Vertical Temperature Distribution Research Articles

Early frost detection in wheat using machine learning from vertical temperature distributions

Frost damage significantly reduces global wheat production. Temperature development in wheat crops is a complex and dynamic process. During frost events, a vertical temperature gradient develops from soil to canopy due to the heat loss from the soil and canopy boundary. Understanding these temperature gradients is essential for improving frost management strategies in wheat crops. We hypothesise that the relationship between the temperatures of the canopy, plant and ground can be an early indicator of frost. We collected infrared thermal (IRT) images from field-grown wheat crops and extracted the temperatures from the canopy, plant and ground layers. We analysed these temperatures and applied four machine learning (ML) models to detect coldness scales leading to frost nights with different degrees of severity. We implemented a gated recurrent unit, convolutional neural network, random forest and support vector machines to evaluate the classification. Our study shows that in these three layers, temperatures have a relationship that can be used to determine frost early. The patterns of these three temperatures on a frost night differ from a cold no-frost winter night. On a no-frost night we observed that the canopy is the coldest, plant is warm, and the soil is warmest, and these three temperatures did not converge. On the other hand, on a frost night, before the frost event, the canopy and plant temperatures converged as the cold air penetrated through the canopy. These patterns in temperature distribution were translated into an ML problem to detect frost early. We classified coldness scales based on the temperatures conducive to frost formation of a certain severity degree. Our results show that the ML models can determine the coldness scales automatically with 93%–98% accuracy across the four models. The study presents a strong foundation for the development of early frost detection systems.

Study on the decompression behavior during large-scale pipeline puncture releases of CO2 with various N2 compositions: Experiments and mechanism analysis

Impurities in the captured CO2 stream from various industrial sources may introduce uncertainty into the transient releases of transportation pipelines. Due to limitations in the experimental scale, there is currently limited analysis of the vertical cross-sectional temperature distribution and the pressure response along the pipeline during the releases of impure CO2. The mechanism by which impurities affect the decompression wave and the alterations in phase-change pathways remains unclear. In this study, building upon the existing large-scale pipeline, we established an impurity injection system. Using the common impurity, N2, as a variable, the decompression behavior of the CO2+N2 mixture in the puncture releases and the influence mechanism of N2 were investigated. The results show that the effect of N2 on sound velocity causes a significant decrease in the decompression wave speed. N2 raises the minimum temperature, and it is more pronounced in large-diameter releases; for instance, the minimum temperature during the 100 mm release is always higher than that in the 50 mm release. The gas-liquid mixture closely follows the dew point line, conforming to the Gibbs equilibrium criterion. The experimental scale mirrors real-world operating conditions, endowing the research findings with practical applicability. Concurrently, it furnishes dependable data for numerical researches.

Concept and ventilation performance demonstration of graded ventilation

Advanced air distribution is essential for the energy-efficient provision of thermal comfort and indoor air quality. This study proposes a novel advanced air distribution, i.e., graded ventilation. The airflow pattern of graded ventilation is characterized by a bimodal distribution of vertical air velocity and a unimodal distribution of vertical air temperature. Graded ventilation possesses four mechanisms for high energy-efficient provision of thermal comfort and indoor air quality. First, graded ventilation has a high conditioned air supply efficiency into the occupied zone, particularly the head level, for both thermal comfort and indoor air quality, due to the push-down and pull-down forces of the internal airflow recycling. Second, graded ventilation decouples outdoor fresh air and return air, with high outdoor fresh air supply efficiency for indoor air quality. Third, graded ventilation utilizes higher-quality conditioned air for the zone, which is more critical to thermal comfort and indoor air quality. Fourth, graded ventilation only handles the cooling load of the outdoor fresh air without handling the cooling load of the return air. Case studies demonstrate that compared with mixing ventilation, Type-I stratum ventilation, Type-II stratum ventilation, and interactive cascade ventilation, graded ventilation improves energy efficiency by 49.7%–55.4%, 24.8%–29.1%, 16.3%–23.3%, and 8.4%–12.3% respectively for thermal comfort and indoor air quality. Therefore, this study advances air distribution for low-carbon, thermally comfortable, and healthy buildings.

