Daytime Temperature Research Articles

Impacts of climate change on fractional vegetation coverage of temperate grasslands in China from 1982 to 2015

The vegetation coverage of temperate grasslands in China has changed substantially due to climate change during the past decades, which significantly affects the function of grassland ecosystems. To appropriately carry out adaptive management and protect temperate grassland vegetation, it is important to understand the variations in fractional vegetation coverage (FVC) of China's temperate grasslands and how they are responding to climate change. Using the GIMMS NDVI and climatic datasets, this study explored the dynamics of FVC and their climatic drivers across the temperate grassland region of China during 1982∼2015. The results showed that the growing season mean FVC increased by 0.12% per year during 1982∼2015. The increases in precipitation and minimum temperature in the growing-season (especially in spring) could enhance the FVC of various vegetation types. In summer, the FVC of temperate steppe and desert steppe could drastically increase with increasing precipitation. In addition, this study found that the impacts of daytime and night-time warming on the FVC of temperate grasslands were asymmetric. Daytime warming can moderately increase FVC of temperate grasslands, while night-time warming could significantly increase it. Furthermore, the increase in summer daytime and night-time temperatures leads to a weak decrease and a moderate increase in FVC, respectively. This asymmetric effect was more evident for the temperate steppe and desert steppe in the central area. In autumn, the temperatures increase had significant positive impacts on the FVC of temperate meadows and steppes. This study highlights the differences in the impacts of climate change at different time scales on the FVC of grasslands with various vegetation types, and indicates that the asymmetric influences of daytime and night-time temperatures in different seasons on FVC must be included in calculating the vegetation coverage of China's temperate grasslands. The results could provide information for maintaining grassland ecosystem functions and managing environmental systems.

Influence of Sudden Stratospheric Warmings on the Migrating Diurnal Tide in the Equatorial Middle Atmosphere Observed by Aura/Microwave Limb Sounder

The Microwave Limb Sounder (MLS) onboard the satellite Aura measures the temperature at 01:44 LST (after midnight) and at 13:44 LST after noon in the equatorial middle atmosphere. The signatures of the migrating solar diurnal tide (DW1) show up in the difference between the night-time and the daytime temperature profiles. We find a good agreement between the equatorial DW1 proxy of the Aura/MLS observations and the migrating diurnal tide estimated by the Global Scale Wave Model (GSWM) in March. The equatorial DW1 proxy is shown for the time interval from 2004 to 2021 reaching a temporal resolution of 1 day. The amplitude modulations of the DW1 proxy are correlated at several altitudes. There are indications of a semi-annual and annual oscillation (SAO and AO) of the DW1 proxy. The composite of 17 events of major sudden stratospheric warmings (SSWs) shows that the equatorial, mesospheric DW1 proxy is reduced by about 10% during the first week after the SSW event. The nodes and bellies of the equatorial DW1 proxy are shifted downward by about 1–2 km in the first week after the SSW. The 14 day-oscillation of the DW1 proxy in the equatorial mesosphere is enhanced from 25 days before the SSW onset to 5 days after the SSW onset.

Impact of Uninsulated Slab-on-Grade and Masonry Walls on Residential Building Overheating

Studies of the effects of removing underfloor insulation and increasing the thermal capacity of building walls are currently found almost exclusively in existing vernacular architecture and rammed-earth buildings, mostly in countries with warm climates. This paper proposes the combined use of these two measures to reduce the risk of overheating in a detached single-family house in a temperate climate during the summer. Experimental studies conducted during the largest heat wave on record in the summer of 2019 showed that peak daytime temperatures decreased by 5.2 °C to 7.1 °C, and peak nighttime temperatures decreased by 4.7 °C to 6.8 °C. Simulation studies taking into account occupant heat showed that the proposed passive methods could, under the IPCC 8.5 scenario, eliminate the need for mechanical cooling in a detached single-family house in the temperate climate of Central and Eastern Europe by 2100. The actual heating energy consumption for the building with an uninsulated floor and increased wall heat capacity was 5.5 kWh/m2 higher than for the reference building, indicating that it can be a near-zero energy building. The proposed concept is in line with the new approach to the energy design of buildings, which should not be limited to reducing thermal energy demand, but should also respond to the needs arising from global warming.

