Clear Days Research Articles

Assessing the impact of green infrastructure on thermal comfort in relation to humidity: A case study in Korea

Problems arising from heatwaves and urban heat islands (UHIs) exacerbated by climate change have prompted diverse adaptation strategies. Although green infrastructure, which positively affects climate change adaptation, has been extensively evaluated, global-scale assessments of UHIs indicate that green infrastructure may not be sufficient to mitigate UHIs in humid regions with annual precipitation exceeding 1000 mm or summer precipitation exceeding 570 mm. However, these assessments primarily focused on UHIs; different results may be obtained for individual heat comfort. As relative humidity increases, the cooling effect of green areas potentially decreases. This suggests the need for additional studies on the impact of short-term precipitation, which increases relative humidity and induces cooling effects on green infrastructure. Korea experiences a humid summer due to the concentration of precipitation (approximately 711 mm of summer precipitation); thus, the contribution of green infrastructure to improving heat comfort might be limited. Therefore, this study investigated the impact of green infrastructure on thermal comfort in relation to precipitation levels using the Wet-Bulb Globe Temperature (WBGT) index and data from weather stations in Korea. Precipitation intensity was categorized into 2-day periods and 10 mm/day. Subsequently, thermal comfort was compared for summers from 1993 to 2022 according to the green infrastructure ratio around the stations. The results indicated that green infrastructure had a cooling effect on clear days but only had a cooling effect on precipitation days when the level of green infrastructure was above the critical ratio. Additionally, green infrastructure reduced the WBGT index if minimal precipitation occurred during the five-day cooling period following precipitation. While green infrastructure remains crucial for climate change adaptation, other strategies must be implemented to improve the thermal environment, particularly in areas with frequent precipitation.

Identifying and validating perceived workload metrics for emergency medical services

The most common workload surrogates used by Emergency Medical Services (EMS)— overall call volume (CV) and unit hour utilization (UHU)—have not been validated. This study investigates the relationship between EMS operational metrics and perceived workload, measured through the NASA task load index (TLX) survey. We paired crew member survey responses with the operational metrics based on dispatch data. Linear regression was used to evaluate the influence of each metric on perceived workload. Logistic regression was used to identify values of workload indicating a fair day's work. We found that the overall CV (p < 0.001, R2=0.32) and UHU (p < 0.001, R2=0.22) explained less variability in perceived workload than a priority (P)-stratified CV (p < 0.001, R2=0.41). However, we found no clear fair day's workload threshold. We conclude that a priority-stratified CV is a better workload surrogate than a CV and UHU.

Experimental Evaluation of a Solar-Powered Air Conditioner

Air conditioning is vital in maintaining indoor comfort and improving air quality, particularly in regions with high temperatures and humidity. However, the increasing demand for air conditioning has significant implications for energy consumption and the environment. Solar air conditioning can play a vital role in mitigating such impacts. This study presents an experimental setup that utilizes a solar photovoltaic system to power an air conditioning unit. The system is installed in a 36 m2-research lab at The University of Jordan, equipped with PV panels with a capacity of 2.67 kWp, a battery pack, a charge controller, an inverter charger, and an air conditioning unit. Two testing scenarios are conducted: an on-grid system connected to the electrical grid and an off-grid system operating independently. A clear sky day and a partially cloudy day were selected for each scenario in testing. The results were evaluated based on the solar fraction, energy consumption, and operational time fraction (OTF). The solar fraction was found to be higher during periods of higher demand and ambient temperature, and the average OTF was 70 % for all trials. In off-grid trials, the system had maintained operation solely on PV power during the studied load profile in the clear sky day. In contrast, limitations in charging power caused system shutdown in the partially cloudy trial. An economic analysis for the local payback period (PBP) was conducted based on the Hourly Analysis Program and PVsyst software simulation, which shows an attractive simple local PBP for on-grid and off-grid systems of 6.91 and 6.4 years, respectively.