Multi-dimensional investigation of ceiling jet temperature characteristics beneath curved ceiling produced by fire in the utility tunnel

To study the temperature profile beneath the curved ceiling from a multi-dimensional perspective, an experimental investigation was conducted in utility tunnels with two different sizes, and a series of models were established to predict a two-dimensional longitudinal temperature profile and transverse temperature attenuation in this study. The prediction models for the two-dimensional longitudinal temperature profile were developed by modeling the vertical temperature distribution, thermal boundary layer thickness, Gaussian thermal layer thickness and maximum longitudinal temperature attenuation. Through the experimental validation on two sizes, it is found that the proposed prediction model can express the longitudinal temperature profile from a two-dimensional view within the relative error range of 20%. Besides, the prediction model for transverse temperature attenuation was established by the definition of characteristic tilt angle, and the three detailed expressions of this model were proposed according to different types of ceiling jets after impingement. The proposed prediction model for transverse temperature attenuation was also validated, and the verification results showed that the relative error of the transverse temperature attenuation prediction model can be controlled within a 25%. The developed prediction models in this study can be applied in the fire protection engineering of utility tunnels.

Detecting the role of Stokes drift under typhoon condition by a fully coupled wave-current model

The impacts of Stokes drift and sea-state-dependent Langmuir turbulence (LT) on the three-dimensional ocean response to a tropical cyclone in the Bohai Sea are studied through two-way coupled wave-current simulations. The Stokes drift is calculated from the simulated wave spectrum of the wave model, Simulating Waves Nearshore (SWAN), and then input to the Princeton Ocean Model with the generalized coordinate system (POMgcs) to represent the Langmuir effect. The Langmuir circulation is included in the vertical mixing of the ocean model by adding the Stokes drift to the shear of the vertical mean current and by including LT enhancements to the Mellor-Yamada 2.5 turbulent closure submodel. Simulations are assessed through the case study of Typhoon Masta in 2005 with a set of diagnostic experiments that incorporated different terms of Stokes production (SP) respectively. It is shown that with the consideration of SP, a deeper mixed layer, an enhanced vertical mixing coefficient KMS, and a more accurate representation of the vertical temperature distribution could be derived. Moreover, the effect of LT in elevating the turbulence mixing is stronger than that of Coriolis Stokes force (CSF) and Craik-Leibovich vortex force (CLVF). LT has a greater influence on the vertical mixing during typhoon than that in normal weather.

Nucleation of ice particles below the snow line

An increase in the total surface area of icy dust aggregates was numerically investigated. The temperature of icy dust aggregates in a protoplanetary disk changes through their vertical motion induced by turbulence. The ice becomes vapor if the maximum temperature exceeds the condensation temperature. The vapor molecules recondense when cooling proceeds. Depending on the cooling rate and the amount of the remaining aggregate, the vapor molecules form pure ice particles through homogeneous nucleation or recondense onto the remaining icy aggregates through heterogeneous nucleation. If homogeneous nucleation dominates, the total surface area substantially increases from the original value. The increase in the total surface area was determined for various ice species and vertical temperature distributions. H2O, NH3, and H2S ice particles can be formed through homogeneous nucleation. The total surface area is increased by a factor of up to 400. The increase in the total surface area can affect protoplanetary disk’s surface density and temperature distributions.

Experimental Study on Effects of Moisture Content and Tree Height on Crown Fire Behaviors of Live Cypress Trees

ABSTRACT Once a fire occurs in urban green belts, the live foliage of some tree and shrub species with larger moisture content than dead fuel can support fire spread, which poses a great threat to the wildland-urban interface (WUI). Cypress tree is widely used as an ornamental vegetation worldwide. This work aims to study the fire and spread behaviors through cypress trees. Experiments were conducted using three tree heights between 0.8 m and 1.6 m and five values of fuel moisture content (FMC) between 30% and 160%. The fuel mass loss, flame shape, vertical temperature distribution and outward vertical heat fluxes were measured. The results showed that for a given tree height, a small enough FMC promoted the burning process and decreased both the maximum heat release rate (HRR) and the time to reach peak HRR compared to a larger FMC. The tree height correlated strongly with the flame height, while the influence of FMC was much smaller. Then, a correlation between the normalized maximum flame height and the normalized maximum HRR was established by taking the crown height as the characteristic length. Reducing the FMC did not necessarily promote the fire spread and trees with large FMCs can support relatively large flame front spread rates. The effect of the tree height on the radiant heat flux was greater than the effect of FMC.

