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In arid regions with limited water resources, numerous reservoirs have been built to support economic and social development. However, how the construction of reservoirs interacts with the surrounding ecosystem to affect temperature remains unclear. Spanning 2018 to 2022 in the Shiyang River Basin, we collected surface water and precipitation, as well as stem and soil samples. Using isotopic methods, we quantified how evaporation in the oasis reservoir‐riparian forest system affects the local climate. Our findings show that the latent heat released by evapotranspiration from the reservoir and riparian forest system reduces the daily maximum temperature and daily temperature range by 7°C and 6°C respectively, compared to downstream areas with sparse vegetation around artificial lakes. Additionally, it enhances local moisture recycling, increasing precipitation. This study reveals regional cooling effect due to interactions between water bodies, the atmosphere, and vegetation. We propose that establishing reservoir‐riparian forest systems can positively impact local climate regulation and serve as an effective strategy for adapting to global climate warming. Plain Language Summary Quantifying evapotranspiration's cooling effect is crucial to understand how water bodies, vegetation, and the atmosphere interact. The construction of water facilities has changed global hydrology and vegetation, especially in arid regions. Clarifying evapotranspiration in arid area reservoirs and nearby vegetation helps address water scarcity and climate change. In this study, a comprehensive observation network was established in Hongyashan Reservoir to quantify the evaporation loss of surface water and the heat absorbed by the vapourization of liquid water in the reservoir‐riparian forest complex system. The results showed that riparian forest accelerated the local water circulation and enhanced the regulation of diurnal temperature difference and diurnal maximum temperature around the region, mainly because the latent heat of water phase transition absorbed a lot of heat. Focusing on the ecosystem and human society at the regional level, the construction of reservoir‐riparian forest composite system will help to expand the ability and resilience of human society to adapt to climate change. Key Points Latent heat due to evapotranspiration reduces the daily maximum temperature and the diurnal temperature range Reservoir‐riparian forest system enhances local moisture recycling, resulting in increased precipitation A substantial portion of raindrops re‐evaporating beneath the clouds, which consumes a considerable amount of heat

The rapid urbanization worldwide has brought various environmental problems. The urban heat island (UHI) phenomenon is one of the most concerning issues because of its strong relation with daily lives. Water bodies are generally considered a vital resource to relieve the UHI. In this context, it is critical to develop a method for measuring the cooling effect and scale of water bodies in urban areas. In this study, West Lake and Xuanwu Lake, two famous natural inner-city lakes, are selected as the measuring targets. The scatter plot and multiple linear regression model were employed to detect the relationship between the distance to the lake and land surface temperature based on Landsat 8 Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS) and Sentinel-2 data. The results show that West Lake and Xuanwu Lake massively reduced the land surface temperature within a few hundred meters (471 m for West Lake and 336 m for Xuanwu Lake) and have potential cooling effects within thousands of meters (2900 m for West Lake and 3700 m for Xuanwu Lake). The results provide insights for urban planners to manage tradeoffs between the large lake design in urban areas and the cooling effect demands.

Vegetation configuration in residential districts improves human comfort by effectively moderating the thermal environment. Herein, the reliability of ENVI-met is verified by comparing the field measured with simulated data, including air temperature and relative humidity. The cooling effect of trees gradually increased with increasing tree coverage. Under the same coverage, trees with a tree crown diameter (TCD) of 3 m have the strongest cooling capacity, followed by trees with a TCD of 7 m, and trees with a TCD of 5 m have the weakest cooling capacity. The cooling capacity of a TCD of 3 m is considerably higher than that a TCD of 5 m and a TCD of 7 m. When the tree coverage ratio is 50%, the difference among the three TCDs is the largest. When the tree coverage is 50% or 70%, the cooling effect of TCD at 7 m is considerably higher than that at 5 m. For different canopy sizes and shapes under the same degree of tree coverage, only when the tree coverage is more than 50% and TCD is 3 m, the cooling capacity of a cylindrical shape is 0.2 to 0.3 °C higher than that of conical and ellipsoidal shapes. However, the difference between conical and ellipsoidal shapes when TCD is 5 or 7 m is not significant (∆Ta < 0.1 °C). Our results suggest that small canopy trees have a better cooling effect than large canopy trees for the same level of coverage.