Wind Profile Retrieval Based on LSTM Algorithm and Mobile Observation of Brightness Temperature over the Tibetan Plateau

Stationary or mobile microwave radiometers (MRs) can measure atmospheric temperature, relative humidity, and water vapor density profiles with high spatio-temporal resolution, but cannot obtain the vertical variations of wind field. Based on a dataset of brightness temperatures (TBs) measured with a mobile MR over the Three-River-Source Region of the Tibetan Plateau from 18 to 30 July 2021, we develop a direct retrieval method for the wind profile (WP) based on the Long Short-Term Memory (LSTM) network technique, and obtain the reliable dynamic variation characteristics of the WP in the region. Furthermore, the ground-based radiative transfer model for TOVS (RTTOV-gb) was employed to validate the reliability of the TB observation, and we analyzed the impact of weather conditions, altitude, observational mode, and TB diurnal variation on the accuracy of the TB measurement and the retrieval of the WP. Results show that the TB from the mobile observation (MOTB) on clear and cloudy days are close to those of the simulated TB with the RTTOV-gb model, while TB measurements on rainy days are far larger than the modeled TBs. When compared with radiosonde observations, the WPs retrieved with the LSTM algorithm are better than the ERA5 reanalysis data, especially below 350 hPa, where the root mean square errors for both wind speed and wind direction are smaller than those of ERA5. The major factors influencing WP retrieval include the weather conditions, altitude, observational mode, and TB diurnal variation. Under clear-sky and cloudy conditions, the LSTM retrieval method can reproduce the spatio-temporal evolution of wind field and vertical wind shear characteristics. The findings of this study help to improve our understanding of meso-scale atmospheric dynamic structures, characteristics of vertical wind shear, atmospheric boundary layer turbulence, and enhance the assessment and forecasting accuracy of wind energy resources.

Validation of initial observation from the first spaceborne high-spectral-resolution lidar with a ground-based lidar network

Abstract. On 16 April 2022, China successfully launched the world's first spaceborne high-spectral-resolution lidar (HSRL), which is called the Aerosol and Carbon Detection Lidar (ACDL), on board the Atmospheric Environment Monitoring Satellite known as Daqi-1 (DQ-1). The ACDL is expected to precisely detect the three-dimensional distribution of aerosol and cloud globally with high spatial–temporal resolutions. To assess the performance of the newly launched satellite lidar, the ACDL-retrieved observations were compared with ground-based lidar measurements of atmospheric aerosol and cloud over northwest China from May to July 2022 using the Belt and Road lidar network (BR-lidarnet) initiated by Lanzhou University in China and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar observations. A total of six cases in the daytime and nighttime, including clear days, dust events, and cloudy conditions, were selected for further analysis. Moreover, profiles of the total attenuated backscatter coefficient (TABC) and the volume depolarization ratio (VDR) at 532 nm measured by the ACDL, the CALIPSO lidar, and ground-based lidar are compared in detail. Comparison is made between the 532 nm extinction coefficient and lidar ratio obtained from ACDL HSRL retrieval and the Raman retrieval results obtained from BR-lidarnet. The achieved results revealed that the ACDL observations were in good agreement with the ground-based lidar measurements during dust events with a relative deviation of about −10.5 ± 25.4 % for the TABC and −6.0 ± 38.5 % for the VDR. Additionally, the heights of the cloud top and bottom from these two measurements were well matched and comparable. Compared with the observation of CALIPSO, the ACDL also shows high consistency. This study proves that the ACDL provides reliable observations of aerosol and cloud in the presence of various climatic conditions, which helps to further evaluate the impacts of aerosol on climate and the environment, as well as on the ecosystem in the future.