Water stratification alters phytoplankton assemblages in scallop farming waters of the North Yellow Sea in China

As evaluation indicators of the primary productivity, the phytoplankton biomass and community structure are of great significance to the fishery industry, which can be driven by ocean currents, nutrients and water stratification. In the present study, the characteristics of phytoplankton assemblages in different water layers of a typical Yesso scallop farming area in Zhangzi Island, the North Yellow Sea were investigated from March 2021 to January 2022. According to the vertical distribution of temperature, water stratification was observed from June to August (stratification period), and disappeared in March, October and the following January with vertical homogeneity (mixing period). 18S rRNA gene sequencing results revealed that Pyrrophyta was the most dominant phylum during the sampling period, with high gene proportions in the stratification (63.36%) and mixing periods (77.35%). The gene proportion of Bacillariophyta in the stratification period was 5.44%, which was significantly lower than that in the mixing period of 8.93% (p < 0.05). Moreover, Pseudo-nitzschia, a toxin-producing taxon affiliated with Bacillariophyta, exhibited a significantly higher proportion in the stratification period than in the mixing period. During the stratification period, a number of toxin-producing taxa such as Pseudo-nitzschia and Karlodinium were enriched in the bottom layer, which was 1.29-fold and 1.37-fold of that in the surface layer, respectively. Redundancy analysis showed that phosphate and water temperature were major environmental factors driving the vertical distribution of phytoplankton assemblages. The phosphate (0.11 μM) and silicate (2.09 μM) concentrations in the surface layer approached the minimum threshold for phytoplankton growth, and the stoichiometric limitation of phosphate was detected in the surface and middle layers. Collectively, these results indicated that the decreased proportion ratio of Bacillariophyta to Pyrrophyta and unfavorable community composition of Bacillariophyta for scallops were observed during summer, which might result from the phosphate limitation driven by water stratification. The results will further our understanding of the dynamics of phytoplankton communities under the background of intensifying ocean stratification and provide ecological guidance for mollusc mariculture.

Indoor thermal nonuniformity of atrium-centered public building: Monitoring and diagnosis for energy saving

Heating ventilation and air conditioning system accounts for over one third of building energy usage, especially for public buildings due to large indoor heat source and high ventilation and thermal comfort requirement compared to residential buildings. Natural ventilation shows high application potentials in public buildings because of its high-efficient ventilation effect and energy saving potential for indoor heat dissipation. In this paper, the building design is conducted for a science museum and library with atrium-centered natural ventilation consideration. The floor layout, building orientation and internal structure are optimized to make full use of natural ventilation for space cooling under local climatic conditions. A natural ventilation model is established through building field tests to evaluate the air flow and thermal environment under indoor and outdoor pressure differences. The preliminary results show that Building A's courtyard exhibited overheating issues, likely attributed to outdoor solar radiation, whereas Building B's courtyard experienced localized cooling, possibly due to indoor air conditioning system controls. Addressing these concerns necessitates modifications in courtyard design and structure. Moreover, both courtyards displayed vertical temperature gradients, emphasizing the need for effective management of outdoor heat influx and enhancements in indoor ventilation and shading strategies. To mitigate these issues, the study proposed three distinct roof design models and more refined indoor air conditioning system control strategies. The optimization of architectural design can achieve a maximum energy-saving rate of 46.54 %. Furthermore, aligning functional zones with thermal comfort areas was recommended to enhance overall building thermal comfort. The findings and proposed solutions from this study are anticipated to contribute to the enhancement of thermal comfort, energy efficiency, and vertical temperature distribution in large public buildings, catering to user requirements while reducing energy consumption. This research holds significant implications for advancing sustainability and environmental preservation in the realm of architecture.

