Explore the vast range of titles available.

• The drier climates predicted for many regions will result in reduced evaporative cooling, leading to leaf heat stress and enhanced mortality. The extent to which nonevaporative cooling can contribute to plant resilience under these increasingly stressful conditions is not well known at present. • Using a novel, high accuracy infrared system for the continuous measurement of leaf temperature in mature trees under field conditions, we assessed leaf-to-air temperature differences (ΔT leaf–air) of pine needles during drought. • On mid-summer days, ΔT leaf–air remained < 3°C, both in trees exposed to summer drought and in those provided with supplemental irrigation, which had a more than 10-fold higher transpiration rate. The nonevaporative cooling in the drought-exposed trees must be facilitated by low resistance to heat transfer, generating a large sensible heat flux, H. ΔT leaf–air was weakly related to variations in the radiation load and mean wind speed in the lower part of the canopy, but was dependent on canopy structure and within-canopy turbulence that enhanced the H. • Nonevaporative cooling is demonstrated as an effective cooling mechanism in needle-leaf trees which can be a critical factor in forest resistance to drying climates. The generation of a large H at the leaf scale provides a basis for the development of the previously identified canopy-scale ‘convector effect’.

• Temperature is a key control over biological activities from the cellular to the ecosystem scales. However, direct, high-precision measurements of surface temperature of small objects, such as leaves, under field conditions with large variations in ambient conditions remain rare. Contact methods, such as thermocouples, are prone to large errors. The use of noncontact remote-sensing methods, such as thermal infrared measurements, provides an ideal solution, but their accuracy has been low (c. 2°C) owing to the necessity for corrections for material emissivity and fluctuations in background radiation L bg. • A novel ‘dual-reference’ method was developed to increase the accuracy of infrared needle-leaf surface temperature measurements in the field. It accounts for variations in L bg and corrects for the systematic camera offset using two reference plates. • We accurately captured surface temperature and leaf-to-air temperature differences of needle-leaves in a forest ecosystem with large diurnal and seasonal temperature fluctuations with an uncertainty of ± 0.23°C and ± 0.28°C, respectively. • Routine high-precision leaf temperature measurements even under harsh field conditions, such as demonstrated here, opens the way for investigating a wide range of leaf-scale processes and their dynamics.

Seasonal differences of temperature are crucial components of the Earth’s climate system. However, the relatively short observational record, especially for East Asia, has limited progress in understanding seasonal differences. In this study, we identify ten tree-ring chronologies separately correlated with local winter (December–February) temperatures and twelve different tree-ring chronologies separately correlated with summer (June–August) temperatures across East Asia. Using these discrete seasonal tree-ring chronologies, we develop two independent winter and summer temperature reconstructions covering the period 1376–1995 CE for East Asia, and compare them with model simulations. Our reconstructions show a more significant volcanic cooling and earlier onset of modern warming in summer than in winter. The reconstructed summer-minus-winter temperature decreased since as early as the late 19th century, which has driven the current state of seasonal temperature difference to out of the natural variability since the 1370s. Climate models could generally reproduce the variability and trends in seasonal reconstructions, but might largely underestimate seasonal differences due to the fact that seasonal expressions on external forcing and modes of internal variability are too small. Our study highlights the importance of using proxy-based seasonal reconstructions to evaluate the performance of climate models, and implies a substantial weakening of seasonal temperature differences in the future.

The responses of Ulva species to diurnal temperature difference remain poorly understood. In this present study, we cultured Ulva prolifera under different diurnal temperature treatments with 22°C for photoperiod and 22, 20, 18, 16, 14, and12°C for dark period, respectively (noted as 22-22, 22-20, 22-18, 22-16, 22-14, and 22-12°C treatments). The growth, pigment contents, photosynthesis, superoxide dismutase (SOD) activity, soluble proteins, and sugars were measured. The main results were shown as follows: (1) The growth of U. prolifera was enhanced by the moderate diurnal temperature difference, and the highest growth rate was observed at 22-18°C. (2) Compared with 22-22°C treatment, the thalli grown under 22-18°C condition showed lower chlorophyll a (Chla) content, respiration rate ( R d ), the ratio of R d , and gross photosynthetic rate ( R d / P g ) as well as the net photosynthetic rate ( P n ), while the lowest P n was observed at 22-12°C. (3) The maximum quantum yield ( F v / F m ) was enhanced by diurnal temperature difference, while the effective quantum yield ( F v ′/ F m ′) decreased with the decreased in temperature in the nighttime. (4) With the increase of the diurnal temperature difference gradient, the SOD activity decreased and then increased, with the lowest value observed at 22-18 °C, and the soluble protein content showed similar trend. Then we cultured this species at 22-22°C and 22-16°C both under 250 and 60 μmol m −2 s −1 conditions in order to study the combined effects of diurnal temperature change and light intensities. It was found that under both two light levels, 22-16°C-grown thalli showed higher growth rate, while the SOD activity was lower than that grown under 22-22°C condition. Overall, the suitable range of diurnal temperature difference for the growth of U. prolifera was about 4–6°C and also was mediated by light intensity.

