Strong Gusts Research Articles

Height Control System for Wind Turbines Based on Critical Wind Speed Calculation

The increasing frequency of wind turbine failures due to extreme weather conditions necessitates the implementation of new solutions to enhance their operational reliability. This paper presents an automatic rotor drop system specifically designed for wind turbines equipped with the Onipko rotor. The system aims to protect turbines from damage caused by critical wind speeds, reducing maintenance costs and extending the equipment’s lifespan. The unique design of the Onipko rotor allows it to operate at wind speeds as low as 0.1 m/s. However, its high drag coefficient and lack of aerodynamic optimization make it susceptible to mechanical stress and structural instability under strong gusts, requiring additional protective measures. The paper presents a calculation of the critical wind speed at which protective measures must be initiated. Through mathematical modeling, this study demonstrates the effectiveness of the rotor drop system in ensuring safe operation at wind speeds reaching 23.5 m/s. The optimization of the PI controller parameters provides a rapid response and stability, significantly enhancing the resilience of wind turbines to adverse weather conditions.

Quantitative risk analysis of road transportation of hazardous materials in coastal areas

Given the complex climate conditions in coastal areas and their role as key transportation hubs for hazardous chemicals, this study proposes a method to quantitatively and comprehensively evaluate transportation risks. Initially, accident data were analyzed to identify risk factors from five aspects: human, vehicle, materials, environment, and management, based on system safety theory. Subsequently, a risk analysis model was developed using Decision-making Trial and Evaluation Laboratory, interpretive structural model theory, and Bayesian theory to quantitatively assess accident risk levels. The model was applied to a case involving a hazardous chemical accident on a cross-sea bridge, where Bayesian backward reasoning was used to analyze the sensitivity and importance of risk factors. This approach facilitated the key risk factors affecting the safety of hazardous chemical transportation systems. Notably, the study incorporated scenarios involving hazardous material transport vehicles crossing sea bridges into the risk assessment framework, offering valuable insights for management authorities. It also considered the impact of strong side winds-a factor often overlooked-in hazardous material transport. The validation process demonstrated that the method accurately quantifies the risk of hazardous chemical transportation and identifies the key factors influencing accident occurrence. The research highlights that strong gusts of wind significantly impact safety, and human factors are crucial in the overall risk system.

Climatological Observation and Model Simulation of Near-Surface Hourly Maximum Gust Wind in Northern China

Abstract While previous work on the climatology of Northern China has focused on mean wind speed, wind gusts have received comparatively less attention but are equally important to various users. In this paper, an observed hourly maximum gust wind speeds (HMGS) dataset across North China has been created by using time series from 174 meteorological stations. The dataset offers superior quality, high spatiotemporal near-surface HMGS series for North China spanning from 2015 to 2022. The objective of this study is first to improve our understanding of the spatiotemporal gusts climatology in North China by analyzing the observed gust data. Second, we aim to supplement the observational data by using gust analysis and forecast data with a high spatial–temporal resolution from model simulations. The spatial characteristics of the seasonal cycle of the simulated analysis of mean HMGS and the performance in predicting gusts based on the geographical locations and elevations of the validation stations were investigated by comparing it with the observations. Results indicate the following: 1) Wind direction and intensity are affected by the terrain and climate conditions of different weather stations. Stations situated along the Bohai Bay coastal region and at higher-elevation areas of North China exhibit a higher mean HMGS than those located in the coastal and inland plains. 2) The probability density function curves for wind speed and wind direction exhibit notable variations across different elevation intervals. The contribution of moderate and strong gust wind speeds increases gradually with increasing altitude, while the gust directions in mountainous areas exhibit relatively consistent patterns due to the increased exposure to synoptic-scale forcing at higher elevations. 3) The nowcasting prediction system analysis of mean HMGS provides a higher horizontal resolution that is capable of capturing the contrasts between land and sea, as well as the influence of high HMGS associated with large-scale circulations in high-elevation regions. Significance Statement The purpose of this study is to better understand the spatiotemporal gust climatology in North China and the performance of the model-simulated gust analysis and forecast data. This is important because gusts conditions differ due to varying topographic and climatic conditions of different weather stations. Our results provide a valuable insight into the climatological variations of HMGS, their drivers, and identify the deficiencies in the model-simulation gusts.

