Increased occurrence of high impact compound events under climate change

While compound weather and climate events (CEs) can lead to significant socioeconomic consequences, their response to climate change is mostly unexplored. We report the first multi-model assessment of future changes in return periods for the co-occurrence of heatwaves and drought, and extreme winds and precipitation based on the Coupled Model Intercomparison Project (CMIP6) and three emission scenarios. Extreme winds and precipitation CEs occur more frequently in many regions, particularly under higher emissions. Heatwaves and drought occur more frequently everywhere under all emission scenarios examined. For each CMIP6 model, we derive a skill score for simulating CEs. Models with higher skill in simulating historical CEs project smaller increases in the number of heatwaves and drought in Eurasia, but larger numbers of strong winds and heavy precipitation CEs everywhere for all emission scenarios. This result is partly masked if the whole CMIP6 ensemble is used, pointing to the considerable value in further improvements in climate models.

Development of an Algorithm for Prediction of the Wind Speed in Renewable Energy Environments

The aim of this work is to develop an algorithm that is able to provide predictions of wind speed statistics (WSS) in renewable energy environments. The subject is clearly interesting, as predictions of storms and extreme winds are important for decision makers and emergency response teams in renewable energy environments, e.g., in places where wind turbines could be located, including cities. The goal of the work is achieved through two phases: (a) During the preparation phase, the construction of a big WSS database based on computational fluid dynamics (CFD) is carried out, which includes flow fields of different wind directions in all grid numerical points; (b) In the second phase, the algorithm is used to find the records in the WSS database with the closest meteorological conditions to the meteorological conditions of interest. The evaluation of the CFD model (including both RANS and LES turbulence methodologies) is performed using the experimental data of the MUST (Mock Urban Setting Test) wind tunnel experiment.

A Comprehensive Analysis of Light Weight Steel Structure and Wind Load

Review to hot-rolled steel structures, cold-formed steel structures are susceptible to extreme winds because of the light weight of the building and its components. Many modern cold-formed steel structures have sustained significant structural damage ranging from loss of cladding to complete collapse in recent cyclones. This article first provides Review some real damage cases for light steel structures induced by the high winds. After that, the paper reviews research on the damage analysis and evaluation of light steel structures caused by strong winds, which include connection failure, fatigue failure, purlin buckling, and primary frame component instability problems. Moreover, this review will mention some applications of structure damage assessment methods in this area, such as vulnerability analysis and performance-based theory, etc.

Future changes in the extratropical storm tracks and cyclone intensity, wind speed, and structure

Future changes in extratropical cyclones and the associated storm tracks are uncertain. Using the new CMIP6 models, we investigate changes to seasonal mean storm tracks and composite wind speeds at different levels of the troposphere for the winter and summer seasons in both the Northern (NH) and Southern Hemispheres (SH). Changes are assessed across four different climate scenarios. The seasonal mean storm tracks are predicted to shift polewards in the SH and also in the North Pacific, with an extension into Europe for the North Atlantic storm track. Overall, the number of cyclones will decrease by ~5 % by the end of the 21st century, although the number of extreme cyclones will increase by 4 % in NH winter. Cyclone wind speeds are projected to strengthen throughout the troposphere in the winter seasons and also summer in the SH, with a weakening projected in NH summer, although there are minimal changes in the maximum wind speed in the lower troposphere. Large amounts of this change can be associated with changes in the speed of cyclones in the future. Changes in wind speeds are concentrated in the warm sector of cyclones and the area of extreme winds may be up to 40 % larger by the end of the century. The largest changes are seen for the SSP5-85 scenario, although large amount of change can be mitigated by restricting warming to that seen in the SSP1-26 and 2-45 scenarios. Extreme cyclones show larger increases in wind speed and peak vorticity than the average strength cyclones, with the extreme cyclones showing a larger increase in wind speed in the warm sector.

Structural bracing of wooden roofs under the extreme winds

An essential element of every building is a roof that protects it against the influence of weather conditions - rainfall, wind, and temperature changes. The shape of the roof, the type of roof covering, and the slope of the roof have the greatest impact on the type and material solutions. The roof structures are made of wooden, steel, or reinforced concrete. Especially in single-family residential buildings, wooden roof structures are most often used. Wood is perceived by many as the oldest and best building material, valued for its low weight, good strength, elasticity, and high thermal and insulation values. Traditional roof has been used over the centuries. The more common roof in wood framing roof is gable and hip roof which is consist of rafter, ridge, hip, collar tie and joist. The common slop for hip roof is 3/12 to 12/12. By increasing the slop, the length of the hip element in roof increases and needs to brace closely. The aim of the study is to analyse the location of roof braces in hip roof structures, due to the ultimate and serviceability limit states, under dead, live and wind loads based on finite element method model. Two wind speeds of 22 m/s and 40 m/s is taken into consideration. Elements with the different spans, cross-sections and slope of the roof are analysed.

Expected Recurrence of Extreme Winds in Northwestern Sahara and Associated Uncertainties

Estimating the probability of the occurrence of hazardous winds is crucial for their impact in human activities; however, this is inherently affected by the shortage of observations. This becomes critical in poorly sampled regions, such as the northwestern Sahara, where this work is focused. The selection of any single methodological variant contributes with additional uncertainty. To gain robustness in the estimates, we expand the uncertainty space by applying a large body of methodologies. The methodological uncertainty is constrained afterward by keeping only the reliable experiments. In doing so, we considerably narrow the uncertainty associated with the wind return levels. The analysis suggest that not necessarily all methodologies are equally robust. The highest 10-min speed (wind gust) for a return period of 50 years is about 45 ms−1 (56 ms−1). The intensity of the expected extreme winds is closely related to orography. The study is based on wind and wind gust observations that were collected and quality controlled for the specific purposes herein. We also make use of a 12-year high-resolution regional simulation to provide simulation-based wind return level maps that endorse the observation-based results. Such an exhaustive methodological sensitivity analysis with a long high-resolution simulation over this region was lacking in the literature.

Lampiran 1A Paper Sediment Characteristics and Wind Induced Sediment Dynamics in Lake Markemeer, the Netherlands, Aquatic Sciences

In 2007/08, a study was undertaken on thesediment dynamics in shallow Lake Markermeer (theNetherlands). Firstly, sediment characteristics were determined at 49 sites in the lake. Parameters such as median grain size and loss on ignition showed a spatial as well as water depth related pattern, indicating wind-induced sediment transport. Highly significant correlations were found between all sediment parameters. Lake Markermeer sediment dynamics were investigated in a sediment trap field survey at two permanent stations in the lake. Sedimentyields, virtually all coming from sediment resuspension, were significantly correlated with average wind speeds,though periods of extreme winds also played a role.Sediment resuspension rates for Lake Markermeer were high, viz. on average ca. 1,000 g m-2 day-1. The highlydynamic nature of Lake Markermeer sediments must bedue to the overall shallowness of the lake, together with itslarge surface area (dynamic ratio = [H(area)]/[averagedepth] = 7.5); wind-induced waves and currents willimpact most of the lake’s sediment bed. Indeed, near-bed currents can easily reach values 10 cm/s. Measurements of the thickness of the settled ‘‘mud’’ layer, as well as 137Csdating, showed that long-term deposition only takes placein the deeper SE area of the lake. Finally, lake sediment dynamics were investigated in preliminary laboratory experiments in a small ‘‘micro-flume’’, applying increasingwater currents onto five Lake Markermeer sediments.Sediment resuspension started off at 0.5–0.7 cm/s andshowed a strongly exponential behaviour with respect to these currents.