Low Wind Speed Research Articles

The impact of shipping on the air quality in European port cities with a detailed analysis for Rotterdam

Air quality in cities with large maritime ports is considerably impacted by emissions from shipping activity which is of a growing relevance due to an increasing relative contribution. To explore the extent of shipping emissions to ambient air quality, simulations with the chemical transport model LOTOS-EUROS (LOng Term Ozone Simulation – EURopean Operational Smog model) were performed for the year 2018 at an approximate 1 × 1 km resolution for six European cities with large ports, i.e., Rotterdam, Antwerp, Hamburg, Amsterdam, Le Havre, and London. It was found that depending on the investigated city, 6.5%–62% of the nitrogen dioxide (NO2) concentration in the city centres is attributable to shipping activities. This corresponds to contributions of 1.8–11.5 μg/m3 to the ambient air NO2 concentrations. The average NO2 contribution of shipping in these six cities was 28% (7.1 μg/m3). The largest relative contribution was found for Le Havre where 62% (10.8 μg/m3) of the annual average NO2 concentration was caused by shipping emissions. The largest absolute contribution is found for the city centre of Hamburg with 11.5 μg/m3 (41%). The lowest absolute and relative contribution (respectively 1.8 μg/m3 and 6.5%) are found for London, also having the smallest port in terms of tonnage throughput, which is one of the influential factors that determine emission totals, investigated in this study. For the other investigated pollutants, i.e., PM2.5, PM10 and SO2, contributions from shipping were less pronounced with average contribution for all cities of 10% (1.2 μg/m3) 7% (1.5 μg/m3) and 4% (0.16 μg/m3) respectively. To assess the effect of model choices on these results, this study also looked into the choice of simulation resolution and relations between meteorological parameters and NO2 concentrations. Following simulations with varying chemical transport model resolutions (1 × 1 km to 24 × 24 km), it is found that a decrease in ambient air pollutant concentrations away from localized emission sources is more pronounced at higher (1 × 1 km) model resolutions and source contributions are influenced more significantly than total concentrations. Considering meteorology, generally low wind speeds (1–2 m/s) lead to high NO2 concentration in city centres. For the cities where the port is much closer to the city centre (e.g., London, Le Havre, Hamburg and Antwerp) the absolute NO2 concentrations as well as the contributions from shipping emissions become highest for windless conditions. The high concentrations (>60 μg/m3 NO2) only occur when wind speeds fall below 6 m/s.

Energy and exergy analysis of a long-term nonlinear dynamic roll bond PVT solar collector model under Tunisian (North Africa) climatic conditions

Roll-bond type PVT modules drew little attention while offering a higher energy exchange area and an efficient heat transfer solution. Furthermore, comparative studies including exergetic assessment on PVT systems are very limited in the literature. In this paper, a novel and detailed nonlinear dynamic roll bond PVT model is performed under real-world weather conditions that provide reasonable and realistic system performance. By incorporating local solar, thermal, exergy, and electrical models based on five diode parameters, a thorough analysis is conducted. Likewise, a unique, rigorous exergy comparison between PV, thermal, and roll bond PVT systems is conducted. Results reveal that there appears to be a direct relationship between wind velocity and changes in ambient temperature which affect exergy efficiency. Higher irradiance and lower wind speeds lead to increased thermal losses, which lower the electrical exergy efficiency of the PV and PVT solar collectors.The exergy analysis reveals that a PVT system outperforms PV + ST, and findings show that for thermal and electrical parts, the yearly average efficiencies are 33.7 % and 12.27 %, respectively. Findings enable a fast and an accurate assessment of fill factor (FF), which is temperature-dependent, over the course of a year’s worth of PVT collector operation.

