Air Temperature Rise Research Articles

Seasonal Variations in the Thermal Stratification Responses and Water Quality of the Paldang Lake

We evaluated the thermal and chemical stratifications of Paldang Lake using Schmidt’s stability index (SSI) and the chemical stratification index (IC-i) with weekly data from 2013 to 2022. The temporal trends of stratification were analyzed alongside correlations with meteorological, hydrological, and water quality variables. Thermal stratification intensified with rising air temperature and sunshine duration, while hydrological factors like discharge and retention time affected SSI during periods with less than five days of water retention. During summer, fewer occurrences of intense rainfall or early rainfall before August led to stronger stratification. In fall, nutrient influx from external sources during summer stimulated algal growth, increasing Chlorophyll-α (Chl-α) concentrations. Summer rainfall had a significant impact on the strength and duration of stratification in Paldang Lake. Annual rainfall patterns and subsequent changes in discharge were key factors affecting the physical environment of the lake, which in turn determined water quality and the extent of algal blooms. We provide insights into the seasonal stratification and water quality variations in temperate river-type reservoirs like Paldang Lake. SSI and IC-i from this research can be applied to understand stratification and mixing dynamics in other lakes.

Numerical analysis of the subway tunnel thermal environment to predict the train-mounted condenser inlet temperature in the cold climate zone of China

Reasonable control of the subway tunnel thermal environment is the main objective of the ventilation system design, which is critical to the effectiveness of the train-mounted condenser. In this study, a numerical model utilizing the dynamic mesh technique is developed to investigate the subway tunnel thermal environmental characteristics in the cold climate zone of China. Full-scale field measurements are implemented to verify the model’s accuracy. According to the simulation results, the single Piston wind shaft (PWS) (outlet end) is the optimal ventilation system in the cold climate zone of China. The effects of tunnel wall temperature, passenger flow, and regeneration braking system (RBS) efficiency on the subway tunnel thermal environment are thoroughly analyzed, which shows that the tunnel wall temperature has the greatest effect on the air temperature rise of the subway interval tunnel, the passenger flow has the greatest effect on the air temperature rise of the subway station tunnel. In contrast, the RBS efficiency has the least effect on the maximum condenser inlet temperature. On this basis, the predictive model for the maximum and average condenser inlet temperature is proposed. The findings of this study provide a theoretical basis for temperature control in subway tunnels in the cold climate zone of China and contribute to the safe and energy-efficient operation of subway environmental control systems.

Water Use Efficiency in Rice Under Alternative Wetting and Drying Technique Using Energy Balance Model with UAV Information and AquaCrop in Lambayeque, Peru

In the context of global warming, rising air temperatures are increasing evapotranspiration (ETc) in all agricultural crops, including rice, a staple food worldwide. Simultaneously, the occurrence of droughts is reducing water availability, affecting traditional irrigation methods for rice cultivation (flood irrigation). The objective of this study was to determine ETc (water use) and yield performance in rice crop under different irrigation regimes: treatments with continuous flood irrigation (CF) and irrigations with alternating wetting and drying (AWD5, AWD10, and AWD20) in an experimental area in INIA–Vista Florida. Water balance, rice physiological data, and yield were measured in the field, and local weather data and thermal and multispectral images were collected with a meteorological station and a UAV (a total of 13 flights). ETc values obtained by applying the METRICTM (Mapping Evapotranspiration at High Resolution using Internalized Calibration) energy balance model ranged from 2.4 to 8.9 mm d−1 for the AWD and CF irrigation regimes. In addition, ETc was estimated by a water balance using the AquaCrop model, previously parameterized with RGB image data and field weather data, soil, irrigation water, and crops, obtaining values between 4.3 and 7.1 mm d−1 for the AWD and CF irrigation regimes. The results indicated that AWD irrigation allows for water savings of 27 to 28%, although it entails a yield reduction of from 2 to 15%, which translates into an increase in water use efficiency (WUE) of from 18 to 36%, allowing for optimizing water use and improving irrigation management.

