Air Temperature Measurements Research Articles

Indoor air temperature and relative humidity measurements in Finnish schools and day-care centres

Indoor air temperature and relative humidity measurements of schools and day-care centres in two research projects on indoor air conditions in municipal buildings with mechanical ventilation in Finland were combined for a large sample of occupied spaces with typical conditions experienced by users of the buildings. In addition to user experience, the occupied spaces represented the spaces with determining air humidity load when assessing moisture performance of envelope structures. Indoor air temperature was stable excluding extreme external conditions that caused crossings of limit values. Permanence within limit values of the Finnish Classification of Indoor Environment was inadequate leaving all buildings in the lowest classification level S3. Mechanical ventilation in municipal buildings is designed to keep pollutants at moderate level during high occupancy which results in non-existent indoor air moisture excess, which during winter leads to low indoor air relative humidity. Although dry indoor air provides safety of envelope structures, the drawback is poor performance with regards to the recommended range. Dry indoor air has negative effects on the indoor air quality experienced by the users, causing skin and eye irritation.

Modified shape coefficient of building with Thermal considerations: concept, experiment and Application in solar-enriched areas

ABSTRACT The shape coefficient of building (SCB) characterizes the correlation between building shape and building energy consumption. Strictly restricting the SCB was harmful to reducing energy consumption, neglecting the potential benefits of solar radiation. A novel concept and determining method of modified shape coefficient of building (MSCB) were proposed based on the energy dissipating and solar heat gain. Field measurements of the indoor air temperature of model buildings for solar radiation, building orientations, and U-values under natural and heating conditions were conducted in western Sichuan. Results demonstrated that with identical SCB, the indoor thermal environment was substantially affected by the above parameters, proving the one-sidedness of SCB simultaneously. A simulation method verified via the experiments was employed to forecast the dynamic heating load of a real building. The influence of building orientations on the MSCB under actual climatic conditions from different time scales was discussed. Results illustrated that the SCB could be reduced by 34.6% in the present case. The monthly correction factor trend and the heat consumption were consistent. The restriction on SCB could be liberalized moderately even if the heating demand was tremendous. This research could provide a reference for the energy-saving design of passive buildings.

Spatial development indicators as a tool to determine thermal conditions in an urban environment

In the face of climate change and the growing frequency of thermally burdensome conditions, urban morphology and city planning are becoming increasingly important to human health. Architects and policymakers use various tools, including spatial development indicators describing the characteristics of built-up areas, to mitigate urban climate. This study purposed to (1) indicate which widely used spatial development indicators most adequately explained the thermal conditions of the environment, and (2) investigate how large an area most accurately represents the thermal features recorded at a given air temperature measurement site. Selected indexes were used to characterize each of the 21 measuring sites located in Warsaw. First, five spatial development indicators were calculated for three distances from each site. Then, based on data from the air temperature monitoring network, 17 selected thermal characteristics were calculated. The results of the analyses indicated that the Ratio of Biologically Vital Area has the highest impact on the thermal regime with particularly strong influence on the lowest daily temperature values. The paper proves that the thermal conditions of a given location in the diverse space of a city are more precisely represented by a large area than by its nearest surroundings.

Estimasi Sensor Temperatur Udara Automatic Weather Station Menggunakan Algoritma Hybrid Arima-MLP

Abstract
 Air temperature sensor is installed in an enclosure with a relative humidity sensor at a height of 1.25 meters from the ground. This sensor is routinely calibrated every year through a field comparison mechanism using standard portable. However, air temperature sensor has potential to experience troubles due to technical or non-technical factors. Estimation of temperature data can overcome loss data. This study aims to design an estimation model for air temperature sensor data using the ARIMA-MLP hybrid algorithm. Estimated air temperature sensor is focused on AWS Cisurupan in Garut Regency, West Java on 2019. The estimated data has an interval of 10 minutes. Outlier detection uses range check and step check methods. Missing data imputation method utilizes multiple linear regression-based interpolation. ARIMA-MLP hybrid algorithm is able to detect elements of linearity and nonlinearity of air temperature measurements. This algorithm meets WMO requirements regarding air temperature measurements, if training data is used with a minimum percentage of 85% of the entire modeling dataset. The resulting RMSE value is less than 0.20C.
 Keywords: air temperature, Automatic Weather Station, hybrid ARIMA-MLP

