Search Results (95)

Many airports now consider implementing urban-cooling measures as proven strategies to reduce energy use and improve environmental conditions. Studies have also shown that reflective surfaces on roofs and grounds can have beneficial effects on thermal environment and airport workers’ productivity. To date, no studies have been undertaken to specifically assess whether any effects on aircraft performance would also result from implementing these measures. In this exploratory study, high-resolution micrometeorological modeling and remote-sensing analysis were undertaken to quantify the potential reductions in fuel use and, thus, emissions from aircraft taxiing on cooler surfaces. The results suggest small but non-zero benefits in terms of emissions and takeoff-roll distances. Using the Dallas–Ft. Worth International Airport (DFW) as a case study and Boeing 737 aircraft type as an example, it is found that if taxiways and shoulders albedo is increased to 0.35, an average of 2.3 kg CO₂ can be saved per single taxi-out or taxi-in operation around midday and about 1.5 kg CO₂ earlier in the morning or later in the evening. It is also found that even though runways albedo remains unchanged, cooler air advected over runways from modified taxiways can reduce the takeoff-roll distance by an average of 3% around midday that tapers off to an average of 1% early in the morning or late evening. Indeed, these are small effects per single taxi-in or taxi-out operation but when scaled by some 2000 arrivals and departures per day at DFW, saving 4000–5000 kg CO₂ per day, and if further scaled by the number of eligible airports, the impacts become significant. Furthermore, the effects reported here are from taxiway and shoulder modifications alone; if combined with the effects from cool roofs and other cool ground surfaces at terminals, tarmacs, ramps, and parking areas, the benefits will add up significantly. Limitations in this study, that would be addressed in future work, include simplifying assumptions regarding aircraft-engine performance, specifications, and aircraft types mix and operations. Full article

Atmospheric ammonia (NH₃) is an important alkaline precursor of secondary inorganic aerosols, but its variability in livestock- and agriculture-influenced peri-urban environments remains poorly constrained. In this study, atmospheric NH₃ was measured at a peri-urban site in Chuncheon, South Korea and its variability was examined in relation to micro-meteorology, source direction, and surface–atmosphere exchange. Mean NH₃ concentrations were 200.8 ± 91.1 ppb during the April campaign, 83.0 ± 34.4 ppb during the May campaign, and 27.9 ± 16.2 ppb during the December campaign, indicating higher NH₃ levels during the April and May campaigns than during the December campaign. Campaign-specific correlation analyses showed that the relationships between NH₃ and micrometeorological variables differed among the observation periods, with robust associations observed in April and May but not in December. Moreover, the higher NH₃ concentration in the April campaign than in the May campaign, despite the lower mean temperature, indicates that the observed variability was not controlled by temperature alone. Conditional probability function analysis showed that elevated NH₃ concentrations in the April and May campaigns were mainly associated with southwesterly winds, suggesting the influence of nearby livestock and agricultural sources. The Penman–Monteith-derived latent heat flux further showed that daytime NH₃ enhancement coincided with evaporative surface-exchange conditions potentially favorable for volatilization, although it did not directly quantify manure-derived NH₃ emissions. In contrast, the December campaign showed lower NH₃ concentrations, weaker source-directional patterns, and limited latent heat flux influence, suggesting suppressed volatilization and intermittent local accumulation under stable conditions. These results indicate that the conditions associated with short-term NH₃ variability differed among the selected campaigns, reflecting complementary influences of source direction and campaign-specific micrometeorological and surface-exchange conditions, highlighting the need for concurrent gas- and particle-phase measurements to assess potential implications for PM_2.5 formation. Full article

