Search Results (439)

Artificial high-reflectivity ground covers are a potential strategy to increase rear-side irradiance and energy yield in bifacial photovoltaic systems, especially in utility-scale plants with single-axis trackers. This paper reports field evidence from a pilot plant in southern Brazil (27.4° S, 48.4° W), where four reflective covers—a white film, a pearl-white film, a black-and-pearl film, and a white geomembrane—were evaluated against a gray gravel reference. The study combines albedo and spectral characterization, rear-to-front irradiation ratios, energy-yield comparisons, soiling assessment, thermal analysis, and operational observations. Broadband albedo increased from 25% for gray gravel to 53–58% for the reflective films and 72% for the geomembrane. Reflective films increased the rear-to-front irradiation ratio to around 20% and delivered energy gains close to 9%, while the geomembrane achieved the highest irradiance enhancement and gains exceeding 10%. Inverter current limitations led to clipping, indicating that measured gains may underestimate the full energy potential of the reflective covers. Estimated thermal losses were insignificant compared with measured gains, while soiling and fixation methods affected long-term feasibility. The results confirm the technical potential of reflective covers, while showing that utility-scale deployment must consider not only optical performance, but also optical stability, electrical limitations, cleaning and anchoring requirements, drainage adaptations, operation and maintenance practices, and cost constraints. Full article

Surface heat sources play a critical role in shaping meteorological conditions and permafrost dynamics on the Tibetan Plateau. To better understand surface heat source variability in the permafrost region, multiyear observational data from an isolated permafrost site and a continuous permafrost site were used to analyse the variability. The results indicated that the surface heat source at the isolated permafrost site remained relatively stable, whereas that at the continuous permafrost site increased significantly, at a rate of approximately 2.2 Wm⁻²yr⁻¹. The proportions of sensible and latent heat fluxes in the surface heat source budget varied with the season. Overall, the proportion of latent heat flux was greater than that of sensible heat flux in summer and autumn, whereas the proportion of sensible heat flux was greater than that of latent heat flux in winter and spring. The peak proportion for both fluxes exceeded 80%. A random forest model effectively captured the variations in the surface heat source. And the machine learning simulation indicated that soil temperature, downward shortwave radiation and albedo were identified as major contributors to the surface heat source, collectively accounting for more than 88% of the overall variability at both sites. The impacts of snow cover on the surface heat source varied with intensity. The increasing trend of the surface heat source was closely related to climate warming in autumn and winter. A significant but weak positive correlation was observed between vegetation and the surface heat source. Full article

High-latitude regions are witnessing unprecedented wildfires and accelerated warming. This study explored wildfire patterns and land changes within the high-latitude Indigenous Tłı̨chǫ territory in the Northwest Territories, Canada. It used the Two-Eyed Seeing approach, which combines Western science, or Scientific Ecological Knowledge (SEK), with Indigenous knowledge, or Traditional Ecological Knowledge (TEK). This method integrated Earth observation data with insights from Tłı̨chǫ Elders and officials. We analyzed spatiotemporal variations in burned areas, land surface temperature (LST), albedo, snow cover, soil moisture, and land-cover types. A listening and storytelling session with community Elders provided an in-depth Indigenous perspective. Our findings indicate a concerning shift in wildfire activity on Tłı̨chǫ land, primarily driven by the interplay between climate change and land-cover changes. Land-cover estimates over the past fifteen years indicate that nearly half of the forested areas on Tłı̨chǫ-owned land have been converted to other land-cover types, with shrublands increasing twofold and grasslands expanding tenfold. We observed significant increases in spring and summer LSTs (p < 0.05), alongside decreases in precipitation and snow cover (p < 0.05), consistent with the Elders’ observations. The decline in topsoil moisture, coupled with rising temperatures, has triggered a positive feedback loop in forested areas, intensifying future wildfire risk. The study’s implications extend beyond the Tłı̨chǫ territory, suggesting a broader significance for climate resilience and Indigenous stewardship. It highlights the significance of place-based, integrated research for understanding complex wildfire behavior and land-cover transformations. The study indicates that the Two-Eyed Seeing approach, which weaves local Indigenous knowledge with quantitative Earth observations, not only improves analytical precision but also provides a collaborative framework for developing targeted strategies to mitigate the effects of increasingly severe fire regimes and land-cover changes. Full article

