High Surface Heat Research Articles

Advancing Subseasonal Surface Air Temperature and Heat Wave Prediction Skill in China by Incorporating Scale Interaction in a Deep Learning Model

AbstractAccurate subseasonal predictions of high surface air temperature (SAT) and heat wave events 10–30 days in advance are crucial for mitigating the risks of extreme weather; however, they pose a challenge for current operational models. In this study, we trained a convolutional neural network (CNN)‐based deep learning model to exploit the modulations in China's SAT by precursor signals across different timescales to improve predictions of future SAT and heat wave events. This CNN model demonstrated superior capability in capturing the evolution of SAT anomalies and the occurrence of heat wave events with forecast lead times beyond 20 days, compared with that of the operational models of the China Meteorological Administration and European Centre for Medium‐Range Weather Forecasts. Explainability analysis highlighted that subseasonal SAT predictability in China is driven primarily by large‐scale intraseasonal perturbations from both lower‐ and higher‐latitude regions of Eurasia and interannual variability.

Circulation responses to surface heating and implications for polar amplification

Abstract. A seminal study by Hoskins and Karoly (1981) explored the atmospheric circulation response to tropospheric heating perturbations at low latitudes and midlatitudes. Here we revisit and extend their study by investigating the circulation and temperature response to low, middle, and high latitude surface heating using an idealised moist grey radiation model. Our results corroborate previous findings showing that heating perturbations at low latitudes and midlatitudes are balanced by different time-mean circulation responses – upward motion and horizontal-temperature advection, respectively. Transient eddy heat flux divergence plays an increasingly important role with latitude, becoming the main circulation response at high latitudes. However, this mechanism is less efficient at balancing heating perturbations than temperature advection, leading to greater reliance on an additional contribution from radiative cooling. These dynamical and radiative adjustments promote stronger lower-tropospheric warming in response to surface heating at high latitudes compared to lower latitudes. This elucidates the mechanisms by which sea ice loss contributes to polar amplification in a warming climate.

Development and manufacturing of beryllium-armoring ITER enhanced heat flux FW toward series production in China

ITER’s enhanced heat flux (EHF) first wall (FW) provides thermal shielding to the other components behind it and limits its plasma boundary, consequently bearing high surface heat loads up to 4.7 MW m−2. China developed the EHF FW technologies in steady stages by making small mock-ups, semi-prototypes and a full-scale prototype (FSP), working toward series production at the Southwestern Institute of Physics. All the key technologies for bimetallic diffusion bonding, welding and assembly have been fully qualified. The Be armor tile size effects on thermal-fatigue performance have been evaluated using a pulsed high heat flux test with an EMS-400 electron beam facility. It was found that both the Be/CuCrZr bonding and its thermal-fatigue life are highly dependent on the tile size, and 12 × 12 mm2 Be tiles are acceptable for the required performance, either as individual tiles or in castellation by cutting larger ones. Small-scale mock-ups with such Be tiles survived 16 000 thermal cycles at 4.7 MW m−2, while EHF FW fingers with 16 × 16 mm2 Be tiles demonstrated unstable performance. In contrast, only BE tiles larger than 24 × 12 mm2 showed reliable diffusion bonding with the CuCrZr heat sink by hot isostatic pressing and consequently should be castellated into smaller ones. The manufacturing of the FSP finger goes through complex thermal cycles, using CuCrZr alloys in age-strengthening plus cold-rolling states, enabling it to maintain its tensile strength to the level of 285 MPa and its mean grain size less than 100 µm. The pipe welding for finger pairing and its assembly with the central beam are demonstrated, including enabling welding to be carried out twice for repair in a narrow space. The FSP showed good finger alignment, dimensional control and reliable vacuum tightness without any blockage of cooling channels.