This study evaluated the individual and interactive effects of straw management, tillage systems, and wheat growth stages on surface energy balance (SEB) dynamics in a semi-arid wheat production system, with particular focus on net radiation (Rn), sensible heat flux (H), latent heat flux (LE), Bowen ratio (β), and energy partitioning (EP). A field experiment was conducted during the 2022–2023 growing season using a split–split plot design with two straw management treatments, four tillage systems, and three growth stages. Surface energy balance components were estimated through field-based micrometeorological measurements. Data were analysed using ANOVA, variance partitioning analysis, and Pearson correlation analysis. All experimental factors significantly affected SEB components, although growth stage represented the dominant source of variability, accounting for 42–58% of total variance. Flowering stage consistently promoted the highest LE values and the lowest β and EP values, indicating enhanced evaporative cooling during maximum crop development. Conservation-oriented tillage systems substantially modified thermal partitioning, with no-tillage (NT) significantly increasing LE and reducing H relative to conventional tillage (CT). The combination of straw incorporation and NT during flowering (IS + NT + S2) produced the highest LE value (129.15 W m⁻²) and one of the lowest H values (18.35 W m⁻²). Bowen ratio progressively decreased from CT (8.57) to NT (1.44), confirming a shift from sensible to latent heat exchange under conservation-oriented management. Crop phenology and conservation-oriented soil management jointly regulated thermal partitioning and evaporative cooling in semi-arid wheat systems. NT combined with straw incorporation substantially enhanced latent heat exchange while reducing sensible heating, particularly during flowering. This study provides novel field-based evidence regarding the combined influence of straw management, tillage systems, and wheat phenology on SEB dynamics under semi-arid conditions, contributing to improved understanding of land–atmosphere interactions and climate-adaptive agricultural management strategies. Full article

Climate change and rising global temperature values lead to a cascade of effects on human health and well-being. Methodologies for assessing thermal conditions and identifying areas with increased thermal stress are important for enhancing the quality of life in urban environments. This study is aimed at developing a methodology that combines high-resolution simulation data with surface meteorological observations for application in urban thermal stress assessment. Eleven urban public sites within the metropolitan area of Athens, Greece (i.e., squares and parks) were simulated using the three-dimensional microclimate model ENVI-met. The model was validated using micrometeorological data from field campaigns conducted in summer, autumn and winter. The validation results confirmed that ENVI-met showed satisfactory performance for further research analysis. Subsequently, Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) were calculated using data from weather stations operated by the National Observatory of Athens and the Hellenic National Meteorological Service. PET and UTCI were then spatially interpolated using a mixed modeling and kriging method, with parameters optimized based on statistical validation metrics derived from the ENVI-met simulations. Finally, seasonal bioclimatic maps were produced to identify areas experiencing unfavorable thermal conditions. The spatial analysis revealed distinct seasonal patterns in the distribution of unfavorable thermal conditions across the Athens metropolitan area. Full article

In urban environments, large buildings influence air quality in their surroundings by altering natural wind patterns, obstructing airflow or creating high-velocity wind tunnels, often resulting in stagnant zones that trap pollutants. Furthermore, the extensive shadows cast by these structures reduce ground-level temperatures. For urban planners, accounting for these aerodynamic, thermal and air quality effects is important to fostering healthier, more livable cities. In this work, measurements assessing how shadow and micrometeorological conditions—driven by the proximity of large buildings—influence PM_2.5 levels were conducted in an urban commune of Santiago, Chile, during the winter and spring seasons. This commune is characterized by a mixture of one-story houses and high-rise buildings. PM_2.5 and meteorological parameters were measured outside three pairs of houses in winter of 2021, one of which received shadow from a nearby building and the other was under the sun. In one pair of houses, PM_2.5 concentrations were elevated in the shaded site exclusively during the winter months. This was attributed to shadow-induced temperature reductions, which likely increased local atmospheric stability and inhibited pollutant dispersion. However, this effect was limited to periods of low wind speed; during the spring, the transition to a higher wind speed regime facilitated sufficient mechanical mixing to neutralize the thermal influence of the shadow, resulting in no detectable difference between the sites. In another pair of houses, the result was attributed to the difference in wind speed in one of the houses, because the building acts as a windbreak, no shading effect were observed. Regarding the third pair of houses, no significant impact on PM_2.5 concentrations was observed in the whole period. This lack of variation is likely attributable to the absence of substantial micrometeorological differences between the two sites. Full article