Influence of spring and autumn frosts on Impatiens glandulifera populations in the Sofia region (Bulgaria)

The present study aims to analyze and determine to what extent spring and autumn frosts affect the population size and life cycle of this invasive alien species (IAS). The study area is located in the immediate vicinity of the capital Sofia and covers the  Iskar River stream and its tributaries in the gorge between Plana and Lozenska Mountains (Southwestern Bulgaria). The study was carried out in the period 2020-2022. Six permanent sample plots (PSP), each measuring 10 m2, were established in characteristic localities of I. glandulifera populations along the Iskar River and its tributaries (Table 1). Each year, during the spring and autumn frosts, the percentage of dead individuals of I. glandulifera relative to the total number of individuals of this species in the PSP was recorded. During the autumn frosts, the number of alive individuals in the following phenological stages was also recorded: flowering; fruiting; dispersal of fruits and seeds; end of growing season. The results show that frosts in the study area did not significantly affect the population size and life cycle of I. glandulifera. The death of the whole population оccurs only in permanent periods of negative daytime temperatures, however a significant part of the individuals at that time are in a generative stage of development. The temperature conditions in the area favor the invasiveness of I. glandulifera, extending the vegetation period of this species and the possibilities for its reproduction and spread.  

The heat response regulators HSFA1s promote Arabidopsis thermomorphogenesis via stabilizing PIF4 during the day.

During summer, plants often experience increased light inputs and high temperatures, two major environmental factors with contrasting effects on thermomorphological traits. The integration of light and temperature signaling to control thermomorphogenesis in plants is critical for their acclimation in such conditions, but the underlying mechanisms remain largely unclear. We found that heat shock transcription factor 1d (HSFA1d) and its homologs are necessary for plant thermomorphogenesis during the day. In response to warm daytime temperature, HSFA1s markedly accumulate and move into the nucleus where they interact with phytochrome-interacting factor 4 (PIF4) and stabilize PIF4 by interfering with phytochrome B-PIF4 interaction. Moreover, we found that the HSFA1d nuclear localization under warm daytime temperature is mediated by constitutive photomorphogenic 1-repressed GSK3-like kinase BIN2. These results support a regulatory mechanism for thermomorphogenesis in the daytime mediated by the HSFA1s-PIF4 module and uncover HSFA1s as critical regulators integrating light and temperature signaling for a better acclimation of plants to the summer high temperature.

Urban Heat Variation and Temperature Lapse Rate in the Kathmandu Valley

The rate of urbanization growth has accelerated and made urban areas comparatively warmer than surroundings which are the main issues of urban heat worldwide. The Kathmandu Valley is one of the million plus cities with the fastest rate of urbanization and consequent extreme heat. In this study, urban heat was analyzed using both in-situ and satellite-based observation and estimated temperature lapse rate. The Mann Kendell test, Sen’s slope, raster image analysis and lapse rate estimation methods were used. The results showed that average temperature difference in between urban core and surrounding was 4.07°C from 1990 to 2020. Likewise, the summer day temperature in Putalisadak was 8.8°C higher than the Nagarkot. The maximum temperature has increased in all stations where Godavari station has increased significantly (0.073°Cyr−1, p<0.0001). During all seasons, the daytime temperature is higher than the nighttime temperature. The maximum 32.86°C daytime temperature was recorded on August 4, 1pm and the minimum temperature was 3.67°C on Jan 20, 6am, 2020 at the city core. Similarly, the highest temperature was recorded at 31°C in Bagbazar and 33°C in Patan on July 10 and July 11, 2022 respectively when the humidity was lower. Satellite-based observation also shows that the urban heat scenario of the Kathmandu Valley was higher in the urban core which was ranges from 21.06 to 26.09 during 2000-2020. The temperature of the city has increased. However, temperature lapse rate in response to Nagarkot (reference station) is normal i.e decreased temperature in response to increased height. The higher lapse rate is generally found in the Godavari and lower was observed in the Machhegaoun. Overall, the Kathmandu Valley is getting more warmer compared to the surroundings. This comprehensive study is useful to explore the understanding of urban heat islands and temperature lapse rate in the major cities in compared to the surroundings in Nepal.

