Variations In Wind Direction Research Articles

Reply to comment by Haag et al. on “Resurfaced paleodunes from the Botucatu erg amid Cretaceous Paraná volcanics” by Hartmann and Cerva-Alves (2021)

We reported several scientific discoveries, implicitly recognized by the commenters: Fronteira Oeste Rift; description of a unique, forgotten 15,000 km2 area in Brazil that displays the contact of a large Cretaceous paleoerg with a large continental basaltic province; Catalán andesite covering most of the active erg; abundant evidence of hydrothermalism and vapor explosion from the Guarani Aquifer into and over overlying seal rocks; minor ergs not observed above the first lava flows; shape and structure of numerous barchan and seif paleodunes indicate more variable wind directions than previously reported. We used the methodology required to describe the processes. Cerro do Jarau is a compound paleodune (barchan and seif). We acknowledge the qualified comments made by the commenters, but our main evaluation remains unmodified. Continued studies will lead to significant contributions to the understanding of this major eolian-basaltic province in a unique relationship in the continents.

Comparative Study of Univariate and Multivariate Long Short-Term Memory for Very Short-Term Forecasting of Global Horizontal Irradiance

Accurate global horizontal irradiance (GHI) forecasting is crucial for efficient management and forecasting of the output power of photovoltaic power plants. However, developing a reliable GHI forecasting model is challenging because GHI varies over time, and its variation is affected by changes in weather patterns. Recently, the long short-term memory (LSTM) deep learning network has become a powerful tool for modeling complex time series problems. This work aims to develop and compare univariate and several multivariate LSTM models that can predict GHI in Guntur, India on a very short-term basis. To build the multivariate time series models, we considered all possible combinations of temperature, humidity, and wind direction variables along with GHI as inputs and developed seven multivariate models, while in the univariate model, we considered only GHI variability. We collected the meteorological data for Guntur from 1 January 2016 to 31 December 2016 and built 12 datasets, each containing variability of GHI, temperature, humidity, and wind direction of a month. We then constructed the models, each of which measures up to 2 h ahead of forecasting of GHI. Finally, to measure the symmetry among the models, we evaluated the performances of the prediction models using root mean square error (RMSE) and mean absolute error (MAE). The results indicate that, compared to the univariate method, each multivariate LSTM performs better in the very short-term GHI prediction task. Moreover, among the multivariate LSTM models, the model that incorporates the temperature variable with GHI as input has outweighed others, achieving average RMSE values 0.74 W/m2–1.5 W/m2.

Design wind loads for local flexible cladding of structures based on wind tunnel tests

Damage and ultimate failure of cladding elements may play an important part in the wind-resistant performance of structural system. Particularly for those claddings made from lightweight and flexible materials, they are more sensitive and vulnerable to wind excitation. This study proposes an approach of reducing the design wind loads for the local flexible cladding of structures, where the significant geometric nonlinear effect of the cladding is considered. In the light of stress equivalence principle and finite element analysis, the equivalent design wind load for the local flexible cladding is presented with consideration of reducing extreme wind pressure which is usually used for the design of rigid cladding and resulted from statistical analysis of experimental pressure measurement. In view of characteristics of wind pressure distribution on local flexible cladding units, the reduction coefficient of extreme wind pressure at varying wind directions is also given to build wind load evaluation system for the flexible cladding. The effects of wind pressure gradient and correlation on determining the design wind loads are respectively quantified by fluctuating factor and synchronous factor in order to further explore their action mechanism. Moreover, a case study is performed to examine the effectiveness and reliability of this proposed approach in actual application, where the results of extreme wind pressure, reduction coefficient and relevant influencing parameters are analyzed. It proves that this evaluation system is not limited by the external geometry of structures, and can help to optimize the wind-resistant design of the cladding economically, especially for the local flexible cladding susceptible to variation of fluctuating wind pressures.

