calculated using the modified Hermite method. The results indicate that the skewness and kurtosis of the windward region of the 4:1 rectangular cylinder remain relatively unchanged with varying wind angles. In contrast, the skewness and kurtosis in the separation and wake zones are significantly influenced by changes in the wind angle. Most wind pressures on the 4:1 rectangular cylinder exhibit negative bias and a softening process. The non-Gaussian properties are most prominent at the corner of the wake zone. The peak factor of 2.5 (used in Chinese code) or peak factor g,G based on Gaussian processes on the separation and wake zones of interest are much smaller than the peak factors g,NG calculated based on the modified Hermite method. Ignoring non-Gaussian properties underestimates extreme wind pressures by at least 20%–30%. Therefore, non-Gaussian properties must be considered when calculating wind pressure extremes for similar rectangular structures. Additionally, the peak factor value in the Chinese code should be increased appropriately to ensure structural safety.

Ultrasound-guided popliteal sciatic nerve block for surgical anesthesia in wound care patients with ongoing anticoagulant/antiaggregant therapy: A single-center, prospective study.

Ultrasound-guided peripheral nerve blocks may be a good alternative in patients under antithrombotic drugs. We evaluated the efficacy of ultrasound-guided popliteal sciatic nerve block in patients undergoing lower extremity wound debridement of whom antithrombotic drugs could not be stopped. We focused on hemorrhagic complications related to sciatic nerve block. Wound care patients followed by Cardiovascular Surgery Department scheduled for lower extremity wound surgery were included in this prospective observational study. Data was collected between March 2021 and September 2022. All patient were under antithrombotic therapy and discontinuation of anticoagulant drugs were not possible. Single-insertion and multiple-injection sciatic nerve block at popliteal region was applied to all patients under ultrasound guidance. Primary outcome was the rate of hemorrhage. Secondary outcomes were block onset times, block success and postoperative analgesia times. Data of 105 patients was evaluated, 87 were male and 18 were female. Mean patient age was 61.92 ± 10.06, mean patient body mass index was 25.68 ± 6.33. All patients were under 1 or more antithrombotic drugs. Only one minor hematoma was detected by postoperative ultrasonography control in 1 patient. Hemorrhage complication rate was 1 of 105 (% 0.95, 95% CI, 0.00024-0.051). Overall block success rate was 99.05%. Mean block onset time was 16.27 ± 5.69 minutes. Mean postoperative analgesia time was 19.5 ± 11.22 hours. Sciatic nerve block under ultrasound guidance using in-plane technique was safe and provided sufficient surgical anesthesia and postoperative analgesia for lower extremity wound debridement surgery in patients on antithrombotic drugs.

Fire severity and plant productivity recovery in a mixed grass prairie wildfire driven by extreme winds

Background Wildfire on rangelands in the mixed grassland can severely disrupt livestock operations. Understanding how fire severity impacts post-fire production recovery is important for grazing management. Aims We examined how topography and other environmental factors influence wildfire severity, or the consumption of biomass and exposure of soil, under extreme (>120 km h−1) wind conditions in native mixed grass prairie in western Canada. We also examined how variation in fire severity impacts grassland production recovery. Methods Fire severity and production recovery were measured using the bare soil index (BSI) and normalised difference vegetation index (NDVI). Impacts of topography, wind exposure, and site capability on fire severity and production recovery were assessed using generalised additive models. Key results Fire severity varied as a function of slope, wind exposure and fuel load. Severity peaked at NDVI between 0 and 0.4, values associated with high litter content and minimal green vegetation. Interactions between slope and aspect with respect to dominant wind direction generated very high fire severity on slopes greater than 15° that faced into the wind. Production recovery increased moderately with higher fire severity and recovery was generally higher on sites with lower potential productivity. Implications Post-fire production recovery was rapid; fire severity and site capability had only modest impacts on recovery rates demonstrating the resilience of grassland ecosystems to even severe wildfire.

Exploring the Influence of Tropical Cyclones on Regional Air Quality Using Multimodal Deep Learning Techniques

Tropical cyclones (TC) are dynamic atmospheric phenomena featuring extreme low-pressure systems and powerful winds, known for their devastating impacts on weather and the environment. The main purpose of this paper is to consider the subtle involvement of TCs in the air quality index (AQI), focusing on aspects related to the air quality before, during and after cyclones. This research employs multimodal methods, which include meteorological data and different satellite observations. Deep learning approaches, i.e., ConvLSTM, CNN and Real-ESRGAN models, are combined with a regression model to analyze the temporal variability in the air quality associated with tropical cyclones. Deep learning models are deployed to uncover complex patterns and non-linear interdependencies between cyclones’ features and the AQI to give predictive insights into the air quality fluctuations throughout the different stages of tropical cyclones. Furthermore, this study explores the aftermaths of TCs in terms of the air quality with respect to post-cyclone recovery. The findings offer an enhanced view of the role of TCs in the regional or global air quality, which will be useful for policymakers, meteorologists and environmental researchers. Utilizing a CNN for tropical cyclone (TC) classification and the extra trees regressor (ETR) for AQI prediction results in accuracy of 92.02% for the CNN and an R2 of 83.33% for the ETR. Hence, this work adds to our knowledge and enlightens us on the complex interactions between TCs and the air quality, highlighting wider public health concerns regarding climate adaptation and urban renewal.