Evaluation of Fire Suppression Performance for Multiple-Fire-Source Fire Using Water Mist-Type Fire-Suppression Equipment for Railway Passenger Cabin

The fire suppression performance of a mist fire-extinguishing system in railway passenger cabin was evaluated using a performance evaluation method based on multiple fire sources. Scenarios were analyzed for a simulated space in the railway vehicle cabin of the Daegu Urban Railway Line 3 using automatic fire-suppression system methods based on railway-vehicle technical standards. Three n-heptane fire pools were positioned inside the test space. When the spray fire-extinguishing equipment was operated at 10 and 20 bar after 30 s of ignition, the variations in the temperature of the test space and the fire-extinguishing characteristics, such as the time taken to stop the fire-extinguishing equipment, were analyzed. The experimental results showed that the internal temperature of the cabin initially increased after ignition. However, when the fire- extinguishing equipment was operated 30 s after ignition, the internal temperature of the cabin stopped increasing and started to decrease, satisfying the fire safety standard that the fire must be completely extinguished within 5 min. The temperature decreased more rapidly when the operating pressure was 20 bar than when it was 10 bar. In addition, the vertical temperature distribution analysis showed that the temperature of the upper part was higher than that of the lower part, owing to thermal buoyancy. However, the design of the nozzle location is critical because the temperature decreases more slowly far from the nozzle of the mist fire-extinguishing system, which can be dangerous.

Correction method for temperature measurements inside clouds using rotational Raman lidar.

Rotational Raman lidar is an important technique for detecting atmospheric temperature. However, in cloud regions with strong elastic scattering conditions, elastic scattering crosstalk (ESC) is prevalent due to insufficient out-of-band suppression of the optical filter, resulting significant deviations in temperature retrieval. To address this challenge, a temperature correction technique for optically-thin clouds based on the backscatter ratio is proposed. Using the least-squares method, a temperature correction function is formulated based on the relationship between the ESC and backscatter ratio of clouds. Subsequently, the backscatter ratio is used to correct the rotational Raman ratio of clouds, thereby obtaining the vertical distribution of atmospheric temperature within the cloud layer. The feasibility of this method was assessed through numerical simulations and experimentally validated using a temperature and aerosol detection lidar at the Xi'an University of Technology (XUT). The results indicate that the difference between the retrieved temperature profile under high signal-to-noise ratio conditions and radiosonde data is less than 1.5 K. This correction technique enables atmospheric temperature measurements under elastic scattering conditions with a backscatter ratio less than 115, advancing research on atmospheric structure and cloud microphysics.

A high-resolution dataset for lower atmospheric process studies over the Tibetan Plateau from 1981 to 2020

ABSTRACT A high-resolution meteorological dataset (≤10 km) over the Tibetan Plateau (TP) is the foundation for investigating and predicting the weather and climate over Asia. The TP Subregional Dynamical Downscaling (TPSDD) dataset is a newly developed high-spatial-temporal resolution gridded dataset for land‒air exchange processes and lower atmospheric structure studies over the whole TP region, taking the climate characteristics of each TP subregion into consideration. The dataset spans from 1981 to 2020, covering the TP with a temporal resolution of 2 hr and spatial resolution of 10 km. Meteorological elements of the dataset include near-surface land–air exchange parameters, such as downward/upward longwave/shortwave radiation flux, sensible heat flux, latent heat flux, etc. In addition, the vertical distributions of 3-dimensional wind, temperature, humidity, and pressure from the surface to the lower stratosphere are also included. Independent evaluations were conducted to verify the performance of the TPSDD dataset by comparing TPSDD/reanalysis with surface and vertical observations through the calculation of statistical parameters. The results demonstrate the accuracy and superiority of this dataset against reanalysis data, which provides great potential for future climate change research.

Thermal properties of treatment wetlands operated under freezing conditions.