Exploring dispersion modelling for resuspended pollen particles in a heterogeneous urban environment

ABSTRACT Urban air quality assessment in regard to biogenic emissions such as airborne pollen grains (PGs) is indispensable in the urban environment which significantly affects human health, climates, ecosystems, and energy production. Dispersion and deposition of PGs because of resuspension events (ReSE) are investigated using computational fluid dynamics (CFD). The mechanisms in PGs movement are achieved through the Lagrangian formulation-based discrete-phase model (DPM). The observed pollen grains distribution pattern is highly spatially dependent on heterogeneous urban obstacles as it induces modified characteristics of the wind flow field. Wind-urban structure interplays in PGs concentration variation. The simulated results identify the pollen hot-spot zones, where vortical flow features and low wind speed dominate. This approach offers a detailed understanding of the dispersion patterns of airborne PGs in urban environments because of ReSE with high resolution.

Experimental Study of the Vibration of Blades Induced by Flow and Sound in a Plane Cascade under Low Wind Speed

Experimental Study of the Vibration of Blades Induced by Flow and Sound in a Plane Cascade under Low Wind Speed

A decade of curtailment studies demonstrates a consistent and effective strategy to reduce bat fatalities at wind turbines in North America

Abstract There is a rapid, global push for wind energy installation. However, large numbers of bats are killed by turbines each year, raising concerns about the impacts of wind energy expansion on bat populations. Preventing turbine blades from spinning at low wind speeds, referred to as curtailment, is a method to reduce bat fatalities, but drawing consistent inference across studies has been challenging. We compiled publicly available studies that evaluated curtailment at six wind energy facilities in North America across 10 years. We used meta‐regression of 29 implemented treatments to determine fatality reduction efficacy as well as sources of variation influencing efficacy. We also estimated species‐specific fatality reduction for three species that comprise most fatalities in North America: hoary bat (Lasiurus cinereus), eastern red bat (Lasiurus borealis) and silver‐haired bat (Lasionycteris noctivagans). We found that curtailment reduced total bat fatalities by 33% with every 1.0 ms−1 increase in curtailment wind speed. Estimates of the efficacy for the three target species were similar (hoary bats: 28% per ms−1, 95% CI: 0.4%–48%, eastern red bats: 32% per ms−1, 95% CI: 13%–47% and silver‐haired bats: 32% per ms−1, 95% CI: 3%–53%). Across multiple facilities and years, a 5.0 ms−1 cut‐in speed was estimated to reduce total bat fatalities by an average of 62% (95% CI: 54%–69%). Mortality reductions at individual facilities in any given year were estimated to fall between 33%–79% (95% prediction interval). Inter‐annual differences rather than inter‐site or turbine characteristics accounted for most of the variation in efficacy rates. Species‐specific average mortality reduction at 5.0 ms−1 curtailment wind speed was 48% (95% CI: 24%–64%) for hoary bats, 61% (95% CI: 42%–74%) for eastern red bats and 52% (95% CI: 30%–66%) for silver‐haired bats. Practical implication. curtailment reduced bat mortality at wind turbines in this North American study. Efficacy increased proportionally as curtailment speed is raised, and patterns and rates of efficacy were similar across species. This indicates that curtailment is an effective strategy to reduce bat fatalities at wind energy facilities, but exploration of further refinements could both minimize bat mortality and maximize energy production.

The height of the diurnal atmosphere: The twilight

An equation has been derived through which the height of the diurnal atmospheric layer (lower atmosphere) can be calculated using ground base twilight image analysis. This equation relies on the angular altitude of the twilight with the dip at that moment. Based on the images, it was found that true twilight of dawn occurs at a dip of 14.90° ± 0.17° as detected by the camera or ∼15° by considering the elevation above sea level (while it may be delayed to ∼14.7–14° with the naked eye), which is accompanied by an average twilight angular altitude of 2.66° ± 0.23°. From these values, the twilight height is estimated to be 303.80 ± 5.69 km above sea level. It is shown that the twilight region is the peak zone of the thermosphere. Its height also varies with time according to changes in various atmospheric parameters. Lower wind speeds, higher relative humidity, higher dew point, and lower temperatures resulted in a higher altitudinal angle of the atmosphere and consequently a greater diurnal atmospheric layer’s thickness. Image analysis shows that the thermosphere always has a maximum value of light brightness during the night even before the appearance of twilight. Additionally, It defined the light source, shapes, and stages of twilights that detected by images. This implies that sky image analysis is an inexpensive method for understanding the properties and various parameters of the atmosphere.

