Maximum Temperature Variation Research Articles

Geometrical Parametric Study on Steel Beams Exposed to Solar Radiation

A finite element thermal analysis was conducted in this study with the aim of evaluating the influence of the geometrical parameters of steel sections on their thermal response under solar radiation. Four W12 and W24 standard steel beams were investigated under the solar irradiation conditions of a sunny summer day. The finite element analysis was carried out using COMSOL Multiphysics considering the Sun’s movement from sunrise to sunset, reflected radiation from the ground, surface convection of air and long wave radiation as the main boundary thermal loads. The temperature-time variation at different locations in the sections, vertical temperature distributions, temperature gradient distributions and thermal stress distributions were investigated. The results showed that the daily maximum temperatures, temperature variation, temperature and temperature gradient distributions and thermal stresses are influenced by the geometry of the steel section. The flange width and flange thickness were found to be the controlling parameters during the noon hours, while these parameters in addition to web depth control the shading effect during the afternoon. On the other hand, web thickness affects the temperature of webs at sunrise and sunset times. Geometrical ratios like Wf/H, Wf/tf2 and 2Wf/Htf were the most influential parameters on temperatures, temperature gradients and thermal stresses of steel beams subjected to solar radiation. The investigated section with the maximum Wf/tf2 value of 0.96 (W12 × 58) recorded the highest top-surface noon temperature, while section W24 × 84 with the lowest Wf/tf2 value of 0.60 exhibited the lowest temperature.

A new method to simulate dispersion plate-type fuel assembly in a multi-physics coupled way

The plate-type fuel has an excellent thermal–mechanical behavior as a type of nuclear fuel. To simulate and analyze the behavior of plate-type fuel assembly under irradiation conditions, a fuel performance analysis code BEEs-Plates was developed based on MOOSE (Multiphysics Object-oriented Simulation Environment). The properties, mechanical behavior, and irradiation effects of dispersion fuel meat were simulated by using the equivalent property models, and a one-dimensional Petrov-Galerkin stability model was used to solve the governing equations of coolant. The coupling between the three-dimensional solid domain and the one-dimensional fluid domain was also realized. The JRR-3 research reactor fuel assembly model was then used to perform the coupling simulation, and the assembly’s temperature, stress, strain distribution, and coolant temperature, the size of the channels, flow distribution were analyzed. The results under the boundary conditions and input parameters applied herein show that the burnup effect has limited effects on the thermohydraulic performance of the assembly, with the variation of maximum temperature below 1 K and the change of channel width below 3.9%. However, its mechanical behavior is greatly affected by burnup, with the maximum stress of 396.2 MPa at the meat-cladding interface. The uneven power distribution causes the assembly to bend to one side, but its effect on the coolant flow distribution is negligible.

Study of the effect of climate variation on irrigated and rainfed rice productivity based on aquacrop crop modelling simulation (Case Study of Java Island)

Aquacrop is free-licensed Food and Agricultural Organization’s crop modelling that requires minimum inputs of climate variables namely rainfall, maximum temperature, minimum temperature variables and geographic information of the area to be simulated (longitude, latitude, altitude). This study aims to measure the difference in irrigated and rainfed rice productivity from the Aquacrop crop modelling simulation to the influence of climate pattern variations in Java Island, Indonesia. The k-means clustering method applied to the rainfall, maximum, and minimum temperature variables from the bias-corrected MERRA2 data resulted in two climate regions. The principal component analysis result showed that the maximum and minimum temperature variables are the variables that most contribute to the determination of the clustering area using the k-means method compared to the rainfall variable. This study has calculated the probability of the irrigated and rainfed rice productivity resulting from the Aquacrop simulation in those climate regions during La Nina [El Nino] years that will be higher [smaller] than the mean value of rice productivity during neutral years. However, the validation between the actual irrigated and rainfed rice productivity with the Aquacrop simulation results from 2001-2014 showed low correlation values that vary between negative and positive values in all climate regions. Meanwhile, the validation on the El Nino composite years generally showed positive correlation values. In addition, the neutral and La Nina composite years resulted in varying correlation values between negative and positive correlation.