The use of treatment wetlands (TWs) presents particular challenges in regions with sub-zero winter temperatures, due to reduced biological activity and risk of pipe breakage or clogging due to freezing. We studied the vertical temperature distribution in four pilot-scale TWs exposed to winter temperatures in order to determine the impact of operational system parameters and the role of insulation on heat conservation inside the filtering bed. The overall temperature pattern was similar in all wetlands, with a trend of increasing temperature from the surface toward the bottom during the cold season. No freezing was detected in the wetlands despite average daily temperatures as low as -20 °C. Influent water temperature and hydraulic loading had a stronger influence on TW temperatures in winter than air temperature. The vertical distribution of temperatures in TWs is more sensitive to hydraulic loading variation in the percolating operating condition than in the saturated flow with forced aeration configuration. Our results suggest that TW systems can remain operational under cold winter conditions provided the surface is properly insulated by vegetation, mulch and/or snow.

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.

Finite elements simulation MHD free convection in a rectangular embedded corrugated rods cavity filled with CuO/water nanofluid

The convective heat transfer and fluid is investigated in a rectangle chamber along with corrugated heated rods. For preferable novelties, this study considered porous media, micropolar fluid and an inclined magnetic field effect. The physical illustrations of nanofluid flow is assimilated in terms of differential equations. We use the finite element approach to tackle the fluid flow and heat transfer in rectangular chamber. Flow regulating parameters are Rayleigh number, Darcy number and Hartman number. The horizontal and vertical velocities and temperature distribution are provided through the use of contour plots and line graphs. The results show that heat transmission rates increase due to the increasing values of Hartmann number. Because Lorentz forces are resistive, the velocity profile tends to flatten down as long as Hartman number increases. The Nusselt number and velocity profile have greater values around the heat boundaries.

Evaluation of new radio occultation observations among small satellites at Venus by data assimilation

We conducted observing system simulation experiments (OSSEs) for radio occultation measurements (RO) among small satellites, which are expected to be useful for future Venus missions. The effectiveness of the observations based on realistic orbit calculations was evaluated by reproduction of the “cold collar”, a unique thermal structure in the polar atmosphere of Venus. Pseudo-temperature observations for the OSSEs were provided from the Venus atmospheric GCM in which the cold collar was reproduced by the thermal forcing. The vertical temperature distributions between 40 and 90 km altitudes at observation points were assimilated. The result showed that the cold collar was most clearly reproduced in the case where the temperature field in high-latitudes was observed twice a day, suggesting that the proposed observation is quite effective to improve the polar atmospheric structure at least. Although the cold collar was also reproduced in the OSSEs for Longwave Infrared Camera (LIR) observations, the result seemed unrealistic and inefficient compared to that obtained in the RO OSSEs. The present study shows that the OSSEs can be used to evaluate observation plans and instruments in terms of reproducibility of specific atmospheric phenomena, and applied to future missions targeting planetary atmospheres.

Temperature field test and prediction using a GA-BP neural network for CRTS II slab tracks

AbstractThe CRTS II slab track, which is connected in a longitudinal direction, is one of the main ballastless tracks in China, with approximately 7365 km of operational track. Temperature loading is a very vital factor leading to slab track damages such as warping and cracking. While existing research on temperature distribution rests on either site tests in special environments or theoretical analysis, the long-term temperature field characteristics are not clear. Therefore, a long-term temperature field test for the CRTS II slab track on bridge-subgrade transition section was conducted to analyze the temperature field. A GA-BP (genetic algorithm optimized back propagation) neural network was trained on the test data to predict the temperature field. The vertical and lateral temperature distributions in four typical days were carried out. We found that the temperature along the track was distributed in a nonlinear manner. This was particularly distinct in the vertical direction for depths of less than 300 mm. The highest and lowest daily temperatures and the daily range of the temperature were analyzed. With the increasing depth, the daily highest temperatures and range of the temperature were smaller, the daily lowest temperatures were higher, and the time corresponding to this peak value appeared later in the day. Both the highest and lowest daily temperature could be predicted using the GA-BP neural network, though the accuracy in predicting the highest temperature was higher than that in predicting the lowest temperature.

