Diurnal Temperature Variations Research Articles

Research on Climate Drivers of Ecosystem Services’ Value Loss Offset in the Qinghai–Tibet Plateau Based on Explainable Deep Learning

As one of the highest and most ecologically vulnerable regions in the world, the Qinghai–Tibet Plateau (QTP) presents significant challenges for the application of existing ecosystem service value (ESV) assessment models due to its extreme climate changes and unique plateau environment. Current models often fail to adequately account for the complex climate variability and topographical features of the QTP, making accurate assessments of ESV loss deviations difficult. To address these challenges, this study focuses on the QTP and employs a modified ESV loss deviation model, integrated with explainable deep learning techniques (LSTM-SHAP), to quantify and analyze ESV loss deviations and their climate drivers from 1990 to 2030. The results show that (1) between 1990 and 2020, the offset index in the eastern QTP consistently remained low, indicating significant deviations. Since 2010, low-value clusters in the western region have significantly increased, reflecting a widening range of ecological damage caused by ESV losses, with no marked improvement from 2020 to 2030. (2) SHAP value analysis identified key climate drivers, including temperature seasonality, diurnal temperature variation, and precipitation patterns, which exhibit nonlinear impacts and threshold effects on ESV loss deviation. (3) In the analysis of nonlinear relationships among key climate drivers, the interaction between diurnal temperature range and precipitation in wet seasons demonstrated significant effects, indicating that the synergistic action of temperature variation and precipitation patterns is critical to ecosystem stability. Furthermore, the complex nonlinear interactions between climate factors exacerbated the volatility of ESV loss deviations, particularly under extreme climate conditions. The 2030 forecast highlights that wet season precipitation and annual rainfall will become key factors driving changes in ESV loss deviation. By combining explainable deep learning methods, this study advances the understanding of the relationship between climate drivers and ecosystem service losses, providing scientific insights for ecosystem protection and sustainable management in the Qinghai–Tibet Plateau.

A revised ocean mixed layer model for better simulating the diurnal variation in ocean skin temperature

Abstract. Sea surface temperature (SST) is a crucial parameter in climate, weather, and ocean sciences due to its decisive role in ocean–atmosphere interactions. Identifying errors in the prognostic scheme used by the current European Centre for Medium-range Weather Forecasts (ECMWF) model for predicting the diurnal variation in ocean skin temperature led to a revisit and revision of the ocean mixed layer (OML) model. Validation of the revised model was conducted by comparing simulated temperatures at the sub-skin level and 1 m depth with observations from shipborne infrared measurements and buoys. These comparisons revealed a strong correlation, with an absolute mean deviation of less than 0.1 K and a standard deviation under 0.5 K, which are found to be comparable to errors in satellite observations of SST. Given that these results are derived from the same model simulations, the error statistics for the simulated skin temperature and its diurnal variation should have the same degree of accuracy. Furthermore, the simulation results closely align with anticipated solar radiation distributions, whereas ERA5 ocean skin temperature shows a significant lack of alignment with solar radiation. Consequently, the revised OML model shows promising potential for improving the simulation of diurnal SST variations in weather and climate models.

Effect of double-layer formwork curing on the early temperature field and properties of precast concrete components in environments with large diurnal temperature variations

An efficient double-layer formwork curing method using an “inner supporting formwork + outer insulation formwork” was proposed in this study to address the early cracking of precast concrete components in high altitude regions. Steel and plywood formwork were designed as inner support formwork, while polystyrene (PS) and polyurethane (PU) were used as outer insulation formwork. Indoor experiments and two finite element methods (The complete simulation method focuses on computational accuracy, and the equivalent simulation method emphasizes computational efficiency) were employed to analyze the evolution of the concrete temperature field under different double-layer formwork curing methods throughout the curing period, combined with compressive strength and pore structures testing. The results show that steel + 5-mm-thick PU insulation formwork curing method can significantly mitigate the impact of large diurnal temperature variations on the internal temperature of concrete. Unlike traditional steam-curing, this method does not deteriorate the pore structure or compressive strength of the concrete. This study is of great significance in addressing the problem of early cracking of precast concrete components exposed to large diurnal temperature vriations in high altitude regions.