Windshear Detection in Rain Using a 30 km Radius Coherent Doppler Wind Lidar at Mega Airport in Plateau

Convective weather is often accompanied by precipitation and windshear, seriously endangering the safety of aircraft during takeoff and landing. However, under rainfall conditions, conventional wind lidars have a limited detection range due to significant signal attenuation. To solve this problem, a 200 mm temperature-controlled telescope coated with a hydrophobic film is applied in the coherent Doppler wind lidar system to improve the detection capability in rain. The maximum detection range of the lidar is extended to 30 km and demonstrated at Kunming Changshui International Airport at an altitude of 2102 m. Firstly, the detection accuracy and maximum detection range of the lidar are verified. Through the analysis of the horizontal wind field under two typical convective weather conditions, it is found that convective weather often accompanies low-level convergence and divergence structures, leading to headwind shear and crosswind shear on the airport runway. From the vertical profile, it is shown that the triggering of convective weather is accompanied by low-level southwest winds and high-altitude northeastern winds. According to the statistics of wind speed and direction on clear and rainy days over 9 months, rainy days are usually caused by the invasion of cold air from Northeast China, resulting in airport windshear. In summary, the enhanced lidar can effectively identify and analyze windshear during rainy days, which is very useful for aviation safety, especially for takeoff and landing in all weather conditions.

Hazard or Non-Hazard Flood: Post Analysis for Paddy Rice, Wetland, and Other Potential Non-Hazard Flood Extraction from the VIIRS Flood Products

VIIRS flood products have been widely used by the National Weather Service (NWS) for river flood monitoring, and by the Federal Emergency Management Agency (FEMA) and the International Charter Program for rescue and relief efforts. However, some water bodies, like irrigated or flooded paddy rice fields, and water in seasonal wetlands, are detected as floodwater instead of permanent, seasonal, controlled, or normal water in the VIIRS flood products. Because these kinds of floodwater don’t cause any severe disasters, they should be delineated as non-hazard floods to differentiate from real hazardous floods, the latter of which generally pose a significant risk and damage to human life, property, and the environment. Hazardous floods are usually caused by intensive rainfall, rapid snowmelt, or ice jams, they appear accidentally and tend to be short-term events. Non-hazard floodwaters generally result from tides, wetlands, agricultural irrigation, and other human activities, and thus they appear regularly and often stand for a longer time. Therefore, non-hazard floodwaters are some kind of standing water and usually have much larger long-time flood frequency or probability than hazardous floods. Based on this feature, it’s possible to combine long-time flood frequency calculated as the ratio of total flooding days over total clear days, including both flooding and no-flooding days, from VIIRS flood products with some additional information, such as agriculture statistics and land cover and land use map, to identify non-hazard floodwater in paddy rice fields and wetland. In this study, non-hazard floodwater bodies are classified into four types: paddy rice fields, wetlands, riparian and coastal tidal flooding, and other non-hazard floods, including possible fishing ponds. In this study, we selected several examples, such as the 2023 California flood event and some large paddy rice fields in China, to demonstrate how to identify water in paddy rice fields. The Florida flood event due to Hurricane Ian in 2022 is used to demonstrate how to separate wetlands from real hazardous floods. In addition to non-hazard floodwaters in wetlands, some coastal tidal flooding in Florida is also detected. The non-hazard floodwaters extracted from the proposed methods are compared with change detection analysis and good agreement is found. The paddy rice fields obtained from this study are compared and evaluated with the rice distribution data from the USDA. The quantitative evaluation results from the confusion matrix calculation demonstrate that the accuracy is 99.96%, recall is 83.69%, precision is 61.57%, and the F1-score is 70.95%. The high accuracy indicates that the method developed in this study for paddy rice field extraction from the VIIRS flood products is feasible.