Accuracy of the application of mobile technologies for measurements made in headings of the Kłodawa Salt Mine

Abstract The “Kłodawa” salt mine, due to geological conditions and continuous salt extraction, is subject to a range of measurements documenting the speed of changes in the geometry of the chambers. Cyclic surveys are conducted under challenging conditions several hundred metres underground. Consequently, measurement methods used for determining the parameters of the ongoing clamping should be of high precision but also be resistant to dense dust (in fields of active mining) and strong gusts (near ventilation shafts). The research presented here concerns the analysis of the possibilities of solutions offered by modern technologies in mine conditions. Test measurements were conducted at observation stations using linear bases stabilized with metal pins. The base points were located in the aisles, ceiling, and bottom of the chamber in Field 1 of “Kłodawa” salt mine at the depth of 600m. Point clouds mapping the object were acquired using a Leica RTC360 3D laser scanner and two mobile devices: Motorola G100 smartphone and iPad Pro with LiDAR technology using the Pix4Dcatch application. The accuracy of the point cloud from the Leica RTC360 3D laser scanner was determined by comparing it with classic measurements taken with a Leica Disto laser rangefinder. The repeatability and accuracy of the point cloud from a smartphone were examined using statistical analysis based on Pearson’s correlation coefficient and cross-correlation. An attempt was also made to approximate the correlation between the obtained errors and two parameters: the number of images and the size of the object.

Flow measurement in the southern coast of the Caspian Sea

Oceanographic monitoring was conducted in the southern basin of the Caspian Sea to evaluate the physical structure of seawater and sea currents. This monitoring aimed to gather data and analyze the characteristics of the seawater, including temperature, salinity, density, and other relevant parameters. Additionally, the monitoring also focused on studying the patterns and dynamics of sea currents in the region. The collected data and analysis from this monitoring period provided valuable insights into the oceanographic conditions of the southern basin of the Caspian Sea. During storm events, a high level of correlation between the current and wind data was observed in the southern basin of the Caspian Sea during the 2017-2018 monitoring period. The measured current data indicated that the predominant directions were north (N) and northwest (NW). It was observed that strong gusts predominantly originated from the north (N) and northwest (NW) directions. Additionally, a smaller portion of the strong gusts was observed to come from the South-Southeast (S-SE) direction. These findings indicate that the prevailing wind patterns during the monitoring period were primarily from the north and northwest, with a lesser contribution from the South-Southeast direction. The current profiles observed during the monitoring period in the southern basin of the Caspian Sea were primarily influenced by the general circulation pattern of the region. This circulation pattern played a significant role in shaping the current profiles observed during the measurements. In terms of the surface current speed, the maximum recorded value was approximately 200 cm/s, which occurred in January. This indicates that there were instances of relatively high-speed currents in the southern basin of the Caspian Sea during that time. The evaluation of inter-annual variability in vertical structure and seawater temperature profiles during the monitoring period confirmed the presence of seasonal stratification in the water column of the southern basin of the Caspian Sea. This stratification was observed to consist of different layers, including the surface mixed layer, thermocline, and deep-water layers. The formation of these layers is indicative of the seasonal variations in temperature and density within the water column. The vertical changes in the water’s physical parameters during the monitoring period revealed the formation of stratification in the southern basin of the Caspian Sea. In March, it was observed that the water temperature decreased from 11.5°C at the surface to 8.5°C at a depth of 100 m, indicating the presence of a temperature gradient. As the monitoring progressed into May, the stratification became stronger, with the surface water temperature reaching around 23°C. By August, the surface layer of the sea water experienced a significant increase in temperature, reaching 29°C. These observations highlight the development of stratification and the seasonal variations in water temperature during the monitoring period in spring and summer seasons. The water temperature beneath the thermocline layer, specifically at a depth of 100 meters, was recorded to be around 8-8.5 oC. Additionally, the water salinity in the water column exhibited fluctuations between 12-12.5 (psu). Monitoring and understanding physical properties variations are crucial for assessing the oceanographic conditions and their potential impact on marine ecosystems in the southern basin of the Caspian Sea.