Preparation of novel reticulated porous ceramics with textured structures enabled by in situ generated interlocking Al2O3 platelets

Al2O3 reticulated porous ceramics (ARPCs) are extensively employed in high-temperature catalytic support, molten metal filtration, and porous media combustion because of their high specific surface area and heat resistance. The high specific surface area is usually maintained by high apparent porosity, but unfortunately, the accompanying poor mechanical properties severely compromise the durability of ARPCs. To synergistically improve the mechanical properties and apparent porosity, a new strategy was proposed to prepare ARPCs with textured structures of in situ interlocking Al2O3 platelet integration using vacuum impregnation Na3AlF6–SiC–Al2O3 slurry technique. The obtained textural structure had a significant strengthening effect on ARPCs, attributed to the increased contact area among non-equiaxed grains, and the compact growth of Al2O3 platelets with high aspect ratios provided the high apparent porosity and specific surface area of ARPCs, resulting in compressive strength as high as 3.93 MPa at an apparent porosity of 85.31 %, as well as the degradation of Congo red up to 75.35 % due to the Al2O3 platelets facilitating the loading of TiO2.

Study on hot isostatic pressing conditions of ARAA for fabrication of the breeding blanket first wall

The helium-cooled concept with solid breeding materials is one of the candidates for demonstration fusion power reactor (DEMO) breeding blanket. The first wall (FW) is a core component of the breeding blanket. The FW should keep the structural integrity during the normal plasma operation which is subject to high surface heat flux, neutron wall load, and high coolant pressure simultaneously. Various fabrication methods have been studied for the development of the FW fabrication technologies. This study focuses on FW fabrication technologies with hot isostatic pressing (HIP) bonding which is considered as the most promising method for achieving such complex shape like FW having internal cooling channels. We investigated the HIP bonding conditions using Advance Reduced Activation Alloy, ARAA, which is a reduced activation ferritic-martensitic steel under development in Korea. Temperature, holding time and pressure were considered as the parameters to optimize the HIP bonding conditions. The microstructures around the HIP joints changed with respect to the HIP bonding temperature. The amount of oxide particles around the HIP joints varied depending on the degassing conditions. The tensile strength of the HIP joint was not greatly affected by the presence of the HIP bonding line and degassing conditions. On the other hand, it has been confirmed that the Charpy absorbed energy of the HIP joint was significantly affected by degassing conditions. An increase in oxide particles around the HIP joints occurred when degassing temperature and vacuum level were low, and as the quantity of oxide particles increased, the Charpy absorbed energy of the HIP joint decreased substantially.

Blind magmatism abets nonvolcanic continental rifting

Tectonic forces alone cannot drive rifting in old and thick continental lithosphere. Geodynamic models suggest that thermal weakening is critical for lithospheric extension, yet many active rifts lack volcanism, seeming to preclude this process. We focus on one such rift, the Tanganyika-Rukwa segment of the East African Rift System, where we analyze local seismicity for shear wave anisotropy and couple the results with numerical modeling. The strongest splitting measurements are from earthquakes with paths sampling lower crustal regions of high compressional-to-shear wave velocity ratios and have fast polarization directions parallel to the local mantle flow, implying the existence of oriented melt lenses. This lower crustal magmatism and observed high surface heat flow are consistent with substantial lithospheric weakening and explain the enigmatic relief and increasing strain accommodation along the rift axis. We conclude that progressive nonvolcanic rifting is assisted by deep crustal melts yet to breach the surface.

Preparation of a novel SiO2/PMMA nanocomposite with high transparency, thermal stability, and superior surface hardness via gamma‐radiation polymerization