Understanding crop water use is essential for improving agricultural water management and ensuring sustainable food production, especially in regions with limited water resources. Evapotranspiration (ET) is a key component of the hydrological cycle, directly influencing irrigation planning and crop productivity. However, accurately estimating ET at local scales remains a challenge due to the limitations of conventional measurement methods and the difficulty of integrating high-resolution remote sensing data. This study investigates the estimation of terrestrial evapotranspiration (ET) in a sugarcane cultivation area located in the northern coastal region of Paraíba, Brazil, using meteorological data and aerial images acquired by an Unmanned Aerial Vehicle (UAV). We adapted the PT-JPL model to estimate ET at the local scale, using thermal and multispectral imagery obtained from UAVs. Data validation was performed using surface energy balance measurements obtained from a micrometeorological tower, thereby enabling comparison of estimated and observed ET values. The results demonstrated strong correlations between modeled predictions and field measurements of net radiation (R² = 0.85), with performance metrics indicating moderate reliability for local-scale simulated ET when compared to flux-tower-based ET (R² = 0.48; RMSE ≈ 0.045 mm/30 min). This research highlights the potential of integrating UAV-based remote sensing with the PT-JPL model to improve understanding of crop water use, support irrigation management, and contribute to sustainable agricultural practices. Full article

Micro-meteorological monitoring systems have been widely deployed in power grids, providing essential data to support the prevention and mitigation of ice- and wind-related disasters. However, understanding of the associated error mechanisms and quantitative evaluations under freezing rain and snow remains limited, particularly in complex field environments. This study presents a field-based quantitative assessment of two key variables, air temperature and wind speed, based on comparative observations collected over multiple winter icing cycles. We analyze the coupled effects of low temperature, ice accretion, and solar radiation on temperature measurements through multi-configuration sensor comparison, and characterize the dynamic response of cup anemometers under icing conditions using cross-correlation lag analysis. Results show that temperature error is dominated by sensor installation configuration and solar radiation. Under weak solar radiation, unshielded sensors tend to record lower temperatures than a standard Stevenson screen, but once radiation exceeds 200 W/m², they warm rapidly and exhibit maximum positive biases of ~8–10 °C. Ice accretion further induces a cold bias of ~1 °C and a response lag of 5–18 min, while suppressing the rapid warming driven by shortwave radiation. For wind measurements, cup anemometers show clear underestimation during ice accretion, with the error increasing nonlinearly with ice thickness to ~20% before freezing-induced failure occurs. These findings provide a basis for improved sensor deployment and interpretation of field monitoring data in cold, humid, and icing-prone environments, although the quantitative results are site-dependent. Full article

This study investigates the vertical variation and temporal characteristics and indicates the sources of black carbon (BC) and brown carbon (BrC) within particulate matter fraction PM₁ during light (November–December 2024) and heavy (January–February 2025) haze episodes in Bangkok, Thailand, a topic where data are still limited data regarding Southeast Asian megacities. Continuous measurements were conducted at 30 and 110 m above ground level, together with particle size distribution measurement, micrometeorological observations, and backward air mass trajectory analysis. During the haze periods, the highest particle number concentrations occurred in the 0.3–0.4 µm size range, indicating dominant contributions from combustion-related emissions and secondary aerosol formation. Mean PM₁ mass concentrations during the heavy haze episodes were more than 2.5 times higher than those during light haze. BC concentrations increased substantially during heavy haze, while the BC fraction of PM₁ remained relatively constant (~10%). In contrast, the BrC fraction reached nearly 20%, reflecting an increasing influence of biomass burning emissions associated with regional transport. Combined analyses of BC/BrC relationships, wind-direction dependence, and air mass trajectories demonstrate mixed contributions from local fossil fuel combustion and long-range transport of biomass burning aerosols during severe haze events. Full article

Precision field measurements were conducted to evaluate the mechanism of organic basin mulching on water and thermal dynamics in arid date palm orchards in central Saudi Arabia. Partly mulched zones (20 m radius) and fully mulched basins were compared with adjacent bare soil using micrometeorological sensors and microlysimeters. In partly mulched areas, soil heat flux (G) decreased by 68.3% while sensible heat flux (H) increased up to 86.9% during late spring, indicating enhanced energy redistribution. Bare soil exhibited slightly negative latent heat flux (λE) in early spring, reflecting vapor adsorption, whereas fully mulched basins substantially reduced evaporation, with Water Conservation Efficiency Index (WCEĪ) values of 0.33 in spring and 0.27 in summer, corresponding to 33% and 27% water savings, respectively. Root-zone thermal moderation, quantified by the Root-Zone Thermal Moderation Index (RTMI), confirmed effective buffering of subsurface temperatures by 6–7 °C across 2–10 cm depths, despite slightly elevated surface temperatures. These results demonstrate that basin mulching stabilizes soil moisture, moderates diurnal thermal fluctuations, and optimizes soil–atmosphere energy partitioning under arid conditions. By integrating direct lysimeter measurements with continuous energy flux observations and index-based analysis, this study provides novel, field-based insights into the dual role of organic mulching in enhancing water conservation and thermal regulation in arid date palm orchards. Full article