Acoustic effects of drone flights during sudden decelerations

With introduction of U-Spaces into European urban airspaces, unmanned aircraft traffic is expected to increase in the coming years. The growing number of unmanned aircraft, common known as drones, raises the question of the noise impact of these vehicles. So far, this new noise source has only been investigated acoustically in a rudimentary way. The German Environment Agency has, therefore, launched a measurement campaign with various small drone models to investigate acoustic effects. Since drone flights must be designed to be safe, a measurement campaign was conducted in which the models performed a full braking maneuver just before the measurement microphone. This is the case for collision avoidance or when strong gusts of wind occur. In addition, binaural measurements were recorded to provide psychoacoustic findings, as these parameters may be related to the degree of annoyance perceived by the public. In this paper, the measurements and results are presented. Noise levels of the overflights arecompared with noise levels of the deceleration maneuvers. In addition, psychoacoustic quantities such as loudness or sharpness are used and compared for both maneuvers. Finally, conclusions are drawn for the evaluation of drone noise, which can be used for future noise regulations or standardization.

A Numerical Study About the Flow Around Motorbike with Different Types of Fairing When Travel Through Crosswind

Riding a motorbike possess to a dangerous situation because of its stability and balance. Crosswind has a significant impact on riding since, with a strong gust, it can easily drive the motorbike off the road or into another lane or traffic. A numerical study has been conducted to investigate the aerodynamic loads of the drag, side, and lift coefficient and to analyze the flow pattern occurs of the motorbike with different types of fairing when travel under various angle of crosswind that was set ranging 0◦, 15◦, 30◦, 60◦ to 90◦. Two models of Yamaha YZF M1 with different types of fairing were designed using SolidWorks 2020 and then simulated using Ansys CFX with 25m/s as the velocity for main and crosswind inlet. The aerodynamic loads coefficient was calculated for each model and the streamlines flow were analyzed. The aerodynamic loads coefficient was found increases as the yaw angle increases. Half fairing model was found to have higher aerodynamic coefficient compared to fully fairing model since half fairing model was not aerodynamic shape.

Wind Gust Parameters in the Lower Troposphere Based on Doppler Lidar Data

AbstractWind gusts are common small‐scale weather phenomena characterized by a rapid increase in wind speed over a short period of time. Wind gusts affect a wide range of interests, including aviation safety, wind energy and professional skiing, while strong gusts can also cause severe weather events and limit visibility. However, the characteristics of gusts in the lower troposphere are not yet well understood, especially at the top of the boundary layer. In this paper, the gust parameters in the lower atmosphere at different heights and their diurnal variation characteristics are examined based on Doppler lidar data from the gentle coastal topography of Shandong Province, China. The results show that all the gust parameters have distinct stratification characteristics, with significantly different diurnal variations below 400 m, between 400 and 1,200 m, and above 1,200 m (above the ground, same below). Wind gusts are considered to be the result of turbulent disturbances superimposed on the background airflow, and strong turbulence could cause the instantaneous winds to significantly deviate from the mean airflow. The magnitude of the peak gust is mainly controlled by the mean flow, but the gust factor, which is the ratio of the peak gust to the mean flow, is almost independent of the mean flow and has a strong positive correlation with the turbulence intensity. These results imply that gusts of different properties occur at varying altitudes, with differences depending on turbulence intensity and mean airflow, and provide an observational basis for studies of gust structure.