Association of Postpartum Temperature Exposure with Postpartum Depression: A Retrospective Cohort Study in Southern California.

Postpartum depression (PPD) has been associated with biological, emotional, social, and environmental factors. However, evidence regarding the effect of temperature on PPD is extremely limited. We aimed to examine the associations between postpartum temperature exposure and PPD. We conducted a retrospective cohort study using data from Kaiser Permanente Southern California electronic health records from 1 January 2008 through 31 December 2018. PPD was first assessed using the Edinburgh Postnatal Depression Scale (score ) during the first year of the postpartum period and further identified by using both diagnostic codes and prescription medications. Historical daily ambient temperatures were obtained from the resolution gridMET dataset (https://www.climatologylab.org/gridmet.html) and linked to participants' residential addresses at delivery. Postpartum temperature exposures were measured by calculating various temperature metrics during the period from delivery to PPD diagnosis date. A time-to-event approach with a discrete-time logistic regression was applied to estimate the association between temperature exposure and time to PPD. Effect modification by maternal characteristics and other environmental factors was examined. There were 46,114 (10.73%) PPD cases among 429,839 pregnancies ( age y). Increased PPD risks were positively associated with exposure to higher mean temperature [adjusted odds ratio (aOR) per interquartile range increment: 1.07; 95% confidence interval (CI): 1.05, 1.09] and diurnal temperature range (; 95% CI: 1.06, 1.10); the associations were stronger for maximum temperature compared with minimum temperature. The temperature-related PPD risks were greater among African American, Asian, and Hispanic mothers and among mothers years of age compared with their counterparts. We also observed higher effects of temperature on PPD among mothers exposed to higher air pollution or lower green space levels and among mothers with lower air conditioning penetration rates. Maternal exposure to higher temperature and diurnal temperature variability during the postpartum period was associated with an increased risk of PPD. Effect modification by maternal age, race/ethnicity, air pollution, green space, and air conditioning penetration was identified. https://doi.org/10.1289/EHP14783.

Incorporating Diurnal and Meter-Scale Variations of Ambient CO2 Concentrations in Development of Direct Air Capture Technologies.

To be implemented on climate-relevant scales, direct air capture of CO2 (DAC) will require large capital-intensive facilities and careful attention to cost minimization. In making decisions among potential sites for DAC facilities, all of the factors that will impact process cost and efficiency should be considered. In this paper we focus on a factor that has previously received little attention in the DAC community, namely variations in atmospheric conditions on hourly time scales and length scales of meters. We present data curated from extensive previous studies of biosphere-atmosphere fluxes with observations of CO2 concentration, temperature, and relative humidity (RH) with hourly resolution from many sites in North America. These include locations where typical diurnal variations in CO2 concentration during summer months exceeds 150 ppm. These variations are larger than the seasonal variations that exist between averaged CO2 concentrations in winter and summer, and they are highly correlated with diurnal variations in temperature and RH. Diurnal variations are dependent on the height above ground at which CO2 concentrations are measured, with smaller variations existing at heights of 10 m or more than at ground level. We illustrate the potential implications of these short-term variations for the operation and optimization of a DAC process with process-level calculations for a specific adsorption-based process using amine-rich adsorbents.

Assessing diurnal land surface temperature variations across landcover and local climate zones: Implications for urban planning and mitigation strategies on socio-economic factors

Rising temperatures and rapid urbanization globally reinforce the need to understand urban climates. We investigated the influence of land cover and local climate zones (LCZs) on diurnal land surface temperature (LST) in various seasons in greater Delhi region, India, and their implications on socio-economic factors. Day LST was the highest in the summer and night LST in the monsoon, which also had the lowest diurnal differences in LST. Higher height and density of built-up features contributed to greater heat at night. During the day, open built-up and vegetated areas experienced relatively less heat than their compact equivalents. The lowest diurnal difference was in medium height compact urban zones and tall vegetation. Social inequity in access to urban cooling was indicated by large low-income and heat-vulnerable populations inhabiting the hottest LCZs. This research highlighted that even in semi-arid and subtropical climates, spatial planning policy should consider both the seasonality and diurnal differences in temperature as much as appropriate morphologies for design of thermally comfortable and climate resilient urban spaces. These policies should address the evidenced social inequities in heat exposure to reduce the adverse health impacts on vulnerable groups and therefore contribute to wider societal and economic benefits of healthier populations.