TBCC engine is a new type of engine that integrates a turbine engine and ramjet engine design to achieve engine from start-up to high Mach number flight. Jet precooling technology injects cooling medium into the turbine inlet and achieves cooling effect on high-temperature incoming flow through evaporative phase change, effectively improving the upper limit of the turbine engine. This article establishes an inlet model with NACA0018 airfoil support, and uses the Standard k – ε turbulence model and DPM model to establish a calculation method for gas-liquid two-phase flow and heat transfer model. The influence of jet direction and water vapor ratio (W/A) on jet precooling effect is studied. The results indicate that the influence of jet direction on the cooling effect is the result of the combined action of the two orthogonal velocities of the droplet. As the droplet velocity increases, the optimal jet angle continuously increases. For low-speed droplets, a 180° jet angle has a worse cooling effect than a 0° jet angle. As the water vapor ratio increases, the cooling effect continues to enhance, but the evaporation rate decreases continuously. Excessive water vapor ratio seriously affects the safety of aircraft engines.

The development of urban blue-green spaces is highly recommended as a nature-based solution for mitigating the urban heat island phenomenon, improving urban sustainability, and enhancing resident well-being. However, limited attention has been given to the accumulative impact of the cooling effect and the comparison of different types of landscapes. Based on the maximum and accumulative perspectives, this study selected 375 green spaces, water bodies, and urban parks in 25 cities of the Yangtze River Delta (YRD) region in China to quantify their cooling effect. Correlation and regression analyses were employed to identify the dominant factors influencing the cooling performance. The results indicated that (1) compared to other landscape patches, water areas, and parks exhibited a reduction in daily average air temperature by 3.04 and 0.57 °C, respectively. Urban parks provided the largest cooling area (CA) of 56.44 ha in the YRD region, while water bodies demonstrated the highest cooling effect (CE) of 6.88, cooling intensity (CI) of 0.02, and cooling gradient (CG) of 0.99. (2) From the maximum perspective, the perimeter of the patches played a dominant role in CA and CE for all landscape patch types, contributing more than 40% in CA variation. (3) The dominant factors varied among different landscape types from accumulative perspectives. Green spaces were influenced by road density, shape index, and the proportion of water bodies within the CA, whereas water bodies were primarily affected by the coverage of blue spaces. Vegetation growth and densely populated surroundings contributed the most to the cooling of parks. These findings enhanced the comprehension of the cooling effect in comparable urban contexts and provided valuable insights for sustainable urban management.

The urban heat island (UHI) effect has a serious negative impact on urban ecosystems and human well-being. Mitigating UHI through nature-based methods is highly recommended. The cooling effect of urban blue infrastructure (UBI) can significantly alleviate the effects of UHI. Revealing the crucial influencing factors of the cooling effect of UBI is of great significance for mitigating the UHI effect. In this study, the water-cooling intensity (WCI) and water-cooling range (WCR) were used to quantitatively analyze the cooling effect of UBI in Hefei city in summer. Furthermore, the influencing factors and their interactions with the cooling effect of UBI were investigated based on the Geodetector model. The results revealed that: (1) The surface thermal environment of the built-up area of Hefei presented obvious spatial differentiation characteristics. (2) There were nine influencing factors that significantly influenced the WCI variation, with the greatest influencing factor of road density. In contrast, only the landscape shape index had a significant effect on WCR variation. (3) The interaction of environmental characteristics, water body characteristics, and socioeconomic characteristics had a significant influence on the cooling effect of UBI, and the interaction relationship between the influencing factors was mutually enhanced. The findings from our research can provide a theoretical reference and practical guidance for the protection, restoration, and planning of UBI as a nature-based solution to improve the urban thermal environment.

The mid-Holocene (MH; 6 ka) is one of the benchmark periods for the Paleoclimate Modeling Intercomparison Project (PMIP) and provides a unique opportunity to study monsoon dynamics and orbital forcing (i.e., mostly precession) that differ significantly from the present day. We conducted a data–model comparison along with a dynamic analysis to investigate monsoonal (i.e., East Asian summer monsoon; EASM) precipitation changes over East Asia during the MH. We used the three phases of the PMIP simulations for the MH, and quantitatively compare model results with pollen-based climate records. The data–model comparison shows an overall increase in the summer monsoon precipitation, except a local decrease during the MH. Decomposition of the moisture budget into thermodynamic and dynamic components allows us to assess their relative role in controlling EASM precipitation during the MH, and to investigate the precipitation changes obtained from pollen records in terms of physical processes. We show that the dynamic effect, rather than the thermodynamic effect, is the dominant control in increased EASM precipitation during the MH in both the proxy records and models. The dynamic increase in precipitation results mainly from the enhancement of horizontal monsoonal moisture transport that is caused by intensified stationary eddy horizontal circulation over East Asia. In addition, a cloud-related cooling effect reduced the thermodynamic contribution to the increase in EASM precipitation during the MH.