Experimental study on thermal performance of reverse flow solar collector for dual heating applications

AbstractThe present study investigated the performance of dual function reverse flow solar collector (RFSC). The impact of the mass flow rate of air and water on outlet temperature, thermal performance, and overall performance of dual‐function solar air heater (SAH) has also been investigated. An experimental investigation of three different working models namely, Model‐A: SAH, Model‐B: solar water heater (SWH), and Model‐C: integrated solar air‐water heater (SAWH) for dual heating applications was performed to analyze the actual performance of these models. The investigation of the impact of time intervals on the water inlet and outlet temperatures at various mass flow rates of water is conducted to analyze the time‐varying efficiency of SWH systems. Furthermore, the effect of solar intensity on the performance of the dual‐function heating system has also been explained. The result reveals that the maximum thermal efficiency of Models: A and B can be achieved at about 78.8% and 67.9%, at a mass flow rate of 0.0644 and 0.10 kg/s, respectively, according to the experimental findings. The maximum temperature rise of air and water reaches about 52.4 and 55.58°C for Models A and B, respectively. The total efficiency of Model C reaches 81.69%, exceeding that obtained in Models A and B individually. The efficiency, outlet temperature of the fluid, and heat transfer effectiveness of the system strongly depend on the mass flow rate. The increase in heat removal factor is negligible for a higher flow rate (more than 0.10 kg/s).

150-year daily data (1870–2021) in lakes and rivers reveals intensifying surface water warming and heatwaves in the Pannonian Ecoregion (Hungary)

Study regionPannonian Ecoregion, Hungary. Study focusBridging the gap between atmospheric influences and aquatic environments, this study embarked on a comprehensive reconstruction of daily surface water temperatures across lakes and rivers within the Pannonian Ecoregion over an extensive period of 150 years (1870–2021). New hydrological insights for the regionThe analysis revealed a clear warming trend in waters over the past 150 years, and majority of this warming occurred in recent three to four decades (average warming rate: 0.317 °C/decade). Seasonal patterns indicated that winter and spring exhibited faster warming rates, followed by autumn and summer. There has been a significant increase in the number, duration, and intensity of heatwaves in both lakes and rivers, particularly pronounced in the last 30–40 years, and with the rise of air temperatures, river and lake heatwaves tend to intensity. These findings underscore the escalating impact of climate change on freshwater systems in the Pannonian Ecoregion, emphasizing the urgent need for mitigation measures. As the first study on river and lake heatwaves in Hungary and one of the few studies on river heatwaves worldwide, this study will provide reference for analysing extreme thermal events in aquatic systems.

How have atmospheric components of the local water cycle changed around the abrupt climatic shift over France?

The significant increase in surface air temperature experienced by Western Europe over the last few decades has resulted in an abrupt warming in France, around 1987/1988 years. This climatic shift impacted hydrological cycle, particularly by reducing runoff in spring and summer. Evapotranspiration and precipitation have been identified as the main drivers of climatic water balance. But the impact of the 1987/1988 climatic shift on local water cycle over France has not been quantified yet. This study tries to assess the consequences of this rapid warming on the main climatic components of local water cycle. Climate variables linked to the water cycle extracted from a reanalysed observed climate database are analysed using robust Bayesian change points detection and mean comparison techniques. After the abrupt rise in surface air temperature and surface solar radiation, water demand increases significantly on almost the entire French territory in spring, summer and autumn. Our results show that, from March to May, the vegetation cover is able to respond to this increase by drawing from the soil water reservoirs. But in summer, most of the territory is facing a significant rise in water constraint (i.e. difference between potential and actual evapotranspiration), extending on the last decade over autumn. In spring and summer, the increase in potential evapotranspiration is the main driver of the intensification of water constraint. In the beginning of autumn, longer dry spell also plays a major role in the lengthening of periods of water constraint. This innovative study highlights the specific impact of a climatic shift on the main components of the atmospheric water balance at regional and local scale. As the observed changes in climate hazard linked to water cycle affect growth cycle of the majority of the vegetation covers and crops, this could lead to a worsening of hydric stress events. As such climatic shifts are expected to happen again in the future, their impacts on the local water cycle represent a major issue for natural terrestrial ecosystems as well as for agriculture.