Microclimate monitoring in commercial tomato (Solanum Lycopersicum L.) greenhouse production and its effect on plant growth, yield and fruit quality

IntroductionHigh annual tomato yields are achieved using high-tech greenhouse production systems. Large greenhouses typically rely only on one central weather station per compartment to steer their internal climate, ignoring possible microclimate conditions within the greenhouse itself.MethodsIn this study, we analysed spatial variation in temperature and vapour pressure deficit in a commercial tomato greenhouse setting for three consecutive years. Multiple sensors were placed within the crop canopy, which revealed microclimate gradients.Results and discussionDifferent microclimates were present throughout the year, with seasonal (spring – summer – autumn) and diurnal (day – night) variations in temperature (up to 3 °C, daily average) and vapour pressure deficit (up to 0.6 kPa, daily average). The microclimate effects influenced in part the variation in plant and fruit growth rate and fruit yield – maximum recorded difference between two locations with different microclimates was 0.4 cm d-1 for stem growth rate, 0.6 g d-1 for fruit growth rate, 80 g for truss mass at harvest. The local microclimate effect on plant growth was always larger than the bulk climate variation measured by a central sensor, as commonly done in commercial greenhouses. Quality attributes of harvested tomato fruit did not show a significant difference between different microclimate conditions. In conclusion, we showed that even small, naturally occurring, differences in local environment conditions within a greenhouse may influence the rate of plant and fruit growth. These findings could encourage the sector to deploy larger sensor networks for optimal greenhouse climate control. A sensor grid covering the whole area of the greenhouse is a necessity for climate control strategies to mitigate suboptimal conditions.

Investigation of Factors Affecting Corrosion Mechanisms in Latent Heat Thermal Energy Storage Systems

Concentrated Solar Power (CSP) plants integrated with Latent Heat Thermal Energy Storage (LHTES) systems offer a promising solution for dispatchability, reliability, and economic concerns generally associated with renewable energy technologies. These systems, however, require an operational life of up to 30 years to compete with power plant systems operating on fossil fuels. This is a significant challenge due to the high temperatures and corrosive eutectic salts utilised in LHTES systems. Additionally, these systems and its subcomponents are expected to be under varying degrees of stress due to the diurnal cyclic temperature variations inherent in the plant’s operational cycle. Hence, it is crucial to understand the various factors that can affect the operational life of materials used in such applications and conduct thorough material compatibility studies to assess the combined impact of these operating conditions on corrosion mechanisms. This study presents a novel static immersion test approach using modified Compact Tension (CT) specimens manufactured from 316L to investigate the effects of Na2CO3:NaCl (59.45:40.55 wt.%) salt, elevated temperatures (700 ℃ for up to 1000 hours), and stress on corrosion induced in the alloy. The post-exposure results are characterised with Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) shows that corrosion mechanisms are significantly affected by factors such as high operating temperatures leading to changes in both corrosion morphology and rate, high stresses causing localised preferential corrosion, as well as corrosive salt and oxygen availability affecting the type of corrosion induced.