AbstractHeat‐resistant, highly surface‐hardened, and transparent composites of poly(methylmethacrylate) (PMMA) play a significant role in modern devices. However, conventional PMMA‐based composites with high nanoparticle loadings often compromise transparency for high surface hardness and heat resistance due to nanoparticle aggregation and poor interfacial compatibility. In this work, we successfully fabricated an exceptional composite (MSiO2/PMMA composites) with high transparency, superior heat resistance, and high surface hardness using γ‐ray irradiation‐induced polymerization of methyl methacrylate (MMA) containing uniformly dispersed SiO2 that was modified by 3‐methacryloxypropyl trimethoxysilane and trimethylchlorosilane. Specific silanes were utilized for polarity regulation to reduce the agglomeration of SiO2 nanoparticles and improve compatibility with MMA. Compared to pure PMMA, the 40‐MSiO2/PMMA composite sample exhibited significantly improved thermal stability in terms of the temperature at 10% weight loss (T10%), glass transition temperature (Tg), and decreased coefficient of thermal expansion (CTE). Furthermore, this composite achieves a very high surface hardness (pencil hardness of 6H versus H for pure PMMA) while maintaining transparency similar to PMMA. These MSiO2/PMMA composites open up new avenues to enhance the performance and durability of materials used in various industries such as electronics, optics, automotive, and aerospace.

Graphene footprints in energy storage systems—An overview

With the nanomaterial advancements, graphene based electrodes have been developed and used for energy storage applications. Important energy storage devices like supercapacitors and batteries have employed the electrodes based on pristine graphene or graphene derived nanocomposites. This review mainly portrays the application of efficient graphene and derived nanocomposites in substantial energy storage devices (supercapacitors and Li ion batteries). The structural and physical features of graphene-based nanocomposites such as high surface area, robustness, heat stability, electron conduction, specific capacitance, charge or energy density, charge-discharge performance, capacity, cyclic stability, performance life, etc. have been found beneficial for these devices. Despite the superior nanocomposite features and ensuing high devices performance, numerous challenges need to be overcome to attain future desirable energy storage device performance.

Thermal structure beneath Changbaishan Volcano, northeastern Asia: new insights from temperature logging and numerical modelling

SUMMARY Changbaishan Volcano is considered one of the most hazardous active volcanic fields in northeastern Asia, and it has been the subject of increasing concern due to its unrest from 2002 to 2006. The physical conditions of magma chambers in the crust, particularly temperature and pressure, are crucial factors that determine the tempo and magnitude of volcanic eruptions, which are closely linked to potential hazards. However, the lithospheric thermal structure, which strongly influences rheological behaviour and melting, has been poorly studied. We conducted direct geothermal measurements and numerical forward modelling to address this issue to confirm whether a crustal magma chamber lies beneath the caldera as in earlier geophysical interpretations. We first reported four heat-flow data sets in Changbaishan Volcano. The research findings indicate that the heat flow value near the Tianchi caldera is remarkably high, at 270±16 mW m−2. As the distance from the caldera increases, the heat flow gradually decreases to a normal continental heat flow value of 75 mW m−2. 3-D transient heat simulations with a magma cooling model and a continuous magma supply model demonstrate the thermal effect of the magma chamber. The best-fitting model for the Tianchi magma system is an ellipsoidal magma chamber with a depth of 8–14 km, a 20 km east–west axis and a 70 km north–south axis, supplied with magma from the asthenosphere for 2 Myr. The high surface heat flow and crustal temperatures suggest that magma is active beneath Changbaishan Volcano within the middle-upper crust, and volcanic reactivation could occur. Thus, further research on the lithospheric thermal structure is necessary to understand the potential volcanic hazards associated with Changbaishan Volcano.

Crustal and uppermost mantle structures imaged by teleseismicP-wave traveltime tomography beneath the Southeastern Korean Peninsula: implications for a hydrothermal system controlled by the thermally modified lithosphere