Temporal variation of wind speed and wind direction and interrelationship between air temperature and wind speed for different climatic seasons Northern State, Sudan

The research aims to study the temporal variability of wind speed and direction and their correlation with air temperature in different climatic seasons in Northern State, to produce broad data base on winds variability and interrelationship between air temperature and wind speed for different climatic seasons. Mean monthly and daily climatic data dating back to 2001(first season) and 2011(second season) were obtained from Karima meteorological station representing three different climatic seasons namely: April for summer, August for autumn and December for winter. Data were subjected to simple regression analysis, statistical analysis and computations were done by “Excel 2000”. The results showed that the wind speed varied widely during each month and day even within the same climatic season. In two seasons, the diurnal variation for different climatic seasons Apr., Aug. and Dec. was much lower than the monthly; due to the higher monthly variability of wind speed. The results also revealed that the prevailing direction of winds was generally northwards. The results of April in the first season are presented as an example; the mean daily wind speed (Va) ranged from 0.6 to 17m/s, with a mean of 7.2m/s, a STD of 4.3 and a CV of 60%. The daily mean data ranged from 5.4 (3hrs) to 8.2 (24hrs), with a mean of 7.2m/s, a STD of 1.1 and a CV of 15.3%.The prevailing wind direction decreases in the following order: N>NE=NNE>NNW. The monthly variability of the air temperature in the two seasons decreased in the following order: winter> summer> autumn. Significant, inversely proportional and cubic wind speed-temperature correlations in the two seasons for Aug. and Dec. were (P<0.05, r=0.362); (P<0.01, r= 0.488); (P<0.001, R=585) and (P<0.001, r= 0.679), respectively.

Aeroelastic modeling to study the wind-induced response of a self-supported lattice tower

The results from a 1:50 scale aeroelastic model of a self-supported steel lattice tower subjected to simulated hurricane winds are presented. The lattice tower considered is a typical structure that is used as part of a tower-insulator-conductor system for electrical transmission infrastructure. The aeroelastic tests were conducted at the NSF Wall of Wind Experimental Facility (WOW EF) at the Florida International University (FIU). The tower was tested at various wind speeds ranging from 50 m/s to 92 m/s (equivalent full-scale speeds) for varying wind directions. Two system identification (SID) techniques were utilized to evaluate along-wind aerodynamic damping and compare with theoretical estimates. The SID techniques were also utilized to evaluate crosswind aerodynamic damping. A buffeting analysis was conducted to estimate the response of the tower and compare it to measured values at the WOW. Drag and moment coefficients were calculated from the measured responses, and the dynamic amplification factors (DAF) as well as gust effect factors were computed. The analysis required consideration of the variation of the turbulence intensity along the height of the tower in the buffeting analytical equations. The drag coefficients are shown to agree with values proposed in the current standards. However, there might be a need to introduce base moment coefficients in lattice tower design. The resonance contribution is shown to reach a maximum of 18% of the peak response of the tower.

Measuring Potential Coastal Sailing Mobility With the Loose-Footed Square Sail

Measures of potential sailing mobility are essential for understanding the functioning of ancient maritime links. This requires measuring potential sailing mobility of coastal sailing runs, as well as direct passages in the open sea. Quantitative works attempting to measure potential sailing mobility have shortcomings related to the use of averaged wind data, thereby losing knowledge of wind variability; non-inclusion of the human factors impacting mobility; and not using methods of measuring coastal sailing. The method presented here was developed to measure potential sailing mobility of coastal sailing runs, based on using the patterns of hourly wind direction and speed variability – and specifically the coastal breeze cycle. Wind variability is extracted from a large dataset of data at high spatiotemporal resolution, employing millions of simulations which enable developing meaningful information from big data. This method has demonstrated its applicability to measuring coastal sailing mobility in several developmental case studies in the eastern Mediterranean, introducing realistic measures of mobility that include coefficients of mobility and of time spent waiting for favourable winds. Complementing a previously developed method to measure potential sailing mobility on direct open-sea passages, this new method can now provide a comprehensive toolkit for mapping potential sailing mobility. Such mapping is a valuable input to research on maritime networks and maritime-related developments.

Awareness level of climate change among paddy farmers

This study examined the awareness level of paddy farmers on climate change. Among the 29 districts of Tamil Nadu, Nagapattinam district was selected to conduct the present study. This is situated in coastal area and very often subjected to natural calamities which were mainly reflected on the rice cultivation to the worst status. Data for the study were collected from 200 respondents selected through simple random sampling technique. The study revealed that majority (71.50 %) of the respondent had medium level of awareness of climate change followed by high (17.00 %) and low (11.50 %) category. More than eighty per cent of the respondents were aware about the issues viz., receipt of low rain fall (90.50 %), uneven distribution of rain fall (89.00 %), frequent cyclone (87.00 %) and reduction in number of rainy days (86.50 %). The awareness level was found to be minimum in the issues like acid rain (34.50 %), variation in wind speed and direction (44.50 %), increasing heat and cold waves (48.00 %). The study concluded that the majority of farmers were aware of climate change but some of them were lacked in detail information about climate change. Therefore, it is suggested that extension education should be strengthened to boost farmers’ awareness level on climate change in detailed and prepare them for adaptation measures and that appropriate technologies be promoted for adaptation by farmers.