Experimental investigation into the effects of endplate designs for a Savonius turbine

Abstract Wind energy is experiencing a trend of exponential growth in both literature and industrial employment, emphasizing its current pivotal role in achieving carbon neutrality by replacing fossil fuels. Vertical axis wind turbines (VAWTs) particularly Savonius rotors operate at a lower tip-speed-ratio (TSR) range compared to horizontal axis wind turbines (HAWTs). The Savonius rotor has good starting characteristics, making it suitable to be placed in urban areas with lower wind speeds. Due to its low efficiency, studies on augmentation and optimization have been conducted to improve its blade and deflector designs. Extensive research has established a common consensus that the use of endplates significantly improves the aerodynamic performance of the Savonius rotor. However, limited research has been undertaken to explore the endplate design further. In this study, wind tunnel tests were conducted on different endplate ratios, to investigate the effects of endplate design on the aerodynamic performance of a conventional Savonius turbine. Three different Savonius rotor with no endplate, semi-circular endplate and circular endplate were designed and manufactured. Experiments were conducted in an open-type suction wind tunnel at a constant measured wind velocity of 5.89 m/s. The turbine’s performance for different endplate ratios was evaluated across a TSR range of 0.2 to 1.0. The performance was assessed based on the maximum power generated and its self-starting ability. From the experimental results, the circular endplate ratio of 1.1 shows a significantly high coefficient of power compared to both semi-circular and without endplates. This is due to reduced spanwise spillage and enhanced airflow capture by the rotor. The endplates direct incoming air to the advancing blade and overlap region, resulting in the increased pressure difference between the concave and convex sides of both the advancing and returning blade, thereby improving the power efficiency of the turbine with 1.1D diameter endplate and semi-circular endplate by 296.6% and 6.9% compared to no endplates case.

Ventilation performance study of a high-speed train cabin based on displacement ventilation and mixed ventilation

Indoor ventilation systems play an important role in controlling energy consumption, thermal comfort, and airborne pollutants. This work is concerned with whether the combination of displacement and mixed ventilation can overcome these systems' respective shortcomings to improve the ventilation performance of high-speed train cabins. This work is based on computational fluid dynamics. The results show that when more fresh airflow enters the compartment from the top vents, the flow field is mainly driven by mechanical forces, and two vortices are formed. When more fresh airflow enters the compartment from the bottom vents, the flow field is mainly driven by thermal buoyancy. Meanwhile, the airflow mainly spreads upward, with lower cooling energy consumption, lower wind speed, higher ventilation efficiency, and smaller longitudinal diffusion of pollutants, but increased temperature difference. When the ratio of top and bottom supply air flow is 75%/25%, thermal comfort can be improved, while balancing energy consumption and air quality. If there was a disease outbreak, the flow rate of the bottom air supply could be increased appropriately. To further improve the ventilation performance, on the one hand, it is necessary to appropriately increase the temperature of the bottom air supply, and on the other hand, it is necessary to avoid short-circuiting of the airflow, due to the lack of synergy between thermal buoyancy and mechanical force. The results of the study can provide a reference for safeguarding passengers and improving the ventilation design of high-speed trains.

Evaluation of LM 43.8P blade performance at different hub height wind speeds using blade element momentum theory