The use of amino acids as bioactive substance: a strategy to increase yield in summer arugula (Eruca sativa L. Mill) crops

Foliar application of amino acids can assist crops to maintain homeostasis under diurnal temperature variations and excessive solar irradiance. The objectives of this study were to investigate the effects of the organic fraction and mineral nutrients of an amino acid solution on arugula plants and the effects of weekly applications of this solution on their growth and biomass yield. Two experiments were conducted in a completely randomized design, in a greenhouse (Experiment 1) and on open-field benches (Experiment 2), in Iracemápolis, SP, Brazil. Experiment 1 consisted of foliar applications of water (control), a solution containing 59 and 40.9 g ha-1 of nitrogen and sulfur, respectively (N+S), and a solution containing 85 g ha-1 of amino acids, with seven replications. Experiment 2 consisted of four different number (0, 1, 2, and 3) of weekly foliar applications of 85 g ha-1 of amino acids, with six replications. Chlorophyll a fluorescence, chlorophyll and carotenoid contents, and fresh and dry biomass weights were evaluated in both experiments. In Experiment 1, shoot fresh weight of plants treated with amino acids increased by 21% and 6% compared to those in the control and N+S treatment, respectively. Amino acid application increased chlorophyll and carotenoid contents, improving photosynthetic performance by increasing effective quantum efficiency of photosystem II and photochemical quenching. In Experiment 2, weekly application of 85 g ha-1 of amino acids increased shoot fresh weight by approximately 10% per application. Therefore, foliar application of amino acids can increase fresh biomass of arugula plants grown under both mild and warmer climate conditions.

Dramatic Influence of Temperature on Charging

Charging of cables outside of a spacecraft has been cited as the cause of multiple spacecraft anomalies based upon correlations with peaks in the energetic electron environment and because the electron flux exposure of external cables is much higher than internal cables. However, external cables are subject to much wider temperature changes than hardware located inside a thermally regulated spacecraft. Temperature affects bulk resistivity and radiation-induced conductivity, but temperature is often ignored in charging analyses and tests. In this paper, temperature effects are combined with a diurnal temperature variation and an external electron environment to simulate the charging of an external coax. The simulation shows that the coax dielectrics behave as perfect insulators during the cold portion of the 24 h cycle, but the accumulated charge leaks out during the hot portion of the cycle. There is no memory or hysteresis of charge density from one day to the next. This behavior is compared to the behavior of materials inside the spacecraft, where low flux and stable temperatures lead to charging time constants ranging from weeks to months that produce a slow, stair-step increase of trapped charge in response to multiple electron storms. These variations in charging response explain why some anomalies correlate best with peak 24 h average flux, whereas others correlate well with 14- or 21-day averaged flux. Analyses and tests used to qualify designs or investigate anomalies must account for the dramatic effects that temperature variation can have on the charging of insulators and isolated conductors.

Temperature Dynamics in Early Pregnancy: Implications for Improving In Vitro Fertilization Outcomes

In assisted reproductive technology, in vitro fertilization involves cultivating embryos in an artificial environment, often yielding lower-quality embryos compared to in vivo conditions. This study investigated core body temperature (CBT) fluctuations in mice during early pregnancy. Their CBT was measured with a high temporal resolution to identify the optimal thermal conditions during the first five days post-fertilization, aiming to improve in vitro culture conditions. Data were collected from 12 female mice, with 8 becoming pregnant, using temperature loggers every minute for 11 days. Data analysis focused on trends, circadian rhythms, frequency components, and complexity using multiscale entropy (MSE). The results for the pregnant mice showed a mean CBT increase from 37.23 °C to 37.56 °C post-mating, primarily during the light phase, with a significant average rise of 0.58 °C. A Fourier analysis identified dominant 24, 12, 8, and 6 h components, with the 24 h component decreasing by 57%. Irregular fluctuations decreased, and MSE indicated increased complexity in the CBT time series post-mating. These results suggest that reducing diurnal temperature variations and maintaining a slightly elevated mean CBT of approximately 37.5 °C, with controlled minor fluctuations, may enhance embryo quality in pregnant mice. This study provides a reference for temperature regulation in embryo culture, improving embryo quality by aligning in vitro conditions with the natural thermal environment of the fallopian tubes.