An adaptive aerodynamic approach to mitigate convective losses from solar cavity receivers

We explore the potential for adaptive air barriers to mitigate convective heat losses from cavity receivers, especially at large tilt angles, using both suction and blowing nozzles. A heated scaled-down cylindrical cavity receiver was fitted with nozzles on four sides of the aperture, at 30° to the aperture plane. The tilted cavity receiver was mounted in a large wind tunnel to allow systematic variation of wind speed and direction. The effectiveness of different nozzle arrangements was calculated from the measured convective heat losses for a series of different mitigation strategies. The results reveal that a suction nozzle mounted at the bottom of the aperture is more effective than a blowing nozzle mounted at the top of aperture for tilt angles of θ= 45°, and under different wind speeds. The effectiveness ranged from 0 at a low suction flow rate to ~80% at a high suction flow rate. With the use of three suction nozzles, at the bottom and both sides of aperture, the effectiveness decreased markedly for both tilt angles and all wind speeds. For more challenging conditions of a 45° tilt angle and 45° yaw angle, the most effective approach is the use of suction through nozzles aligned diametrically opposite to the wind, while other nozzle combinations were ineffective in mitigating losses. Finally, the results highlight the need to apply an adaptive aerodynamic strategy that can respond to measured changes in the environmental conditions to achieve the highest thermal efficiency.

A simulation-driven online scheduling algorithm for the maintenance and operation of wind farm systems

Wind turbines experience stochastic loading due to seasonal variations in wind speed and direction. These harsh operational conditions lead to failures of wind turbines, which are difficult to predict. Consequently, it is challenging to schedule maintenance actions that will avoid failures. In this article, a simulation-driven online maintenance scheduling algorithm for wind farm operational planning is derived. Online scheduling is a suitable framework for this problem since it integrates data that evolve over time into the maintenance scheduling decisions. The computational study presented in this article compares the performance of the simulation-driven online scheduling algorithm against two benchmark algorithms commonly used in practice: scheduled maintenance and condition-based monitoring maintenance. An existing discrete event system specification simulation model was used to test and study the benefits of the proposed algorithm. The computational study demonstrates the importance of avoiding over-simplistic assumptions when making maintenance decisions for wind farms. For instance, most literature assumes maintenance lead times are constant. The computational results show that allowing lead times to be adjusted in an online fashion improves the performance of wind farm operations in terms of the number of turbine failures, availability capacity, and power generation.

Wind farm yaw control set-point optimization under model parameter uncertainty

Wake steering, the intentional yaw misalignment of certain turbines in an array, has demonstrated potential as a wind farm control approach to increase collective power. Existing algorithms optimize the yaw misalignment angle set-points using steady-state wake models and either deterministic frameworks or optimizers that account for wind direction and yaw misalignment variability and uncertainty. Wake models rely on parameterizations of physical phenomena in the mean flow field, such as the wake spreading rate. The wake model parameters are uncertain and vary in time at a wind farm depending on the atmospheric conditions, including turbulence intensity, stability, shear, veer, and other atmospheric features. In this study, we develop a yaw set-point optimization approach that includes model parameter uncertainty in addition to wind condition variability and uncertainty. To enable computationally efficient online set-point optimization under model parameter uncertainty, a simplified, approximate parameter distribution estimation method is used. The optimization is tested in open-loop control numerical experiments using utility-scale wind farm operational data for which the set-point optimization framework with parametric uncertainty has a statistically significant impact on the wind farm power production for certain wind turbine layouts at low turbulence intensity, but the results are not significant for all layouts considered nor at higher turbulence intensity. The set-point optimizer is also tested for closed-loop wake steering control of a model wind farm in large eddy simulations of a convective atmospheric boundary layer (ABL). The yaw set-point optimization with model parameter uncertainty reduced the sensitivity of the closed-loop wake steering control to increases in the yaw controller update frequency. Increases in wind farm power production were not statistically significant due to the high ambient power variability in the turbulent, convective ABL.