Experimental Investigation of Solar Air Heater with Energy Storage Unit

The present study investigates a single-pass solar air collector (SAC) linked to a thermal energy storage unit. This system is designed to store energy by using a cement mortar molds storage bed during daylight hours and subsequently reutilize it at night. A solar collector was used in this research, which was consecutively connected to the cement mortar molds bed. High-density cement mortar molds (570 kg) were used as a storage medium. The experiments were conducted on clear days for two random days at a constant airflow rate (0.0217 kg/s) for the climate of Mosul City, Iraq. The study assessed the parameters influencing the thermal performance of the SAC integrated with the cement mortar molds storage bed. Measurements of solar radiation intensity and air temperatures at various locations were recorded. The data indicated that the cement mortar molds storage bed achieved a temperature difference of approximately 10? post-sunset, with this difference sustained for 4-5 hours. The cement mortar molds bed demonstrated the capability to retain heat for an extended post-sunset, releasing it during nighttime.

To aspirate or not to aspirate – Impact of active versus passive ventilation on urban heat (island) indicators

The present paper reports on the impact of ventilation mode – active versus passive – of instrument screens for air temperature measurements on canopy urban heat (island) indicators. This is done using air temperature data gathered in the Antwerp (Belgium) area in July 2013, in an experimental set-up composed of an urban and a nearby rural climate station, each equipped with both actively and passively ventilated temperature sensors. The resulting data shows an air temperature bias between the passively and actively ventilated measurements of up to approximately 2 °C, the highest values occurring under conditions of a high solar radiation load and low wind speed. Yet, the canopy urban heat island (UHI) increment, i.e., the urban-rural air temperature difference, is hardly affected by the ventilation method, which is ascribed to the fact that high UHI increments occur mainly at night when, in absence of solar radiation, active ventilation has a lesser influence on measured temperature. Conversely, urban heat indicators involving daytime air temperature, such as heatwave degree days (HWDD) or Steadman's apparent temperature, tend to produce overly high values when use is made of passively ventilated temperature measurements.

Monitoring The Temperature And Humidity Air In The Room Using A Sensor IOT-Based DHT-11

Air is an important element in everyday life.Therefore the air must have quality so as not to have a negative impact on the body. Low air humidity can cause drying of the air membranes, and if the air humidity in a room is too high it can result in high growth of microorganisms. Abnormal humidity levels can become a respiratory problem and interfere with human health. The temperature and humidity monitoring device is designed based on the NodeMCU ESP8266 and the DHT-11 sensor to measure air temperature and humidity. This study aims to make it easier to know the temperature and humidity in real-time. A temperature and humidity monitoring tool based on NodeMCU ESP8266 is designed with a DHT-11 sensor to measure air temperature and humidity. temperature and humidity air monitoring results will then be sent via a wifi network connection and displayed on an Android smartphone.

Increase in aerodynamic impedance and energy uptake in response to grazing prohibition in semi-arid grasslands during the beginning of the growing season

In Inner Mongolia, China, semi-arid grasslands have strong winds and radiation in spring, but it is unclear how grazing management influences the connections between aerodynamic and energy balance during this time. During spring, we conducted measurements of radiation, wind speed, and air temperature, for both grazed and grazing-prohibited grasslands. From these results it was found that the temperature gradient differential (ΔT = T0.4m-T2m) between the ground level (T0.4m) and the high height (T2m) is normally negative at night and positive during the day. Grazed grassland was found to have very few negative ΔT values. Albedo and ΔT were higher on the grazed grasslands, while net radiation and aerodynamic roughness (Z0) were lower on the grazed grasslands. According to structural equation modeling (SEM), the grazing prohibited and grazed had no effect on the relationship between surface albedo, air temperature, and humidity. Z0 in grazed grassland exhibited a substantial positive correlation with net radiation (Rn), but was not correlated with albedo. The Z0 of the grazing-prohibited grassland exhibited a substantial negative correlation with albedo, but not with Rn, and Z0 had a significant negative correlation with air temperature. These findings explain how grazing measures affect the vertical variations of surface heat in air.