Although offshore photovoltaic (PV) systems have attracted increasing interest as a solution to land-use limitations, the influence of offshore-specific dynamic environmental conditions on PV performance remains insufficiently understood. Existing studies have primarily focused on static operating conditions or general energy yield comparisons between bifacial and monofacial PV technologies, while the combined effects of wave-induced motion, module tilt-angle, and sea-surface albedo on offshore PV performance have received limited attention. To address this gap, this study develops a parametric simulation framework to investigate the sensitivity of offshore bifacial photovoltaic (biPV) and monofacial photovoltaic (moPV) arrays to key offshore environmental and operational parameters. Given the scarcity of long-term operational data for offshore PV installations, a hypothetical offshore plant located in the Yellow Sea, China, is considered using real meteorological inputs. In this study, 16 kWp offshore biPV and moPV arrays are modeled and compared in terms of their performance through three case studies examining wave motions, tilt-angle variations, and surface albedo effects. Performance metrics such as maximum irradiance, total energy yield, energy yield losses, wave-induced power loss, and bifacial gain (BG) are analyzed and compared. The findings indicate that increasing wave motion diminishes the total energy yield due to higher tilt-angle fluctuations. Nevertheless, the biPV array regularly outperforms the moPV array because of the effect of the rear-side irradiance. The tilt angle analysis reveals a trade-off between energy yield and BG, with BG increasing from 0.05% to over 10% as the tilt angle increases from 10° to 45°. Higher surface albedo further enhances bifacial performance, increasing BG from 4.5% to 17.8% for albedo values of 0.05 and 0.25, respectively. Full article

The Atlantic Meridional Overturning Circulation (AMOC), as the core component of the global thermohaline circulation, exerts a profound influence on the Northern Hemisphere climate. Recent observations show that AMOC intensity has weakened by approximately 15% over the past 40 years, yet the traditional theoretical framework dominated by the North Atlantic Oscillation (NAO) cannot fully explain its spatial heterogeneity. This study systematically quantifies the independent driving mechanism of the Arctic Oscillation (AO) on AMOC decline for the first time by integrating multi-source reanalysis data (ERA5, ORAS5) and CMIP6 model output. Theoretical analysis shows that the AO positive phase regulates the stability of AMOC through two coupled pathways: (1) anomalous wind stress curl leads to the weakening of Ekman suction in the subpolar seas (contribution: 42 ± 6%), inhibiting deep-water formation in the Labrador Sea; and (2) increased freshwater flux through the Fram Strait triggers a negative salinity advection feedback, which leads to shoaling of the North Atlantic high-latitude mixed layer by up to 30 m. The cross-scale interaction reveals that the AO interannual variability amplifies the modulation of the AMOC interdecadal trend. This amplification occurs through the positive feedback of sea-ice albedo. When AO and NAO are locked in opposite phases (AO+/NAO−), the AMOC weakening rate increases to 1.8 Sv/decade (1 Sv = 10⁶ m³/s), whereas the same-phase negative condition (AO−/NAO−) yields a moderate decline of 0.5 Sv/decade. This mechanism corrects the underestimation of the traditional wind-driven circulation theory for high-latitude processes and provides a physical attribution for the CMIP6 models’ systematic underestimation of AMOC sensitivity. The study further constructs the “Arctic Oscillation–subpolar basin–AMOC” three-pole coupling theoretical model and confirms that the Arctic amplification effect enhances the AO–AMOC coupling strength by a factor of 2.3 over the full study period (1979–2020; R² = 0.71, p < 0.01), with an even more pronounced enhancement of 2.1 times during the recent two decades (2000–2020; R² increased from 0.28 to 0.59). These findings have direct implications for coastal risk assessment, as AMOC weakening may accelerate sea-level rise along the North American East Coast and increase the frequency of extreme winter storm surges in European coastal areas. The results provide a dynamic basis for IPCC climate risk assessment and have practical application value for the early warning of extreme cold-wave events. Full article