Mitigation of Airborne Contaminant Spread through Simple Interventions in an Occupied Single-Family Home.

Historically, reducing aerosol-based transmission of respired viruses in indoor environments has been of importance for controlling influenza viruses and common-cold rhinoviruses. The present public health emergency associated with SARS-CoV-2 makes this topic critically important. Yet to be tested is the potential effectiveness of simple interventions that create an isolation zone (IZ) for a suspected/confirmed sick or sensitive person requiring quarantine. The intent in existing homes is to find a practical means to mitigate exposure to airborne contaminants. In creating an IZ in an occupied single-family home in the study, four simple strategies were tested. The test configurations were: (1) IZ windows closed with IZ bathroom exhaust ventilation fan off, (2) IZ windows closed with IZ exhaust fan on, (3) IZ window open with IZ exhaust fan off, and (4) IZ window open with IZ exhaust fan on. Incense-generated fine particulate matter (PM2.5) was used as a marker for virus transmission. The measured transfer of PM2.5 from the IZ into the main zone (MZ) of the house enabled us to determine the relative effectiveness of four containment strategies. Collectively, the data from pressure differential (across zones) and PM2.5 measurements suggested that the best containment strategy was achieved through continuously operating the bathroom exhaust fan while keeping the windows closed in the IZ (configuration 2). Interventions using open windows were found to be less reliable, due to variability in wind speed and direction, resulting in an unpredictable and sometimes detrimental pressure differential in the IZ with reference to MZ. Our findings strongly suggest a simple IZ exhaust ventilation strategy has the potential for mitigating the risk from the airborne spread of contaminants, such as SARS-CoV-2.

Impacts of Ambient Air Pollution on Health Risk in Korea: A Spatial Panel Model Assessment

This paper investigates the impact of air quality pollution on respiratory health risk in Korea. In particular, we consider transboundary effects of particulate matter (PM10) on the health risk of pneumonia by using the spatial panel model. PM10, generated by natural phenomena and anthropogenic activities, migrates to neighboring areas contributing to not only local but also ambient regional health risks. We employ the spatial panel model to explain the spillover effects of air pollution on the respiratory health risk. The panel data covers environmental, demographic and economic variables that are associated with pneumonia of 120 local districts in Korea during the period from 2010 to 2015. Empirical evidence based on non-spatial and spatial models commonly indicates that the impact of air pollution on pneumonia-related risk is significant. The spatial panel model assessment reveals improvement in explanation and evidences more significant effect of ambient air pollution on pneumonia related hospital visits. As such, evidences of spatial dependence and borderless impacts of air pollution on the health risk of pneumonia are found to be strong. We also investigate the spatial dynamics of the potential association between air pollution and respiratory diseases with respect to variations in wind direction by extending the conventional weight matrix specification. Empirical results imply that transboundary effects of PM10 on health risk are stronger for districts located downwind from Northwest districts than from other directions.

2D Parametric Model for Surface Wave Development Under Varying Wind Field in Space and Time

AbstractA fully consistent 2D parametric model of wave development under spatially and/or time varying winds is developed. Derived coupled equations are written in their characteristic form to provide practical means to rapidly assess how the energy, frequency and direction of dominant surface waves are developing and distributed under varying wind forcing conditions. For young waves, nonlinear interactions drive the peak frequency downshift, and the wind energy input and wave breaking dissipation are governing the wave energy evolution. With a prescribed wind wave growth rate, proportional to (u*/c) squared, wave breaking dissipation must follow a power‐function of the dominant wave slope. For uniform wind conditions, this choice for the growth rate imposes solutions to follow fetch laws, with exponents q = −1/4, p = 3/4 correspondingly. This set of exponents recovers the Toba's laws, and imposes the wave breaking exponent equal to 3. A varying wind direction can then drive spectral peak direction changes, leading to the occurrence of focusing/defocusing wave groups over localized areas where wave‐rays merge and cross. Significant (but finite) local variations of the energy are then expected under varying wind forcing. Propagating away from a stormy area, wave rays generally diverge, leading to dispersive swell systems. Examples of practical applications of this model are provided in (Kudryavtsev et al., 2021, companion paper).