Microclimate and Vegetation Structure Significantly Affect Butterfly Assemblages in a Tropical Dry Forest

Understanding the factors that influence the diversity and distribution of butterfly species is crucial for prioritizing conservation. The Eastern Ghats of India is an ideal site for such a study, where butterfly diversity studies have yet to receive much attention. This study emphasized the butterfly assemblages of three prominent habitats in the region: open forests, riparian forests, and dense forests. We hypothesized that riparian forests would be the most preferred habitat for the butterflies, as they provide suitable microclimatic conditions for butterflies. The study collected samples for 35 grids of 2 × 2 km2 for each habitat during the dry months (December–June). We considered the relative humidity, temperature, light intensity, elevation, and canopy cover to assess their influences on butterfly richness and abundance. We also considered the impact of disturbances on their distribution. We used structural equation modeling and canonical correspondence analysis to quantify the correlation and causation between the butterflies and their environment. The study recorded 1614 individual butterflies of 79 species from 57 genera and 6 families. During the study, we found that temperature was the most significant factor influencing butterfly richness. Relative humidity was also important and had a positive impact on butterfly richness. Riparian forests, where daytime temperatures are relatively low, were the most preferred microhabitat for butterflies. Open forests had greater species diversity, indicating the critical significance of an open canopy for butterflies. Though riparian forests need greater attention concerning butterfly distribution, maintaining open and dense forests are crucial for preserving butterfly diversity.

102 Growth Performance in Pigs fed a High Soybean Meal Diet During Heat Stress

Abstract In the U.S. swine industry, feeding programs are focused on using feed ingredients that are easily digestible and cost effective. With the predicted increases in soybean processing, pig producers may have increased availability of a cost-effective protein source in soybean meal (SBM). This expanded availability of SBM may result in feeding protein above the ostensible requirements, which would likely intensify the thermic effect of digestion, potentially increasing the susceptibility of the pig to heat stress (HS). Heat stress has damaging effects on feed intake and growth performance, costing the swine industry >$900 million annually. Therefore, the study objectives were to evaluate the effects of dietary crude protein diets (in the form of SBM) during HS on growth performance in growing pigs. Growing pigs (n = 40; initial BW = 55 ± 5.6 kg) were allocated into six treatments: 1) thermoneutral (TN) ad libitum control diet (TN-Ctl; n = 6), 2) TN pair-fed (PF) control diet (PF-Ctl; n = 6), 3) HS ad libitum control diet (HS-Ctl; n = 8), 4) TN ad libitum high SBM diet (TN-SBM; n = 6), 5) TN PF high SBM diet (PF-SBM; n = 6), and 6) HS ad libitum high SBM diet (HS-SBM; n = 8). The control diet included 15% crude protein (CP) while the high SBM diet included 23% CP with excess amino acids. The study consisted of two periods: Period 1 (P1; 7 d) in which all pigs were housed in TN environments (26.7 ± 1.4°C) with ad libitum access to respective diets. Period 2 (P2; 21 d), HS groups were exposed to cyclical HS with daytime temperatures reaching 35°C and evening temperatures decreased to 29.4°C. During P2, PF groups were fed to respective HS-Ctl or HS-SBM equivalents in TN conditions. Pigs exposed to HS had an overall increase in rectal temperature and respiration rate (0.91°C and 45 bpm, respectively; P ≤ 0.01) and HS-SBM pigs had increased evening rectal temperature (± 0.13°C; P ≤ 0.01), relative to HS-Ctrl. Overall, HS decreased ADFI (19%; P ≤ 0.01), ADG (26%; P ≤ 0.01) and increased F:G (10%; P ≤ 0.01) irrespective of dietary CP levels. Loin muscle area (P = 0.19) and backfat (P = 0.98) were not different between the TN and HS pigs regardless of diet. Circulating blood urea nitrogen levels did not differ between HS and TN pigs (P = 0.68), but an increase was observed in pigs fed the SBM diet relative to the control diet (P ≤ 0.01). In summary, these results demonstrate that HS decreases growth performance, but the negative effects are not augmented by feeding a high SBM diet.

Optimizing Indoor Hemp Cultivation Efficiency through Differential Day–Night Temperature Treatment