Vertical Characteristics of HCHO and NO2 in Suburban Shanghai: Understanding of Ozone formation sensitivity via Secondary HCHO

Abstract Since ozone (O3) pollution in China is on the rise, vertical distribution of nitrogen dioxide (NO2) and formaldehyde (HCHO) and their role towards O3 formation are critical towards designing O3 control strategies. Seasonal characteristics of aerosols, HCHO and NO2 were investigated over suburban Shanghai using Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) from June 2020 to May 2021. For HCHO, the highest average vertical mixing ratios (VMRs) were observed for summer (0.775 ppb), followed by autumn (0.719 ppb), spring (0.718 ppb) and winter (0.672 ppb) at ground level. Seasonal trends in NO2 VMRs were observed to be opposite to that of HCHO with peak values occurring during winter (2.212 ppb) at the ground level followed by autumn (1.881 ppb), spring (1.415 ppb) and summer (1.124 ppb). In vertical, aerosols depicted a Gaussian shape with a higher values between 0.2 - 0.5 km. An exponential decay in NO2 VMRs is observed from 0.0 km to 3.0 km while the integral component of HCHO was found to be concentrated up to 2.0 km particularly during summer months. The vertical distribution of NO2 in different seasons mainly appeared below 0.5 km, while that of HCHO appeared within the range of 0.2-1.0 km. Both aerosols and NO2 tend to be higher during haze days compared to non-haze days while HCHO was found to be higher during clear days owing to high photochemical activity on a clear day. Based on the ratio of HCHO to NO2 (RFN), this study attempted to quantify the vertical characteristics of O3 sensitivity for different seasons. The results indicated that the O3 sensitivity was VOC-limited both at lower (generally, 0.0 - 0.6 km) and higher heights (1.8 - 3.0 km) while some transition limited scenarios were found at middle height (0.7 – 1.7 km) particularly during daytime. The results depicted that secondary HCHO is a crucial factor controlling on O3 sensitivity over Shanghai where enhanced ratio of VOC limited regime was observed with secondary HCHO for all the seasons.

Photovoltaic-integrated advancements for sustainable water production: Developing and evaluating an enhanced hybrid solar desalination system

The global water crisis demands innovative solutions, and solar desalination is a promising avenue. However, traditional systems often suffer from low yields. This study centres on the development, assessment, and economic feasibility of the Enhanced Hybrid Solar Still (EHSS), a pioneering approach to sustainable clean water production. Integrating photovoltaic technology, the EHSS targets a minimum daily output of 15 L/m2. Computational Fluid Dynamics (CFD) simulations guide the design optimisation, identifying an optimal configuration of 4 mm basin thickness, a 2 mm glass cover thickness, and a 56° slope. The EHSS is a single component that comprises of passive operation and advanced components integration, including monocrystalline solar panels, a hybrid MPPT inverter, a deep cycle battery, and a custom water heater, to enhance the yield. The EHSS undergoes a comprehensive assessment encompassing distillate quality, efficiency, and economic viability. In passive mode operation (solely using solar radiation), clean water yields range from 4.7111 L/m2·day to 2.1309 L/m2·day. Transitioning to active mode operation (employing photovoltaics and additional components) significantly enhances yields to a range of 19.7 L/m2·day. Impressively, the EHSS consistently delivers an average daily water yield of 16.85 L/m2, and also its purity meets World Health Organization standards for drinking water. The PV systems exhibit a charge rate of 14.28 % per hour on clear days and 9 to 11 % per hour on semi-cloudy days, with the battery depleting at 16.66 % per hour at 70 °C operational temperature. Comparative analysis against traditional systems showcases an efficiency increase from 25.61 % to an outstanding 64.01 % for the optimised EHSS (PV system and appurtenances). A strong correlation (coefficient of 0.9701) between experimental and simulation results indicates robust relationships. Over a 20-year lifespan, cost analysis reveals a per-litre cost of 0.0892 US dollars for the EHSS, compared to 0.0374 US dollars for traditional systems. Extended lifespans further underscore the economic feasibility of the EHSS, emphasizing its role in providing sustainable clean water solutions.