Influence of Wind Speed and Direction on the Combustion Parameters of the Exposed XPS Insulation Wall

Most of the fire accidents of exterior insulation in recent years started with the ignition of unprotected and exposed insulation materials. The fire spread on the thermal insulation layer will be affected by outdoor wind. In this paper, the influence of wind direction and wind speed on wall fire propagation characteristics was studied by carrying out medium sized experiments. The temperatures on the wall surface, radiation heat flux nearby, the infrared image and flame image were recorded during the tests with variation of wind direction and wind speed. It is found that with the increase of the angle between the wind direction and the wall, the surface temperature of the material, the radiation heat flux released decreases.This study results can provide valuable references for optimizing the fire safety design of exterior insulation layer.

The distribution and nature of star dunes: A global analysis

Abstract Star dunes, which occur on Mars and Titan and are also evident in Earth’s stratigraphic record, are widespread in the world’s drylands and 25 provinces have been identified and characterised based on an analysis of Google Earth images. They occur in East Asia, Western Asia, the Americas, southern Africa and northern Africa. Star dunes are absent in inland Australian, Kalahari and Indian sand seas and in the southern Sahara. Morphometric measurements across a wide range of sites reveal star dune densities of 7 to 81 per 100 km2 (mean 30 per km2), dune widths of 125–3071 m (mean 895 m) and heights of 4–291 m (mean 75 m). Star dunes have a great diversity of forms, which include simple pyramids, complex features, checkerboard patterns, symmetrical and asymmetrical forms, stars along linear dunes and stars along transverse dunes. In some areas star dunes show an association with mega-domes. In this paper they are classified into 10 types, though it is clear that some dunes may show characteristics of more than one type. Star dunes develop in areas with low rainfall, variable wind directions and in association with topographic barriers. They are a more widespread and varied phenomenon than has previously been recognised.

A study on the leeway drift characteristic of a typical fishing vessel common in the Northern South China Sea

Leeway drift characteristics of drifting objects are essential to accurately forecast the drifting trajectory of lost persons, boats and other objects. Traditionally, leeway coefficients of the drifting objects are calculated using the observed wind, current and drift speed data from field experiments. Based on the combined samples of four drift experiments for a new type of 20 m length fishing vessel common in the northern South China Sea, this study determine the wind-induced drift characteristic through leeway speed, downwind component of leeway (DWL), crosswind component of leeway (CWL) coefficients, and explore how the fishing vessels drift in the surface water with the wind effect. Both the combined samples’ mean value and standard deviation (std) of the three rates (containing leeway rate, absolute DWL rate, and absolute CWL rate) show a decreasing trend as wind speed at 10 m increasing. Changes of the coefficients along with wind speed should be considered in the future calculation of drift simulation. Sign changes of CWL is observed in low wind speed, and the sharp variations of wind speed or wind direction. The forecast search area and the probability distribution of drift particles are sensitive to the wind condition and the frequencies of sign change respectively.

Replacing a third-generation wave model with a fetch based parametric solver in coastal estuaries

Within a restricted estuarine environment, the use of third-generation wave models for predicting wave heights can be computationally expensive, signaling a need for model development that reduces the computational costs of existing coupled hydrodynamic models. This study focuses on the development and testing of a parametric wave solver that incorporates four wave height formulations (SMB, SPM, TMA, and CEM) for predicting wave properties in a restricted estuarine environment. The emphasis is on improved efficiency without affecting accuracy, allowing for ensemble wave-surge forecasting to be performed on desktop computational resources. Evaluation of the performance of the parametric solver is twofold, first the parametric solver is compared to a third-generation wave model, Simulating Waves Nearshore (SWAN), for the Indian River Lagoon domain, which lies on Florida's east coast. Then both the parametric solver and SWAN are compared to in-situ ADCP wave data at a point in the estuarine domain. The creation of three different synthetic wind fields allows for model comparison, with wind fields permitting testing of the parametric model in order to reproduce (1) fully developed conditions, (2) wind speed variability, and (3) wind direction variability in tropical storm level wind events. For consistency comparison, wave height solutions over the same domain are generated by SWAN and the parametric models. Comparisons made between the parametric model performance and SWAN show a 4-member parametric model is accurate to within 87% globally, with a runtime improvement of over two orders of magnitude compared to SWAN. The parametric model's ensemble average wave height solution was 5.5% less than the in-situ measured wave height; the SWAN solution was 5.5% greater than the measured wave height at the same location. Therefore, the parametric wave model proves to be a viable alternative to running an expensive third-generation wave model for predicting waves in an enclosed estuarine system.