Abstract An investigation was conducted on a three-bladed rotor similar to AVANTIS AV908. The rotor blade is appropriate for a Class I wind turbine generator and consists of three LM 43.8P blades. The 2.5 MW gearless wind turbine generator has a rated rotational speed of 16 rpm. An analysis of the LM 43.8P blade’s aerodynamics was carried out using the Blade Element Momentum (BEM) Theory to assess the turbine’s performance at different hub height wind speeds. The study employed three BEM models, including the original BEM concept without correction factors, the BEM Theory by DNV/Ris0, and the BEM Theory obtained from GH Bladed. The rotor radius is 45.1 m, and the blade comprises five different airfoils with a design tip speed ratio of 7.557. The axial and tangential induction factors, lift and drag coefficients, aerodynamic forces, and torque profiles as a function of the nondimensional rotor blade were calculated and compared with the numerical solutions obtained from the BEM models at varying upstream wind speeds. The calculation results revealed that with the original BEM concept, the axial induction factor for this particular blade became larger than 0.5 when the upstream wind speed was less than 7.45 m/s. This suggests that the Momentum Theory becomes invalid for lower wind speeds. However, the thrust force, driving force, and torque may be considerably over-predicted with hub height wind speeds larger than 9.50 m/s. It was found that out of the three models considered, the GH Bladed BEM model bears a striking resemblance with the actual power curve of AV908 with a confidence level above 95%, as indicated by a correlation coefficient of 0.99915 and a t-value of 0.51606 using Student’s t-test, implying that the two power curves have no significant difference.

RANCANG BANGUN TURBIN ANGIN SUMBU VERTIKAL TIPE SAVONIUS DENGAN KETERBATASAN AREA YANG ADA DI GEDUNG PERKULIAHAN TEKNIK ELEKTRO UNIVERSITAS UDAYANA

The concept of electrical vitality includes the persistent utilize of vitality in standard of living. Renewable vitality that can be changed over into electrical vitality is wind vitality utilizing PLTB. The transformation of wind energy from motor vitality to electrical vitality is the most work of a PLTB framework, with a wind turbine as the most component. The Savonius windmill, for case, is able of working at lower wind speeds, such as those in Indonesia. The aim of this research is to design a Savonius Turbine PLTB with turbine dimensions of 50cm diameter, 50cm height, 25cm blade diameter, and 3 blades. The test results show that the lowest turbine speed is 78 rpm and the highest is 111.5 rpm before the generator is loaded at wind speeds of 3 m/s and 5 m/s. After the generator is loaded with a resistance of 5 W, the lowest turbine speed is 39.5 rpm and the highest is 95.5 rpm at wind speeds of 3 m/s and 5 m/s. The highest turbine efficiency is 10.27%. The lowest torque was 0.07 Nm, and the highest was 0.28 Nm at wind speeds of 3 m/s and 5 m/s.

Atmospheric H2O2 during haze episodes in a Chinese megacity: Concentration, source, and implication on sulfate production

Atmospheric hydrogen peroxide (H2O2), as an important oxidant, plays a key role in atmospheric chemistry. To reveal its characteristics in polluted areas, comprehensive observations were conducted in Zhengzhou, China from February 22 to March 4, 2019, including heavy pollution days (HP) and light pollution days (LP). High NO concentrations (18 ± 26 ppbv) were recorded in HP, preventing the recombination reaction of two HO2• radicals. Surprisingly, higher concentrations of H2O2 were observed in HP (1.5 ± 0.6 ppbv) than those in LP (1.2 ± 0.6 ppbv). In addition to low wind speed and relative humidity, the elevated H2O2 in HP could be mainly attributed to intensified particle-phase photoreactions and biomass burning. In terms of sulfate formation, transition-metal ions (TMI)-catalyzed oxidation emerged as the predominant oxidant pathway in both HP and LP. Note that the average H2O2 oxidation rate increased from 3.6 × 10−2 in LP to 1.1 × 10−1 μg m−3 h−1 in HP. Moreover, the oxidation by H2O2 might exceed that of TMI catalysis under specific conditions, emerging as the primary driver of sulfate formation.

