Vertical Temperature Variations Research Articles

Temporal and spatial changes in the environmental lapse rate distribution over the Arctic

Abstract The Environmental Lapse Rate (ELR) depicts how the temperature near the surface varies with altitude and can be used for temperature downscaling coarse resolution data and for understanding boundary layer processes. We calculated the ELR using ERA5 reanalysis data, examined its temporal and larger-scale spatial variability, and found a prevalent seasonal ELR cycle over the Arctic. There are extensive positive ELR values resulting from pervasive inversions over most of the Arctic in winter; hence, we also explored the possible factors that lead to inversions in polar regions. Our results can serve as a reference for future research on the inversions in different morphological regions at different pressure levels. By improving the characterization of the ELR, we obtain a more explicit representation of the vertical temperature variation across the Arctic region and examine potential trends in ELR over time. Our results challenge the commonly assumed fixed ELR values that are typically used in the Arctic region in, for example, correcting ice-core temperature reconstructions or estimating higher-resolution runoff from land ice.

Spatio-Temporal Variation of Virtual Temperature in Ilorin, Kwara State, Nigeria

This study investigates the diurnal and vertical variations of virtual temperature (Tv) and ambient temperature (T) from 2013 to 2023 in Ilorin. Data analysis reveals that Tv peaks between 1200 and 1400 hours daily, influenced mainly by relative humidity and inversely by temperature changes, with no significant pressure impact. At the planetary boundary layer, Tv and T exhibit marginal differences, converging higher in the troposphere due to diminishing specific humidity. Temporal trends indicate a surface temperature increase of 0.065 degrees and a Tv increase of 0.016 degrees over the past decade. While no simple linear correlation between Tv and relative humidity was found, seasonal patterns suggest potential underlying correlations. This highlights the complex interplay of atmospheric variables in influencing virtual temperature and underscores the need for further investigation into seasonal effects.

An Experimental Study for Air Temperature Distribution in a Conditioned Room Using Various Vertical Locations of Conditioned Air Ducts

The Air distribution phenomenon is most useful in thermal environment study and its effectiveness. The main aim of this investigation is to examine and discover the thermal properties of the inside area and its thermal environment. The experimental work for research was studied at the first-floor lab of the government women’s polytechnic, Bhopal. The experiment was conducted in the summer and winter seasons in a closed-conditioned room with the arrangement of a conditioned air discharge duct. The conditioned air was discharged through the circular pipe duct which was set vertically. The duct has arrangements to discharge the air through various vertical positions as the lower duct (L), middle duct (M), and upper duct (U). This experimental work investigates supply air velocity and vertical temperature variation effectiveness inside said test room. The experiment results were collected with lower, middle, and vertical duct opening conditions respectively. The vertical temperature variation and air velocity at the outlet of the duct were noted with considerable points at 1 m from each inside the test room space. The outcome of the results shows the indoor thermal environment and vertical temperature distribution were affected by the discharge air duct position and supply air velocity. The temperature profile vertically impacted when the measuring test point position was near the discharge air duct and it became quite consistent in respective measurements from a large distance.

Non-uniform temperature fields in steel tubes with different inclinations under solar radiation

The temperature distribution within steel tubes is subject to non-uniformity due to the influence of surrounding environmental factors, which could pose safety concerns for steel structures. In response, this study undertook a comprehensive long-term experimental investigation, aimed at elucidating the temperature distribution characteristics of inclined steel tubes. The results underscored the non-uniform distribution of temperature fields in steel tubes under the influence of solar radiation, with notable sensitivity to their inclinations and orientations. In addition, a numerical simulation model specifically tailored to represent the thermal behavior of inclined steel tubes was developed and subsequently validated using empirical data gathered from the aforementioned experiments. Based on the developed simulation model, the thermal behaviors of a steel-arch-tower were numerically analyzed. It was shown that distinct vertical temperature variations exist across different sections of the tower, while the horizontal temperature differentials exhibit consistent trend. The outcomes of this combined experimental and numerical study provide useful references to understand the thermal effects in steel structures.