To address the issues of poor universality, high cost, and difficulty in parameter acquisition associated with existing methods for estimating crop evapotranspiration (ET_c) in greenhouses, this study focused on tomato plants in a Venlo-type greenhouse (Zhenjiang, Jiangsu Province, from 20 November 2024 to 9 January 2025) to explore the applicability of the surface renewal (SR) method in greenhouses. Micrometeorological data were collected by deploying high-frequency temperature sensors and other equipment. The accuracy of sensible heat flux (H) estimation by the traditional Snyder method and the Chen method was compared. Based on the latent heat flux (LE) measured by the evaporimeter method, the actual sensible heat flux was derived through an energy balance model, which was then used for comparative verification with the estimation results of the two methods. The results showed that the Chen method, which incorporates friction velocity (u*) and does not rely on the empirical calibration coefficient α, is adaptable to the characteristics of non-uniform airflow in greenhouses. Under sunny conditions (R² = 0.722 during the day and R² = 0.712 at night) and cloudy conditions (R² = 0.7558 during the day and R² = 0.754 at night), the estimation accuracy of the Chen method was significantly higher than that of the Snyder method. Moreover, for the entire experimental period, the R² value reached 0.733, the Pearson’s r coefficient was 0.856, and the outlier rate was as low as 9.1%. This study innovatively applies the SR method to semi-closed heated greenhouses, making a clear distinction from previous SR studies conducted in open-field environments and providing a new approach for the accurate estimation of greenhouse heat flux. Full article

Global warming and urban expansion impose far-reaching, negative implications on the quality of the outdoor thermal environment in residential areas. Due to its potential for microclimate regulation and easy configuration with less site restrictions, the transitional space is an effective mitigation measure to transform existing outdoor spaces for thermal discomfort. The point of this article is to explore the optimum design parameters of the transitional space for increasing outdoor thermal comfort, with a focus on its orientation, aspect ratio (H/W), plan aspect ratio (L/W), and enclosure degree. The ENVI-met micro-meteorological model is adopted to visualize the environmental parameters after field measurement whereas the Ecotect is applied to validate the thermal performance under different design variants. The simulation results show that the thermal performance of geometry and orientation for the transitional space is seasonally discordant. On account of giving consideration to balance the double demands of solar shading in summer and solar gain in winter, a south-oriented transitional space with the windward side enclosure, length-width ratio of 2:1, and aspect ratio with 1.2 produces a greater thermal environment in Tianjin, China. Combined with the previous literature, south-oriented transitional spaces have a comparative advantage in balancing year-round thermal comfort for most cases; the deviation of the preferred orientation in the corresponding cities from the due south orientation is within 90° of a counterclockwise rotation. The lower aspect ratio (approximately below 1), deeper shape, and lower enclosure of the transitional spaces is appropriate for tropical and subtropical areas to avoid excessive sunshine; for temperate climates with hot summers and cold winters, such as in Tianjin, the reverse happens. Full article

This work analyzes the behavior of the boundary layer subjected to stresses by obstacles using hourly measurements, in the form of time series, of meteorological variables (temperature (T), relative humidity (RH), and magnitude of the wind speed (WS)) in a given period. The study region is Santiago, the capital of Chile. The measurement location is in a rugged basin geography with a nearly pristine atmospheric environment. The time series are analyzed through chaos theory, demonstrating that they are chaotic through the calculation of the parameters Lyapunov exponent (λ > 0), correlation dimension (D_C < 5), Kolmogorov entropy (S_K > 0), Hurst exponent (0.5 < H < 1), and Lempel–Ziv complexity (LZ > 0). These series are simultaneous measurements of the variables of interest, before and after, of three different volumetric geometries arranged as obstacles: a parallelepiped, a cylinder, and a miniature mountain. The three geometries are subject to the influence of the wind and present the same cross-sectional area facing the measuring instruments oriented in the same way. The entropies calculated for each variable in each geometry are compared. It is demonstrated, in a first approximation, that volumetric geometry impacts the magnitude of the entropic fluxes associated with the measured variables, which can affect micrometeorology and, by extension, the climate in general. Furthermore, the study examines which geometry favors greater information loss or greater fractality in the measured variables. Full article