How do driving factors affect the diurnal variation of land surface temperature across different urban functional blocks? A case study of Xi'an, China

A comprehensive and in-depth understanding of the formation mechanisms of the urban thermal environment is the basis for thermal environment regulation, however, there is insufficient knowledge regarding how driving factors influence daytime and nighttime land surface temperature (LST) within urban functional blocks (UFBs). We selected Xi'an, China as a case study, integrating remote sensing data including ECOSTRESS, Landsat-8, and Gaofen-1, along with geographic data including road network, areas of interest, points of interest, building footprint, and mobile phone signaling. It divided 10 types of UFBs, inverted daytime and nighttime LST, calculated 5 types of driving factors, and finally analyzed the contribution and marginal effects of driving factors on day-night LST using boosted regression tree. The results showed that LST and its driving factors differed significantly in different times and UFBs. Industrial blocks and urban villages had higher LST in the daytime, while residential blocks, commercial blocks, and public service blocks had higher LST in nighttime. Industrial blocks were the dominant blocks that drove the overall LST up during the day, while residential blocks were the dominant blocks at night. Location distance (-) and population density (+) affected LST in all UFBs during day and night, NDVI (-), building density (+), and floor area ratio (-) were key factors for most UFBs during daytime, and NDVI (+), surface albedo (-), and point density of interest (+) were key factors during nighttime. Most of the driving factors had significant influence thresholds, but there were small differences across UFBs. This paper aims to elucidate the mechanisms by which driving factors influence urban LST during day and night across different UFBs, thereby providing new support for more targeted thermal environment regulation and diurnal trade-offs at the block scale.

Role of Strong Sea Surface Temperature Diurnal Variation in Triggering the Summer Monsoon Onset Over the Bay of Bengal in a Climate Model

AbstractThe earliest Asian summer monsoon onset (SMO) occurs in the Bay of Bengal (BoB), heralding the coming of the rainy season. In late April or early May, the strong sea surface temperature (SST) diurnal variation accompanied by ocean surface warming triggers the SMO. However, this observed diurnal cycle intensity cannot be reasonably simulated by state‐of‐the‐art climate models, resulting in a spurious delayed SMO. To address this issue, the SST diurnal cycle parameterized by a diagnostic sublayer scheme was incorporated into a climate model named FIO‐ESM v2.0. The large diurnal amplitude of SST contributes to surface warming and changes atmospheric circulation. Consequently, the high‐pressure anomaly at high levels and an inverted trough at low levels promote more convective activity, triggering an earlier SMO. Our findings improve the ability of climate models in simulating the evolution of the Asian monsoon system.

Multifactor-coupled study on freeze-thaw forces of rocks in cold regions

This study delves into the mechanical properties of steep and rocky slopes subjected to long-term freeze-thaw actions. Considering the unique climatic conditions in cold regions, especially the significant impact of seasonal and diurnal temperature variations on slope excavation, the research focuses on a high-cold region iron ore mine. Four types of rocks commonly found in the mining area are thoroughly examined, taking into account the hydrogeological conditions of the mining area. The study systematically analyzes the mechanisms of various factors such as weathering, freeze-thaw cycles, and ice-water phase changes on the stability of cold region fractured rock masses. The research reveals that under prolonged freeze-thaw actions, crack water within the rock continuously undergoes ice-water phase changes, generating substantial freeze expansion forces that result in structural damage to the rock mass. This damage is evident not only in the development of existing microcracks but also leads to the generation of new fractures, ultimately causing deterioration in the rock mass structure. The study of the evolution patterns of freeze-thaw forces contributes to a better understanding of slope stability issues in cold region mineral resource extraction, offering crucial insights for the design, construction, and operation of related engineering projects.

High heat tolerance, evaporative cooling, and stomatal decoupling regulate canopy temperature and their safety margins in three European oak species.