We present a transdisciplinary Teaching–Learning Sequence (TLS) for lower secondary school students that integrates climate change education with the promotion of gender equality in science. The TLS connects theoretical understanding with practical engagement through laboratory demonstrations, simulations, and accessible experiments. The sequence addresses key topics in sustainability education, including incoming and outgoing radiation, the greenhouse effect, energy transformations, and energy sources, through activities involving the electromagnetic spectrum, infrared imaging, selective transparency, absorption, and albedo. It also includes inquiry-based explorations of electromagnetic induction, miniature hydroelectric and wind power systems, Stirling engines, photovoltaic and concentrated solar technologies, and combustion-related CO₂ acidification. A distinctive feature of the TLS is the explicit integration of the social dimension of sustainability through discussion of the Matilda Effect and the historical case of Eunice Newton Foote, with the aim of challenging persistent gender stereotypes in STEM. The intervention was implemented with 12–13-year-old students and evaluated through pre- and post-tests, written explanations, closed-ended questions, drawings, and the Draw-A-Scientist Test. The results indicate a significant improvement in students’ understanding of climate-related scientific concepts and in their critical awareness of misinformation and climate denial strategies. While the sequence did not significantly increase students’ engagement in climate action, the gender-focused activities promoted strong critical reflection on stereotypes and on the role of women in science. Full article

A methodology for deriving high-resolution (5-km) surface shortwave radiative (SWR) fluxes over the Arctic was applied to observations acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) during the spring and summer melt season (March–September) of 2007, when the Arctic experienced a historically significant and well-documented decline in sea ice extent. The derived SWR fluxes were used to estimate solar heat input into the Arctic Ocean during the melt season, a task that had not previously been undertaken at such high spatial resolution. According to the National Snow and Ice Data Center (NSIDC), Arctic sea ice extent reached a record minimum of 4.13 million km² on 16 September 2007, approximately 38% below the 1979–2000 climatological mean and 24% below the previous record minimum in 2005. This extreme reduction in sea ice resulted in several weeks of ice-free opening along portions of the ‘Northwest Passage’. Availability of high spatial resolution SWR fluxes in the Arctic is particularly important for improving estimates of solar heat input into the Arctic Ocean, especially within the highly heterogeneous marginal ice zone. To facilitate comparison with sea ice concentration products from NSIDC, the MODIS-derived 5-km SWR fluxes were aggregated to 0.25° equal-area grid cells (approximately 25 km resolution). Our results show that the abrupt increase in the open water fraction produced anomalies in solar heating to the upper ocean exceeding 300%, hereby enhancing the ice–albedo feedback mechanism and promoting further sea ice melt. The estimated monthly cumulative solar heat input to the ocean for a nominal 1° grid cell was 164.9 MJ m⁻² in May. In contrast, the corresponding four 0.25° sub-grid cells, resolved using the high-resolution MODIS data, exhibited cumulative heat inputs of 58.0, 93.0, 189.3, and 296.4 MJ m⁻², respectively. Although the average heat input for the 1° grid cell (165 MJ m⁻² was similar to the average value obtained from the four 0.25° grid cells (159 MJ m⁻² the substantial sub-grid variability is important because the oceanic and sea-ice responses to solar heating are highly nonlinear. Consequently, unresolved spatial variability can significantly affect the magnitude of derived quantities and associated feedback processes. These findings demonstrate the importance of high-spatial-resolution radiative flux information for accurately quantifying ocean heating and ice–ocean interactions in the Arctic. Full article