This study was conducted to determine the optimal temperature difference in day–night indoor cultivation conditions to enhance the flower yield and functional component contents of female hemp plants. Hemp clones were cultivated under five distinct day and night temperature differences (DIF) during the reproductive stage. The daytime and nighttime temperature settings were as follows: 18:30 °C (negative 12 DIF), 21:27 °C (negative 6 DIF), 24:24 °C (0 DIF), 27:21 °C (positive 6 DIF), and 30:18 °C (positive 12 DIF). Seven weeks after transplantation, the growth parameters, leaf gas exchange, total phenolic compounds, 2,2-diphenylpicrylhydrazyl scavenging activity, and cannabinoid contents were analyzed. The total shoot biomass based on dry weight was highest at 21:27, reaching 41.76 g, and lowest at 30:18, measuring 24.46 g. However, the flower biomass, which is the primary production site, was highest at 24:24 and lowest at 18:30, showing a 4.7-fold difference. The photosynthesis-related parameters were temperature-dependent and strongly correlated with biomass production. The cannabinoid content of the hemp leaves increased at 21:27, whereas that of the hemp flowers increased at 27:21. The findings of this study indicate that the optimal temperature condition for female hemp flower production in a limited space is positive 6 DIF treatment, which corresponds to 27:21 °C. These results can contribute to advancements in indoor crop cultivation technology.

Why Has the Summertime Central U.S. Warming Hole Not Disappeared?

Abstract A cooling trend in summer (May–August) daytime temperatures since the mid-twentieth century over the central United States contrasts with strong warming of the western and eastern United States. Prior studies based on data through 1999 suggested that this so-called warming hole arose mainly from internal climate variability and thus would likely disappear. Yet it has prevailed for two more decades, despite accelerating global warming, compelling reexamination of causes that in addition to natural variability could include anthropogenic aerosol–induced cooling, hydrologic cycle intensification by greenhouse gas increases, and land use change impacts. Here we present evidence for the critical importance of hydrologic cycle change resulting from ocean–atmosphere drivers. Observational analysis reveals that the warming hole’s persistence is consistent with unusually high summertime rainfall over the region during the first decades of the twenty-first century. Comparative analysis of large ensembles from four different climate models demonstrates that rainfall trends since the mid-twentieth century as large as observed can arise (although with low probability) via internal atmospheric variability alone, which induce warming-hole-like patterns over the central United States. In addition, atmosphere-only model experiments reveal that observed sea surface temperature changes since the mid-twentieth century have also favored central U.S cool/wet conditions during the early twenty-first century. We argue that this latter effect is symptomatic of external radiative forcing influences, which, via constraints on ocean warming patterns, have likewise contributed to persistence of the U.S. warming hole in roughly equal proportion to contributions by internal variability. These results have important ramifications for attribution of extreme events and predicting risks of record-breaking heat waves in the region. Significance Statement Our paper makes a significant contribution to analysis of a cooling trend in summer (May–August) daytime temperatures since the mid-twentieth century over the central United States, contrasting with strong warming over the remainder of the United States and having important ramifications for assigning cause to and predicting record-breaking heat waves in the region. Observations and model simulations reveal the critical importance of hydrologic cycle change resulting from ocean–atmosphere impacts. Precipitation has increased substantially over the region as a result of atmospheric circulation trends consisting of generally lower pressure and cooler air advection into the region. The persistence of this pattern of increased rainfall/lower temperatures is likely due to near-equal contributions of external forcing (climate change) and internal climate variability.

Predicting maximum temperatures over India 10-days ahead using machine learning models

In the months of March-June, India experiences high daytime temperatures (Tmax), which sometimes lead to heatwave-like conditions over India. In this study, 10 different machine learning models are evaluated for their ability to predict the daily Tmax anomalies 10 days ahead in the months of March-June. Several model experiments were carried out to identify an optimal model to predict daily Tmax anomalies over India. The results indicate that the AdaBoost regressor with Multi-layer Perceptron as the base estimator is an optimal model to predict the Tmax anomalies over India in the months of March-June. The optimal model predictions are benchmarked against 10-day persistence predictions and the predictions from the Climate Forecast System (CFS) reforecast. The results indicate that the machine learning model skill is higher than persistence and comparable to CFS reforecast 10-day predictions in April and May. In March and June, the machine learning models have low skill scores and perform no better than persistence. These results indicate that the machine learning models are promising tools to predict the surface air maximum temperature anomalies over India in April and May and can complement predictions from more sophisticated numerical models.

