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Northern China experienced a severe sand and dust storm (SDS) on 14/15 March 2021. It was difficult to simulate this severe SDS event accurately. This study compared the performances of three dust-emission schemes on simulating PM10 concentration during this SDS event by implementing three vertical dust flux parameterizations in the Comprehensive Air-Quality Model with Extensions (CAMx) model. Additionally, a statistical gusty-wind model was implemented in the dust-emission scheme, and it was used to quantify the gusty-wind contribution to dust emissions and peak PM10 concentration. As a result, the LS scheme (Lu and Shao 1999) produced the minimum errors for peak PM10 concentrations, the MB scheme (Marticorena and Bergametti 1995) underestimated the PM10 concentrations by 70–90%, and the KOK scheme (Kok et al. 2014) overestimated PM10 concentrations by 10–50% in most areas. The gusty-wind model could reasonably reproduce the probability density function of 2-min wind speeds. There were 5–40% more dust-emission flux and 5–40% more peak PM10 concentrations generated by the gusty wind than the hourly wind in the dust-source regions. The increase of peak PM10 concentration caused by gusty wind in the non-dust-source regions was higher than in the dust-source regions, with 10–50%. Implementing the gusty-wind model could help improve the LS scheme’s performance in simulating PM10 concentrations of this severe SDS event. More work is still needed to investigate the reliability of the gusty-wind model and LS scheme on various SDS events.

This study analyzes the contribution of large-scale turbulent structures, including very large-scale and large-scale motions, to the streamwise turbulent kinetic energy and momentum flux in comparison with the contribution of the gusty wind disturbances based on the high-quality data obtained from the field measurements conducted in the near-neutral surface layer. The results of this study denote that the gusty wind disturbances contain only a portion of the energy contained in very large-scale motions and do not contain any of the information contained in large-scale motions. The amount of lost contributions to the streamwise turbulent kinetic energy and momentum flux increases linearly with the friction velocity, eventually becoming 53% and 67%, respectively. This indicates that large-scale turbulent structures (very large-scale motions and large-scale motions) better describe the coherent structures in the atmospheric surface layer when compared with the gusty wind disturbances.

When the relation between the interconnected grid and the main system is weak, once a serious failure occurs in the tie line both the local small grid and the large grid, the local weakly connected grid will disconnect from the main grid and into island operation. Due to the small number of island operating units and the overall capacity and inertia are very small, the system frequency and voltage are easy to fluctuate in a large range, and operational stability is very prominent. This paper studied the effects the stability of isolated island grid for gusty wind and gradual wind. At the same time, the island system stable operation for different ratio of wind generator is also studied. Finally, by analyzing the regulating effect of reactive energy compensation device, voltage stability of wind electricity is improved.

Wave and meteorological observations from free‐drifting buoys deployed during four field campaigns were collated to evaluate the impact of wind gustiness on wave evolution. Met‐ocean conditions included wind speeds up to 25 m/s and mixed seas and swell. Analysis of bulk characteristics indicates that wave heights in gusty winds are 20%–50% larger than wave heights in steady winds. Spectral characteristics, including the peak frequency, peak energy, and spectral tail shape, indicate more developed waves in gusty winds than steady winds for the same mean wind speed. Observed spectral differences are linked to wind‐wave growth through analysis of mean square slope, equilibrium friction velocity, and growth rate. The total energy input to the wave spectrum and the actively forced frequencies differ between gusty and steady winds. Results support hypotheses of a higher “effective” wind in gusty conditions and emphasize the need for robust formulation of gustiness in wave models.

Cold pools formed by precipitating convective clouds are an important source of mesoscale temperature variability. However, their sub‐mesoscale (100 m–10 km) structure has not been quantified, impeding validation of numerical models and understanding of their atmospheric and societal impacts. We assess temperature variability in observed and simulated cold pools using variograms calculated from dense network observations collected during a field experiment and in high‐resolution case‐study and idealized simulations. The temperature variance in cold pools is enhanced for spatial scales between ∼5 and 15 km compared to pre‐cold pool conditions, but the magnitude varies strongly with cold pool evolution and environment. Simulations capture the overall cold pool variogram shape well but underestimate the magnitude of the variability, irrespective of model resolution. Temperature variograms outside of cold pool periods are represented by the range of simulations evaluated here, suggesting that models misrepresent cold pool formation and/or dissipation processes. Plain Language Summary Cold pools are cool gusty winds beneath thunderstorms that are formed by cooling from rainfall. They have many important impacts in the atmosphere and on society but are difficult to properly simulate in numerical weather models. The variability in cold pool temperature is an understudied feature of cold pools but which is important to represent in numerical models. In this study, we examine cold pool temperature variability from a dense network of surface weather station observations collected during a field campaign, and we compare those observations to numerical simulations of cold pools in a range of environments. We find that cold pools enhance temperature variability for distances greater than ∼5 km but suppress variability on smaller distances, and that the magnitude of cold pool temperature variability is strongly dependent on the environment and cold pool lifetime. We also show that numerical models, even at very high resolutions, are not able to properly simulate the magnitude of cold pool temperature variability. We highlight areas for improvement in numerical models that may help to improve simulations of cold pool variability, including land‐atmosphere interactions, turbulence, and conversion processes between water vapor and condensed water in storms. Key Points Cold pool impacts on sub‐mesoscale temperature variability are quantified using variograms derived from observations and simulations Cold pools enhance temperature variability on scales between 5 and 15 km, but the magnitude varies strongly with lifetime and environment High‐resolution case‐study and idealized simulations underestimate the magnitude of cold pool variability, irrespective of resolution