The rapid expansion of urbanization in recent decades has intensified the urban heat island effect, driven by reduced vegetation cover, widespread use of heat-absorbing materials, and increases in surface and atmospheric temperature that may reach 5–6 °C. These conditions negatively impact well-being, quality of life, and human health. In response, numerous studies have examined mitigation strategies based on high-albedo materials and urban vegetation. This systematic review analyzes 225 peer-reviewed articles published between 2016 and 2025 addressing urban heat mitigation, surface thermal conditions, urban vegetation, outdoor thermal comfort and microclimate simulations. It provides a comprehensive synthesis, highlighting key findings and implications for future research. According to the Köppen–Geiger classification, most studies were conducted in humid subtropical and warm Mediterranean climates. The analysis focuses on urban canyon interventions, where vegetation is primarily modeled as shading trees (79.2%), along with other forms such as grass or shrubs (27.1%), mainly during the summer season. Results indicate that integrated mitigation strategies combining vegetation and high-albedo surfaces (≈0.8) generally provide greater cooling benefits than isolated interventions. Overall, the findings underscore the importance of the interaction between vegetation shading and surface properties for mitigating urban heat in outdoor spaces. Full article

Outdoor thermal comfort in hot, arid regions critically influences campus open-space use and the sustainability of university campuses, including reduced cooling energy demand and enhanced livability, yet validated integrated assessments remain scarce. This study aims to explore the relationship among microclimate conditions, thermal comfort, and the sustainable use of campus open spaces in a hot, arid region, with the goal of identifying design strategies that enhance both user comfort and environmental sustainability. The study incorporated: (1) a site audit; (2) exploratory RayMan simulations (n = 180, unvalidated) calculating Physiological Equivalent Temperature (PET) across five zones; and (3) a June survey (n = 156, 52% response rate). Physical analysis revealed height-to-width ratios of 0.13–0.30, representing an 80–91% deficit below the 1.5 minimum commonly recommended benchmark for effective shading in the literature. Unvalidated simulations estimated a mean annual PET of 31.2 °C (SD = 4.8 °C), with 17.6% of annual PET values within the comfort range and 65.2% within the hot range. For June, unvalidated simulations estimated 4% of PET values within the comfort range, while 35.5% of respondents reported thermal comfort (mean ASHRAE 1.66, warm range)—a descriptive discrepancy of 31.5 percentage points. Self-reported social factors (friends: 79.8%) ranked higher than shading space selection responses; behavioral observations are required to confirm actual use patterns. Priority interventions from physical analysis and user reports include optimized shade, cool materials (albedo ≥ 0.60), and intentional greening—subject to validation with calibrated measurements. By linking microclimate modification to increased open-space usability and reduced cooling energy demand, this research contributes to sustainable campus planning frameworks. Pending field validation and seasonal surveys, the quantitative thermal comfort estimates should be considered exploratory rather than conclusive. Full article

This paper presents an experimental comparison of the instantaneous power generation of standard and bifacial photovoltaic modules under real operating conditions. The study focuses on short-term effects caused by spatially variable albedo and tracker-induced changes in module orientation. Both modules were installed on the same mobile single-axis tracking platform and had identical rated front-side power, which ensured nearly identical operating conditions and independent MPPT operation. The experimental campaign included five ground surfaces: grass, river sand, grey paver, light aggregate, and dark aggregate. For each surface, electrical parameters and albedo were recorded over the full investigated geometrical range, covering relative solar azimuth from −60° to +60° and module tilt from 0° to 90°. The measured increase in power generation of the bifacial module relative to the standard module depended strongly on the ground surface. Over the full investigated range, the gain was 6.4% for grass, 11.3% for river sand, 5.9% for grey paver, 13.6% for light aggregate, and 4.5% for dark aggregate. These results confirm that, in bifacial photovoltaic systems with tracking, the ground surface and its reflective properties significantly affect the rear-side contribution and instantaneous power output. Consequently, albedo should not be treated as a constant or spatially homogeneous parameter when assessing short-term bifacial PV performance. Full article