Effects of temperature on the deflection of cable-stayed bridges during cantilever erection

To investigate the effects of temperature on the deflections of cable-stayed bridges under cantilever construction, the girder and tower of bridges are considered cantilever beams with continuous elastical supports, whose supported stiffness depends on the tensile stiffness of the cables. Then, a finite element model of the beams is built to formulate an approach for calculating the temperature-induced deflections. In this approach, the temperature actions are considered equivalent loads acting on the beam, and the responses of the bridges are analysed under several types of actions. The effectiveness of the approach was validated using temperature and deflection measurements from the Zengjiang Bridge. The results show that a combination of the daytime temperature actions produced downward deflections of the girder, which reached their maximum at approximately 15:00 during a day period, and the deflections are greatly affected by the vertical-temperature gradient along the girder section, as well as cable-temperature variation. With an increase in the cantilever length, the effect of the latter increases, but the effect of the former decreases. These temperature-induced deflections are restricted by the installation of new cables, and some of them may be unrecovered, which affects the alignment of the girder in the completion state.

Behavioral Pattern of Photovoltaics Enhanced with Automatic Cooling Mechanism

The increase in PV panel temperature with increasing level of solar power and solar flux is a major disadvantage when using Photovoltaics for electricity generation. Nigeria is a country that is blessed with enormous amount of sunlight throughout the year which should make it a good environment for the generation of electricity via photovoltaic technology. The daytime temperature of Nigeria is a major barrier towards the effective generation of electricity via photovoltaic technology. To remedy this issue of temperature, a cooling mechanism has to be considered in the process of any PV system design. An automatic cooling mechanism and an intelligent photovoltaic maximum power point tracker were deployed in the study. Experimental measurements were carried out in real outdoor conditions. The results of the study reveal an average increase of 6.42%, 7.77%, 18.34%, and 18.15% for voltage, current, power and efficiency respectively for the PV module under thermal regulation. This study demonstrates that cooling mechanism should be incorporated in the process of designing photovoltaic systems for optimum energy yield.

DETERMINATION OF WATER-SOLUBLE VITAMINS IN MILK THISTLE FRUITS GROWING NATURALLY IN THE REPUBLIC OF DAGESTAN

The work is devoted to the determination of water-soluble vitamins in the fruits of milk thistle, which grows naturally in some areas of the Republic of Dagestan, differing from each other by natural and climatic conditions: Suleiman Stalsky, Kaitagsky, Magaramkent, Levashinsky and Kulinsky districts. Phenotypic factors (altitude above sea level, soil composition, number of sunny days, precipitation volume, humidity, average daytime temperature, etc.) affected the vitamin composition of milk thistle fruits growing in natural conditions. High-performance liquid chromatography in gradient elution mode was used to determine water-soluble vitamins in milk thistle fruit samples. Nine water-soluble vitamins in milk thistle fruits (ascorbic acid, vitamins B and PP) have been identified and quantified. The variability of the content of water-soluble vitamins in the fruits of wild milk thistle, depending on the growing conditions, has been established. Statistical analysis of the data array on vitamin composition showed the presence of not only significant symbate and asymmetric correlations of the type Y=aX+b (pair correlation coefficient |R|≥0.55), but also close natural correlations (|R|≥0.80) between the content of certain vitamins and individual phenotypic factors.

Understanding the differences in the effect of urbanization on land surface temperature and air temperature in China: insights from heatwave and non-heatwave conditions

Accelerated urbanization and frequent heatwave events pose significant threats to human health. Analyses of the differences in air and land surface temperature (LST) under extreme climates can aid in understanding human-nature ecosystem coupling and the required adaptations to climate change. In this study, we quantified differences in urban and rural temperatures in China under heatwave (CHW) and non-heatwave periods (NHW) conditions and the influence of meteorological factors on these differences. Based on impervious surface data, 2421 urban and rural stations were dynamically classified from 2008 to 2017. Heatwaves were identified using relative thresholds, and differences were explored using meteorological data and MODIS LST data. For LST, urban–rural temperature difference (U-RTempdiff) was highest during the day, whereas air temperature peaks occurred at night, under both NHW and CHW conditions. During CHWs, the daytime U-RTempdiff was greater for LST than for air temperature, reaching 4.24 ± 3.38 °C. At night, U-RTempdiff was slightly lower (1.04 ± 1.41 °C). The proportion of air U-RTempdiff contributed by rural air temperature was significantly higher during CHW nights than during NHW nights, whereas the proportion of land surface and air U-RTempdiff remained relatively stable during daytime. Spatially, the daytime temperature difference in the north decreased with latitude, whereas the difference in the south was lower. Under CHWs, urbanization had a stronger effect on LST than on air temperature, with a slightly smaller difference (0.01 °C yr−1) during the day and a slightly larger difference (0.03 °C yr−1) at night. The contribution of urbanization to LST was higher than that to air temperature, particularly during the day (16.34%). The effects of wind speed and precipitation on the average air urban–rural temperature difference was greater than those of LST under CHW, accounting for 16.13%, with the effects of wind speed being more significant. These results show that a comprehensive perspective is needed to understand the risks associated with a temperature rise risk under extreme climate conditions and to formulate effective mitigation measures that will they improve human thermal comfort under climate change.