Experimental and three-dimensional performance analysis of a bio-inspired fish-ridge vertical axis wind rotor

The savonius vertical axis wind rotor has a simple structure, making it a suitable choice for power generation in small-scale, low wind speed environments. However, its wind energy conversion efficiency is low. To improve the conversion efficiency of the wind rotor using the proposed fish-bridge structure, the wind tunnel tests are conducted to collect actual wind and rotational speeds. In addition, Computational Fluid Dynamics (CFD) simulation is conducted to reveal potential operating mechanisms, with special emphasis on analyzing the effects of aspect ratio and end plate on the performance of the fish-ridge wind rotor. The CFD results show that the wind power coefficient of this wind rotor presents an increasing trend with the increase of the aspect ratio and the area of the end plate, and that with round end plates is improved by 24.26 % compared to that of the wind rotor without end plates, and that with an aspect ratio of 3.5 is improved by 32.58 % compared to that of the wind rotor with an aspect ratio of 1. By increasing the aspect ratio and the end plate area of the wind rotor, the contact airflow is raised and concentrated, which improves the aerodynamic performance of the wind rotor.

A bioinspired triboelectric wireless anemometer with low cut-in wind speed for meteorological UAVs

Currently, unmanned aerial vehicles (UAVs) play a pivotal role in meteorological wind speed measurements. Nevertheless, existing anemometers exhibit notable issues, including excessive weight, high cost and high cut-in wind speed. This investigation introduces a biomimetic owl wing airfoil wind speed sensor utilizing the principles of the triboelectric nanogenerator (BOW-TENG) designed for UAV applications. Inspired by owl wings, an airfoil configuration with superior aerodynamic characteristics is ascertained, subsequently fabricating it into an impeller, and a wind speed sensor with low weight, low cost and low cut-in wind speed is developed. Experimental results affirm the BOW-TENG’s precision in depicting wind speed across the range of 1.6–10.7 m/s, featuring a sensitivity of 21.893 Hz/(m·s−1), a goodness of fit R2 of 0.9995, and a remarkable resolution of 0.057 m/s. The sensor weighs only 30 g. Furthermore, a cost-effective triboelectric signal processing system is devised for integrating the BOW-TENG into the UAV, as well as the optimal positioning for BOW-TENG on the UAV is identified through simulations. The relative wind direction can be calculated from signals of the BOW-TENGs on the four arms of the UAV. Ultimately, application experiments demonstrate the feasibility of employing BOW-TENG for wireless wind speed transmission from UAVs. This work incorporates bionics and proposes a practical application of triboelectric sensors for UAVs, as well as a solution for developing wind speed sensors in the field of meteorological UAV detection.

A Two-Stage Operation Strategy for Energy Storage under Extreme-Heat-with-Low-Wind-Speed Scenarios of a Power System

Changes in weather conditions directly impact the output of wind power, photovoltaic systems, and other forms of uncontrollable power generation. During extreme weather events, the output from wind and photovoltaic sources is typically reduced. In light of this, this paper proposes a two-stage operational strategy for energy storage, under scenarios of extreme-heat-with-low-wind-speed, in power systems. Firstly, historical data on wind and solar power, along with weather characteristics, are collected to analyze the power output during multi-day periods of extreme heat and low wind speed. Then, Monte Carlo simulations are employed to generate multi-day load curves with inherent uncertainties, based on regional load characteristics of the power system. Finally, a two-stage operation strategy for energy storage charging and discharging is established. In the first stage, normal operations are conducted to identify periods of power shortage across various types of loads. In the second stage, based on the identified moments of power shortage from the first stage, charging and discharging constraints are applied to the energy storage systems. The feasibility and effectiveness of this two-stage operational strategy are then validated through simulations, using historical data to generate scenarios of multi-day extreme-heat-and-low-wind-speed conditions.

Momentum transfer and foam production via breaking waves in hurricane conditions

Generated under hurricane conditions, a slip layer composed of foam, spray, bubble emulsion, etc. determines the behavior of surface drag with wind speed. This study estimates foam's contribution to this behavior. A logarithmic parametrization of surface drag is introduced, where the effective roughness length of the underlying surface is decomposed into three fractional roughness lengths. These correspond to the foam-free area (as determined by open-ocean data at low wind speeds and laboratory data at high wind speeds), which includes the effects of spray, bubble emulsion, etc., and ocean areas covered by whitecaps and streaks, each weighted by their respective coverage coefficients. A key concept of this approach is the use of well-established experimental bubble-size spectra produced by breaking surface waves to obtain the foam-produced effective roughness length. This method provides a fair correlation of the logarithmic parametrization of surface drag against wind speed with a wide class of experimental data. Additionally, this approach estimates the hurricane's potential intensity, demonstrating reasonable agreement with experimental findings.