Based on the monthly outputs of the Couple Model Intercomparison Project phase 5 (CMIP5), the present study examines the contributions of direct and indirect effects of CO2 to the response of the sensible heat (SH) over the Tibetan Plateau (TP). Under global warming, the TP SH features an uniform increase during November–April (NDJFMA). During NDJFMA, the SH change over the TP can be mainly attributed to the uniform SST increase induced by CO2 increasing. This uniform SST increase warms the atmosphere. In turn, it leads to: (1) reduction in snowfall over the TP, with maximum over south TP; (2) increased snowmelt mainly above 3000 m and decreased snowmelt near or south of 3000 m elevation south of TP. The net effects of snowfall and snowmelt are towards the reduction of the snow cover over the TP, which may alter the snow-albedo feedback. Consequently, more solar radiation is absorbed by the TP surface, and the TP surface warms. The surface–air temperature difference increases, which leads to the increase in SH. In addition, the enhancement of the SH offsets the increase in absorbed solar radiation and balances the radiation budget. On the above processes, the SST pattern slightly cancels out the TP SH increase; the contributions of CO2 direct radiative effect and residual terms are relatively small. Over the grids with elevations no less than 3000 m, the averaged changes are generally linear.

Purpose The purpose of this study is to design a new type of cold plate to improve the thermal performance of liquid-cooled thermal management system of lithium-ion batteries. Design/methodology/approach A cold plate with leaf type channels is proposed to enhance the cooling performance. Effects of the leaf type channel parameters (i.e. channel angle 20°, 40°, 60°, 80°; coolant mass flow rate 0.25 × 10–3, 0.50 × 10–3, 0.75 × 10–3, 1.00 × 10–3, 1.25 × 10–3 kg·s−1; channel number 1, 3, 5, 7) on the performance are numerically investigated by using a 3D mathematical model. Findings Compared to the traditional I type channels, the leaf type channels have better cooling performance. It is found that the battery temperature variation and channel pressure drop are decreased with decreasing channel angle and increasing channel number. In addition, the cooling performance can be improved by increasing the coolant mass flow rate. Practical implications This study can provide guidance for the development of novel effective cold plates. Originality/value The design of cold plates with leaf type channels can be used in liquid-cooled thermal management system to reduce the battery temperature difference.

The thermodynamic characteristics of double-row angular contact wheel bearings are important for the bearing operational condition monitoring and structural design. The load distribution and power consumption distribution of the bearing are obtained by establishing a thermal-force coupling model of the double-row angular contact wheel bearing. Combining with the thermal network and finite element analysis method, the steady-state temperature field of the bearing under test conditions is achieved. Also a box-type encapsulated fiber-optic grating temperature sensor is designed for investigating the effects of working condition parameters on the axial and circumferential temperature distributions of the bearing. And a comparative analysis with the predicted results is carried out. The results show that there are obvious temperature differences in the axial and circumferential direction of double-row angular contact wheel bearing under combined load. The speed, axial force and radial force all affect the bearing temperature rise and temperature distribution.

This study utilizes in situ measurements and numerical weather prediction forecasts curated during the Coupled Air–Sea Processes Electromagnetic Ducting Research (CASPER) east field campaign to assess how thermodynamic properties in the marine atmospheric surface layer influence evaporation duct shape independent of duct height. More specifically, we investigate evaporation duct shape through a duct shape parameter, a parameter known to affect the propagation of X-band radar signals and is directly related to the curvature of the duct. Relationships between this duct shape parameter and air sea temperature difference (ASTD) reveal that during unstable periods (ASTD < 0), the duct shape parameter is generally larger than in near-neutral or stable atmospheric conditions, indicating tighter curvature of the M-profile. Furthermore, for any specific duct height, a strong linear relationship between the near-surface-specific humidity gradient and the duct shape parameter is found, suggesting that it is primarily driven by near-surface humidity gradients. The results demonstrate that an a priori estimate of duct shape, for a given duct height, is possible if the near-surface humidity gradient is known.

This paper describes the thermal lag correction for Glider Payload Conductivity Temperature Depth Profiler data with a poor sampling rate. In particular, the thermal lag correction is more vulnerable to the influence of temperature data. According to variations in salinity with depth and the vertical downcast speed of the glider, salinity data are divided into five parts, and a method based on Morison et al. is proposed to determine the correction parameters. At 40–94 dbar and 140–280 dbar, the salinity difference is dominated by the temperature difference. At 94–140 dbar, the salinity difference is immune to the temperature difference and has a greater influence on the thermal lag-induced salinity error correction. After the sectional correction, the accuracy of the typical salinity interval is upgraded from 0.011 to 0.006 psu, which shows the effectiveness of this sectional method on correcting temperature difference.

Freshwater availability is increasingly under pressure from growing demand, resource depletion and environmental pollution. Desalination of saline wastewater is an option for supplying households, industry and agriculture with water, but technologies such as reverse osmosis, evaporation or electrodialysis are energy intensive. By contrast, membrane distillation (MD) is a competitive technology for water desalination. In our study, response surface methodology was applied to optimize the direct contact membrane distillation (DCMD) treatment of synthetic saline wastewater. The aim was to enhance the process performance and the permeate flux Jp (L/m2·h) by optimizing the operating parameters: temperature difference ΔT, feed velocity Vf, salt concentration [NaCl], and glucose concentration [Gluc]. The results are a high permeate quality, with 99.9% electrical conductivity reduction and more than 99.9% chemical oxygen demand (COD) removal rate. The predicted optimum permeate flux Jp was 34.1 L/m2·h at ΔT = 55.2 °C and Vf = 0.086 m/s, the two most significant parameters. The model created showed a high degree of correlation between the experimental and the predicted responses, with high statistical significance.