Urban parks have been shown to form park cool islands (PCIs), which can effectively alleviate the negative influences of urban heat islands (UHI). However, few studies have examined the detailed characteristics of PCIs, the effect of urban park features on their individual temperatures, and monthly variation in PCIs. Land surface temperature (LST) retrieved from Landsat 8 TIR images between May and October were used to represent the thermal environment. Urban park characteristics were extracted from high-resolution GF-2 images. Using these datasets, the relationships between urban park characteristics and PCIs were explored in this study using Changchun, which has a snow climate, as a case study. The results showed the following: (1) the urban parks exhibited a cooling island effect, and the PCIs showed significant monthly variations with the highest intensities in the hot months; (2) the effects of composition (e.g., park size and the percentage of water area) on LSTs and PCIs showed significant monthly variability and were stronger than the configuration effects. Furthermore, an unexpected, negative correlation between PCIs and the area of park grass was also found; and (3) larger parks tended to have stronger PCI intensities and extents of influence. For parks larger than 30 ha, the cooling effects extended approximately 480 m from the park edge between June and August. For all of parks during the study duration, the rate of temperature increase was highest within 60 m from the park edge. The PCI we employ specifically in this study is characterized by LST.

BackgroundIn densely populated urban centers, increased air temperature due to urban heat island (UHI) effect can undermine the thermal comfort and health of citizens. Research has shown that large urban parks can mitigate the effect of UHIs and improve thermal comfort, especially in the warmer months of the year when temperature changes are more noticeable. This study investigated the cooling effect intensity (CEI) of the Retiro Park in the center of Madrid at three different distances from its southern edge and the impact of this cooling effect on thermal comfort from physiological and psychological perspectives. This investigation was performed by measuring microclimate data and conducting a survey simultaneously during the summer days.ResultsThe results showed that the CEI of the park varies with distance from its edge. Because of this effect, air temperature within the 130 m and 280 m distance of the park was, respectively, 1.6 °C and 0.9 °C lower than the temperature at the 520 m distance (the nearest heat island). After examining the effect of the park in terms of physiological equivalent temperature (PET), it was found that the PET at the 130 m and 280 m distance of the park was 9.3% and 5.4% less than the PET in the heat island domain. More than 81% of the respondents (in all three areas) had a mental image of the park as the place where they would experience the highest level of outdoor thermal comfort, and this rate was higher in the areas closer to the park. The analysis of citizens’ responses about perceived thermal comfort (PTC) showed that citizens in areas with higher CEI had perceived a higher degree of thermal comfort from the psychological perspective.ConclusionThis study demonstrates the significant role of large urban parks located in the core of the populated cities in providing thermal comfort for citizens from both physiological and psychological perspectives. Additionally, the results of this study demonstrated that among the environmental (natural and artificial) factors around the park (topography, urban structure, etc.), the aspect ratio has the greatest impact on thermal comfort.

Context Urban parks play a critical role in alleviating urban heat island effects, affecting human development directly and background climatic conditions greatly influence the intensity of their cooling effects. Objectives Here, focusing on 108 urban parks in four major cities across different climate zones—temperate subhumid continental climate (Shenyang city), north temperate continental monsoon climate (Zhengzhou city), subtropical monsoon humid climate (Wuhan city), and subtropical monsoon climate (Nanning city) in China, we explored the optimal area threshold for cooling effectiveness in urban parks under different background climatic conditions. Methods Using land surface temperature (LST) inversion data, the cooling intensity and cooling distance of each park were analyzed by temperature classification, buffer analysis and segmentation function, and the influence of 11 landscape elements on the cooling effect characteristics of parks and regional differences were explored. Results The results indicate: (1) Surface temperature inversion aligns with actual conditions during summer noon, with all four cities experiencing a heat island effect. (2) The average park cooling effect distance (PCE d ) across all parks in the four cities is 161 m, the average park cooling effect intensity (PCE i ) was 2.73 °C, the maximum PCE d was 437.35 m, and the maximum PCE i reached 6.9 °C. (3) The perimeter-to-area ratio (PARA) is the most influential parameter negatively correlated with park cooling effect, while the most influential positively correlated factor is park area (AREA). Interestingly, the number of factors that enhance the park cooling effect decreased from north to south. (4) The park area thresholds for optimal cooling effect in Shenyang, Zhengzhou, Wuhan, and Nanning was 7.27 ha, 8.08 ha, 9.69 ha, and 44.42 ha, respectively. Conclusions All four cities in the study area experience urban heat island effects. Overall, the most influential positive landscape element correlating with the park cooling effect was park area. Therefore, planning parks according to optimal cooling effect area thresholds can maximize land use efficiency, enhance cooling value, and promote urban and human development.