SUMMARYThe southeastern Korean Peninsula (SeKP) has experienced intense deformation owing to subduction and backarc extension at the eastern continental margin of the Eurasian Plate, leading to the formation of complex tectonic structures. Abnormally high surface heat flux, Cenozoic volcanism, signatures of mantle degassing and hydrothermal alteration, and several active fault systems with extensional sedimentary basins have been identified; however, the major driving forces that promote local seismic events and hydrothermal activities remain enigmatic. Here, we constructed 3-D P-wave velocity of the crust and upper mantle in the SeKP for the first time using a teleseismic traveltime tomography method and an extensive data set obtained from a dense seismic network. Our model revealed three distinct velocity patterns at different depths: (1) in the upper crust (depth ∼0–10 km), a low-velocity anomaly beneath the Cenozoic sedimentary basin exhibiting a prominent lateral velocity contrasts with higher velocities in the Cretaceous sedimentary and plutonic rocks; (2) a N–S trending low-velocity anomaly extending from the lower crust to the uppermost mantle (depth ∼20–35 km) beneath the major active fault systems interpreted as a thermally or mechanically weakened structure that could transfer high surface heat flux and transport mantle-driven gases and (3) a low-velocity anomaly adjacent to the Cenozoic basin in the upper mantle at depths of 35–55 km interpreted as the higher temperature upper mantle. Via a series of geodynamic simulations, we demonstrated that the extensional deformation at the eastern continental margin during the Early to Middle Miocene locally enhanced the temperature of the crust and upper mantle beneath the SeKP. We propose that a hydrothermal system, resulting from the thermally modified lithosphere of the continental margin, has contributed to the enhanced local seismicity and geothermal activities observed in the SeKP region.

Marine Heatwave Characteristics in the Makassar Strait and Its Surrounding Waters

This study aimed to investigate the characteristics of marine heatwaves (MHWs) in the Makassar Strait and adjacent waters (MSAW) using the Optimum Interpolation Sea Surface Temperature (OISSTv2) dataset from 1982 to 2021. The analysis revealed a significant positive trend in the frequency and duration of MHWs, while the mean and maximum intensities displayed a negative trend over the 40-year period. By examining two different phases of the Pacific Decadal Oscillation (PDO), it was observed that the cold phase (more frequent La Niña events than El Niño) had higher MHW frequency and duration, whereas the warm phase (more frequent El Niño events than La Niña) exhibited higher mean and maximum intensities. Moreover, the occurrence of high-intensity MHWs was associated with weakened winds, the decaying phase of El Niño and positive Indian Ocean Dipole (IOD), and high net surface heat flux (NSHF). An intriguing finding emerged, indicating a notable lag of 7–9 months (10 months) between El Niño (positive IOD) events and the emergence of high-intensity MHWs. This lag suggests that MHWs are more likely to manifest during the transition towards La Niña and negative IOD conditions. Additionally, the study highlighted a stronger correlation between the El Niño–Southern Oscillation and MHW intensity in the MSAW compared to the IOD. Furthermore, the different intensities of MHWs were found to be linked to NSHF, which exhibited higher values during the warm phase of the PDO compared to the cold phase.

Heat transfer analysis of water-ethylene glycol (50:50) based nanofluid over a cone with the influences of magnetic field and uniform heat generation/absorption

Aim:The novelty of the problem is to examine the heat transfer analysis of H2O–C2H6O2 (50:50) mixture based Al2O3 and Fe3O4 over a heated and spinning down-pointing vertical cone with the effect of heat generation or absorption in the presence of magnetic field. Findings:Results are demonstrated in terms of graphs to examine the influence of various physical parameters that come across such as Magnetic parameter M, Spin parameter ϵ, Nanoparticle volume fraction ϕ, Heat generation or absorption parameter Δ, velocity slip parameter Γ1 and thermal slip parameter Γ2 on dimensionless velocity profile F′(y), G(y) and temperature profile H(y). The effect of M, ϵ, ϕ, Δ,Γ1,Γ2on skin friction and local Nusselt number are examined in tabulation form. Significant outcomes:It is pointed out that enhancement in Magnetic parameter and thermal slip parameter leads to declination of the velocity profile. Influence of Heat generation or absorption parameter magnifies the thermal characteristic of the flow. Moreover, the numerical statistics was triggered and catalogued to analogize the results of existing outcomes with those of previous literature for some special cases and established excellent agreement. Fe3O4 possess 0.78% and 0.92% of high surface drag force and heat transfer rate respectively than Al2O3 with respect to heat generation or absorption parameter. Approach:The system of partial differential equations is transformed into set of nonlinear ordinary differential equations. Solutions for the system of nonlinear Ordinary differential equation are obtained by Numerical method. The numerical scheme is developed based on fourth order Runge Kutta scheme along with shooting techniques. Practical implications:In this current growing scenario, engineers and scientists are making an endeavour to gratify the global needs. Nanofluids are considered as inevitable one for achieving industrial and global needs. The investigation of heat transfer over rotating cone with the effect of magnetic field is of considerable interest due to its presence in industrial and technological applications. Especially in the design of turbines and turbo equipment’s and in understanding the path of flight of rotating wheels.