Microclimate and seed bank under Pithecellobium keyense (Fabaceae) in a coastal scrubland

AbstractMicroclimatic conditions affect seeds' survival, dormancy, and germination, which are determinants in vegetation succession and recovery. The semiarid coastal scrublands of Yucatan, Mexico are very important because of the environmental services they provide thus, studies are needed in disturbed sites in relation to seed viability and microclimate. In this study, we characterized the microclimate and seed bank under Pithecellobium keyense shrubs, during the rainy and dry seasons. We collected soil samples and measured microenvironmental variables under adult P. keyense at three different positions under the canopy of every studied individual (“open” or completely sunny, “half‐shaded,” placed at the border of the canopy, and “fully shaded” placed under the canopy, next to the stem of the shrub). Photosynthetic photon flux density (PPFD), minimum night‐time temperature, and maximum daytime temperature behaved differently among positions under the canopy both in rainy and dry seasons. During the rainy season, seed viability was no different among microenvironments, while in the dry, the highest was found in the fully shaded and the lowest in the open position. Microclimatic variables under the canopy of P. keyense had an effect on the probability of seed viability in Chuburná; and this effect was stronger in the dry season.Abstract in Spanish is available with online material.

Understanding Agriculturists' Perception and Adaptation to the Current Climate Patterns in Jaman South Municipality, Ghana

This paper examines agriculturists’ perception and adaptation to climate change in Jaman South Municipality of Ghana, utilizing a mixed research approach. The study engaged 150 farmers from five farming communities, alongside 10 local agricultural extension officers. Data were collected through questionnaires and structured interviews administered via face-to-face interactions. The data underwent analysis involving calculations of frequencies, percentages, means, standard deviations, and utilization of the probit regression model. Respondents identified significant changes in rainfall patterns, including shortened planting seasons, reduced rainfall amounts, extreme dry spells, heavy rainfall, erratic patterns, and shifts in onset and cessation. Temperature changes were also reported, with increased daytime and nighttime temperatures. These changes were perceived to have adversely affected crop production in the study area. To this effect, farmers have employed diverse adaptation strategies, such as crop diversification, cover cropping, mulching, crop rotation, composting and use of organic fertilizers, adjusting planting time, land rotation, and use of drought-tolerant crop varieties to tackle these climatic changes. Age, level of education, engagement with extension services, and farmers' experience in farming emerged as the most influential factors for predicting the selection of strategies to adapt to climate change. This study contributes insights to policymakers and practitioners striving to bolster adaptive capacity in the face of climate change.

An alternative nighttime radiative cooling paint using glass microspheres in water-based acrylic paint

An alternative method for producing radiative cooling paint using sustainable and cost-effective green materials, which can significantly reduce indoor temperatures. Prior research on radiative cooling systems revealed that multilayer metal oxide systems require expensive raw materials and high-end facilities, limiting large-scale production. Therefore, this study aimed to identify optimal conditions for producing radiative cooling paint using commercial spherical glass microspheres and titanium dioxide nanoparticles. The study investigated the effect of glass microsphere size, quantity, and coating thickness on emissivity and light reflectance. Results showed that glass microsphere size did not significantly affect emissivity. However, increasing coating thickness and glass microsphere quantity initially increased emissivity but stabilized at saturation points. The addition of glass microspheres decreased light reflectance, increasing temperatures during the daytime. The radiative cooling efficiency of the paint was tested, and the results showed that the glass microsphere content significantly affected the reduction in daytime temperatures. A mixture content of 45 and 75 wt% reduced the temperature by 2.96 and 3.09 °C, respectively, lower than the ambient temperature during the nighttime. The double layer of titanium dioxide/glass microspheres paint was more effective at cooling than the single layer of 45% glass microspheres, despite similar emissivity values. HIGHLIGHTS Commercial spherical glass microspheres and titanium dioxide nanoparticles are used as raw materials. Glass microsphere quantity and coating thickness are found to affect emissivity and light reflectance. A mixture of 45 and 75wt% glass microsphere content is shown to significantly reduce nighttime temperatures. Double layer paint is more effective at cooling than single layer paint despite similar emissivity values. GRAPHICAL ABSTRACT