EXPERIMENTAL STUDIES OF THE PERFORMANCE EFFICIENCY OF A WIND TURBINE WITH COMBINED BLADES

This article studies the aerodynamic characteristics of a wind turbine at different streamline parameters. For this purpose, an experimental sample of the plant with combined power elements in rotating cylinders form with fixed blades was fabricated. The airflow velocity was varied, ranging from 3 to 12 m/s. The results of the experiment to study the variation of the angle α of the fixed blade position relative to the cylinder from the air flow velocity were analyzed. The changes in aerodynamic forces from the air flow velocity are graphically presented. It was found that at the optimal angle α = 0 ° of the fixed blade relative to the cylinder, the maximum values of aerodynamic forces were obtained. Graphs of the dependence of aerodynamic coefficients on the Reynolds number are also constructed, in which it is established that, at α= 0º, the minimum value of the lift coefficient is 0.012 N and the maximum value of the drag coefficient is 10.07 N at Re = 1∙105. The presented results show the effectiveness of the combined use of the and the fixed blade. The experimental results obtained on the aerodynamic parameters of a wind turbine can be used in the development of prototypes of installations designed for low wind speeds.

Commercial Small-Scale Horizontal and Vertical Wind Turbines: A Comprehensive Review of Geometry, Materials, Costs and Performance

The effective exploitation of renewable energy sources is one of the most effective solutions to counter the energy, environmental and economic problems associated with the use of fossil fuels. Small-scale wind turbines (converting wind energy into electric energy with a power output lower than 50 kW) have received tremendous attention over the past few decades thanks to their reduced environmental impact, high efficiency, low maintenance cost, high reliability, wide wind operation range, self-starting capability at low wind speed, limited installation space, reduced dependence on grid-connected power and long transmission lines, low capital costs, as well as the possibility to be installed in some urban settings. However, there are significant challenges and drawbacks associated with this technology from many different perspectives, including the significant discrepancy between theoretical performance data provided by the manufacturers and real field operation, that need to be investigated in greater depth in order to enable a more widespread deployment of small-scale wind turbines. In this review, a complete and updated list of more than 200 commercially available small-scale horizontal and vertical wind turbine models is provided and analysed, detailing the corresponding characteristics in terms of the number and material of blades, start-up wind speed, cut-in wind speed, cut-out wind speed, survival wind speed, maximum power, noise level, rotor diameter, turbine length, tower height, and specific capital cost. In addition, several scientific papers focusing on the experimental assessment of field performance of commercially available small-scale horizontal and vertical wind turbines have been reviewed and the corresponding measured data have been compared with the rated performance derived from the manufacturers’ datasheets in order to underline the discrepancies. This review represents an opportunity for the scientific community to have a clear and up-to-date picture of small-scale horizontal as well as vertical wind turbines on the market today, with a precise summary of their geometric, performance, and economic characteristics, which can enable a more accurate and informed choice of the wind turbine to be used depending on the application. It also describes the differences between theoretical and in-situ performance, emphasizing the need for further experimental research and highlighting the direction in which future studies should be directed for more efficient design and use of building-integrated small-scale wind turbines.

An Experimental Performance Assessment of a Passively Controlled Wind Turbine Blade Concept: Part A—Isotropic Materials