Heatwaves and soil droughts are increasing in frequency and intensity, leading many tree species to exceed their thermal thresholds, and driving wide-scale forest mortality. Therefore, investigating heat tolerance and canopy temperature regulation mechanisms is essential to understanding and predicting tree vulnerability to hot droughts. We measured the diurnal and seasonal variation in leaf water potential (Ψ), gas exchange (photosynthesis Anet and stomatal conductance gs), canopy temperature (Tcan), and heat tolerance (leaf critical temperature Tcrit and thermal safety margins TSM, i.e., the difference between maximum Tcan and Tcrit) in three oak species in forests along a latitudinal gradient (Quercus petraea in Switzerland, Quercus ilex in France, and Quercus coccifera in Spain) throughout the growing season. Gas exchange and Ψ of all species were strongly reduced by increased air temperature (Tair) and soil drying, resulting in stomatal closure and inhibition of photosynthesis in Q. ilex and Q. coccifera when Tair surpassed 30°C and soil moisture dropped below 14%. Across all seasons, Tcan was mainly above Tair but increased strongly (up to 10°C > Tair) when Anet was null or negative. Although trees endured extreme Tair (up to 42°C), positive TSM were maintained during the growing season due to high Tcrit in all species (average Tcrit of 54.7°C) and possibly stomatal decoupling (i.e., Anet ≤0 while gs >0). Indeed, Q. ilex and Q. coccifera trees maintained low but positive gs (despite null Anet), decreasing Ψ passed embolism thresholds. This may have prevented Tcan from rising above Tcrit during extreme heat. Overall, our work highlighted that the mechanisms behind heat tolerance and leaf temperature regulation in oak trees include a combination of high evaporative cooling, large heat tolerance limits, and stomatal decoupling. These processes must be considered to accurately predict plant damages, survival, and mortality during extreme heatwaves.

Descriptive, Hospital-Based, 10-Year Study of Malaria Transmission in Goa, a Southwest Indian State in the Malaria Elimination Phase.

The South Asia International Center of Excellence for Malaria Research, an NIH-funded collaborative program, investigated the epidemiology of malaria in the Indian state of Goa through health facility-based data collected from the Goa Medical College and Hospital (GMC), the state's largest tertiary healthcare facility, between 2012 and 2021. Our study investigated region-specific spatial and temporal patterns of malaria transmission in Goa and the factors driving such patterns. Over the past decade, the number of malaria cases, inpatients, and deaths at the GMC decreased significantly after a peak in 2014-2015. However, the proportion of severe malaria cases increased over the study period. Also, a trend of decreasing average parasitemia and increasing average gametocyte density suggests a shift toward submicroscopic infections and an increase in transmission commitment characteristic of low-transmission regions. Although transmission occurred throughout the year, 75% of the cases occurred between June and December, overlapping with the monsoon (June-October), which featured rainfall above yearly average, minimal diurnal temperature variation, and high relative humidity. Sociodemographic factors also had a significant association with malaria cases, with cases being more frequent in the 15-50-year-old age group, men, construction workers, and people living in urban areas within the GMC catchment region. Our environmental model of malaria transmission projects almost negligible transmission at the beginning of 2025 (annual parasitic index: 0.0095, 95% CI: 0.0075-0.0114) if the current control measures continue undisrupted.

Analysis of Thermal and Dielectric Loss Features of Lunar Regolith Considering Real‐Time Effect Solar Irradiance

AbstractSolar irradiance received at the lunar surface is crucial for interpreting brightness temperatures detected by orbiters and for understanding the thermal, physical, and dielectric properties of the lunar regolith. We developed a real‐time effect solar irradiance (ESI) model that accounts for the influence of surface relief and terrain shading. This model was integrated with a standard thermal model to examine ESI fluctuations and their impacts on the diurnal physical temperature variations. To assess the effects of spatial resolution, we selected four locations with significant ESI disparities for simulation, then compared lunar surface temperatures at various spatial scales, ranging from 20 m to 25 km. Utilizing brightness temperature data obtained from the Chang'E‐2 (CE‐2) microwave radiometer (MRM), we integrated the shallow physical temperature profiles with the radiative transfer equation to simulate brightness temperatures and determine dielectric loss at different frequencies. In the Von Kármán crater, the received ESI exhibits a cyclical pattern of approximately 18 years and areas with rugged topography may exhibit larger ESI variations (∼7%). We found that the spatial resolution of ESI has a minimal effect on the physical and brightness temperatures at resolutions of 10 km or coarser. At the shallow layer, the average dielectric loss values are 0.0128–0.0170, 0.0083–0.0110, 0.0055–0.0073, and 0.0061–0.0081 for the CE‐2 frequencies of 3, 7.8, 19.35, and 37 GHz, respectively. The integration of real‐time ESI modeling, thermal dynamics, radiative transfer equations, and observational data enhances our comprehension of the physical temperature profile and thermal characteristics of shallow regolith.