Air temperature characteristics of cable-girder pin joint node of suspension bridge under pool fire

Under the action of high temperature, the mechanical properties of steel structure will be reduced. Cable-girder pin joint nodes (referred to as the node) of suspension bridges are composed of steel structures. Before studying the fire resistance of structures, it is necessary to accurately predict the air temperature characteristics under fire. In this paper, the FDS calculation model of the node is established for the pool fire. The air temperature characteristics of the node are clarified by numerical simulation and theoretical analysis. The effects of main factors such as fire location, wind speed, leakage hole radius and space height are studied. The unfavorable fire scenario and air heating mathematical model are obtained. The main conclusions are as follows: (1) As the fire source distance increases, the peak value of air temperature at the node gradually decreases, while the heating time steadily increases and eventually reaches a stable state. (2) The air temperature at the node initially increases and then gradually decreases as the wind speed increases. (3) Increasing the leakage hole radius from 0.02 m to 0.06 m results in a decrease of approximately 60 % in the air heating time at the node. (4) Increasing the space height from 0.25 m to 1.7 m leads to a maximum decrease of 72 % in air temperature at the node. (6) In the unfavorable fire scenario, the peak air temperature at the node can reach approximately 1200 °C, and the heating time ranges from 67 s to 149 s (7) A mathematical model of the air temperature rise curve, considering the influence of space height, is developed. This model can serve as a theoretical foundation and reference for the study of fire resistance of the node exposed to pool fires.

Spatiotemporal Changes of Glaciers in the Yigong Zangbo River Basin over the Period of the 1970s to 2023 and Their Driving Factors

The glaciers in southeastern Tibet Plateau (SETP) influenced by oceanic climate are sensitive to global warming, and there remains a notable deficiency in accurate multitemporal change analyses of these glaciers. We conduct glacier inventories in the Yigong Zangbo River Basin (YZRB) in SETP for the years 1988, 2015, and 2023 utilizing Landsat and Sentinel-2 imagery, and analyze the glacier spatiotemporal variation incorporating the existing glacier inventory data. Since the 1970s until 2023, the glaciers significantly retreated at a rate of 0.76 ± 0.11%·a−1, with the area decreasing from 2583.09 ± 88.80 km2 to 1635.89 ± 71.74 km2, and the ice volume reducing from 221.7017 ± 7.9618 km3 to 152.7429 ± 6.1747 km3. The most significant retreat occurred in glaciers smaller than 1 km2. Additionally, glaciers on southern aspects retreated slower than the northern counterparts. The glaciers in the western YZRB witnessed a significantly greater shrinkage rate than those in the eastern section, with the most pronounced changes occurring in Aso Longbu River Basin. Furthermore, severe glacier mass deficits were observed from 2000 to 2019, averaging a loss rate of 0.57 ± 0.06 m w.e. a−1. The continuous rise in air temperature has primarily induced a general widespread glacier change in the YZRB. However, diverse topography led to spatial variability in glacier changes with discrepancies as large as several times. The features of individual glaciers, such as glacier size, debris cover, and the development of ice-contact glacial lakes enhanced the local complexity of glacier change and elusive response behaviors to climate warming led by the different topographic conditions.

Rock glaciers across the United States predominantly accelerate coincident with rise in air temperatures

Despite their extensive global presence and the importance of variations in their speed as an essential climate variable, only about a dozen global time series document long-term changes in the velocity of rock glaciers – large tongue-shaped flows of frozen mountain debris. By analysing historical aerial photographs, we reconstruct here 16 new time series, a type of data that has not previously existed for the North American continent. We observe substantial accelerations, as much as 2–3 fold, in the surface displacement rates of rock glaciers across the mountains of the western contiguous United States over the past six to seven decades, most consistent with strongly increasing air temperatures in that region. Variations between individual time series suggest that different local and internal conditions of the frozen debris bodies modulate this overall climate response. Our observations indicate fundamental long-term environmental changes associated with frozen ground in the study region.

Effect of bedroom environment on sleep and physiological parameters for individuals with good sleep quality: A pilot study

Bedroom conditions affect sleep, overall health, and well-being. Field studies reporting measurements of bedroom environment and sleep parameters are almost lacking in the scientific community since the majority of research has been conducted in laboratories. To fill this knowledge gap, we have investigated the associations among bedroom environmental factors (temperature, humidity, CO2, pressure), measured sleep and physiological parameters (heart rate, heart rate variability, and breathing rate) in participants with good sleep quality. Six subjects were enrolled in the study, possessing a minimum of two years of experience in using the wrist actigraph chosen for the experimentation, and exhibiting good sleep quality. The air quality measurements were conducted using the air quality monitor, whereas advanced actigraphs were employed for the assessment of various sleep stage durations. The statistical analysis, carried out applying Linear Mixed Models, revealed that an increase of 100 ppm of CO2 concentration levels is associated with an approximate 0.29 % decline in sleep quality whereas, concerning the effect of the relative humidity, we observed a 0.1 % reduction in sleep quality associated with a 1 % rise in RH. On the other hand, a 1 °C rise in air temperature is associated with an approximate 0.16 % reduction in sleep efficiency, and, at a CO2 concentration of about 900 ppm, the autonomic nervous system (ANS) indicator remains positive for temperature values < 20 °C. These results contribute to mounting evidence underscoring the crucial role of the bedroom atmosphere in facilitating high-quality sleep.