Development of a Self-Regulating Solar Shading Actuator Based on the Thermal Shape Memory Effect

In the field of adaptive building technologies, this research introduces the development of a self-regulating solar shading actuator that utilizes the thermal shape memory effect. The study focuses on addressing the actuator’s performance under diverse environmental conditions. Thermal simulations were carried out during the development of the individual components of the actuator and for the prediction of specific switching temperatures. The investigation includes an analysis of the sunshade’s response to varying environmental conditions, emphasizing its effectiveness on clear summer days and identifying challenges during overcast periods. The critical coordination between the solar collector and the shape memory alloy (SMA) wire is examined, shedding light on the impact of SMA temperature dynamics on the actuation performance. Through the integration of simulation data and real-world measurements, the study validates the thermal model for the solar collector, establishing the robustness of the system’s operation. This research work contributes significantly to the development of intelligent actuators and outlines the importance of validation of SMA-based applications under real conditions.

Daylight Comfort Performance of a Vertical Fin Shading System: Annual Simulation and Experimental Testing of a Prototype

This study aims to develop and evaluate a vertically rotated fin shading system for an energy-efficient, user-friendly office space. The system was designed to protect a 4 × 8 m office room with a south-facing facade from excessive solar radiation and glare. The shading system was modelled and simulated using Rhino/Ladybug 1.6.0 software with Radiance engine, based on real-weather data (*.epw file) for Wrocław, Poland at 51° lat. The simulation calculated the useful daylight illuminance (UDI) for 300–3000 lux and the daylight glare probability (DGP) for ten static and four kinetic variants of the system. The optimal angle of the fin rotation for the static variant was found to be α = 40°. The kinetic variants were activated when the work plane illuminance exceeded 3000 lux, as detected by an internal sensor “A”. The simulation results show that the kinetic system improved the daylight uniformity in the office room, achieving UDI300–3000 values above 80% for more than 40% of the room area. A prototype of the system in a 1:20 scale was built and tested on a testbed at Wrocław University of Science and Technology, using TESTO THL 160 data loggers. The measurements were conducted for a week in early November 2023, and three clear days were selected for analysis. The measurement results indicate that the low solar altitude on clear days causes high illuminance peaks (15–18 Klux) and significant contrast in the room, leading to unsatisfactory DGP values consistent with the simulation outcomes. Therefore, the study concludes that the proposed system may need an additional shading device to prevent glare during periods of low solar altitudes.

DEVELOPMENT AND INSTALLATION OF SOLAR WATER HEATING SYSTEM FOR FEDPODAM HOSTEL

This paper presents the result of the Development, Installation and Performance evaluation of a 500 liter capacity hot water storage tank with an additional 500 liter capacity cold water storage tank that was, developed, installed and tested at Maryam Abatcha female hostel in the Federal Polytechnic Damaturu, Yobe State, Nigeria which is located at latitude 12.290N and Longitude 11.440E using available materials and thermo syphon principle at an average solar radiation of 630W/m2 to investigate the potential of using solar either directly and indirectly for heating water and to compare its cost with electricity. This design utilized a flat plate collector which was chosen because of the simplicity in construction and ease of maintenance. Two collectors of 1m2 each with single glazing were used as a heat exchanger. The surfaces of the collectors were painted with black paint of absorptivity 0.95 and emissivity of 0.09 to improve its absorption capacity. Readings were taken for a period of nine months starting from March, April, May, June, July, August, September, October and November with minimum ambient temperature of 320C. Maximum hot water temperature inside the tank as 82.30C with an average efficiency of 28.06% in June, with clear sunny atmosphere days and November with lower outlet likely due to cold dusty of the period. Test conducted reveal that the system could satisfy the hot /warm water requirements of the hostel. It was also observed that the water temperature is a function of solar radiation while the cloud cover and dust particles were observed to also affect the performance of solar water heating system thereby reducing its efficiency.