Studying and analysis of deformation and stresses in horizontal-axis wind turbine using fluid-structure interaction method

Fluid-structure interaction (FSI) studies have become an important tool in the development of wind turbine blades as well as for analyzing and optimizing Horizontal Axis Wind Turbine (HAWT). The most essential elements for estimating the turbine blade strength to withstand extreme wind loads and aerodynamic performance are the blade deformation and the associated stresses. This study aims to compare the strength and analyze the deformation behavior of two models of HAWT blades. A three-dimensional model was created and loaded into a Finite Element (FE) model for analysis. The Computational Fluid Dynamics (CFD) investigation was coupled with the structural model using one-way FSI. In this article, the effect of the aerodynamics on the blade surface of a small HAWT has been studied numerically and experimentally. The airfoil used for the blade profile is S826 airfoil. To provide an appropriate displacement for static measurements, the blade in the experimental investigation is made of thermoplastic polyurethane material (TPU). It is noted that the current experimental findings verify the simulation results, and a comparison between the simulations and the experimental findings reveals a reasonable agreement. The numerical simulations are also implemented on a HAWT epoxy E-glass unidirectional (EEGUD) material. It can be concluded from this study that the blade deformation and stress on the blades are related to the wind speed. The deformation along the span length exhibits nonlinear variation that gradually increases from the blade root and reaches its maximum at the blade tip position. The tip deflection and equivalent stress were found to increase with an increase in wind speed. The dynamic analysis at different tip speed ratios shows the highest deformation at λ = 4, for wind speed of 20 m/s.

Usefulness of hot shot intermittent infusion online hemodiafiltration plus far-infrared therapy for dialysis patients with lower extremity arterial disease: a case report

BackgroundLower extremity arterial disease (LEAD) occurs at a high frequency in dialysis patients and is associated with a poor prognosis. In recent years, intermittent infusion online hemodiafiltration (I-OHDF) combined with far-infrared therapy (FIR) has been reported as being useful in dialysis patients with LEAD. However, there are also reports of worsening of the ulcers and gangrene in some cases. Hot shot I-OHDF (HS I-OHDF), which involves intermittent infusion of heated dialysate, is reported as being more effective than conventional I-OHDF for improving the plasma refilling rate (PRR) and peripheral circulation. We report the case of a patient in whom a lower extremity ulcer healed only after we switched from I-OHDF + FIR to HS I-OHDF + FIR, and the usefulness of this treatment.Case presentationThe patient was a 41-year-old male dialysis patient with LEAD who showed worsening of the ulcers in the lower extremity before he was switched from I-OHDF plus FIR to HS I-OHDF plus FIR; we compared the changes in the lower extremity blood flow, PRR, degree of wound healing, and subjective symptoms over time after the switch to HS I-OHDF plus FIR as compared with the values prior to the switching. As compared with the values during I-OHDF plus FIR, the lower extremity blood flow and PRR increased markedly during HS I-OHDF plus FIR. The wounds in the lower extremity improved over time during HS I-OHDF plus FIR and showed complete healing after 6 months; evaluation by visual analog scales (VASs) showed improved scores for all of fatigue, pain, coldness, and insomnia, and the patient reported improved subjective symptoms. The mechanism underlying the effectiveness of HS I-OHDF plus FIR in promoting wound healing is unknown, however, we speculated that the temperature change in the intermittent infusion solution resulted in increased blood flow in the true capillaries (resting vessels) and transfer of the nonthermal effects of FIR to more peripheral vessels.ConclusionsThis case demonstrates that combined use of HS I-OHDF with FIR can enhance the efficacy of FIR in dialysis patients with LEAD by increasing the lower extremity blood flow and PRR, which is useful for wound healing.

Converging profile relationships for offshore wind speed and turbulence intensity

Abstract. This paper reduces uncertainty in the quantification of offshore wind speed and turbulence intensity. A range of industry standard relationships, including those from International Electrotechnical Commission (IEC) and International Organization for Standardization (ISO), are compared with an extensive set of met mast data collected offshore northwestern Europe over recent decades. Analysis initially focused on over 1000 independent storm peak events identified within the 10 min mean wind speed data. Time series and coherent vertical profiles were subjected to detailed scrutiny and analysis, considering wind speeds at various averaging periods, turbulence intensity and gust factors. Most peak events were associated with neutral atmospheric conditions, so they were well represented by the ISO Frøya profile, with a shear close to the IEC power law exponent of α= 0.11. A new pragmatic approximation of atmospheric stability in terms of relative shear is outlined, bringing together key elements of the IEC and ISO standards. New empirical relationships to quantify offshore wind ambient turbulence intensity are described. A simple generalised form of gust factor relationship is adopted, with a coefficient that varies with averaging period. Distinct recommendations are made for estimating peak 10 min mean winds from peaks in 1 or 3 h mean winds. Finally, a simplified workflow for the estimation of extreme offshore winds is used to show how IEC and ISO relationships can be effectively combined.