Strong Variability in the Thermal Structure of Tibetan Lithosphere

AbstractWe present a model of thermal lithospheric thickness (the depth where the geotherm reaches a temperature of 1300°C) and surface heat flow in Tibet and adjacent regions based on a new thermal‐isostasy method. The method accounts for crustal density heterogeneity, is free from any assumption of a steady‐state lithosphere thermal regime, and assumes that deviations from crustal Airy‐type isostasy are caused by lithosphere thermal heterogeneity. We observe a highly variable lithospheric thermal structure which we interpret as representing longitudinal variations in the northern extent of the subducting Indian plate, southward subduction of the Asian plate beneath central Tibet, and possible preservation of fragmented Tethyan paleo‐slabs. Cratonic‐type cold and thick lithosphere (200–240 km) with a predicted surface heat flow of 40–50 mW/m2 typifies the Tarim Craton, the northwest Yangtze Craton, and most of the Lhasa Block that is likely refrigerated by underthrusting Indian lithosphere. We identify a “North Tibet anomaly” with thin (<80 km) lithosphere and high surface heat flow (>80–100 mW/m2). We interpret this anomaly as the result of removal of lithospheric mantle and asthenospheric upwelling at the junction of the Indian and Asian slabs with opposite subduction polarities. Other parts of Tibet typically have intermediate lithosphere thickness of 120–160 km and a surface heat flow of 45–60 mW/m2, with patchy anomalies in eastern Tibet. While different uplift mechanisms for Tibet predict different lithospheric thermal regimes, our results in terms of a highly variable thermal structure beneath Tibet suggest that topographic uplift is caused by an interplay of several mechanisms.

Design of a Prototypical Mock-Up for the Experimental Investigation of WCLL First-Wall Performances

A large research effort is currently ongoing within the framework of the EUROfusion consortium for the study and design of a water-cooled lithium–lead (WCLL) breeding blanket (BB). This concept will be tested in ITER through the installation of a test blanket module (TBM) and it is one of the two candidates adopted as driver BBs in DEMO. In this framework, at the ENEA research centre of Brasimone, the realization of the experimental platform, W-HYDRA, is envisaged. The platform is dedicated to the support of the development of WCLL BB and ITER TBM and the investigation of the DEMO balance of plants. One of the most important experimental infrastructures is the water-loop facility, the aim of which is to provide water at a high pressure and temperature (PWR conditions), with a sufficient mass-flow rate and power for the experimental testing of BB and TBM components. The facility will be equipped with a vacuum chamber and an electron beam gun for the reproduction of high surface heat flux on plasma-facing components. In the present work, the design of a prototypical mock-up (MU) of the WCLL BB first wall is described. The MU is used to investigate the thermal, hydraulic and structural behavior of the current first-wall design under relevant heat loads at the expected operational conditions. The delineation of the main experimental test’s features and the instrumentation needed is assessed in the paper. A preliminary CFD calculation on the prototypical MU and the computational results are also presented.