Aeolian dunes morphodynamics and wind regime reconstruction in mid-latitudes of the Gondwana during Early Permian, Aracaré Formation, Sergipe-Alagoas Basin, Brazil

Aeolian systems play an important role in palaeoclimatic studies, allowing the inference of arid regions in different geological periods, in addition to being the best records for acquiring palaeowind data. Morphodynamic reconstruction of ancient aeolian dunes is extremely important for understanding the local wind regime. This study aims to contribute to the morphodynamic reconstruction of aeolian deposits of the Aracaré Formation in response to Gondwana's palaeoclimatic variations and to indicate the prevailing wind regime. Permian Aracaré Formation is located in the Sergipe-Alagoas Basin, northeast region of Brazil, and exhibits sand accumulation of successive sets of aeolian cross-strata which are interpreted as dry aeolian system. Aracaré Formation is characterized by smaller cross-bedded sets of barchanoid dunes at the base that are overlaid by larger cross-bedded sets of transverse dunes. Aeolian cross-strata show a repetitive alternation of grainflow and wind-ripple packages, separated by reactivation surfaces indicating seasonal variations in wind direction. Cross-strata mean vectors dip consistently towards ESE when corrected for the palaeogeographic position of the Lower Permian. Cyclic stratification pattern suggests an alternation of westerly transverse winds responsible for dune migration, followed by reverse winds that caused dune reworking and led to the formation of reactivation surfaces and the related deposition of wind-ripple. Sometimes, reverse winds are more intense (storms?), strongly eroding the lee face of the aeolian dunes, generating master reactivation surfaces. The comparison between the wind patterns of Aracaré Formation and Sakmarian climate models showed good correlation with disposition of westerlies wind regime in mid-latitude in Gondwana landmass.

Reducing wind farm power variance from wind direction using wind farm layout optimization

This paper investigates reducing power variance caused by different wind directions by using wind farm layout optimization. The problem was formulated as a multi-objective optimization. The [Formula: see text] constraint method was used to solve the bi-objective problem in a two-step optimization framework where two sequential optimizations were performed. The first was maximizing the mean wind farm power alone and the second was minimizing the power variance with a constraint on the mean power. The results show that the variance in power estimates can be greatly reduced, by as much as [Formula: see text], without sacrificing mean plant power for the different farm sizes and wind conditions studied. This reduction is attributed to the multi-modality of the design space which allows for unique solutions of high mean plant power with different power variances due to varying wind direction. Thus, wind farms can be designed to maximize power capture with greater confidence.

Study of Spatial Distribution Characteristics for Dust Raised by Vehicles in Battlefield Environments Using CFD

For a pulsed laser transmitted in the raised dust from battlefield vehicle movement, the premise of obtaining its transmission properties and anti-jamming method is to acquire the spatial distribution rules of dust mass concentration. In this study, the emission mechanism for vehicle-raised dust in the battlefield environment is analyzed, as well as various influencing factors of the dust emission velocity. A finite volume method (FVM)-based model for simulating the spatial dispersion of dust raised by a certain moving tank is built, and the effects of mass flow rate, traveling speed, wind speed and wind direction on the spatial distribution of dust mass concentration are explored in the battlefield environment. The results show that the raised dust is plume-shaped within the computational domain, and the spatial mass concentration of plume is positively correlated with the mass flow rate. Besides, it is necessary to determine the impact of tank travelling speed on the spatial mass concentration of dust based on the relationship between the travelling speed and the dust mass flow rate. Although front wind reduces the spatial mass concentration of dust plumes, the reduction rate decelerates when the wind speed exceeds 4 m/s. Crosswind leads to the deflection and decreased mass concentration of dust plumes. Under varying wind directions, the variation of crosswind component exerts a more pronounced influence on the spatial mass concentration of dust than that of the front wind component. This study provides a technical support for the further study of near-ground laser weapon system against vehicle dust interference in the battle field.