Tailoring of plasmonic functionalized metastructures to enhance local heating release

Abstract Plasmonic nanoheaters are reported that produce a significant local heating when excited by a 532 nm wavelength focused laser beam. A significant temperature increase derives from the strong confinement of electric field enabled by the specific arrangement of Au nanodisks constituting the nanoheater. The thermal response is much more sensitive when layering the gold nanoheaters by a thick layer of doped polymer, reaching a temperature variation of more than 250 °C. The modulation of the excitation by a chopper enables the fine control of the thermal response with a measured maximum temperature variation of about 60 °C in a single period. These intriguing features can be efficiently exploited for the design of novel systems finding application in nano medicine and nano chemistry.

Distributed Temperature Monitoring Inside Ytterbium DFB and Holmium Fiber Lasers

A distributed temperature monitoring inside a cavity of ytterbium DFB and holmium fiber lasers has been demonstrated with a spatial resolution of 1 and 5 mm, respectively, for the first time to the best of our knowledge. For this, we use an optical backscatter reflectometer, which measures intracore temperature, and compare it with the data of an IR thermographic camera, which measures temperature from the surface of a fiber. In the case of holmium fiber laser pumped at a wavelength of 1125 nm with a power of 6 W, the maximum temperature variation along the ∼3-m active fiber reaches ∼60 °C. In the case of ytterbium DFB laser, we observe a strong inhomogeneity of the temperature along the DFB cavity, which leads to a significant decrease in the lasing efficiency. When pumped by a single-mode laser diode at a wavelength of 976 nm with a power of up to 526 mW, the maximum temperature difference reaches 37 °C for the 37-mm DBF cavity.

Relationship between exercise-induced muscle soreness, pain thresholds, and skin temperature in men and women.

Infrared thermography (IRT) has gained popularity in sports medicine for determining whether changes in skin temperature relate to pain and muscle damage. Such a relationship would support IRT as a non-invasive method to monitor these physiological responses. However, the literature remains controversial. Here, we determine the relationship between exercise-induced muscle soreness (DOMS), pain, and skin temperature in men and women before and after exercise. Twenty-two physically active adults (10 men and 12 women) completed a squat exercise protocol to induce muscle damage. Skin temperature, DOMS, and pressure pain threshold (PPT) were assessed in the quadriceps pre, post-exercise, and 48h post-exercise. DOMS increased similarly in men and women post-exercise and 48h post-exercise. PPT was lower in women compared to men. PPT decreased 48h post-exercise for men but did not differ between the moments for women. Skin temperature responses were sex-dependent. Mean and maximum temperatures increased post-exercise for men, and maximum temperature reduced 48h post-exercise. In women, the minimum temperature increased 48h post-exercise. DOMS was not predicted by skin temperature but showed a direct association between pre and 48h post-exercise variation of maximum skin temperature and PPT. We conclude that there is a sex-dependent effect in analyzing skin temperature changes in response to exercise, something that seems to not have been addressed in previous studies. To date, inferences are generally assumed as similar for both men and women, which we show may not be the case.

“ENSO Influence on Western European summer and fall Temperatures”

AbstractIn certain regions, such as Europe, the increase in global air-temperatures in the world is translated into more frequent extreme events. Recent studies suggest that the increasing intensity in heatwaves seems to be related to the interannual variability of the mean temperature, a finding that motivates the search for its possible predictability. El Niño Southern Oscillation (ENSO) is the principal predictor of global climate variability at interannual timescales. Its impact on the European climate has been deeply studied in relation to rainfall variability, but only a few studies exist that focus on its impact on temperature. In this work, we focus on the analysis of the interannual variability of maximum and minimum temperature in order to find some predictability and trends. To that end, we choose the western European region, which has experienced intense heatwaves and is also the main region of air temperature interannual variability in Europe. Our results indicate that the ENSO impact on temperatures over this region is non-linear and non-stationary. We have found the way in which, during the decades prior to 1980s, the increase in temperatures is related to La Niña in summer and to El Niño in fall during the decades after the 1980s, which shows a change in the seasonality of the impact. We study the dynamical mechanisms involved, which suggest a circumglobal response for summer and an arching-like teleconnection pattern in fall. The aforementioned warmer conditions in western European temperatures are found to be significantly correlated to ENSO characteristics of previous seasons, which suggests a potential source for improving the seasonal forecast.