Application of spectral analysis to determine the magnetic source depths in ibarapa district, oyo state, sw nigeria

The method of spectral analysis was applied to the total aeromagnetic intensity data covering the district of Ibapara, located on the Nigeria Basement Complex in Oyo State, SW Nigeria. Prior to the spectral analysis, inclined magnetisation was converted to vertical, reduced to the pole and filtered out in order to more correctly reflect spatial location and morphology of magnetic sources over geological bodies, and enhance the effects of shallower sources over deeper ones. The data was divided into blocks and sub-blocks, and was spectrally analysed for the depths to the deep- and shallow-seated magnetic sources. The Curie-point-depths computed from these depths vary between 20.8 and 32.73 km, indicating that the magnetized basement rocks are at different elevations and are probably block faulted. The correlation of shallow Curie-point-depth with the Older Granites inferred that the low Curie-point-depth is due to magmatic intrusion in the highly deformed migmatite unit, the main geologic unit. The surface heat flows derived from the Curie-point-depths vary between 40.82 and 62.84 with a mean of 50.10 mW m-2, with areas having high surface heat flow presumed to be areas of recent intrusions where the elevated heat has transformed appropriate minerals to sapphire, tourmaline and aquamarine. Correlations of the surface heat flows and the average geothermal gradients on one hand and the Curie-point-depth on the other, unlike global compilation, yielded close empirical relations that are attributed to homogeneous geology of the area.

Local phase and thermal behaviors in pool boiling on different wettability surfaces

In this work, we study the effect of surface wettability on boiling heat transfer and critical heat flux through experimental and numerical methods. In the experiments, four surfaces with different wettability, i.e., bare, SiO2-coated, TiO2-coated, and PTFE-coated on smooth sapphire surfaces, were examined. The visualization results of liquid–vapor phase distributions on the boiling surfaces indicated that the behaviors of dry spots, bulk liquid, and microlayers on the surfaces are significantly deviated from each other surface with varying wettability. Particularly, the rewetting behaviors of the relatively large dry spots occurred under the high heat flux condition showed that the surrounding liquid to wet the dry spots suffers a stronger resistance from the evaporative force at the triple contact line for the less wettable surface. In the numerical analysis, the local surface temperature and heat flux data on the boiling surfaces were obtained and systemically analyzed. The numerical results showed that the nucleate boiling regime can be maintained under the high heat flux condition by the repetitive process of nucleation of the dry spots and their destructions by the wetting of the surrounding liquid, i.e., quenching. However, for a particular dry spot appeared at a high surface heat flux, the quenching action was seriously limited, and the spot expanded irreversibly on the surface, indicating the CHF trigger. From the numerical results, we found that such a dry spot could be initiated by overheating the spot beyond a critical temperature limit which increases with the surface wettability and the heat flux focusing effect around the spot. Finally, the local and transient boiling behaviors were analyzed using the boiling curves separated into wet and dry regions.

Combining Dense Seismic Arrays and Broadband Data to Image the Subsurface Velocity Structure in Geothermally Active South‐Central Utah

AbstractSouth‐central Utah is characterized by Quaternary volcanism, current geothermal activity, and unusually high surface heat flux across the region. Additionally, there are three operating geothermal power plants in this region, known as the Sevier thermal area. This setting is very similar to that found in the Coso geothermal area. However, the source and lateral extent of subsurface heat in Utah is poorly understood. We use temporally separated geophone arrays combined with regional broadband data to perform ambient noise seismic tomography to study the subsurface shear velocity structure in the region. We find good recovery of ocean‐seism excited Rayleigh wave signals between the periods of 5 and 10 s. For each period, we measure the Rayleigh wave phase velocity and ellipticity across the region using the beamforming methodology and horizontal to vertical (H/V) amplitude ratio. Finally, we combine spline‐based 1D shear velocity models inverted using Rayleigh wave phase velocity and H/V measurements on a 2D, beamforming discretized grid to construct a final 3D model. The final 3D model has many similarities to imaged velocity models at the Coso geothermal area. We find a strong correlation between low velocity anomalies and high surface heat flux and geothermal activity. Additionally, we find a laterally continuous low‐velocity anomaly between 5 and 15 km depth, which may represent elevated temperature of hundreds of degrees Celsius, partial melt, and/or the presence of water, and a common heat source across the region which likely originates from the mantle.