This paper is the first part of a two-part series, which presents preliminary findings on a novel flexible curved wind turbine blade designed for passive control, comparing its aerodynamic performance and behavior against a conventional straight blade. Characterized by its ability to twist around its longitudinal axis under bending loads, the flexible curved blade is engineered to self-regulate in response to varying wind speeds, optimizing power output and enhancing operational safety. This design utilizes inherent elasticity and specific geometric configurations to develop torsional loads, resulting in continuous adjustment of the blade’s pitch angle via twist–bend deformation. The study focuses on a comparative analysis conducted in a wind tunnel, testing both a small-scale model of the conventional blade and the flexible curved blade of equivalent diameter. Results indicate that the flexible curved blade concept successfully moderates its rotational speed and power output at higher wind speeds and demonstrates the capability to start generating power at lower wind speeds and stabilize power effectively, aligning with sustainability goals by potentially reducing reliance on active control systems. Despite promising outcomes, passive control mechanisms did not activate at the designed wind speeds, revealing a misalignment between expected and actual performance and underscoring the need for further refinements in blade design and control settings. Additionally, the power coefficient (Cp) versus tip speed ratio (TSR) comparison showed that flexible curved blades operate within a lower TSR range and exhibit controlled capping of power under high wind conditions, marked by a distinctive ‘hook-like’ feature in Cp behavior. This study confirms the feasibility of designing and manufacturing passively controlled wind turbine blades tailored to specific performance criteria and underscores the potential of such technology. Future work, to be detailed in a subsequent paper, will explore further optimizations and the use of Glass Fiber-Reinforced Polymer (GFPR) composite materials to enhance blade flexibility and performance.

Ocean Contribution to Coastal Heavy Rainfall During Dry Season (Case Study of Bengkulu 2016-2022)

This study aims to determine the contribution of the ocean to the intensity of heavy rainfall in Bengkulu, Indonesia during the dry season (2016-2022). The primary data used in this study is daily rainfall data from the Bengkulu Meteorology Climatology and Geophysics Agency BMKG station. In addition, supporting data are also used in the form of rain parameters, 10 m wind, sea surface temperature, and sea surface currents from ERA5 reanalysis data with daily temporal and spatial resolution of 0.05°. The method used is a composite method that calculates 64 samples of heavy rain. The results showed that low-speed winds formed an eddy in the sea area west of Sumatra which together with heavy rains resulted in an increase in sea surface temperature. In addition, for the 2019 dry season case study, 1 m/s winds near the Bengkulu coast are associated with heavy rainfall (>100 mm) and during the 2022 dry season, 1-4 m/s winds spread from the coast to the Indian Ocean sea, causing rainfall (>50 mm) on the Bengkulu coast and surrounding areas. When sea surface temperatures are high there is the potential for heavy rainfall in areas of low wind speed. The current in each year is different and has a pattern, every year a strong current from the Indian Ocean will move towards the coastal area every 3-year period. When in 2016 the current (>1 m/sec) is in the Indian Ocean, then the following year 2017 the current (>1 m/sec) shifts closer to the coastal area until in 2018 a strong current is on the coast and the following years a stronger current comes from the Indian Ocean.

Concentrations and Oxidative Potential of PM2.5 and Black Carbon Inhalation Doses at US–Mexico Port of Entry

Located between Mexico and the US, the San Ysidro/El Chaparral Land Port of Entry (SYPOE) is one of the busiest border crossings in the world. People with activities at the SYPOE are exposed to vehicular pollutants, especially particles with aerodynamic diameters < 2.5 µm (PM2.5) and black carbon (BC), both associated with adverse health effects. This study presents the first PM2.5 and BC concentration measurements collected on the Mexican side of the SYPOE. The oxidative potential (OP) for PM2.5 and the inhalation dose of BC for people at the border were also evaluated. Autumn and winter showed the highest PM2.5 concentrations (at 28.7 μg m−3 and 28.2 μg m−3, respectively). BC concentration peaked in the winter of 2017 (at 5.7 ± 6 μgm−3), demonstrating an increase during periods with low wind speeds. The highest OPDTT of PM2.5 was reached in winter, with a value of 18.5 pmol min−1 µg−1 (0.6 nmol min−1m−3). The highest average daily inhalation dose for pedestrians was registered in the autumn of 2018 (5.9 μg for a 60-min waiting time), whereas, for workers, it was in the winter of 2017 (19 μg for a 10-h shift on average). Decreasing waiting times for pedestrians and adjusting work schedules for border workers on high concentration days could ameliorate environmental justice.