Simulating Diurnal Variations of Water Temperature and Dissolved Oxygen in Shallow Minnesota Lakes

In shallow lakes, water quality is mostly affected by weather conditions and some ecological processes which vary throughout the day. To understand and model diurnal-nocturnal variations, a deterministic, one-dimensional hourly lake water quality model MINLAKE2018 was modified from daily MINLAKE2012, and applied to five shallow lakes in Minnesota to simulate water temperature and dissolved oxygen (DO) over multiple years. A maximum diurnal water temperature variation of 11.40 °C and DO variation of 5.63 mg/L were simulated. The root-mean-square errors (RMSEs) of simulated hourly surface temperatures in five lakes range from 1.19 to 1.95 °C when compared with hourly data over 4–8 years. The RMSEs of temperature and DO simulations from MINLAKE2018 decreased by 17.3% and 18.2%, respectively, and Nash-Sutcliffe efficiency increased by 10.3% and 66.7%, respectively; indicating the hourly model performs better in comparison to daily MINLAKE2012. The hourly model uses variable hourly wind speeds to determine the turbulent diffusion coefficient in the epilimnion and produces more hours of temperature and DO stratification including stratification that lasted several hours on some of the days. The hourly model includes direct solar radiation heating to the bottom sediment that decreases magnitude of heat flux from or to the sediment.

Hydro Magnetic Effect on Thread Stretching Surface with Mounted Obstacles in Porous Medium

In this paper, Finite element Model is applied for investigation of fluid flow over a stretching sheet in existence of magnetic field. Finite element method is applied to find the influence of melting heat transfer on fluid flow behavior over a stretching sheet in presence of magnetic field. we investigated the flow of fluid flowing through the fins plate under the influence of the magnet. The fins were on the board and the end of the plate. In the case of chamfer fins, the maximum temperature variation is observed. In this fins, the maximum temperature of T = 2.5 and minimum temperature is T = 3. in general, we conclude that the temperature flow around the rectangular fins has a maximum value than 2 other modes. In triangular fins, the fluid temperature vector around the fins has more intensity than other modes and the temperature gradient around it is larger than the previous one and the fluid flow at the end of the plate also has more temperature than the Rectangular fins. The maximum amount of fluid concentration has been observed around the first fin of chamfer mode in range of X=0.05 to X=0.1. In general, the fluid concentration around the triangular fins is higher than other modes. the maximum amount of fluid concentration is found in the triangular fins on the surface. Their concentration from the first fin reaches a value of 2.5 and in the last fin at a value of 1.4.

An alternative approach to evaluate fuel/air mixing quality

ABSTRACTA practical method to evaluate quantitatively the uniformity of fuel/air mixing is essential for research and development of advanced low-emission combustion systems. Typically, this is characterised by measuring an unmixedness parameter or a uniformity index. An alternative approach, based on the fuel/air equivalence ratio distribution, is proposed and demonstrated in a simple methane/air venturi mixer. This approach has two main advantages: it is correlated with the fuel/air mixture combustion temperature, and the maximum temperature variation caused by fuel/air non-uniformity can be estimated. Because of these, it can be used as a criterion to check fuel/air mixing quality, or as a target for fuel/air mixer design with acceptable maximum temperature variation. For the situations where the fuel/air distribution non-uniqueness issue becomes important for fuel/air mixing check or mixer design, an additional statistical supplementary criterion should also be used.