Strong surface winds in Storm Eunice. Part 1: storm overview and indications of sting jet activity from observations and model data

Strong surface winds in Storm <i>Eunice</i>. Part 1: storm overview and indications of sting jet activity from observations and model data

Gust alleviation by spanwise load control applied on a forward and backward swept wing

The present paper investigates the feasibility of gust load alleviation at transonic speeds on a backward swept and a forward swept transport aircraft configuration. Spanwise-distributed control surfaces at the leading and trailing edges are employed to control gust-induced wing bending as well as wing torsion moments. The deflection amplitude and temporal flap actuation are determined by a novel scheme that builds on the aerodynamic strip theory. The aerodynamic effectiveness of the actuators is taken from a data base, computed from either 2D infinite swept wing simulations, or from yawed computations that take the effects of boundary-layer cross flow and the local sweep angle of the control surface into account. The present numerical flow simulations reveal that careful application of control laws at the trailing edge alleviates wing bending moments caused by strong vertical gusts by 85–90%, for both aircraft configurations. The application of leading-edge flaps introduces significant nonlinear aerodynamic interactions, that make the control of torsional moments comparably challenging. Here, the present results indicate that about 60% of wing torsion loads due to strong gusts can be removed.

Vision-Based UAV Landing with Guaranteed Reliability in Adverse Environment

Safe and accurate landing is crucial for Unmanned Aerial Vehicles (UAVs). However, it is a challenging task, especially when the altitude of the landing target is different from the ground and when the UAV is working in adverse environments, such as coasts where winds are usually strong and changing rapidly. UAVs controlled by traditional landing algorithms are unable to deal with sudden large disturbances, such as gusts, during the landing process. In this paper, a reliable vision-based landing strategy is proposed for UAV autonomous landing on a multi-level platform mounted on an Unmanned Ground Vehicle (UGV). With the proposed landing strategy, visual detection can be retrieved even with strong gusts and the UAV is able to achieve robust landing accuracy in a challenging platform with complex ground effects. The effectiveness of the landing algorithm is verified through real-world flight tests. Experimental results in farm fields demonstrate the proposed method’s accuracy and robustness to external disturbances (e.g., wind gusts).

Influence of Porosity on Drag Coefficient of Perforated Road Signs

To ensure the structural stability of road signs against strong gusts of wind, perforated road signs with sign boards perforated at regular intervals have been adopted for use in urban road infrastructure. However, ASCE 7-22 standards do not consider the drag coefficient of signs with low porosity, i.e., less than 30%. Therefore, here, computational fluid dynamics (CFD) analysis was performed to analyze the drag coefficient of perforated road signs with a porosity of less than 30%. The aspect and clearance ratios, which are the width/height ratio of a perforated road sign and the height of the perforated road sign/its distance from the ground, respectively, were set as parameters. Subsequently, the drag coefficient of perforated road signs with a porosity of 30% was calculated, and the effect of porosity and wind speed on the drag coefficient of perforated road signs was analyzed. Results show that the drag coefficient of perforated road signs decreased as the porosity increased, with a drag coefficient reduction effect of up to 0.85 times. Furthermore, perforated road signs with a high clearance ratio exhibited significant decreased drag coefficient. For perforated road signs, the drag coefficient does not show a clear correlation with wind speed.

Chile and its Potential Role Among the Most Affordable Green Hydrogen Producers in the World

As result of the adverse effects caused by climate change, the nations have decided to accelerate the transition of the energy matrix through the use of non-conventional sources free of polluting emissions. One of these alternatives is green hydrogen. In this context, Chile stands out for the exceptional climate that makes it a country with a lot of renewable resources. Such availability of resources gives the nation clear advantages for hydrogen production, strong gusts of wind throughout the country, the most increased solar radiation in the world, lower cost of production of electrical supplies, among others. Due to this, the nation would be between the lowest estimated cost for hydrogen production, i.e., 1.5 USD/kg H2 approximately, scenario that would place it as one of the cheapest green hydrogen producer in the world.