High spatial resolution long-term temperature profiling to inform near-shore atmospheric sound propagation

Atmospheric sound propagation depends on factors such as surface characteristics and meteorological parameters. Effective numerical modeling of atmospheric sound propagation requires reliable and realistic input parameters. One of the most influential factors is the air temperature profile. This work examines the application of experimentally determined air temperature profiles in acoustic modeling of littoral environments. Long term measurements of near-surface air temperature profiles over water and marsh grass are presented. Data have been recorded using temperature loggers affixed to two permanent 7 m masts. The loggers were positioned with a 1 m vertical spacing. A common approach to characterize the near-surface boundary layer uses Monin–Obukhov Similarity Theory (MOST). This work compares high spatial resolution air temperature measurements with measurement-informed profiles based on MOST. The development of a more experimentally grounded set of assumptions will ultimately contribute to the improvement of atmospheric acoustic transmission loss models in near shore environments.

Long‐term changes in the frequency of exceptionally cold and warm months and seasons at selected stations in Europe in the early instrumental period

AbstractExtreme thermal conditions have been known for a long time as is evidenced by the oldest preserved historical accounts referring to weather. However, direct data, that is, air temperature measurements, which began in Europe in the 17th century, are the only reliable source of information. They provide insight into how climate evolved over the characteristic period of the climate timeline known as the Little Ice Age. This study focuses on extreme climatic phenomena, referred to here as exceptionally cold (EC) and exceptionally warm (EW) months and seasons that occurred in the early instrumental period (until 1830). The research is based on average monthly air temperature values (of different lengths) from five meteorological stations in Europe. The Central England Temperature series (CET) offers the longest series that spans 172 years whereas Padua has the shortest, 57 years. Consequently, the year 1659, which is the start date of the Central England Temperature series, marks the beginning of the study period for the research presented in this article. Thermally anomalous periods are identified based on the standard deviation of the average temperature from the corresponding long‐term average (1831–2020). The highlights of the study include the identification of the pronounced prevalence at all five stations of EC months and seasons when compared to EW months and seasons, especially in Western Europe (CET) during the Maunder Minimum. The study also finds a lack of synchronicity in the timing of the anomalous periods under investigation in the different parts of Europe.

Assessing the Cooling Potential of Tailing Piles for Urban Heat Mitigation in Germany’s Ruhr Metropolitan Area—A Case Study of the Rungenberg in Gelsenkrichen

Elevated air temperatures in cities with potential negative effects on, e.g., residents are a major challenge for urban planning. Open green spaces on hills where at night air can cool and drain into residential areas are of great importance to ameliorate the heat load in urban areas. In the Ruhr Metropolitan Region in Germany, tailing piles from the former coal mining industry offer a previously neglected potential for cooling neighbourhoods. The genesis and drainage of cold air on tailing piles have not been extensively investigated so far. Tailing piles are often located in or nearby residential areas and are exposed as open spaces, where cold air can build up and drain into the surrounding neighbourhoods due to their slopes. In the present study, the genesis of cold air and the cold air drainage are empirically investigated using thermal infrared imagery and air temperature measurements during one night in 2019 at the Rungenberg tailing pile in Gelsenkirchen. Furthermore, the cooling effect on the adjacent residential area, Schüngelberg, was studied. The results indicate that cold air builds up at Rungenberg and drains into Schüngelberg. However, the cold air flow into the residential area was blocked by a brick wall located at the foot of the Rungenberg tailing pile. More awareness should be given to the cooling potential of tailing piles, and urban planners should improve this cooling potential by keeping tailing piles open and removing barriers located in the drainage pathways in order to alleviate urban heat.