Identifying key driving mechanisms of heat waves in central Chile

This study explores the main drivers of heat wave (HW) events in central Chile using state-of-the-art reanalysis data (ERA5) and observations during the extended austral summer season (November to March) for the period 1979–2018. Frequency and intensity aspects of the HW events are considered using the total number of the HW events per season and the amplitude. We first contrast ERA5 with several surface meteorological stations in central Chile to evaluate its ability to capture daily maximum temperature variability and the HW events. We then use synoptic- and large-scale fields and teleconnection patterns to address the most favorable conditions of the HW events from a climatological perspective as well as from the extreme January 2017 HW event that swept central Chile with temperature records and wildfires. ERA5 tends to capture temperature extremes and the HW events at the inland stations; on the contrary, it has difficulties in capturing the maximum temperature variability at the coastal stations, which is plausible given the complex terrain features and confined coastal climate zone (only $$\sim $$ 7% of all grid boxes within central Chile). The composite HW days based on ERA5 reveals a mid-level trough-ridge dipole pattern exhibiting a blocking anticyclone on the surface over a large part of southwest South America. Relatively dry and warm easterly flow appears to accompany the anomalous warming in a large part of central Chile. The temporal evolution of the HW events yields a wave-like propagation pattern and enhancement of trough-ridge pattern along the South Pacific. This meridional dipole pattern is found to be largely associated with the Pacific South American pattern. In addition, the Madden–Julian Oscillation (MJO) appears to be a key component of the HW events in central Chile. In particular, while active MJO phases 2 and 7 promote sub-seasonal patterns that favor the South Pacific dipole mode, synoptic anomalies can superimpose on them and favor the formation of a migrating anticyclone over central-southern Chile and coastal lows over central Chile. Agreeing with the climatological findings, the extreme January 2017 HW analysis suggests that an eastward migratory mid-latitude trough-ridge pattern associated with MJO phase 2 was at work. We highlight that in addition to large- and synoptic-scale features, sub-synoptic processes such as coastal lows can have an important role in shaping the HW events and can lead to amplification of temperature extremes during the HW events.

Investigation on the temperature uniformity and efficiency of cold start-up for proton exchange membrane fuel cell stack based on catalytic hydrogen/oxygen method

The catalytic hydrogen/oxygen reaction method is one of the primary ways to realize the rapid cold start of proton exchange membrane fuel cell (PEMFC). In this study, the start-up capacity of the catalytic hydrogen/oxygen reaction method is systematically investigated. A tremendous nonuniformity of temperature distribution is found under the condition of one-way mixture gas supply. A reverse feeding unit (RFU) is invented to realize a double-way gas supply to solve this problem. With the aid of RFU, the temperature uniformity during cold start is greatly improved. When the flow rate is 30 L min−1 and air fraction is 24%, the average and the lowest temperature take 55 s and 79 s respectively to rise from −32 °C to 0 °C, and the maximum temperature variance is 12.6. However, the lowest temperature of stack only arrives at −11.8 °C in 79 s when one-way mixture gas is supplied, and the temperature variance evidently increase to 21.4. After the preheating period, the output performance using RFU is 6.01% higher than the one-way gas supply method when the loading current is 250 mA cm−2. The temperature uniformity and power output is improved remarkably by the RFU.

Study on battery thermal management of autonomous underwater vehicle by bionic wave channels with liquid cooling