A study of evaporation duct characteristics in the South China Sea during the Winter of 2017

The evaporation duct (ED) near the sea surface is the most frequent type of duct that traps and redirects electromagnetic waves over longer or shorter distances. This study uses radiosonde data from the South China Sea Two-Island Monsoon Experiment (SCSTIMX) in 2017 and the Weather Research and Forecasting (WRF) model to study the ED and ED height (EDH). We enhanced the vertical resolution to 26 layers in the lowest 134 m. The simulations indicate that EDs were prevalent throughout the South China Sea (SCS) area in winter 2017, where the prevailing surface winds are strong northeasterly. The EDH exhibits diurnal variations and significant variability across the SCS. The WRF simulations of ED and EDH generally agree with observations of the trajectory of Taiwan-O.R.1. Our results indicate that the WRF model can simulate the pattern of ED and EDH over SCS. Results reveal that Yonsei University (YSU) boundary layer (BL) parameterization more accurately simulates the vertical temperature and humidity variations in the lower atmosphere, with stronger winds and higher EDH in most areas. The YSU and the Medium Range Forecast Model (MRF) BL schemes show similar ED patterns to the Taiwan-O.R.1 SCS radiosonde observations but consistently underestimate the EDH. While strong surface winds in the winter SCS may contribute to a higher EDH, the strong surface wind-induced vertical mixing also modifies sea surface air temperature, relative humidity, and vapor pressure, affecting the vertical refractivity. Our results indicate that sea surface air temperature is a more reliable factor affecting EDH in the simulations.

Prediction of heat and mass transfer inside 3D frost microstructure

In the present study, a CFD model based on 3D frost microstructure is developed. The desublimation phase change coupled with mass transfer of water vapor to ice surface and heat conduction through the tortuous ice crystals are calculated to predict accurate heat transfer process inside the frost microstructure. Air velocity and temperature inside the frost structure after 30 min operation are significantly lower than those inside 10 min operation, which are influenced by the structural change of the ice crystals. Vertical variations in ice crystal surface temperature and ice surface mass flux are also calculated, which varied between the frost structures operated for different periods. At 70 μm height of the frost, the mass flux at the ice crystal surface shows significant decrease from 7.48 × 10−5 kg/m2s for the frost structure at 10 min to 1.82 × 10−5 kg/m2s for that at 30 min. This study provides new and fundamental information to understand the mechanism of frost growth which is very important in refrigeration, cryogenics, and aerospace industry, etc.

Gender disparities in thermal responses under vertical air temperature differences

The effects of vertical temperature differences (VTD) on human thermal comfort have attracted growing attention from researchers when utilizing split air conditioners for winter heating. This study underscores the need to investigate the influences of gender disparities in the context of significant vertical temperature variations, a critical aspect that has not yet been comprehensively explored. Twenty gender-balanced subjects were exposed to a variety of stratified thermal environments created by a split air-conditioner. Their overall and local perceptual and physiological responses were measured at various operative temperatures and VTD. Results show that females have lower thermal sensation vote (TSV) and mean skin temperature under the same environments compared to males. Neutral operative temperatures of females and males are 23.7 ˚C and 20.8 ˚C, respectively. On the cold side, lower leg and foot thermal sensations are dominant whereas chest and back are dominant on the warm side. When females rated “slightly warm” (TSV equaled 1) or “warm” (TSV equaled 2), or males rated “slightly cool” (TSV equaled −1), increased VTD can lower thermal acceptability. The research findings have significant implications for the understanding of gender requirements of stratified heating environments and for maximizing the thermal comfort of the two genders.