Study on the effect of obstacles on smoke diffusion and airflow structure in subway stations

Although obstacles exist in every subway station, the impact of obstacles on smoke diffusion characteristics is always overlooked. This work investigates the effect of rectangular obstacles on the ceiling temperature distribution, vertical temperature distribution, and airflow field structure in a subway station fire scenario. Small-scale experiments and numerical simulations are conducted considering varied fire location, heat release rate, blockage ratio, and obstacle location. A dimensionless temperature rise ratio is proposed to quantify the obstacle influence. The key results include (1) Obstacles would cause a proportional decrease in the ceiling temperature rise behind. And the proportion is positively correlated with the blockage ratio but not related to heat release rate, fire location, and obstacle location. (2) The influence of obstacles on vertical temperature rise presents hierarchical characteristics. The same proportional decrease is observed in the smoke layer at the top. As the height decreases in the mixture layer, the temperature rise ratio would also decrease gradually. The air layer at the bottom is kept at a small temperature rise ratio. (3) The wake area behind the obstacle is composed of a recirculation area and a wake recovery area. There is less smoke and slower airflow velocity in the wake area, which means the acquired temperature rise rule is not applicable in this area. A calculation method of the length of the wake area based on the airflow velocity characteristics is presented. This work aims at arousing attention on the influence of obstacles in the fire smoke studies in subway stations.

Evaluation of heating capacity of shallow ground heat exchangers in different Locations– A case study of two administrative districts of Xi'an

As a case study, two administrative districts of Xi'an are selected. Eight sites are drilled for shallow ground heat exchangers (SGHEs), and thermal response tests (TRTs) are conducted on the ground to investigate the heating capacity of SGHEs in different locations. The vertical distribution of initial ground temperature is identified using a temperature sensing system in TRTs. Simultaneously, the real-time inlet and outlet water temperatures of SGHEs are monitored by controlling heating power and buried pipe flow rate to be constant, and the thermophysical parameters of the ground are derived. A three-dimensional full-scale numerical model for buried pipe heat transfer is developed based on the results of TRTs. The heating capacity distribution of SGHEs is determined by clarifying the characteristics of buried pipe heat transfer at various locations and depths. The results showed that the maximum difference in geothermal gradient and ground thermal conductivity is 51.2 °C/km and 0.51 W/(m·K) respectively, indicating that the ground parameters vary significantly within the chosen places. The heat transfer intensity of SGHEs is directly related to buried pipe depth and mean circulating water temperature at the same locations. The same prediction formula can describe the heat transfer intensity of SGHEs at various locations.

Controlling effects of cap rocks on the formation of deep geothermal resources

Cap rocks with high thermal insulation are important for deep geothermal systems at a depth of 3000‒6000 m. Based on the deep geothermal geological conditions in the Fujian-Guangdong-Hainan area of South China, this study established an ideal geological model of reservoir-cap rock assemblages and simulated the geothermal field distribution of cap rocks of different thicknesses and thermal conductivity. The simulation results show that the vertical geothermal temperature distribution in an uplifted area of a depression was present as inverted mirror reflections relative to the elevated area of the basement. Specifically, the isotherms above the elevated area are convex in shape, while those below the elevated area are concave. There is a temperature equilibrium line between the convex and concave isotherms. The heat flow moves from the depressed area to the uplifted area below the temperature equilibrium line and migrates in an opposite direction above the line. On this base, this study conducted the inversion of geothermal temperature fields in typical areas with thin, moderately thick, and thick cap rocks. The results indicate that, at the depth of 3000–6000 m, areas with thin cap rocks (igneous rock zone in the coastal area of Fujian) mainly host moderate- to low-temperature hydrothermal resources; areas with moderately thick cap rocks (Yuezhong Depression) have the geothermal temperature ranging between 100 °C and 200 °C and may develop moderate- to high-temperature hydrothermal resources and hot dry rocks (HDRs), with the former superimposing on the latter; and areas with thick cap rocks (onshore Beibuwan Basin) have a geothermal temperature of 120‒220 °C, and contains mainly moderate- to high-temperature hydrothermal resources and HDRs. Therefore, it is recommended that the evaluation, exploitation, and utilization of deep geothermal resources be carried out according to the burial depth of the temperature equilibrium line and the specific demand for geothermal resources.