There is a strong global increase in the installation of renewable energy power plants, due to increasing energy demand in the electricity generation sector and fast cost reduction. Recent studies indicate that the installation and operation of photovoltaic (PV) power plants have negligible microclimatic effects, although there are minor effects on night temperature in some cases, which, however, do not justify climate or environmental change. The development of solar energy and the installation and operation of PV power plants serve as a key solution for the energy transition to reduce carbon emissions and to address global warming. Despite the benefit of emission reduction, the deployment of solar energy through the installation of solar power plants causes land cover changes and may have minor effects on the surface energy balance by modifying roughness and albedo, biodiversity by disturbing habitats, and water resources by requiring water for cooling and cleaning. These changes may also lead to minor climatic, ecological, and social impacts. The objective of the paper consists of assessing the potential microclimatic effects of photovoltaic power plants based on satellite-based land surface temperature (LST) analyses. Specifically, the potential change in the land surface temperature, both under photovoltaic panels and on the panels, in relation to the temperature of the surrounding area is being examined in this study. The implementation is conducted in Mediterranean ecosystems, which are considered vulnerable agroecosystems due to increased climate variability. The final Landsat-based time series analysis further supports this synthesis, reporting that monthly LST differences between the PV Park and surrounding area are negligible and do not indicate a meaningful microclimate alteration attributable to PV operations. Accordingly, the evidence supports the core conclusion: utility-scale PV deployment does not constitute a driver of climate change, and the documented effects are best understood as localized surface–atmosphere energy-balance perturbations whose sign and magnitude depend on land cover, seasonality, and operation. Full article

The Aconcagua River Basin is one of the most important basins in Chile, supporting a large percentage of economic activities such as intensive agriculture, mining, agroindustry, manufacturing, and hydropower generation. This basin is highly sensitive to climate change because it relies primarily on snowmelt and glacier contributions for water availability. In recent decades, a water deficit has been reported affecting water supply for the entire basin. This study focuses on changes in snow cover in the headwater catchment of the Aconcagua Basin and their relationship with meteorological conditions. The databases rely on satellite remote sensing and climate reanalysis data, using Landsat and MODIS collections for Snow Cover Area (SCA) data and ERA5 reanalysis for meteorological data, respectively. SCA, albedo, air temperature and relative humidity, in addition to snowfall, were assessed using Sen’s slope and Mann–Kendall non-parametric test to estimate trends and their significance. The results showed a decrease in SCA of about 99.1 and 138.2 km² per decade for MODIS and Landsat, respectively. Reanalysis datasets are related to the increase in warming trends, which accelerate the snow melting process and reduce water availability for the summer season. Hence, these results suggest the need to increase the ground-based snow monitoring stations to validate satellite data. Finally, the results can be used for new insights into water management at the basin scale in order to promote water use efficiency. Full article

The VRB represents one of the most important glacierized regions in the upper Amu Darya Basin (UADB), where glacier and snow dynamics play a key role in regional water resources. This study investigates glacier changes in the VRB during 2000–2025 based on multi-source remote sensing and GIS analysis, while long-term climatic variability since 1970 is used to provide background context for regional climate conditions. The results show a significant reduction in glacier area from 4440.9 km² in 2000 to 3955.2 km² in 2025, corresponding to a loss of 485.7 km² (10.94%). The glaciers are mainly distributed on northern and northeastern slopes at elevations between 4000 and 5000 m a.s.l., where climatic conditions favor their preservation. The basin also contains numerous surge-type glaciers, accounting for approximately 60% of all surge-type glaciers in the Pamir region, with advances ranging from 0.4 to 3.6 km. Climatic analysis indicates a warming trend of 0.15–0.31 °C per decade during 1970–2025, accompanied by pronounced seasonal variability in snow cover and gradual decreases in surface albedo associated with increased dust and black carbon concentrations. Glacier thinning is particularly evident in the lower glacier zones, while hydrological analysis shows that glacier and snow meltwater strongly influence river runoff. These results highlight the sensitivity of glaciers in the VRB to climatic and environmental changes and emphasize the importance of continued monitoring and adaptive water resource management in the VRB. Full article