Technique and results of determination of vertical variations in rock thermal properties, temperature gradient and heat flow

The paper describes the results of experimental geothermal studies of the formation surrounding Savitskaya-300 well (depth 3555 m) drilled in the Volga-Ural oil and gas basin (Orenburg region, Russia). The work was aimed, firstly, at obtaining geothermal data for basin modeling and, secondly, at improving the instrumental and methodological foundations of experimental studies. Continuous core profiling of the rock thermal conductivity, volumetric heat capacity, and thermal anisotropy was performed on all 2886 recovered core samples with the total length of 329.1 m. Additional measurements were conducted at fluid saturation and elevated temperatures. For non-cored intervals, the rock thermal properties were determined from well-logging data and via measurements on rock cuttings. The studied formation is characterized by high thermal heterogeneity at both the level of strata (horizons) and individual samples. Significant thermal anisotropy up to 1.50–1.66 in the lower part of the well has been observed. To obtain data on vertical variations of equilibrium temperature and its gradient, temperature logging was performed 7 times within the 2 to 186 days of well shut-in. New data on the recovery of temperature and its gradient after drilling are important for the practice of applied and fundamental geothermal surveys. A significant increase in heat flow with depth was established based on the results of temperature gradient and rock thermal conductivity determination for 34 depth intervals. The observed general vertical variation in the whole depth range of the well up to ∼3.3 km depth can be attributed to paleoclimatic effect in the Late Pleistocene-Holocene, while the sharp increase in heat flow at ∼3.3 km within Fransian sediments is possibly due to advective heat transfer by fluid filtration. The apparent heat flow was established to be 84.3 mW⋅m−2 in the lower section of the well, below 3.3 km. The value may be close to the steady-state heat flow value, which is 84% higher than the previous published average data for the studied area.

Temperature gradient of composite PK girder based on monitoring and long-term simulation

Bridge structures exposed to the environment are inevitably affected by the thermal load which is closely related to the type of section. In this study, the temperature field of a composite Pasco-Kennewick (PK) section girder was monitored in situ for the first time. Meanwhile, a refined finite-element model (FEM) of the temperature field was established and verified with measured temperatures. The temperature distribution and variation characteristics were analyzed using measured temperatures. On this basis, the simplified profiles of vertical temperature gradient (VTG) and transverse temperature gradient (TTG) were proposed. The representative values of temperature differences with a 100-year return period were predicted by extreme value analysis (EVA) with the samples of temperature differences obtained through 23-year numerical simulation. Finally, comparisons were made between the temperature gradients of composite PK section and the recommendations in current specifications. The results show that the vertical temperature distributions and variations on different webs have apparent differences. Meanwhile, remarkable transverse temperature differences exist on the top plate and bottom plate. Five VTGs and four TTGs are proposed with totally different simplified profiles. The representative values of positive temperature differences in TTGs are larger than those in VTGs, as well as the absolute values of negative temperature differences. The proposed temperature gradients are significantly distinct from the recommendations in current specifications. These temperature gradients are expected to improve the stipulation about the temperature action of bridges.

Acoustic and gravity waves in the ocean: a new derivation of a linear model from the compressible Euler equation

In this paper, we construct an accurate linear model describing the propagation of both acoustic and gravity waves in water. This original model is obtained by the linearization of the compressible Euler equations, written in Lagrangian coordinates. The system is studied in the isentropic case, with a free surface, an arbitrary bathymetry, and vertical variations of the background temperature and density. We show that our model is an extension of some models from the literature to the case of a non-barotropic fluid with a variable sound speed. Other models from the literature are recovered from our model through two asymptotic analyses, one for the incompressible regime and one for the acoustic regime. We also propose a method to write the model in Eulerian coordinates. Our model includes many physical properties, such as the existence of internal gravity waves or the variation of the sound speed with depth.