As lithium-ion batteries (LIBs) are used in autonomous underwater vehicles (AUVs) power systems, their thermal safety and reliability have seriously inhibited the development of AUVs toward high speed and long voyage. However, the related research on AUVs' battery thermal management is very limited. In this article, a novel and efficient liquid cooling scheme is proposed, for battery thermal management of AUV, which adopts bionic wave cooling channels. A three-dimensional heat dissipation model of the battery was developed, which considered the influence of battery internal resistance and state of charge on battery heat generation. The effects of discharge rate, channel shape, coolant mass flow rate, coolant inlet direction, and dynamic operation strategy on the battery maximum temperature and temperature variation were investigated during discharging process. It was found that the battery with bionic wave channels was superior to the battery with straight channels, regarding cooling efficiency. The maximum temperature and temperature difference of the former decreased by 12.8 and 5.3 K compared with the latter at 5C current discharging rate. Based on the bionic wave channels, increasing the mass flow rate of coolant was the most efficient route to reducing the maximum temperature and improving the uniformity of the battery temperature. A mass flow rate equal to 2.5 × 10−4 kg s−1 is reasonably recommended by considering the cooling efficiency comprehensively. The direction of the coolant inlet had little effect on the maximum temperature of the battery, but it significantly improved the uniformity of the battery temperature. Under the premise of meeting the cruising requirements of AUVs, alternating low-rate and high-rate discharge was more conducive to improving the temperature behavior of the battery. The conclusions of this article can provide reference for the battery thermal management system of AUVs.

The influence of target surface position on plasma characteristics in dual-pulse fiber-optic laser-induced breakdown spectroscopy

Laser-produced plasmas of dual-pulse fiber-optic laser-induced breakdown spectroscopy with different target positions relative to the waist region of laser focusing are studied using fast imaging and optical emission spectroscopy (OES). The laser energy of the two laser pulses is both maintained at around 18 mJ (i.e. the total energy is 36 mJ). The inter-pulse delay is kept at 250 ns. Ten spot sizes changing from 947 to 543 μm are obtained by precisely adjusting the distance between the focusing lens and the target surface. The profile of laser beam output from fiber shows a distinct top-hat shape. When approaching the dual-pulse waist region, the self-absorption and self-reversal of matrix iron lines gradually become intense while the plasma emission is enhanced, but the signal-to-noise ratio of minor elements gradually decreases. Under a similar spot size, the emission intensity with the target surface behind the waist region is weaker than that in front of the waist region and also with greater jitters. The target surface position is optimized to deviate from the waist region by ~ 1.3–1.6 mm towards the focusing lens for improving SNR of minor elements, corresponding to the lens-to-sample distances of 11.8–12.1 mm. Plasma morphology has undergone a transformation from stream- to umbrella-like structure using the recorded Intensified Charge-Coupled Device (ICCD) images. The expansion distance of the plasma front is increased from 1.07 to 1.28 mm, and the plasma volume is increased from 0.59 to 1.60 mm3. Besides, by utilization of OES, the maximum variation of plasma temperature and line broadening width rise to 2702 K from 1630 and to 0.0492 from 0.0316 nm along the vertical direction. The significant increase of optical thickness and nonuniformity of plasma temperature and density is the main reason for the intensification of self-absorption.

Temperature Impact on Telenomus podisi Emergence in Field Releases of Unprotected and Encapsulated Parasitoid Pupae.

This work aimed to evaluate the influence of temperature on the emergence of Telenomus podisi throughout the soybean development cycle, using encapsulated and unprotected pupae releases, in four different possible locations where pupae can be deposited during release. The trial was carried out in a randomized block design in a 2 × 4 factorial scheme: two parasitoid pupae release strategies (encapsulated and unprotected) × four pupae locations (between soybean lines of planting, bottom third, middle third, or upper third of plant canopy) with 5 replicates. There were no significant interactions between the studied factors. In the vegetative stage (V2 and V9), a smaller percentage of emergence of parasitoid adults was observed between soybean lines of planting (37.1% and 23.4% for V2 and V9 , respectively). The highest maximum temperatures were recorded between the soybean lines, with the greatest variations in maximum and minimum temperatures (55.2°C and 21.3°C) in V2 and (52.8°C and 23.9°C) inV9. In the reproductive stages (R1, R4, and R7), the observed temperatures were lower when compared to those observed in the vegetative stages (V2 and V9), with no difference in the emergence of parasitoid adults, which was above 70% in stage R1 and above 80% in R4 and R7. Regarding the pupae (encapsulated or unprotected), both allowed similar adult emergence. Therefore, it can be concluded that both unprotected and encapsulated pupae can be released, but those releases during the soybean vegetative development stage should be avoided due to the high temperatures to which pupae can be exposed.