Harnessing Machine Learning Algorithms to Model the Association between Land Use/Land Cover Change and Heatwave Dynamics for Enhanced Environmental Management

As we navigate the fast-paced era of urban expansion, the integration of machine learning (ML) and remote sensing (RS) has become a cornerstone in environmental management. This research, focusing on Silchar City, a non-attainment city under the National Clean Air Program (NCAP), leverages these advanced technologies to understand the urban microclimate and its implications on the health, resilience, and sustainability of the built environment. The rise in land surface temperature (LST) and changes in land use and land cover (LULC) have been identified as key contributors to thermal dynamics, particularly focusing on the development of urban heat islands (UHIs). The Urban Thermal Field Variance Index (UTFVI) can assess the influence of UHIs, which is considered a parameter for ecological quality assessment. This research examines the interlinkages among urban expansion, LST, and thermal dynamics in Silchar City due to a substantial rise in air temperature, poor air quality, and particulate matter PM2.5. Using Landsat satellite imagery, LULC maps were derived for 2000, 2010, and 2020 by applying a supervised classification approach. LST was calculated by converting thermal band spectral radiance into brightness temperature. We utilized Cellular Automata (CA) and Artificial Neural Networks (ANNs) to project potential scenarios up to the year 2040. Over the two-decade period from 2000 to 2020, we observed a 21% expansion in built-up areas, primarily at the expense of vegetation and agricultural lands. This land transformation contributed to increased LST, with over 10% of the area exceeding 25 °C in 2020 compared with just 1% in 2000. The CA model predicts built-up areas will grow by an additional 26% by 2040, causing LST to rise by 4 °C. The UTFVI analysis reveals declining thermal comfort, with the worst affected zone projected to expand by 7 km2. The increase in PM2.5 and aerosol optical depth over the past two decades further indicates deteriorating air quality. This study underscores the potential of ML and RS in environmental management, providing valuable insights into urban expansion, thermal dynamics, and air quality that can guide policy formulation for sustainable urban planning.

An Increase in Stream Water DOC Concentrations May Not Necessarily Imply an Increase in DOC Fluxes in Areas Affected by Acid Deposition and Climate Change—An Example from Central European Catchments

Over a period of 30 years (1993–2022), headwater catchments in the Slavkov Forest (Czech Republic) exhibited a robust increase in stream water DOC (dissolved organic carbon) concentrations following a significant reduction in acidic atmospheric deposition. Sulfur deposition decreased from 34 kg ha−1 yr−1 in 1993 to 2.6 kg ha−1 yr−1 in 2022. Three Norway-spruce-dominated research sites—Černý Potok (CEP), a 15.2 ha peatbog catchment, Lysina (LYS), a 27.3 ha granitic catchment, and Pluhův Bor (PLB), a 21.6 ha serpentinite catchment, were investigated. The three–year average DOC concentration increased from 48.2 mg L−1 (1993–1995) to 68.3 mg L−1 (2020–2022) at CEP (0.69 mg L−1 yr−1). LYS showed an increase from 16.9 mg L−1 to 25.4 mg L−1 (0.30 mg L−1 yr−1 annually). The largest increase was recorded at PLB, with an increase from 15.7 mg L−1 to 36.7 mg L−1 (0.89 mg L−1 yr−1). A decline in ionic strength was identified as the main driver of the DOC increase. The annual runoff declined significantly at CEP and LYS from 465 mm to 331 mm as a result of rising air temperatures and reduced precipitation between 2014 and 2022. PLB (average of 266 mm) did not show a statistically significant decline. Recently, PLB experienced significant deforestation that likely lowered transpiration and thus increased catchment runoff. As a result, DOC fluxes did not change significantly at CEP (average 210 kg ha−1 yr−1) and LYS (90 kg ha −1 yr−1). However, PLB’s DOC flux more than doubled, increasing from 44 to 106 kg ha−1 yr−1. Drivers connected with global change, such as increasing temperatures, or potential chemical drivers, such as reductions in Al concentrations and pH changes, were not able to explain the observed changes in DOC concentra tions and fluxes.