The modulation effect of ice thickness variations on convection in icy ocean worlds

ABSTRACT It has been long puzzling whether the ice thickness variations observed on Enceladus can be sustained solely by a polar-amplified bottom heating. The key to this question is to understand how the upward heat transport by convective plumes would be interfered by the temperature and salinity variations beneath the ice due to the ice thickness variations, which, however, has yet to be explored. Here, we find that the horizontal temperature variation induced by the ice topography can easily be orders of magnitude greater than the vertical temperature variation induced by bottom heating using scaling analysis. Due to the dominance of horizontal temperature gradient, convective plumes are completely shut off by a stratified layer under the thin ice formed out of baroclinic adjustment, largely slowing down the vertical tracer transport. The stratified layer will also deflect almost all of the core-generated heating towards the regions with thicker ice shell, destroying the ice thickness gradient. These results allow us to put an upper bound on the core-generated heating on Enceladus, which is crucial for the estimate of habitability. Scaling laws for the bottom heat flux to penetrate the stratification are derived and examined. This scaling can be used to constrain the maximum ice thickness variations induced by heterogeneous bottom heating on icy satellites in general, which can be used to differentiate icy satellites that generate the majority of heat in the ice shell from those that generate the majority of heat in the silicate core.

A symmetrical exponential model of soil temperature in temperate steppe regions of China

Abstract Global warming has caused changes in various ecological processes and has potential to change ecosystems’ stability. In spite of comprehensive studies to investigate air temperatures under global warming, much less is known about changes in soil temperatures, particularly in deep layers. Herein, we used 30 years of soil temperature data from a temperate steppe region to assess vertical characteristics and their changes in soil temperature from the surface to a depth of 3.20 m. We determined, apparently for the first time, that the soil temperature is the lowest at 0.2 cm layer at an annual level. Furthermore, the vertical variation of soil temperature (temperature variation with soil depth) strictly conformed to composite exponential function curves, and there were two composite exponential function curves that are symmetric to each other, to represent soil temperature in a pair of months with a difference of 6 months. Parameters in the functions changed as the soil warmed over 30 years. This finding explored the pattern of soil temperature in deep layers depending on the mathematics model. Model building and understanding is beneficial for predicting vertical and temporal extensions of soil temperature and their impact on below-ground processes in regional ecosystem.

An experimental study of off-centred rotating thermal convection: a laboratory model for the tidal effects

A novel experiment was performed in rotating Rayleigh–Bénard convection (RRBC), wherein the convection cell with radius $R$ was shifted away from the rotation axis by a distance $d$ . In this case, the centrifugal force felt by a fluid parcel (characterized by the Froude number $Fr$ ) can be decomposed into an axisymmetrical part $Fr_R$ and a directed one $Fr_d$ . It has been reported that the global heat transport enhances at $Fr_{d,c}$ and then reaches an optimal state at $Fr_{d,max}$ (Hu et al., Phys. Rev. Lett., vol. 127, 2021, 244501). In this paper, the local properties after the offset effects set in are investigated further, which show different features before and after $Fr_{d,max}$ . The local temperature measurements at the cell centre reveal that the bulk flow turns from a turbulent state into a laminar state at $Fr_{d,max}$ , which is consistent with the particle image velocimetry results. This transition can be qualitatively understood by an equivalent tilted RRBC system. As for the hot and cold coherent structures near the sidewall, their vertical temperature variations reach a minimum at $Fr_{d,max}$ , implying that these structures are mostly uniform in the vertical direction at $Fr_{d,max}$ . Their temperature contrasts show a linear dependence on $Fr_d$ and start to deviate from this linear behaviour when $Fr_d>Fr_{d,max}$ . Besides the dominant effects of $Fr_d$ , the secondary effects of $Fr_R$ are also investigated. Due to the positive effect of $+Fr_R$ on the cold structure and the negative effect of $-Fr_R$ on the hot one, the cold structure is more coherent than the hot one, but its size is smaller. The shift of the cold cluster centre from the farthest point is also larger than the shift of the hot one from the nearest point.