Metrological Evaluation of the Building Influence on Air Temperature Measurements

This paper describes the metrological procedure carried out for the evaluation of the building influence on air temperature measurements. This evaluation aims to produce reliable conclusions, information, and data to contribute to the WMO siting classification schemes for air temperature measurements. For this purpose, a field experiment was designed, deployed, and carried out. As a result, one-year-lasting air temperature measurements were collected and analyzed. In this field experiment, a 200 m wide building is the unique artificial heat source and the unique object projecting shades over a flat surface (no discernible slope) in an open space bigger than 40,000 m2, covered with short grass. Eight calibrated thermometers, equipped with the same model of artificially ventilated radiation shields, were set up at a height of 1.5 m from the ground and at different distances from a 200 m wide building. This configuration provides the observation of the horizontal air temperature radially distributed from the building and, as a conclusion, it enables the quantification of the building influences on air temperature measurements at different distances from the building. This document describes the field experiment, the analysis procedure, the evolution of the building influence on air temperature measurements along the day, and the impact of other meteorological parameters on this building effect. Two different building effects are observed: the positive building effect, where the air temperature decreases with the distance to the building, and the negative building effect, where the air temperature increases with the distance to the building. It is also noticed that the building influence is higher on clear days and the daily maximum building influence values are directly linked with the corresponding maximum solar irradiance. The influence of wind on the building effect is also analyzed, reaching the conclusion that due to characteristic of local winds, in terms of low speed and direction, the wind impact could be considered as negligible. The maximum values of building influence on air temperature measurements, the associated uncertainty analysis, and the conclusions are presented in this paper. All these points have been addressed using metrological principles with the purpose of giving consistency and robustness to the evidence presented here.

Modeling urban air temperature using satellite-derived surface temperature, meteorological data, and local climate zone pattern—a case study in Szeged, Hungary

Urban air temperature is a crucial variable for many urban issues. However, the availability of urban air temperature is often limited due to the deficiency of meteorological stations, especially in urban areas with heterogeneous land cover. Many studies have developed different methods to estimate urban air temperature. However, meteorological variables and local climate zone (LCZ) have been less used in this topic. Our study developed a new method to estimate urban air temperature in canopy layer during clear sky days by integrating land surface temperature (LST) from MODIS, meteorological variables based on reanalysis data, and LCZ data in Szeged, Hungary. Random forest algorithms were used for developing the estimation model. We focused on four seasons and distinguished between daytime and nighttime situations. The cross-validation results showed that our method can effectively estimate urban air temperature, with average daytime and nighttime root mean square error (RMSE) of 0.5 ℃ (R2 = 0.99) and 0.9 ℃ (R2 = 0.95), respectively. The results based on a test dataset from 2018 to 2019 indicated that the optimal model selected by cross-validation had the best performance in summer, with time-synchronous RMSE of 2.1 ℃ (R2 = 0.6, daytime) and 2.2 ℃ (R2 = 0.86, nighttime) and seasonal mean RMSE of 1.5 ℃ (R2 = 0.34, daytime) and 1.2 ℃ (R2 = 0.74, nighttime). In addition, we found that LCZ was more important at night, while meteorological data contributed more to the model during the daytime, which revealed the temporal mechanisms of the effect of these two variables on air temperature estimation. Our study provides a novel and reliable method and tool to explore the urban thermal environment for urban researchers.

Possible Global Generation Region of Nonlinear Whistler‐Mode Chorus Emission Waves at Mercury

AbstractChorus waves are a kind of intense electromagnetic emission wave in magnetized planets and can play important roles in the kinetic electron dynamics in planetary magnetospheres. Rapid changes of the ring electron current belt in Mercury’s magnetosphere and the contribution of chorus waves have remained long‐standing scientific issues from the first Mercury flyby observations by Mariner 10 in 1970s because of the small size of the magnetosphere. Based on theoretical analyses and simulations successfully reconstructing Earth’s chorus wave properties, we report on possible generation regions of chorus waves in Mercury’s magnetosphere. The theoretical analysis for low‐temperature‐anisotropy electrons shows a clear asymmetric day–night spatial distribution of the possible chorus generation region because of the difference in the nonlinear convective wave growth along the magnetic field lines. Simulation results show a rapid enhancement of the ring electron current belt by resonant interactions with repetitive chorus waves. Our study suggests that energetic electrons in Mercury’s magnetosphere can be enhanced locally by nonlinear chorus wave–particle interactions.