Trend analysis of air temperature in a megacity between two continents: the synoptic weather station in İstanbul Atatürk Airport

İstanbul is the largest city located in the Mediterranean Basin and has a medium to high risk of climate change and future climate risks. Changes in temperature and other weather variables have had significant impacts on İstanbul. In this context, there is a need for studies on the issues of climate monitoring and climate change vulnerability to reduce the adverse impacts. The aim of this study is to investigate the temperature trends of synoptic weather station in İstanbul Atatürk Airport between 1973 and 2023 to have a general idea about how the temperature has changed over the last half-century and to establish statistically whether a trend is significant or not. The values of minimum (Tmin), maximum (Tmax) and mean (Tmean) temperature related parameters were estimated. Annual, monthly and seasonal temperature trends are also analyzed. The findings of this study indicate a significant (p < 0.001) rise in the mean air temperature (Tmean) of İstanbul over the past 51 years (1973–2023), with an annual warming trend of 0.06 °C. The strongest increasing trend in seasonal mean air temperatures has been observed in the summer season, with an increase of 0.08 °C per year. The trend analysis also shows a statistically non-significant increase in yearly average minimum temperature (Tmin) between 1973 and 2023, with a rate of 0.04 °C per year. However, the annual maximum temperature (Tmax) has shown no changes.

Assessing the Volatility of Daily Maximum Temperature across Germany between 1990 and 2022

Climate change causes a global rise in mean air temperature and an increased frequency of temperature extremes. Recent studies link sharp temperature changes between consecutive days to increased mortality, reduced economic growth, and negative effects on ecosystems. This study assesses the variability of the daily maximum air temperature between two consecutive days (i.e., temperature volatility) across Germany from 1990 to 2022. Using observation-based raster data of maximum daily temperature at 0.1° × 0.1° spatial resolution, we assess temperature volatility regarding: (1) magnitude, (2) seasonality, (3) directionality (day-to-day warming vs. cooling), and (4) trends. Further, we analyse land cover changes during the period and examine their correlation to extreme temperature volatility (Tve). The results show that Tve mostly occurred during spring and summer. The magnitude of Tve increased with distance to the coast north-west to south during all seasons and was highest during spring and summer (&gt;10 °C). Overall, Tve was particularly associated with day-to-day cooling (in spring, summer, autumn), while in winter, &gt;60% of days were associated with warming in north and central Germany. Less than 12% of Germany showed significant trends in median Tve associated with warming over the period. Significant trends included increases (&gt;0.26 °C/year) and decreases (−0.09 °C/year) in extreme day-to-day warming during autumn and winter in northeastern Germany. In spring, the majority (&gt;60%) of southern areas showed significant positive trends (up to 0.16 °C/year) in Tve associated with day-to-day cooling. During winter, summer, and autumn, trends in extreme day-to-day cooling were insignificant in over 80% of Germany. Within all land cover types, Tve predominantly varied between 6 °C and 9 °C. Changes in land cover, especially transforming coniferous forests for agricultural purposes, were accompanied by increasing Tve up to 0.49 °C. Understanding rapid temperature changes is crucial for climate change mitigation strategies and limiting the impacts on human health and on the environment.

On a relation between shrinking of sea ice coverage and climate warming in the marine Arctic