Community assemblages and species coexistence of prokaryotes controlled by local environmental heterogeneity in a cold seep water column

The distribution and heterogeneity characteristics of microbial communities in cold seep water columns are significant factors governing the efficiency of methane filtering and carbon turnover. However, this process is poorly understood. The diversity of vertically stratified microbial communities and the factors controlling the community assemblage process in the water column above the Haima cold seep were investigated in this study. The prokaryotic community diversities varied distinctly with vertical changes in hydrochemistry. Cyanobacteria dominated the light-transmitting layers and Proteobacteria dominated the deeper layers. With respect to microbial community assemblages and co-occurrence networks, stochastic processes were particularly important in shaping prokaryotic communities. In the shallow (≥85 m) and mesopelagic water columns (600–800 m), microbial community characteristics were affected by deterministic processes, reduced network connectivity, and modularity. Microbial community diversities and assemblage processes along a vertical profile were influenced by the vertical variations in pH, temperature, DIC, and nutrients. Stochastic processes may have facilitated the formation of complex co-occurrence networks. Briefly, the distribution of local environmental heterogeneity along the vertical dimension could drive unique microbial community assemblage and species coexistence patterns. This study provides new perspectives on how microorganisms adapt to the environment and build communities, and how species coexist in shared habitats.

Simplified method for estimating restraint moment induced by vertical temperature gradient in continuous prestressed concrete bridges and verification using AASHTO BDS

Diurnal and seasonal temperature variations cause uniform temperature changes, vertical temperature gradients, and horizontal temperature gradients. Vertical temperature gradients occur when the bridge deck absorbs heat due to solar radiation more than the bottom parts of bridge girders. Consequently, the vertical temperature gradient causes redistribution of bearing reactions, and induces additional flexural stresses in continuous spans. Estimating the vertical temperature gradient effect on continuous concrete bridges requires knowledge of thermal analysis of statically indeterminate structures or advanced three-dimensional (3 D) finite element (FE) analysis. Therefore, this article focuses on developing a simplified analysis method for estimating vertical temperature variations effects on continuous prestressed concrete bridge girders, which is required for bridge design. Restraint moments induced by vertical temperature gradients are investigated using 3 D FE analysis. A total of 115 bridges with different configurations (number of spans, girder spacing, and girder type) were analyzed to estimate the positive thermal moments at support locations. Results from these analyses were then used to develop simplified equations for estimating the positive restraint moments due to vertical temperature gradients from AASHTO LRFD Bridge Design Specifications (BDS). The developed equations are validated using John James Audubon Bridge #2 field data, and for other AASHTO LRFD temperature zones.

Numerical investigation of the information complexity in Lorenz system based on Shannon entropy

To quantify the information embedded in the Lorenz system, the Shannon entropies (also named information entropies) of the convection rate, the horizontal temperature variation, and the vertical temperature variation are calculated under the conditions of different values of the three parameters which are proportional to Prandtl number, Rayleigh number, and the liquid layer dimension respectively. Generalized autoregressive conditional heteroskedasticity models are employed to represent the change of the Shannon entropies with that of the three parameters.

Mixing zone delimitation for submarine outfall in tropical marine water using the uranine dilution measurement approach

Submarine outfalls are standard wastewater management systems implemented in coastal areas. This manuscript presents a methodology for mixing zone delimitation of wastewater plume discharged through a submarine outfall in tropical marine waters. Sodium fluorescein (Uranine) was used as a tracer to track wastewater mixing and dilution factor in the coastal water of Cartagena de Indias (Colombia). Historical marine water quality, marine currents, and meteorology data were obtained, and analyzed. Two field campaigns were carried out to monitor coliforms, enterococci, and uranine concentrations in the studied area. The results showed that the water column was well mixed, and stratification was negligible due to the low vertical variations in temperature (29.0–29.35 °C), salinity (35.8–36.2), and density (1022.6–1023.0 kg ⋅ m−3). The initial dilution during the dry to the rainy (April) and from the rainy to the dry (December) seasons reached similar dilution factors up to 1:43000 in less than 150 m. The regulatory mixing zone was delimited to an area of 6.6 km2. Uranine is suitable for delimiting the wastewater mixing zone in tropical marine waters.