Distributions of gust and peak factors at a pedestrian level in a simplified urban canopy obtained by particle image velocimetry

The complex velocity fields within an urban canopy affect the occurrence of rare weak and strong wind-speed phenomena at the pedestrian level. Although particle image velocimetry (PIV) is widely used to determine velocity components, it has not been applied to pedestrian spaces for rare wind events, owing to the surrounding buildings. Therefore, in this study, two velocity components within a simplified urban canopy layer were measured using time-resolved PIV by inserting a laser optics system into a focal block. We determined the turbulent statistics, probability densities, gust factor (GF), and peak factor (PF) at the pedestrian level within the canopy layer. The probability density functions of the velocity components at positions with a lower mean wind speed tend to be negatively skewed, whereas those at positions with a higher mean wind speed tend to become closer to the Gaussian distribution. The GF values are small in the regions where a larger velocity is observed. However, the PF shows less distribution than the GF, regardless of the measurement position. Owing to the importance of strong gusts, the PF could be a more useful index for evaluating strong winds speed within the urban canopy layer.

Extending the Dynamic Equilibrium Model of Paradox: Unveiling the dissipative dynamics in organizations

The dynamic equilibrium model of organizing has become an influential theoretical framework in paradox research. The model describes paradox management as tightrope-walking, as actors cope with paradoxical tensions through continuous microshifts. The underlying assumption is that once actors accept the paradox and support opposing poles in a consistently inconsistent manner, they can effectively manage organizational tensions. We argue that paradoxical tensions cannot be subsumed under managerial control in this way due to the emergent and unpredictable nature of paradoxes in organizations. Hence, in addition to needing to balance on a tightrope, the tightrope walker may find the rope suddenly pulled in an unexpected direction by a strong gust of wind. To advance theory development, we put forward the concept of dissipative equilibrium to better capture the temporary nature of balance and the continuous vigilance and interventions needed from management to (re)balance an organization in the presence of unexpected developments that are beyond management’s control.

Aerodynamics and aeroelastic performance of a rigid-frame bridge with a bluff body girder subjected to short-rise-time gusts

Short-rise-time gusts in mountainous areas are extreme winds with the characteristics of rapidly varying wind speeds and directions, strong suddenness, and large angles of attack. Currently, studies on long-span bridges under short-rise-time gusts in mountainous areas, especially experimental studies, are limited. In this study, a typical long-span rigid-frame bridge with a bluff body girder located in a mountainous area suffering from frequent gusts was selected. Corresponding sectional and full aeroelastic model tests in a multiple-fan active control wind tunnel were performed to investigate the aerodynamic forces and wind-induced responses under strong gusts. Two aerodynamic measures (i.e., flange slab and stabilizing plate) were applied to mitigate the impact of gusts on the studied bridge. Moreover, numerical simulation analysis was also carried out to investigate the effects of gusts on the wind-induced stresses. The experimental results demonstrated that the gust parameters significantly affect the aerodynamic forces and wind-induced responses of the long-span rigid-frame bridge, especially under construction, although this type of bridge usually shows less wind-related sensitivity under normal monsoon climates. Furthermore, the proposed aerodynamic measures effectively mitigated the displacement responses of the studied bridge subjected to gusts in mountainous areas. This investigation can provide a more comprehensive understanding of the aerodynamics and aeroelastic performance of similar bridges under gusty conditions.