Real-time laser ultrasonic monitoring of laser-induced thermal processes

Intra- and inter-layer integrity of components fabricated with advanced manufacturing techniques, such as laser powder bed fusion, is dependent upon rapid heating, melting, and solidification processes. There is a need for new techniques to provide in situ feedback of these processes. Here a laser-based ultrasonic technique to probe thermal effects induced by a high-power continuous wave laser in titanium samples is described. Numerical simulations were performed to show that, for a spatially uniform heating beam, laser-induced surface acoustic waves are strongly influenced by surface heating conditions, are dispersive in the case of rapid heating, and that an abrupt velocity reduction happens upon the onset of surface melting. Furthermore, laser-based ultrasound experimental results which monitor the transient change of surface wave travel time associated with high power laser surface heating are provided. A pulsed laser is used to generate high frequency surface acoustic waves that propagate through the laser-heated region and are detected using a photorefractive crystal-based interferometer. Qualitative agreement is observed between theory and experiment with both showing a rapid reduction in the surface wave velocity at the onset of illumination and further decrease in surface wave velocity associated with melting. It is demonstrated that changes in the surface wave velocity can be used to track local heating and detect the onset of surface melting in real time.

Spatial mapping and monitoring thermal anomaly and radiative heat flux using Landsat-8 thermal infrared data – A case study of Lamurde hot spring, upper part of Benue trough, Nigeria

The upper Benue trough, northeastern Nigeria is characterized by prominent geologic and tectonic features of diverse scientific and economic interest. Lamurde hot spring is located within one of several deformational structures of the trough; the Lamurde anticline. In this work, we assessed the geothermal energy potential of the area using the Thermal Infra-Red (TIR) band of Landsat-8 data. We used four datasets representing the four seasons of the year to retrieve the Land Surface Temperature (LST) by converting the pixel digital numbers into LST based on the single-channel algorithm. We also used the retrieved LST to spatially map Radiative Heat Flux (RHF) based on the Stefan-Boltzmann radiation law. We validated the results by comparing the Landsat TIR-retrieved LST with MODIS LST product of the same area using a cross-validation technique. The results indicate a reliable fitting coefficient (R2 = 0.801) and Root Mean Square Error RMSE value of 0.756 K. Although significant seasonal variation of both LST and RHF was observed, the rock outcrops associated with the hot spring high surface temperature and heat loss anomalies for all seasons of the year. Peak LST values of 43.7 °C, 35.6 °C, 29.4 °C, and 27.5 °C were respectively recorded in January, April, July, and October from the active thermal area. The average values of RHF obtained from the active thermal area are 11.78, Wm−2, 10.76 Wm−2, 1.22 Wm−2 and 0.168 Wm−2 for January, April, July and October respectively. These are much higher than the global continental value. Comparison with known active geothermal areas from different parts of the world indicates that the area has significantly high surface geothermal parameter indicators.

Three‐Dimensional Thermal Structure of East Asian Continental Lithosphere

AbstractThe thermal structure of East Asian continental lithosphere is critical for understanding its diffuse and variable intracontinental deformation in the Cenozoic. Here, we present a three‐dimensional model of the lithospheric thermal structure of East Asia, using the latest thermal conductivity and radiogenic heat production measurements in mainland China. The results show great lateral heterogeneity of lithospheric temperature. The crust of orogenic belts such as the Tibetan Plateau, the Mongolia Plateau, the Tian Shan orogen, and Northeast China, is generally characterized by high temperatures. Other regions of high crustal temperatures include the southeast coast of China and Lake Baikal. The heat sources for the crust also vary. In the Tibetan Plateau, high crustal temperatures result mainly from radiogenic heat production within the thick crust, indicating the influence of continental collision. However, high heat flow from the upper mantle is the main cause of high surface heat flow in the eastern part of East Asia, where the relatively thin lithosphere and hot asthenosphere is related to the subduction of the Pacific Plate. This subduction is also responsible for Cenozoic continental volcanoes in East Asia.