Arctic amplification (AA) of the climate warming is understood as the excess of the surface air temperature rise in the Arctic over the same process in the non-Arctic latitudes, and it is a fundamental characteristic of the climate during periods of warming. The positive feedback between albedo and shrinking of the sea ice coverage has been identified as the first possible cause of AA. The article presents quantitative estimates of the relationship between the summer decrease and autumn-winter restoration of the ice coverage with the rise of the surface air temperature in the marine Arctic based on data of observations. The mean monthly values of the temperature in the marine Arctic and the mean monthly values of areas covered by the sea ice in the Arctic Ocean and the Arctic seas for the period 1989–2020 were used. It has been found that the observed warming and the decrease of the ice coverage are accompanied by a growth of inter-monthly changes in the coverage and the same in the air temperature. Negative trends in increments of the ice coverage in May–July is indicative of a long-term growth in inter-monthly shrinkage of the ice coverage due to increasing melting, while negative trends in increments of the temperature in the same months is suggestive of a slowdown in the temperature rise from month to month, presumably due to the increasing heat consumption for the snow and ice melting and the water heating. The positive correlation confirms the relation between growing negative inter-monthly differences in the ice coverage and decreasing positive differences in the air temperature during these months. Based on that we determined a sensitivity of the inter-monthly increments of the temperature to the increments of the ice coverage, which was used to estimate the weakening of the positive air temperature trend in May–July over the Arctic Ocean and over the seas of the Northern Sea Route (NSR). Estimating of the relationship between month-to-month changes in temperature and ice coverage in the autumn-winter months meet difficulties due to the strong influence of external heat influx. Only in November and January a slowdown in the air temperature drop from October to November and from December to January had been revealed, with a positive trend in the ice coverage increments.

SENSITIVITY OF THE KOLYMA RIVER RUNOFF TO MODERN CLIMATE CHANGE

The Kolyma River is a large river in the continuous permafrost zone. Its basin is subject to significant climatic changes. An information-modeling complex ECOMAG is employed for the study of water regime features and dynamics. ECOMAG calculates daily water flow rates at specified points based on meteorological data with a one-day resolution.This study analyzes the actual dynamics of water runoff and runoff-forming factors during the period from 1979 to 2013. A physical-mathematical model is adapted for the Kolyma River basin. Furthermore, the study examines the sensitivity of water regime characteristics to changing climate parameters. Calibration and verification demonstrated the ECOMAG’s ability to accurately reproduce observed water discharges for two points on the Kolyma River and the satisfactory performance on its tributary, the Bolshoy Anyui River. The ECOMAG model was for the first time employed for the Kolyma River basin, thus allowing the investigation of climate-related runoff changes. The preliminary statistical analysis revealed that if the average hydrological characteristics in the Kolyma River basin from 2000 to 2013 are compared with those from 1979 to 1999 a 5,1% rise of annual river runoff is evident for the Kolymskoye river section 283 km upstream the Kolyma River mouth (from 99,4 km3 in 1979-1999 up to 104,5 km3 in 2000-2013). The ECOMAG model also effectively captures changes in the annual water runoff and its intra-annual distribution.A rise in the mean annual air temperature by 1,3°C is characteristic of the modern time period. According to weather station data, the air temperature in March, April, November, and December increased by more than 2,5°C. The total annual precipitation increased by 8,3%, with September and March experiencing the most pronounced growth.To gain a more comprehensive understanding of the mechanisms governing the Kolyma River’s response to climate changes, the sensitivity of water runoff characteristics to air temperature and precipitation changes was analyzed using the ECOMAG model to generate artificial meteorological data series. The study demonstrates that water discharge is more sensitive to a 5% increase in precipitation than to a 1ºС rise in air temperature.

Effect of climate change of the quality of Citrus fruit produced in South Africa

Climate change is an observed reality with a significant impact globally. South Africa is not immune to this phenomenon. Like the rest of the world, South Africa experiences rise in mean air temperature and changes in rainfall trends. Since plant systems are influenced by weather, it is expected that climate change will have an effect on the production and quality of fruit. The objective of this study was to determine the impact of climate change on the quality of citrus fruit produced in South Africa. In conducting the study, historical fruit quality data was collected from packhouses in the Eastern and Western Cape provinces of South Africa over a period of 12 and 8 years respectively. Trend analysis was done on the data to determine whether there is a trend that can be observed over the period of data collection. The total soluble solids of fruit showed a marginal increase over the period of observation. Titratable acidity showed a marginal decrease. The incidence of sunburn on fruit seemed to increase over time. Other disorders like decay, creasing and oleocellosis did not show a definite trend of increasing or decreasing over time. Rind disorders seemed to decrease during the period of observation. This report discusses how the observed trends were influenced by changes in rainfall and temperature over the period of observation. It is then concluded that in this case study, the impact of climate change was not very profound and it had both negative and positive effects. The current results point toward a bleak future for citrus producers. To remain profitable, it may be necessary for producers to invest in climate change adaptation technologies. Key words: Climate change, citrus fruit, fruit quality, oleocellosis, titratable acidity

Assessment of universal thermal climate index (UTCI) using the WRF-UCM model over a metropolitan city in India.