Projection of Future Heatwaves in the Pearl River Delta through CMIP6-WRF Dynamical Downscaling

Abstract Recent worldwide heatwaves have shattered temperature records in many regions. In this study, we applied a dynamical downscaling method on the high-resolution version of the Max Planck Institute Earth System Model (MPI-ESM-1-2-HR) to obtain projections of the summer thermal environments and heatwaves in the Pearl River Delta (PRD) considering three shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, and SSP5-8.5) in the middle and late twenty-first century. Results indicated that relative to the temperatures in the 2010s, the mean increases in the summer (June–September) daytime and nighttime temperatures in the 2040s will be 0.7°–0.8°C and 0.9°–1.1°C, respectively. In the 2090s, the mean difference will be 0.5°–3.1°C and 0.7°–3.4°C, respectively. SSP1-2.6 is the only scenario in which the temperatures in the 2090s are expected to be lower than those in the 2040s. When compared with those in the 2010s, hot extremes are expected to be more frequent, intense, extensive, and longer-lasting in the future in the SSP2-4.5 and SSP5-8.5 scenarios. In the 2010s, a heatwave occurred in the PRD lasted for 6 days on average, with a mean daily maximum temperature of 34.4°C. In the 2040s, the heatwave duration and intensity are expected to increase by 2–3 days and 0.2°–0.4°C in all three scenarios. In the 2090s, these values will become 23 days and 36.0°C in SSP5-8.5. Moreover, a 10-yr extreme high temperature in the 2010s is expected to occur at a monthly frequency from June to September in the 2090s. Significance Statement Pearl River Delta (PRD) has been experiencing record-shattering heatwaves in recent years. This study aims to investigate the future trends of summer heatwaves in the PRD by modeling three future scenarios including a sustainable scenario, an intermediate scenario, and a worst-case scenario. Except for the sustainable scenario, summer temperatures in the intermediate and worst-case scenarios will keep increasing, and heatwaves will become more frequent, intense, extensive, and longer-lasting. In the worst-case scenario, extreme heat events that occurred once in 10 years in the 2010s will shorten to once a month in the 2090s. A better understanding of heatwave trends will benefit implementing climate mitigation methods, urban planning, and improving social infrastructure.

Species composition and aphid population seasonal dynamics in vegetable agrocenoses of St. Petersburg and Leningrad region

The purpose of this work was to study the species composition, the dynamics of aphid abundance in vegetable agrocenoses of the Pushkin district of St. Petersburg, as well as Tosnensky and Gatchina districts of the Leningrad region in the conditions of 2021-2022, significantly differing in weather conditions. The catching of insects was carried out using a Malaise trap. In total, during the two-year monitoring period, 40 species of aphids were registrated in the three studied agrocenoses, of which 28 are pests of agricultural crops. The total number of identified species in 2021 was 9 in each of the three research areas; the total number of captured insects was 99. At the end of May – beginning of June, the migration potential of aphids was high, active migration to secondary hosts was observed, however, abnormally high daytime temperatures in June – July with minimal precipitation had a detrimental effect on phytophages. In the weather conditions favorable for the development of aphids during the growing season of 2022, 11 species of aphids were caught in the Pushkinsky district of St. Petersburg, 12 in the Gatchina district, 20 in the Tosnensky district, that is, an increase in the species composition of phytophages was 2.2 times compared to 2021. In 2022, 279 individuals were registered; the largest number of insects was noted in the Tosnensky district – 171. In all the studied agrocenoses, the most numerous of the harmful species was the gray svidin-cereal aphid Anoecia corni F., damaging the roots of perennial grasses (the maximum number of 128 individuals in the Tosnensky district in 2022). A significant number in the same year was observed in the pea Acyrthosiphon pisum Harr., as well as in the cabbage aphid Brevicoryne brassicae L. Quite rare species of aphids for the North-Western region were recorded in the agrocenosis of the Pushkin district: Oxton and maple aphids. The pink tansy aphid was registered only in the Tosno agrocenosis in June 2022. The Malaise trap proved to be convenient to work with, since it is not stationary, can be installed anywhere in any agrocenosis. It can be recommended to use it, first of all, to assess the species diversity of insects, and secondly, to estimate the number.