WINTERC-G: mapping the upper mantle thermochemical heterogeneity from coupled geophysical–petrological inversion of seismic waveforms, heat flow, surface elevation and gravity satellite data

SUMMARYWe present a new global thermochemical model of the lithosphere and underlying upper mantle constrained by state of the art seismic waveform inversion, satellite gravity (geoid and gravity anomalies and gradiometric measurements from ESA's GOCE mission), surface elevation and heat flow data: WINTERC-G. The model is based upon an integrated geophysical–petrological approach where seismic velocities and density in the mantle are computed within a thermodynamically self-consistent framework, allowing for a direct parametrization in terms of the temperature and composition variables. The complementary sensitivities of the data sets allow us to constrain the geometry of the lithosphere–asthenosphere boundary, to separate thermal and compositional anomalies in the mantle, and to obtain a proxy for dynamic surface topography. At long spatial wavelengths, our model is generally consistent with previous seismic (or seismically derived) global models and earlier integrated studies incorporating surface wave data at lower lateral resolution. At finer scales, the temperature, composition and density distributions in WINTERC-G offer a new state of the art image at a high resolution globally (225 km average interknot spacing). Our model shows that the deepest lithosphere–asthenosphere boundary is associated with cratons and, also, some tectonically active areas (Andes, Persian Gulf). Among cratons we identify considerable differences in temperature and composition. The North American and Siberian Cratons are thick (>260 km) and compositionally refractory, whereas the Sino-Korean, Aldan and Tanzanian Cratons have a thinner, fertile lithosphere, similar to younger continental lithosphere elsewhere. WINTERC-G shows progressive thickening of oceanic lithosphere with age, but with significant regional differences: the lithospheric mantle beneath the Atlantic and Indian Oceans is, on average, colder, more fertile and denser than that beneath the Pacific Ocean. Our results suggest that the composition, temperature and density of the oceanic mantle lithosphere are related to the spreading rate for the rates up to 50–60 mm yr–1: the lower spreading rate, the higher the mantle fertility and density, and the lower the temperature. At greater spreading rates, the relationship disappears. The 1-D radial average of WINTERC-G displays a mantle geothermal gradient of 0.55–0.6 K km–1 and a potential temperature of 1300–1320 °C for depths >200 km. At the top of the mantle transition zone the amplitude of the maximum lateral temperature variations (cratons versus hotspots) is about 120 K. The isostatic residual topography values, a proxy for dynamic topography, are large (>1 km) mostly in active subduction settings. The residual isostatic bathymetry from WINTERC-G is remarkably similar to the pattern independently determined based on oceanic crustal data compilations. The amplitude of the continental residual topography is relatively large and positive (>600 m) in the East European Craton, Greenland, and the Andes and Himalayas. By contrast, central Asia, most of Antarctica, southern South America and, to a lesser extent, central Africa are characterized by negative residual topography values (>–400 m). Our results show that a substantial part of the topography signal previously identified as residual (or dynamic) is accounted for, isostatically, by lithospheric density variations.

Impact of Rainfall Variability on Rural Tea Roads in Kericho, Kenya

Climate variability is a global phenomenon that is posing a threat to the infrastructure and agricultural sector. Intense precipitation often results in the deterioration of rural road infrastructure resulting in inaccessibility. Rainfall and temperature data from 1989 to 2019 was obtained from Kenya Meteorological Department. Data on Greenleaf and cost of repairs and maintenances are from selected tea factories managed by Kenya Tea Development Agency. Data on perception is based on a questionnaire survey of 398 randomly selected tea farmers. Results show that climate variability is experienced in Kericho (p < 0.005). There is a varsity variation in mean maximum temperatures F(0.05, 29) ꞊ 5.564 (p ꞊ 0.009) and mean minimum temperature F(29) =8.503 (p ꞊ 0.000). However, the linear regression analysis shows that rainfall has decreased (y ꞊ 2.5476x - 40.778) while the temperature has increased (y ꞊ 0.028x - 0.4473). There is a significant positive correlation between the amount of rainfall and cost of repairs and maintenances for five factories (r ꞊ 0.122, r = 0.046, r = 0.029, r = 0.255) except one (r = -.261, p ꞊ .466). Therefore, the climate has significantly varied from 1989-2019 and heavy rains occur periodically that damage rural tea roads, thus impacting negatively on tea transportation. There is a need, therefore, for heavy investment of emergency funds for repair and maintenance of rural tea roads based on rainfall variability and heavy rain return period pattern.