First estimation of hourly full-coverage ground-level ozone from Fengyun-4A satellite using machine learning

Ground-level ozone (O3), renowned for its adverse impacts on human health and crop production, has garnered significant attention from governmental and public sectors. To address the limitations posed by sparse and uneven ground-level O3 observations, this study proposes an innovative method for hourly full-coverage ground-level O3 estimation using machine learning. Meteorological data from National Centers for Environmental Prediction global forecasting system, satellite data from Fengyun-4 A(FY-4 A) and Ozone Monitoring Instrument, emission inventory from Multi-resolution Emission Inventory for China, and other auxiliary data are utilized as input variables, while ground-based O3 observations serve as the response variable. The method is applied on a monthly basis across China for the year 2022, resulting in the generation of an hourly full-coverage high-resolution (4 km) ground-level O3 estimation, termed ML-derived-O3. Cross-validation results demonstrate the robustness of ML-derived-O3 yielding a coefficient of determination (R 2) of 0.96 (0.91) for sample-based (site-based) evaluations and a root-mean-square error (RMSE) of 9.22 (13.65) µg m−3. However, the date-based evaluation is less satisfactory due to the imbalanced training data, resulting from the pronounced daily variations in ground-level O3 concentrations. Nevertheless, the seasonal and hourly ML-derived-O3 exhibits high prediction accuracy, with R 2 values surpassing 0.95 and RMSE remaining below 7.5 µg m−3. This study marks a significant milestone as the first successful attempt to obtain hourly full-coverage ground-level O3 data across China. The diurnal variation of ML-derived-O3 demonstrates high consistency with ground-based observations, irrespective of clear or cloudy days, effectively capturing ground-level O3 pollution exposure events. This novel estimation method will be employed to establish a long-term high spatial-temporal resolution ground-level O3 dataset, which holds valuable applications for air pollution monitoring and environmental health research in future endeavors.

Variation the in relationship between urban tree canopy and air temperature reduction under a range of daily weather conditions

Mitigating heat is a vital ecosystem service of trees, particularly with climate change. Land surface temperature measures captured at a single time of day (in the morning) dominate the urban heat island literature. Less is known about how local tree canopy and impervious surface regulate air temperature throughout the day, and/or across many days with varied weather conditions, including cloud cover. We use bike-mounted air temperature sensors throughout the day in New Haven, Connecticut, USA, from 2019 to 2021 and generalized additive mixed models across 156 rides to estimate the daily variation in cooling benefits associated with tree canopy cover, and warming from impervious surface cover in 90 m buffers surrounding bike observations. Cooling is inferred by subtracting the bicycle-observed temperature from a reference station. The cooling benefits from tree canopy cover were strongest in the midday (11:00–14:00, −1.62 °C), afternoon (14:00–17:00, −1.19 °C), and morning (8:00–11:00, −1.15 °C) on clear days. The cooling effect was comparatively smaller on cloudy mornings −0.92 °C and afternoons −0.51 °C. Warming from impervious surfaces was most pronounced in the evening (17:00–20:00, 1.11 °C) irrespective of clouds, and during cloudy nights (20:00–23:00) and cloudy mornings 1.03 °C 95 % CI [1.03, 1.04]. Among the hottest observed days (top 25th percentile of reference station daily maxima), tree canopy was associated with lower temperatures on clear afternoons −1.78 °C [-1.78, −1.78], cloudy midday −1.17 °C [-1.19, −1.15], clear midday −1.12 °C [-1.12, −1.11]. We add a broader spectrum of weather conditions by explicitly including clouds, and greater temporal resolution by measuring throughout the day to bike-based urban heat research. Future mobile sampling campaigns may broaden the spatial extent with more environmental variation, representing an opportunity for public science and engagement.