In November 2016, an unprecedented epidemic thunderstorm asthma event in Victoria, Australia, resulted in many thousands of people developing breathing difficulties in a very short period of time, including 10 deaths, and created extreme demand across the Victorian health services. To better prepare for future events, a pilot forecasting system for epidemic thunderstorm asthma (ETSA) risk has been developed for Victoria. The system uses a categorical risk-based approach, combining operational forecasting of gusty winds in severe thunderstorms with statistical forecasts of high ambient grass pollen concentrations, which together generate the risk of epidemic thunderstorm asthma. This pilot system provides the first routine daily epidemic thunderstorm asthma risk forecasting service in the world that covers a wide area, and integrates into the health, ambulance, and emergency management sector. Epidemic thunderstorm asthma events have historically occurred infrequently, and no event of similar magnitude has impacted the Victorian health system since. However, during the first three years of the pilot, 2017–19, two high asthma presentation events and four moderate asthma presentation events were identified from public hospital emergency department records. The ETSA risk forecasts showed skill in discriminating between days with and without health impacts. However, even with hindsight of the actual weather and airborne grass pollen conditions, some high asthma presentation events occurred in districts that were assessed as low risk for ETSA, reflecting the challenge of predicting this unusual phenomenon.

A comprehensive database of strong winds up until AD 1600 was created based on documentary evidence for the area within the modern-day borders of Poland. Three types of documentary sources were used: handwritten and unpublished, published, and “secondary” literature. The database contains detailed information about occurrences of strong wind (the location/region, time, duration and indexation for intensity, extent and character of damage), along with the exact textual content of the original weather note, the name of the source, and an evaluation of the source's quality. Five categories of strong winds were delimited: 1 – fresh and strong breeze (Beaufort scale 5–7); 2 – gale (8–9); 3 – storm (10–12); 4 – squall (i.e. gusty wind during a thunderstorm); and 5 – tornadoes. The intensity, extent, and character of damage were estimated based on the proposition given by Brázdil et al. (2004), which we slightly modified to include the Baltic Sea and its influence on coastal parts. In the database, 137 thus-defined strong winds were identified. A reliable estimate of some characteristics of the occurrence of strong winds in Poland seems possible from the mid-15th century onwards. The highest number of strong winds occurred in the second half of the 16th century, with a maximum in the 1570s. For each season, the greatest number of strong winds was found for the Baltic Coast and Pomeranian Region, followed by Silesia and Lesser Poland. Storms and gales were most common during the cold half-year (mainly in March, November, and December).

Turbulent and gusty wind conditions can cause generator overspeed peaks to exceed a threshold that then lead to wind turbine shutdowns, which then decrease the energy production of the wind turbines. We derive so‐called “gust measures” that predict when generator overspeed peaks may occur. These gust measures are then used to develop advanced controllers to mitigate generator overspeed peaks so that wind turbines can operate more robustly in difficult wind conditions without exceeding generator overspeed thresholds that would lead to turbine shutdown events. The advanced controllers are demonstrated in nonlinear aeroelastic simulations using the open‐source wind turbine simulation tool OpenFAST. To increase the realism of the simulations, they are run using field‐replicated wind conditions and a wind turbine model based on data from an experimental field campaign on a downscaled demonstrator of a novel extreme‐scale, two‐bladed, downwind rotor design.

Sundowner winds are downslope gusty winds often observed on the southern slopes of the Santa Ynez Mountains (SYM) in coastal Santa Barbara (SB), California. They typically peak near sunset and exhibit characteristics of downslope windstorms through the evening. They are SB’s most critical fire weather in all seasons and represent a major hazard for aviation. The Sundowner Winds Experiment Pilot Study was designed to evaluate vertical profiles of winds, temperature, humidity, and stability leeward of the SYM during a Sundowner event. This was accomplished by launching 3-hourly radiosondes during a significant Sundowner event on 28–29 April 2018. This study showed that winds in the lee of the SYM exhibit complex spatial and temporal patterns. Vertical profiles showed a transition from humid onshore winds from morning to midafternoon to very pronounced offshore winds during the evening after sunset. These winds accompanied mountain waves and a northerly nocturnal lee jet with variable temporal behavior. Around sunset, the jet was characterized by strong wind speeds enhanced by mountain-wave breaking. Winds weakened considerably at 2300 PDT 29 April but enhanced dramatically at 0200 PDT 29 April at much lower elevations. These transitions were accompanied by changes in stability profiles and in the Richardson number. A simulation with the Weather Research and Forecasting (WRF) Model at 1-km grid spacing was examined to evaluate the skill of the model in capturing the observed winds and stability profiles and to assess mesoscale processes associated with this event. These results advanced understanding on Sundowner’s spatiotemporal characteristics and driving mechanisms.

Wind gustiness in the marine atmospheric boundary layer affects significantly the dynamics of air–sea interaction. To understand the impacts of wind gust events, we perform large-eddy simulation of wind turbulence over a travelling wave to investigate the response of the wind field to an impulsive wind speed increase or decrease. It is found that the turbulence fluctuations and the terms in the turbulent kinetic energy budget equation have a delayed response to the change in the mean flow, while the response of the wave-coherent motions is quasi-stationary. The wave-coherent motions are investigated quantitatively through comparison with a viscous curvilinear model developed by Cao et al. (J. Fluid Mech., vol. 901, 2020, A27) and Cao & Shen (J. Fluid Mech., vol. 919, 2021, A38). We observe an asymmetric hysteresis between the growing wind and the decaying wind in the evolution of the form drag and the viscous drag. We find further that the variation of the wave growth rate during the wind gust is related closely to the contribution from the out-of-phase component of the vertical velocity. Our discoveries provide evidence for the necessity of improving non-equilibrium turbulence and wind input modelling to account for the wind gustiness effect in future studies.