Three-Dimensional Dynamic Variations of Ground/Air Surface Temperatures and Their Correlation with Large-Scale Circulation Indexes in Southwest China (1980–2019)

Air/soil temperatures play important roles in land–atmosphere interactions. The three-dimensional (temporal, spatial, and vertical) variations of maximum, mean, and minimum ground soil temperature at 0 cm (GSTx, GSTm, and GSTn, respectively), surface air temperature at 2 m (SATx, SATm, and SATn, respectively), and soil–air temperature difference (SATDx, SATDm, and SATDn, respectively) and their potential linkages with large-scale indexes in Southwest China during 1980–2019 were analyzed. Variations of GST and SAT at the majority of stations (pixels) exhibited significant (p ≤ 0.05) warming, albeit at different rates; consequently, SATD exhibited different variation. Moreover, the period of GST, SAT, and SATD was similar in intra-annual and interannual oscillation but was different in interdecadal oscillation. The variation rate of GST, SAT, and SATD exhibited significant (p ≤ 0.05) correlation with elevation, but with different variation gradient. Notably, asymmetric variation of SATDx (downward trend) and of SATDn (upward trend) with elevation was found at elevations >3 km. Wavelet coherence showed that the Atlantic Multidecadal Oscillation is the dominant factor affecting GST and SAT, whereas the Pacific Decadal Oscillation and the North Atlantic Oscillation make the greatest contributions to SATD. It was found that GST, SAT, and SATD exhibit different variations under the effects of global warming, the driving mechanism of which requires further study.

TRIDENT: A Rapid 3D Radiative-transfer Model for Exoplanet Transmission Spectra

Abstract Transmission spectroscopy is one of the premier methods used to probe the temperature, composition, and cloud properties of exoplanet atmospheres. Recent studies have demonstrated that the multidimensional nature of exoplanet atmospheres—due to nonuniformities across the day–night transition and between the morning and evening terminators—can strongly influence transmission spectra. However, the computational demands of 3D radiative-transfer techniques have precluded their usage within atmospheric retrievals. Here we introduce TRIDENT, a new 3D radiative-transfer model which rapidly computes transmission spectra of exoplanet atmospheres with day–night, morning–evening, and vertical variations in temperature, chemical abundances, and cloud properties. We also derive a general equation for transmission spectra, accounting for 3D atmospheres, refraction, multiple scattering, ingress/egress, grazing transits, stellar heterogeneities, and nightside thermal emission. After introducing TRIDENT’s linear-algebra-based approach to 3D radiative transfer, we propose new parametric prescriptions for 3D temperature and abundance profiles and 3D clouds. We show that multidimensional transmission spectra exhibit two significant observational signatures: (i) day–night composition gradients alter the relative amplitudes of absorption features; and (ii) morning–evening composition gradients distort the peak-to-wing contrast of absorption features. Finally, we demonstrate that these signatures of multidimensional atmospheres incur residuals >100 ppm compared to 1D models, rendering them potentially detectable with the James Webb Space Telescope. TRIDENT’s rapid radiative transfer, coupled with parametric multidimensional atmospheres, unlocks the final barrier to 3D atmospheric retrievals.

Spitzer Dayside Emission of WASP-34b

We analyzed two eclipse observations of the low-density transiting, likely grazing, exoplanet WASP-34b with the Spitzer Space Telescope’s InfraRed Array Camera using two techniques to correct for intrapixel sensitivity variation: Pixel-Level Decorrelation and BiLinearly Interpolated Subpixel Sensitivity. When jointly fitting both light curves, timing results are consistent within 0.7σ between the two models and eclipse depths are consistent within 1.1σ, where the difference is due to photometry methods, not the models themselves. By combining published radial velocity data, amateur and professional transit observations, and our eclipse timings, we improved on measurements of orbital parameters and found an eccentricity consistent with zero (0.0). Atmospheric retrieval, using our Bayesian Atmospheric Radiative Transfer code, shows that the planetary spectrum most resembles a blackbody, with no constraint on molecular abundances or vertical temperature variation. WASP-34b is redder than other warm Jupiters with a similar temperature, hinting at unique chemistry, although further observations are necessary to confirm this.