Regional frequency analysis of extreme wind in Pakistan using robust estimation methods

The quantile estimates of extreme wind speed are needed for various areas of interest using regional frequency analysis (RFA) and extreme value theory. These calculations are crucial for the coding of wind speed. The data was taken from the NASA official website at a 10-meter distance and measured in meters per second (m/s). RFA of annual maximum wind speed (AMWS) using L-moments is performed utilizing annual maximum wind speed data from sixteen sites (16) in Pakistan’s Khyber Pakhtunkhwa province. There are no sites that are found to be discordant. The wards method is used to construct a homogenous region and make two homogenous regions from 16 sites. The heterogeneity test justifies that both clusters are homogeneous. The most appropriate probability distribution from the Generalized Normal (GNO), Generalized Logistic (GLO), Pearson Type-3 (P3), Generalized Pareto (GPA), and Generalized Extreme Value (GEV) distributions is chosen to calculate regional quantiles. According to the L-moments diagram and Z statistics, the GEV for Cluster- Ι and GLO for Cluster- ΙΙ are the best suggestions from the others. Both clusters’ robustness is measured utilizing relative bias (RB) and relative root mean square error (RRMSE). Overall, GEV distribution is fit for cluster-Ι, and the GLO distribution is fit for cluster-ΙΙ. Utilizing the site mean and median as index parameters, we can also find at-site quantiles from regional quantiles. The study’s quantile estimates can be employed in codified structural designs with policy consequences.

Circulation types and their relationship with extreme wind energy generation events in Poland

Circulation types and their relationship with extreme wind energy generation events in Poland

Probabilistic modeling of multivariate extreme non-Gaussian wind loads and its applications in envelope engineering

Probabilistic modeling for non-Gaussian wind load fields under extreme winds is crucial to the quantitative risk and reliability analysis of envelope structures. Based on the multi-point synchronous wind load data during typhoons, a probabilistic model is proposed to characterize multivariate non-Gaussian wind loads to improve the accuracy of the risk analysis considering data dimension reduction. In the proposed model, the Pareto distribution function is utilized to fit the marginal distribution, and the copula function is employed to construct the dependent structure of wind loads from different locations. In the marginal fitted results, the extreme wind load value in the edge region is about 0.10–0.15 higher than those from inner measurement points at quantile p = 95 %. In addition, the variation gradient from the different variable directions is approximately equal, and a sharp variation occurs at the point (0.10, 0.10) for bivariate joint distributions. Engineering applications given in this article are composed of three parts: calculating regional exceeding probability, estimating wind load vector under a specific regional exceeding probability, and determining the location of joint extreme wind loads using the joint gradient value. Finally, risk analysis of existing roof coverings is carried out, the edge corner region is weaker, and two engineering recommendations are given. For determining the regional design wind load, a comprehensive calculation framework considering the temporal dependence of different locations is established, and the reduction rates are in the range (5 %, 25 %).

FuXi-Extreme: Improving extreme rainfall and wind forecasts with diffusion model

FuXi-Extreme: Improving extreme rainfall and wind forecasts with diffusion model

Investigation on typhoon-induced aero-elastic response of membrane structures by wind tunnel test and numerical simulation

Extreme winds, such as typhoons, can lead to serious vibration and damage for flexible membrane roofs. An understanding of the aeroelastic behavior experienced by membrane structures during typhoons is therefore significant to allow well designed in practice. This paper investigates the aeroelastic response of umbrella shaped membrane structures under typhoon experimentally and numerically. The flexible scaled model is tested in typhoon field simulated in wind tunnel to investigate the aeroelastic characteristics varying with wind velocities and wind directions, including displacement response, non-Gaussian characteristics, frequency, modal shape and damping ratios et al. The full coupled fluid-structure interaction numerical model proposed is benchmarked and expanded in parameter discussions. The results indicate that non-Gaussian characteristics appear significant with positive skewness in pressure region and negative skewness in suction region. The probabilistic distribution proves leptokurtic type with kurtosis beyond three. The displacement response in statistics increases almost linearly with wind velocity while the non-Gaussian characteristics remain robust. The high-order mode shapes can be excited in typhoon, and their frequencies and damping ratios vary with wind velocities. The effects of both wind velocity and membrane pretension are proved to be more remarkable than rise-span ratio. This study can address the deficiency of current studies and provisions on the dynamic response of membrane structures in typhoons.