Atmospheric aerosols strongly regulate surface solar irradiance in tropical coastal environments through scattering and absorption. This study examines aerosol–irradiance interactions over Penang, Malaysia, using Aerosol Robotic Network (AERONET) observations of aerosol optical depth (AOD), single scattering albedo (SSA), and extinction Ångström exponent (AE); NASA’s Prediction of Worldwide Energy Resource (POWER) irradiance data; and Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) reanalysis for aerosol compositional context. Bottom-of-atmosphere radiative forcing efficiency (BOA RFE) was quantified for global, direct and diffuse irradiance (GHI, DNI and DHI) under clear- and all-sky conditions during 2014–2018. Results show persistent aerosol-induced attenuation of surface radiation, with GHI and DNI RFE predominantly negative, while DHI RFE remains consistently positive, indicating redistribution of solar energy from direct to diffuse components. Time resolved analysis reveals daily GHI RFE typically ranging from approximately −0.5 to −3.5 W m⁻² per unit AOD, with episodic excursions below −4 W m⁻² per AOD during high-aerosol events, whereas DNI RFE frequently reaches values below −0.8 W m⁻² per AOD, confirming its greater sensitivity to aerosol extinction. In contrast, DHI RFE commonly exceeds +5 W m⁻² per AOD and intermittently surpasses +10 W m⁻² per AOD, reflecting enhanced scattering and multiple-scattering effects. AOD-stratified analysis demonstrates a nonlinear weakening of forcing efficiency with increasing aerosol burden, with mean GHI RFE decreasing from approximately −1.6 to −0.4 W m⁻² per AOD between low- and high-AOD regimes, accompanied by corresponding reductions in DNI (−0.35 to −0.1 W m⁻² per AOD) and DHI (+3.3 to +0.8 W m⁻² per AOD). Overall, aerosol loading is identified as the dominant control on BOA radiative forcing efficiency in this tropical coastal environment, while SSA and AE act as secondary modulators. Full article

Outdoor thermal comfort in university courtyards is a key factor influencing students’ environmental experience and the usability of outdoor spaces in hot-arid climates. Courtyard design may also affect the environmental conditions of adjacent classrooms by modifying solar exposure, shading, air movement, and surface heat gain. Accordingly, this study aims to develop optimized design scenarios for improving outdoor thermal comfort in university courtyards through hybrid passive strategies, including vegetation, shading systems, and cool pavements. To achieve this goal, the research adopted a combined field-based and simulation-based methodology. Field measurements and student questionnaires for 292 students were conducted in courtyards and classrooms of three university buildings in Luxor, Egypt. These buildings represent different urban morphologies, courtyard aspect ratios, geometric configurations, and student densities. In parallel, simulation models were developed using ENVI-met V5.6.1 and Rhinoceros V8 with Grasshopper, to test and compare various design scenarios. Field monitoring revealed that wider courtyards with low aspect ratios (0.28–0.38), lacking trees and finished with concrete paving, recorded lower CO₂ concentrations (around 800 ppm), but experienced higher surface and air temperatures. These elevated temperatures negatively affected outdoor thermal comfort and increased heat gain in classrooms overlooking the courtyards. In contrast, courtyards with higher aspect ratios (0.63–0.82) demonstrated better microclimatic moderation and improved comfort conditions. Simulation results indicate that integrating a belt vegetation pattern of Cassia leptophylla, combined with textile shading and cool pavements with an albedo of 0.5, can reduce the Universal Thermal Climate Index (UTCI) by up to 14.7 °C, shifting conditions toward moderate heat stress. The findings provide practical design guidance for upgrading existing university courtyards and designing future educational buildings in hot-arid climates to enhance student comfort and environmental performance. Full article