Water temperature and energy balance of floating photovoltaic construction water area—field study and modelling

Floating photovoltaics (FPV) are an emerging renewable energy technology. Although they have received extensive attention in recent years, understanding of their environmental impacts is limited. To address this knowledge gap, we measured water temperature and meteorological parameters for six months under FPV arrays and in the control open water site and constructed a numerical model reflecting the water energy balance. Our results showed that FPV arrays caused diurnal variation in water temperature and microclimate. Specifically, we found that FPV had a cooling effect on their host waterbody during the daytime and a heat preservation effect at night, reducing diurnal variation. The diel oscillation of water temperature below FPV panels lagged behind that of open waters by approximately two hours. The microclimate conditions below FPV panels also changed, with wind speed decreasing by 70%, air temperature increasing during the daytime (averaging +2.01°C) and decreasing at night (averaging −1.27°C). Notably, the trend in relative humidity was the opposite (−3.72%, +14.43%). Correlation analysis showed that the degree of water temperature affected by FPV was related to local climate conditions. The numerical model could capture the energy balance characteristics with a correlation coefficient of 0.80 between the simulated and actual data. The shortwave radiation and latent heat flux below FPV panels was significantly reduced, and the longwave radiation emitted by FPV panels became one of the heat sources during the daytime. The combined variations of these factors dominated the water energy balance below FPV panels. The measured data and simulation results serve as a foundation for evaluating the impact of FPV systems on water temperature, energy budget, and aquatic environment, which would also provide a more comprehensive understanding of FPV systems.

Damage and fracture in in-service concrete structures subjected to large diurnal temperature variations based on phase-field approach

In-service concrete structures are exposed to the natural environment for extended periods, making them susceptible to performance degradation and cracking due to large diurnal temperature ranges (DTR). This paper presents the development of a novel thermo-mechanical-fatigue coupling phase-field model to investigate the cracking process in in-service concrete structures under varying DTR conditions. The results indicate that concrete walls exposed to different single-day DTRs (20–60 ℃) exhibit phase-field damage without cracking. The phase-field damage is negligible at a 20 ℃ DTR but increases to 0.41 at a 60 ℃ DTR. Considering temperature fatigue, the concrete wall initiates cracking when the DTR exceeds 40 ℃ within 100 cycles. With an increase in DTR from 40 ℃ to 50 ℃ and 60 ℃, the time for crack nucleation decreases from 70 cycles to 29 and 25 cycles, respectively. Concrete walls subjected to 40 ℃ and 50 ℃ DTR exhibit a single crack on the top surface, whereas those exposed to a 60 ℃ DTR have two cracks on the top surface and one crack on each side. Furthermore, the cracks induced by the DTR are surface cracks that exhibit rapid expansion up to a specific length of approximately 140 mm before stabilizing.

Spatio-Temporal Variation of Virtual Temperature in Ilorin, Kwara State, Nigeria

This study investigates the diurnal and vertical variations of virtual temperature (Tv) and ambient temperature (T) from 2013 to 2023 in Ilorin. Data analysis reveals that Tv peaks between 1200 and 1400 hours daily, influenced mainly by relative humidity and inversely by temperature changes, with no significant pressure impact. At the planetary boundary layer, Tv and T exhibit marginal differences, converging higher in the troposphere due to diminishing specific humidity. Temporal trends indicate a surface temperature increase of 0.065 degrees and a Tv increase of 0.016 degrees over the past decade. While no simple linear correlation between Tv and relative humidity was found, seasonal patterns suggest potential underlying correlations. This highlights the complex interplay of atmospheric variables in influencing virtual temperature and underscores the need for further investigation into seasonal effects.