An improvement of wind gust estimate (WGE) method for squall lines

Severe wind gusts produced by squall lines are difficult to monitor and forecast. This paper assessed and improved the physics-based Brasseur WGE (wind gust estimate) method for diagnosing wind gust of squall lines by coupling the WGE methods with the WRF (Weather Research and Forecasting) model. The simulation results show that the Brasseur WGE method accurately captured the strong gust feature with 32 m·s−1 maximum wind speed during the disastering Shipwreck event occurred over Yangtze River on 1 June 2015, but overestimated the extended area of severe gust speeds. Analysis of the kinematic structure and boundary-layer conditions of the squall line confirmed the theoretical applicability of the Brasseur WGE method for squall lines. A novel gust-front-area limiting method was introduced to modify the Brasseur WGE method, which effectively reduces its gust wind overestimation area. Furthermore, five squall line events occurred in the middle China during 2021 were simulated to test the modified WGE method and the results exhibit significant improvements to the wind gust forecasts, with an average false alarm rate decreased from 0.89 to 0.54, and the critical success index(CSI) increased from 0.1 to 0.4.

The Struggle for the Existence in John Steinbeck’s The Grapes of Wrath

The issue of struggle for existence in John Steinbeck’s The Grapes of Wrath (1939) is examined in this research article. The struggle for existence is a universal topic that appears in Steinbeck’s writings as well. Steinbeck’s works are full of characters who struggle to make both ends meet as migrant farmers during the Great Depression. He admired those who worked hard and lived honourably. The characters were given Steinbeck’s voice and vibe. Their flaws, struggle for survival, and unwavering courage are not only theirs but also Steinbeck's. Even though the fact that he authored fiction, his characters are realistic in their portrayals of contemporary America. The Grapes of Wrath earned Steinbeck both praise and scorn. It’s based on the American Great Depression, which ran from 1929 to 1939. Many people were destroyed by the stock market fall, which resulted in widespread unemployment. The Dust Bowl of the 1930s followed. Due to a lack of rain and strong gusts, the top soil swept away. Farmers were forced to sell their lands to the banks as a result of this. The Grapes of Wrath was inspired by the migrants’ suffering and sacrifice. This single work serves as a testament to the human experience in tough times.

Injury and death associated with jumping castles: A public health issue.