Rapid urbanization increases urban air temperature, considerably affecting health, comfort, and the quality of life in urban spaces. The accurate assessment of outdoor thermal comfort is crucial for urban health. In the present study, a high-resolution mesoscale model coupled with a layer Urban Canopy Model (WRF-UCM) is implemented over the city of Hyderabad (17.3850° N, 78.4867° E) to simulate urban meteorological conditions during the summer and winter period of 2009 and 2019. The universal thermal climate index (UTCI) has been estimated using the model-derived atmospheric variables and a human biometeorology parameter to assess the linkages between the outdoor environment and thermal comfort. Results revealed that during summer, the city experiences nearly 50h of very strong thermal stress, whereas about 120h of slight cold stress are experienced during winter. The urban area in Hyderabad expanded from 5 to 15% during the study period, leading to a 2.5℃ (2.8 ℃) increase in land surface temperature, and a 1.2 (1.9 ℃) rise in air temperature at 2m height and 1.5 (2.5 ℃) UTCI during summer (winter) time. The analysis reveals that the maximum UTCI values were noticed over built-up areas compared to other land classes during daytime and nighttime. The results derived from the present study have shown that the performance of WRF-UCM-derived UTCI reasonably portrayed the significant impact of urbanization on thermal comfort over the city and provided useful insights with regard to urban comfort and welfare.

Assessment of the Potential for Increasing the Energy Efficiency in the Cooling Sector

Cooling supply to ensure the indoor microclimate is becoming more important as global average air temperatures rise. With growing societal demands for higher thermal comfort and increasing individual cooling solutions in the building sector, global energy consumption for cooling is increasing accordingly. Scientific literature and studies estimate that the demand for cooling energy will have a significant impact on global energy demand in the future. In compliance with the European Union goal of achieving climate neutrality by 2050, it is essential to find solutions for reducing energy consumption in the building sector, which is already among the largest energy consumers and greenhouse gas emission producers. Replacing individual cooling solutions with district cooling in urban areas where higher energy density can be reached is one of the solutions for decarbonizing the building sector. To spatially assess the feasibility of district cooling in certain areas, energy demand mapping can be performed. Within this research mapping is carried out using a geographical information system (GIS) tool. The purpose of the mapping is to identify the places in the city of Riga with the highest district cooling potential. Spatial assessment using a GIS tool can be done in different ways – mostly it depends on the available data. The spatial data (buildings) of the cadastral information system and additional detailed information about buildings were obtained from the Latvian open data portal. Information on the type of use of the building, indoor area and the age of building was attached to each building on the map. Then building energy certificate data containing information on specific energy consumption for cooling (kWh/m2 per year) was obtained from the same portal. By processing the data of energy certificates of buildings, excluding outliers, a specific index was obtained for different types of buildings. For the residential sector, the age of the building is also used. Using cadastral data on the indoor area of buildings and the type of building use, the theoretical cooling demand in Riga is calculated and results are quantified and displayed visually. By visualizing the results with the GIS tool, hot spots with the highest cooling energy demand were detected. Results can be further used to calculate the technical and economic justification for the district cooling solutions in specific areas as well as assess the energy efficiency that would be provided by implementation of district cooling solutions.

Interacting impacts of hydrological changes and air temperature warming on lake temperatures highlight the potential for adaptive management.

Globally, climate warming is increasing air temperatures and changing river flows, but few studies have explicitly considered the consequences for lake temperatures of these dual effects, or the potential to manage lake inflows to mitigate climate warming impacts. Using a one-dimensional model, we tested the sensitivity of lake temperatures to the separate and interacting effects of changes in air temperature and inflow on a small, short-residence time (annual average ≈ 20days), temperate lake. Reducing inflow by 70% increased summer lake surface temperatures 1.0-1.2°C and water column stability by 11-19%, equivalent to the effect of 1.2°C air temperature warming. Conversely, similar increases in inflow could result in lake summer cooling, sufficient to mitigate 0.75°C air temperature rise, increasing to more than 1.1°C if inflow temperature does not rise. We discuss how altering lake inflow volume and temperature could be added to the suite of adaptation measures for lakes.