Ammonia (NH₃) emissions affect the environment, climate and human health and originate mainly from agricultural sources like synthetic nitrogen fertilizers. Accurate and replicable measurements of NH₃ emissions are crucial for research, inventories and evaluation of mitigation measures. There exist specific application limitations of NH₃ emission measurement techniques and a high variability in method performance between studies, in particular from small plots. Therefore, the aim of this study was the assessment of measurement methods for ammonia emissions from replicated small plots. Methods were evaluated in 18 trials on six sites in Germany (2021–2022). Urea was applied to winter wheat as an emission source. Two small-plot methods were employed: inverse dispersion modelling (IDM) with atmospheric concentrations obtained from Alpha samplers and the dynamic chamber Dräger tube method (DTM). Cumulative NH₃ losses assessed by each method were compared to the results of the integrated horizontal flux (IHF) method using Alpha samplers (Alpha IHF) as a micrometeorological reference method applied in parallel large-plot trials. For validation, Alpha IHF was also compared to IHF/ZINST with Leuning passive samplers. Cumulative NH₃ emissions assessed using Alpha IHF and DTM showed good agreement, with a relative root mean square error (rRMSE) of 11%. Cumulative emissions assessed by Leuning IHF/ZINST deviated from Alpha IHF, with an rRMSE of 21%. For low-wind-speed and high-temperature conditions, NH₃ losses detected with Alpha IDM had to be corrected to give acceptable agreement (rRMSE 20%, MBE +2 kg N ha⁻¹). The study shows that quantification of NH₃ emissions from small plots is feasible. Since DTM is constrained to specific conditions, we recommend Alpha IDM, but the approach needs further development. Full article

The rapid urbanization processes across the world can be considered one of the most influential factors in climate change, particularly in metropolitan areas. In South America, the growing population and recurrent non-sustainable or controlled urban land management plans are even increasing the negative consequences of urban heat islands. As a representative case study, Soledad in northern Colombia is an area with recurrent strong wind events, which have caused significant damage to property and human lives, conditioning urban plans. This research aimed to assess the micrometeorological conditions in areas of Soledad, where cyclonic events are highly frequent, to gather essential data on urban planning to understand microclimate changes. We conducted in situ measurements of air temperature, surface temperature, wind speed, relative humidity, and atmospheric pressure across different Local Climate Zones (LCZs). Data were analyzed to assess the impact of urban form, vegetation, and sky openness on microclimatic variations. Our results demonstrated that urban morphology, vegetation cover, and sky openness significantly influenced local microclimates, with lower Sky View Factor (SVF) and higher Leaf Area Index (LAI) values contributing to reduced temperatures and improved airflow. Areas with denser urban canyons exhibited higher temperatures and lower wind speeds, emphasizing the need for strategic urban planning to mitigate heat stress and enhance ventilation. Full article

The thermal and optical behavior of different elements in the urban environment is critical for urban climate regulation and planning. This study investigates the micrometeorological conditions prevailing in an urban green space (UGS) in Greece, during the heatwave of July 2023, addressing the effects of various surface materials on thermal dynamics and the urban heat island (UHI) phenomenon. The research is based on ground surface temperature and albedo measurements on different materials in the UGS, in the morning and at noon, showing great temperature differences between the different types of materials. The findings highlight the complex interaction between high-albedo surfaces and surface temperature values, suggesting that the proper selection of materials can highly affect the optical and thermal behavior of the urban environment. Artificial materials absorb more heat compared to natural vegetation, leading to high surface temperature values, reaching at noon, for example, 58.9 °C for asphalt. For the natural surfaces, dry bare soil presents similar thermal behavior (64.1 °C at noon), while green surfaces had much lower temperatures (e.g., 38.3 °C for grass). Thermal comfort indices revealed that July 2023 experienced extensive “very hot” conditions, imposing the urgent need for strategic urban planning to mitigate heat impacts. The study highlights that in order to create climate-resilient environments and improve thermal comfort, it is crucial to include suitable materials and a variety of vegetation in urban design. Such insights into the complex nature of urban microclimate indicates also the issue of the careful selection of materials and plant species in urban greening initiatives to help cities face the UHI phenomenon. Full article