Riparian forests can mitigate warming and ecological degradation of agricultural headwater streams

Abstract Riparian forests are commonly advocated as a key management option to mitigate the effects of agriculture on headwater stream biodiversity and ecosystem functions. However, the benefits of riparian forests might be reduced by uninterrupted catchment‐scale pollution. We studied the effects of riparian land use on multiple ecological endpoints in headwater streams in an agricultural landscape. We studied stream habitat characteristics, water temperature and algal accrual, and macrophyte, benthic macroinvertebrate and fish communities in 11 paired forested and open agricultural headwater stream reaches that differed in their extent of riparian forest cover but had similar water quality. Hydromorphological habitat quality was higher in forested reaches than in open reaches. Riparian forest had a strong effect on the summer water temperature regime, with maximum and mean water temperatures and temperature variation in forested reaches substantially lower than in open reaches. Macrophyte communities differed between forested and open reaches. The mean abundance of bryophytes was higher in forested reaches but the difference to open reaches was only marginally significant, whereas graminoids were significantly more abundant in open reaches. Within‐stream dissimilarity of benthic macroinvertebrate community structure was significantly related to the difference in riparian land use between reach pairs. The relative DNA sequence abundance of pollution‐sensitive Ephemeroptera, Plecoptera, and Trichoptera species tended to be higher in forested reaches than in open reaches. Finally, fish densities were not significantly different between forested and open reaches, although densities were higher in forested reaches. This unequivocal evidence for the ecological benefits of forested riparian reaches in agricultural headwater streams suggests that riparian forest can partly mitigate the adverse impacts of agricultural diffuse pollution on biota. The strong effect of forests on stream water temperature suggest that riparian forest could also mitigate harmful effects on headwater stream biodiversity and ecosystem functions of the predicted more frequent high summer temperatures.

Future changes in the frequency of temperature extremes may be underestimated in tropical and subtropical regions

In a warming world, temperature extremes are expected to show a distinguishable change over much of the globe even at 1.5 °C warming, and in many regions this change has already been detected in observations. Although many studies predict an increase in heat extreme events, the magnitude of the change varies greatly among different models even for the same mean warming. This uncertainty has been linked to differences in land–atmosphere feedback across models. Here we show that a significant constraint for future projections can be based on the ability of climate models to accurately simulate the present day variability of daily surface maximum temperature. An emergent constraint on Coupled Model Intercomparison Project Phase 5 (CMIP5) and 6 (CMIP6) models, applied to ERA5 reanalysis, indicates that the best estimate in hot extreme changes by the end of the century could be worse than previously estimated, mostly for tropical and subtropical regions as well as South and East Asia.

Thermal performance of wall solar chimney integrated with a room under warm and humid conditions

In this paper, an experimental analysis of room ventilation by integrating a wall solar chimney and it is carried out in the warm conditions of India. The performance of wall heat stacks is evaluated for different air channel widths; between absorber and glass plates is 5 cm, 10 cm, 15 cm and 20 cm. In addition to that, ventilation performance of the room with multiple openings is examined. The experimental results show that flow rate and air velocity at chimney outlet increases with increase of air channel breadth between absorber and glass in wall chimney. The highest air velocity of 0.6 m/s and a maximum temperature variation between outlet and inlet of the solar chimney of 5.8 °C was obtained with the air channel width of 15 cm. As far the ventilation performance is concerned; the indoor air temperature is lowered by 1–1.9 °C for the air channel width of 15 cm.