Land surface and air temperature dynamics: The role of urban form and seasonality

Due to the scarcity of air temperature (Ta) observations, urban heat studies often rely on satellite-derived Land Surface Temperature (LST) to characterise the near-surface thermal environment. However, there remains a lack of a quantitative understanding on how LST differs from Ta within urban areas and what are the controlling factors of their interaction. We use crowdsourced air temperature measurements in Sydney, Australia, combined with urban landscape data, Local Climate Zones (LCZ), high-resolution satellite imagery, and machine learning to explore the influence of urban form and fabric on the interaction between Ta and LST. Results show that LST and Ta have distinct spatiotemporal characteristics, and their relationship differs by season, ecological infrastructure, and building morphology. We found greater seasonal variability in LST compared to Ta, along with more pronounced intra-urban spatial variability in LST, particularly in warmer seasons. We also observed a greater temperature difference between LST and Ta in the built environment compared to the natural LCZs, especially during warm days. Natural LCZs (areas with mostly dense and scattered trees) showed stronger LST-Ta relationships compared to built areas. In particular, we observe that built areas with higher building density (where the heat vulnerability is likely more pronounced) show insignificant or negative relationships between LST- Ta in summer. Our results also indicate that surface cover, distance from the ocean, and seasonality significantly influence the distribution of hot and cold spots for LST and Ta. The spatial distribution for Ta hot spots does not always overlap with LST. We find that relying solely on LST as a direct proxy for the urban thermal environment is inappropriate, particularly in densely built-up areas and during warm seasons. These findings provide new perspectives on the relationship between surface and canopy temperatures and how these relate to urban form and fabric.

The ecosystem services supplied by urban green infrastructure depend on their naturalness, functionality and imperviousness

Urban green infrastructure (UGI) can provide key ecosystem services (ES) for human well-being. For this purpose, it is critical to ascertain which characteristics regulate the provision of ES by UGI. In this study, eight ES (water supply, water regulation, waste regulation, nutrient regulation, soil formation, carbon sequestration, air temperature regulation and air humidity regulation) of thirty UGI sites of Zaragoza (Spain), were evaluated using proxy indicators derived from analyzed soil samples, and in-situ measured air temperature and humidity. A principal component analysis was performed to group different ES, and to study the dispersion of different types of UGI along the distinct ES. Additionally, relationships, between the evaluated ES and predictors; flatness, imperviousness, regularity, naturalness and functioning of the UGI sites were studied through linear and quadratic regressions. Large UGI sites such as riparian zones, meanders and natural forests showed relatively high values of ES in contrast with more artificial sites. Moreover, the study showed that water supply, water regulation, soil formation, carbon sequestration and air temperature regulation were significantly and positively related to ecological naturalness and functioning, while imperviousness was the main predictor explaining the reduction of five ES. Our findings provide evidence for the existence of important interactions between predictor variables and ES in UGI. It also showed that the provision of urban ES can be improved expanding the variety and type of green infrastructure sites, decreasing impervious area, and increasing the naturalness and functioning of UGI.

A graphical derivation and statistical evaluation of simplified polynomials to determine vapour pressure deficit for use in ultra-low power microcontroller applications

The aim of this work has been to derive and statistically evaluate the accuracy of second-order and third-order polynomials to determine vapour pressure deficit (VPD). These polynomials take air temperature and relative humidity measurements to determine VPD without the use of an exponential function, as proposed by F W Murray in 1967. Replacing the exponential function with a 2nd or 3rd order polynomial may be beneficial in ultra-low power microcontroller-based measurement applications where; code size, memory usage and power requirements are critical design drivers. However, oversimplification may impact precision. This work presents alternative 2nd order and 3rd order equations that have been derived from a Murray equation dataset where VPD isothermal datasets were plotted against relative humidity. These linear relationships allow y = mx + c analysis where, (i) ‘c’ can be set to zero with a offset in the relative humidity data, and, (ii) ‘m’ can be derived from a 2nd of 3rd order polynomial where ‘m’ = f(T) and is derived using Excel-based fitting of the gradients from the isothermal datasets. The resulting ‘m’ = f(T) 2nd and 3rd order polynomials presented R 2 values of 0.998 04 and 0.999 98 respectively. A Bland-Altman statistical assessment was performed, where the Murray equation (reference) dataset is plotted against the difference between the reference and polynomial datasets using the same air temperature and relative humidity inputs. The difference datasets presented 2-sigma (95% confidence interval) variances for the 2nd and 3rd order polynomials as <±0.1 kPa and <±0.01 kPa respectively. The 2nd and 3rd order polynomials also resulted in a bias values of <0.0037 kPa and <0.0013 kPa respectively. These results suggest that a 3rd order polynomial equation could be used to determine VPD in ultra-low-power microcontroller measurement applications, with minimal impact on VPD measurement precision.