Particle Swarm Optimization for an Optimal Hybrid Renewable Energy Microgrid System under Uncertainty

Microgrids can assist in managing power supply and demand, increase grid resilience to adverse weather, increase the deployment of zero-emission energy sources, utilise waste heat, and reduce energy wasted through transmission lines. To ensure that the full benefits of microgrid use are realised, hybrid renewable energy-based microgrids must operate at peak efficiency. To offer an optimal solution for managing microgrids with hybrid renewable energy sources (HRESs) while taking microgrid reserve margins into account, the particle swarm optimisation (PSO) method is suggested. The suggested approach demonstrated good performance in terms of charging and discharging BESS and maintaining the necessary reserve margins to supply critical loads if the grid and renewable energy sources are unavailable. On a clear day, the amount of electricity sold to the grid increased by 58%, while on a partially overcast day, it increased by 153%. Microgrids provide a good return on investment for their operators when they are run at peak efficiency. This is because the BESS is largely charged during off-peak hours or with excess renewable energy, and power is only purchased during less expensive off-peak hours.

Operation of a solar power plant with dual-axis solar tracker

The paper evaluates the generation of electrical energy by a solar power plant equipped with a solar tracking system using the ASHRAE clear-sky method for calculating solar insolation. The mathematical algorithm uses the MathCad system with data export and analysis in Microsoft Excel. Collected over a month and the operation period in 2022–2023, data on electricity generation by solar stations characterised by an optimal constant angle of inclination of the solar panel and equipped with a solar tracking system were used. By taking into account the varying ambient temperature, dust content, and solar transmission by the solar panel coating, the given algorithm allowed electricity generation by a solar panel to be forecasted with an average absolute error ranging from 0.22 to 9.8. To determine solar insolation for a specific day and the geographical coordinates of the intended construction site of a solar power plant, a mathematical model was developed using MathCad software. The experimental and computational studies carried out on selected clear days, accounting for varying weather conditions, demonstrated the adequacy of this method and its applicability for forecasting electricity generation with different inclination angles of a solar panel. It was established that a solar power plant with a solar tracking system generated 37% more electricity per year than that with fixed solar panels. The ASHRAE Clear-Sky method for calculating solar insolation allows the amount of electricity generated for a specific region to be estimated with minimal input data. Further research will focus on defining and improving methods for forecasting electricity generation by a solar power plant on overcast days.

Experimental investigation of thermal performance evaluation and thermodynamic analysis of domestic box type solar cooker with inclined aperture area

In this paper, the thermal performances of a box solar cooker were rated with F1 and F2 parameters as per Mullick’s procedure [1], the efficiency of the cooker was evaluated using energy and exergy analysis. The solar cooker was designed with an inclined aperture area, realized and experimentally tested at Applied Research Unit on Renewable Energies of Ghardaïa (32.39 °N, 3.78 °E, 463 m), Algeria. The developed cooker is equipped with one reflector mirror on its lid. The experiments have been carried out with the cooker empty, filled with one or two liters of water from 08:00 to 15:00 solar time, the thermal profiles of various components of the cooker were assessed at Ghardaïa site Sahara climatic conditions on clear days in both winter and summer months. According to the values of two figures of merits suggested by International Standards and evaluated by the experimental studies, the configuration with an inclined aperture area of the cooker resulted in good cooking performances, especially in winter when the sun’s elevation is low; keeping the realized cooker performances in range of the international standard tests. The results of this study indicate also that the average daily energy and exergy efficiency of the realized cooker was 16.2 % and 0.90 % respectively, during the experimental period, which indicate a significant difference between the results of energy and exergy analyses. Thus developing such a box solar cooker can improve the efficiency of the design and use a position of the system to prepare food in a shorter time.