A recent tragedy in Davenport, Tasmania, Australia, resulted in the death of six young school children and serious injury to three others when the jumping castle on which they were playing was lifted from the ground in a gust of wind. It became airborne to a maximum height of 10 m and travelled 50 m before becoming lodged in a tree. This incident highlights potential serious health consequences associated with jumping or bouncy castles or inflatable bouncers. Previous studies suggest that one child presents every 46 min to a US emergency department with an injury sustained on a jumping castle.1 We conducted a literature search of MEDLINE and EMBASE for journal articles and used Google to identify news articles on jumping castle-related injuries and deaths. We identified 10 relevant full text journal articles from the USA and Europe, comprising five cohort studies and five case series/reports including 131 164 children/adolescents and 65 429 injuries directly related to jumping castles (Table 1). Olsen2 prospectively identified 112 amusement-park injuries of which 78 occurred on jumping castles over a 7-month period: most were sprains, mainly ankle (37%), fractures (29%), contusions of the back and extremities (18%) and wounds (10%).2 A study reported 49 fractures among children and adolescents playing on jumping castles who presented to a hospital emergency department (ED), only two of whom (aged 4 and 10) required surgery.3 A study using a hospital ED database identified 521 children injured on inflatable bouncers between 2002 and 2013.4 Almost half had fractures (n = 246, 47%), the upper extremity being the most common site (80.5%). These were followed by sprains (31.3%), contusion/abrasion (5.8%), concussion (4.6%), joint dislocation (3.8%), laceration (1.7%) and multiple injuries (0.4%). There was a substantial increase in injuries over time from 1.4 per 1000 in 2002 to 24.4 per 1000 in 2013.4 A prospective study identified 114 children injured on jumping castles who presented to the ED with fractures of the upper limb (humerus, distal radius), ankle sprains and vertebral fractures. Almost 90% of injuries were unwitnessed, parents being alerted by a crying child.5 The largest study, from the USA, used a national database to identify 64 657 injuries due to inflatable bouncers over a 20-year period.1 As reported for other studies, the most common injuries were fractures (27.5%), sprains (27.3%), soft-tissue injuries (18.0%), concussion (7.0%) and lacerations (6.4%). In this large study, an increasing number of injuries were observed over time, the increase being most rapid in recent years.5 We also identified news articles from web-based sources reporting 484 injuries and 28 deaths since 2000, with a trend for increasing numbers over time (Fig. 1). The news media is a helpful source of information: deaths were reported in news items but not in the medical literature. Most reported deaths were associated with jumping castles/inflatable bouncers being lifted off the ground by strong gusts of wind. The median wind speed was 43 km/h (range 8–137 km/h). Some bouncers were not anchored to the ground. Causes of death were not provided. The only Australian report, in 2001, described that 15 children were injured and a 7-year old girl died when a dust devil (‘Willy-Willy’, whirlwind, dust storm) lifted a jumping castle. The USA has the largest number of accidents related to jumping castles (53%), followed by China (11%), the UK (10%) and Australia (8%). Of the 28 reported child deaths related to jumping castle accidents, 29% occurred in China, 11% in the USA and 7% in the UK. This information highlights the potential dangers of inflatable bouncers for children and adolescents. Injury prevention requires adult supervision by centre staff and parents, limiting the numbers of children on the device, and securing the device to the ground. The Australian Standard for owning and operating commercial jumping castles (3533.1.2009) states that the device should be securely anchored and should not be used in inclement weather when wind gusts exceed 40 km/h. However, many reported deaths have occurred when a jumping castle was lifted off the ground by a dust devil, which is extremely unpredictable. Once airborne, jumping castles are often unstoppable and some have travelled up to 1.6 km from their origin. Some countries have banned the use of inflatable devices. Perhaps Australia should follow? APSU activities are supported by the Australian Government Department of Health; the University of Sydney, Faculty of Medicine and Health, Discipline of Child and Adolescent Health; the Children's Hospital at Westmead; and the Royal Australasian College of Physicians. EJ Elliott is supported by an NHMRC-MRFF Next Generation Fellowship (#1135959).

Correlating Extremes in Wind Divergence with Extremes in Rain over the Tropical Atlantic

Air–sea fluxes are greatly enhanced by the winds and vertical exchanges generated by mesoscale convective systems (MCSs). In contrast to global numerical weather prediction models, space-borne scatterometers are able to resolve the small-scale wind variability in and near MCSs at the ocean surface. Downbursts of heavy rain in MCSs produce strong gusts and large divergence and vorticity in surface winds. In this paper, 12.5 km wind fields from the ASCAT-A and ASCAT-B tandem mission, collocated with short time series of Meteosat Second Generation 3 km rain fields, are used to quantify correlations between wind divergence and rain in the Inter-Tropical Convergence Zone (ITCZ) of the Atlantic Ocean. We show that when there is extreme rain, there is extreme convergence/divergence in the vicinity. Probability distributions for wind divergence and rain rates were found to be heavy-tailed: exponential tails for wind divergence (P∼e−αδ with slopes that flatten with increasing rain rate), and power-law tails for rain rates (P∼(R*)−β with a slower and approximately equal decay for the extremes of convergence and divergence). Co-occurring points are tabulated in two-by-two contingency tables from which cross-correlations are calculated in terms of the odds and odds ratio for each time lag in the collocation. The odds ratio for extreme convergence and extreme divergence both have a well-defined peak. The divergence time lag is close to zero, while it is 30 min for the convergence peak, implying that extreme rain generally appears after (lags) extreme convergence. The temporal scale of moist convection is thus determined by the slower updraft process, as expected. A structural analysis was carried out that demonstrates consistency with the known structure of MCSs. This work demonstrates that (tandem) ASCAT winds are well suited for air–sea exchange studies in moist convection.