Small Peltier element to detect real-time heat flux between apple and environment during postharvest storage

Climate control mechanisms in the postharvest chain of fruit and vegetables are predominantly based on air temperature measurements. These, however, do not reflect the real heat exchange between the product and the environment in all situations. The direct recording of the incoming and outgoing heat flux should enable higher-quality statements to be made about the interaction between the food product and the environment since other influencing parameters are also taken into account (e.g. air velocity and radiation). Commercial heat flux sensors are readily available but expensive, and for a variety of reasons, are not suitable for use directly on horticultural products, or are suitable only to a limited extent (e.g. large products, such as melons). In this study, small and low-cost Peltier elements (PE) were primarily tested and successfully validated as an alternative for their use in measuring heat exchange. Cooling, fluctuating temperature, and re-warming tests were applied to evaluate and validate the use of PE during the heat absorption and release of individual apples. The results confirmed the reliable detection of minor heat fluxes, regardless of direction, with small temperature differences (<0.5 °C) between the fruit and the air. The new heat flux measurement methodology has potential applications in agricultural technology, including optimizing packaging, and designing storage equipment.

Alternative Approaches for Real-time Monitoring of the Effectiveness of Hydrogenerator Heat Exchangers

Heat exchangers require periodic maintenance. Offline cleaning scheduled shutdowns are usually needed to restore the exchanger effectiveness, drastically reduced when fouling accumulation occurs. An online real-time alternative for monitoring the effectiveness of exchanger (during a period of eleven months of continuous operation) and an adapted version of the ε-NTU method to calculate its effectiveness are discussed. The experimental difficulties of measuring the mass flow rate and the hot air temperature at the exit of the exchanger is examined. Detailed analysis confirmed that the outlet temperature of the hot fluid could introduce errors of up to 30% in the calculation of the exchanger effectiveness. A skillful treatment of the energy balance is proposed to address the issue. The associated uncertainties are estimated by two independent approaches, the so-called classic method, i.e., the Guide to the Expression of Uncertainty in Measurement and the Monte Carlo method. Both confirmed that measurements of the air outlet temperature accounts for more than 50% of the uncertainty associated with the calculation of the exchanger effectiveness. It is suggested that the conventional method (based on measurements of the outlet air temperature) is not suitable for traditional everyday practices to monitor the effectiveness of the heat exchangers of hydrogenerators.

Smart Temperature Sensor Design and High-Density Water Temperature Monitoring in Estuarine and Coastal Areas.

Acquiring in situ water temperature data is an indispensable and important component for analyzing thermal dynamics in estuarine and coastal areas. However, the long-term and high-density monitoring of water temperature is costly and technically challenging. In this paper, we present the design, calibration, and application of the smart temperature sensor TS-V1, a low-power yet low-cost temperature sensor for monitoring the spatial-temporal variations of surface water temperatures and air temperatures in estuarine and coastal areas. The temperature output of the TS-V1 sensor was calibrated against the Fluke-1551A sensor developed in the United States and the CTD-Diver sensor developed in the Netherlands. The results show that the accuracy of the TS-V1 sensor is 0.08 °C, while sensitivity tests suggest that the TS-V1 sensor (comprising a titanium alloy shell with a thermal conductivity of 7.6 W/(m °C)) is approximately 0.31~0.54 s/°C slower than the CTD-Diver sensor (zirconia shell with thermal conductivity of 3 W/(m °C)) in measuring water temperatures but 6.92~10.12 s/°C faster than the CTD-Diver sensor in measuring air temperatures. In addition, the price of the proposed TS-V1 sensor is only approximately 1 and 0.3 times as much as the established commercial sensors, respectively. The TS-V1 sensor was used to collect surface water temperature and air temperature in the western part of the Pearl River Estuary from July 2022 to September 2022. These data wells captured water and air temperature changes, frequency distributions, and temperature characteristics. Our sensor is, thus, particularly useful for the study of thermal dynamics in estuarine and coastal areas.

How does pollen production of allergenic species differ between urban and rural environments?

Pollen production is one plant characteristic that is considered to be altered by changes in environmental conditions. In this study, we investigated pollen production of the three anemophilous species Betula pendula, Plantago lanceolata, and Dactylis glomerata along an urbanization gradient in Ingolstadt, Germany. We compared pollen production with the potential influencing factors urbanization, air temperature, and the air pollutants nitrogen dioxide (NO2) and ozone (O3). While we measured air temperature in the field, we computed concentration levels of NO2 and O3 from a land use regression model. The results showed that average pollen production (in million pollen grains) was 1.2 ± 1.0 per catkin of Betula pendula, 5.0 ± 2.4 per inflorescence of Plantago lanceolata, and 0.7 ± 0.5 per spikelet of Dactylis glomerata. Pollen production was higher in rural compared to urban locations on average for B. pendula (+ 73%) and P. lanceolata (+ 31%), while the opposite was the case for D. glomerata (- 14%). We found that there was substantial heterogeneity across the three species with respect to the association of pollen production and environmental influences. Pollen production decreased for all species with increasing temperature and urbanization, while for increasing pollutant concentrations, decreases were observed for B. pendula, P. lanceolata, and increases for D. glomerata. Additionally, pollen production was found to be highly variable across species and within species-even at small spatial distances. Experiments should be conducted to further explore plant responses to altering environmental conditions.

Impact of Climate Conditions on Pollutant Concentrations in the Effluent from a One-Stage Constructed Wetland: A Case Study

This paper reports the results of an investigation into the influence of precipitation and air temperature on the efficiency of pollutant removal processes and effluent pollutant concentrations in a one-stage constructed wetland with subsurface vertical flow. We studied an on-site constructed wetland system that used Phragmites australis for the treatment of domestic wastewater. The system was located in central Europe, in the south-east of Poland, in a temperate climate zone with transitional features. Physico-chemical analyses of influent and effluent wastewater, as well as measurements of precipitation and air temperature were carried out in the years 2001–2010. It was shown that the pollutant removal efficiency of the treatment plant was significantly higher in the growing season than outside the growing season (the mean efficiency is usually a few percent higher but generally this parameter is highly varied). This indicated that temperature determined the efficiency of the wastewater treatment. We found that the amount of precipitation affected the concentration of pollutants in the effluent. The more rainfall there was, the lower the content of pollutants in the effluent from the treatment plant, which demonstrated that rainwater diluted the concentrations of pollutants in the treated wastewater—thus improving the efficiency of the wastewater treatment plant.

Citizen and machine learning-aided high-resolution mapping of urban heat exposure and stress

Through conversion of land cover to more built-up, impervious surfaces, cities create hotter environments than their surroundings for urban residents, with large differences expected between different parts of the city. Existing measurements of ambient air temperature and heat stress, however, are often insufficient to capture the intra-urban variability in heat exposure. This study provides a replicable method for modeling air temperature, humidity, and moist heat stress over the urban area of Chapel Hill while engaging citizens to collect high-temporal and spatially-resolved air temperature and humidity measurements. We use low-cost, consumer-grade sensors combined with satellite remote sensing data and machine learning to map urban air temperature and relative humidity over various land-cover classes to understand intra-urban spatial variability of ambient heat exposure at a relatively high resolution (10 m). Our findings show that individuals may be exposed to higher levels of air temperature and moist heat stress than weather station data suggest, and that the ambient heat exposure varies according to land cover type, with tree-covered land the coolest and built-up areas the warmest, and time of day, with higher air temperatures observed during the early afternoon. Combining our resulting dataset with sociodemographic data, policymakers and urban planners in Chapel Hill can use data output from this method to identify areas exposed to high temperature and moist heat stress as a first step to design effective mitigation measures.