Ground Surface Temperature Changes Research Articles

Optical and Thermal Image Processing for Monitoring Rainfall Triggered Shallow Landslides: Insights from Analogue Laboratory Experiments

This study explores the innovative use of digital image processing (DIP) techniques, also named PhotoMonitoring, for analysing the triggering conditions of shallow landslides. The approach, based on the combination of optical and infrared thermographic imaging (IRT), was applied to a laboratory-scale slope, reproduced in a flume test apparatus. Three experiments were conducted to replicate rainfall-induced shallow landslides, applying change detection and digital image correlation analysis to both optical and thermal images. The method combines IRT’s ability to measure ground surface temperature changes with DIP’s capacity to track movement and displacement. Results showed the high reliability of the displacement time-series obtained through IRT-DIP with respect to the reference optical-DIP. The IRT-DIP technique also detects anomaly signals two minutes before landslide occurrence that can be regarded as a possible failure precursor. This study testifies to the potential of image analysis as a remote sensing technique, demonstrating the ability of DIP to capture the dynamics of shallow landslides, as well as the advantages of optical–IRT combinations to follow slope deformation processes during night-time. This approach, if properly adapted to real-scale scenarios, may contribute to a better understanding of landslide behaviour, improve landslide monitoring strategies, and promote more effective early warning systems (EWS).

Optimal Leg Height of Landing Legs to Reduce Risk of ‎Damage from Regolith Ejecta by Retrorocket Exhausts

Over the past decade, there has been a rapid increase in rocket launches. 2022 was a record-breaking year for the ‎aerospace ‎industry, with 180 successful rocket launches into orbit, 44 more than the previous year. Reducing as ‎many risks as possible is ‎essential as interplanetary rocket launches and reusable booster landings become more ‎frequent. One such risk occurs when a ‎rocket/booster lands. During the landing process, the retrorockets spray debris ‎from the loose ground, which may damage the ‎rocket/landing module. Retrorockets are rocket engines that provide ‎a thrust opposing the spacecraft’s motion, causing it to ‎decelerate. This paper studies the effect of landing leg height ‎on ejecta velocity, the volume of debris ejected, and ground ‎surface temperature change. Four landing leg heights ‎were tested with an Estes® E-16 consumer model rocket motor: 0 mm, ‎‎50 mm, 75 mm, and 100 mm. The ‎experiment suggests that the optimal height above the ground’s surface for a simulated ‎landing module based on ‎the volume and velocity of the ejecta is 50 mm. Landing legs that elevate a model rocket this height ‎create an ‎average crater volume of 610.5 mL and a max crater diameter of 10.34 cm. After determining the optimal height, a ‎‎landing leg system was developed. This system was attached to an Aerodactyl TS® model rocket and utilized ‎landing legs that ‎elevated the rocket to a height of 50 mm above the ground at landing.‎‎

Use of Modified Tikhonov Regularization in Analysis of Ground Surface Temperature Variations

Inversion techniques employed in geothermal studies of ground surface temperature (GST) changes are known to have problems of instability and non-uniqueness in numerical solutions. In the present work it is pointed out that some of these difficulties can be overcome through the use of a method based on Tikhonov regularization of order one which imposes smoothing of main parameters. A major disadvantage of this approach is obliteration of weak thermal signals usually present at larger depths at the expense of strong ones present at relatively shallow depths. In the present work we consider a convenient way of minimizing this problem using a method based on Tikhonov regularization of order one. In this approach residuals of observational data are minimized by imposing constraints on the variations of smoothing parameters, that is controlled by the magnitude of regularization coefficients. This is accomplished in two stages of inversion. In the first stage we seek an estimation of the dates of climate events derived from results of temperature logs. Inversion of the second stage allows estimation of the magnitudes of GST variations that are compatible with the ages of climate events of the first stage. The advantage is in finding better solutions without introducing other artefacts on the climate history. Such two-stage Tikhonov regularization procedures has been employed for extracting complementary information on GST history in continental regions of Brazil. The results reveal that the main warming event of the last century has been preceded by several secondary events during the time period of 1400 to the 2000 A.D.

Ground Surface Temperature History Since the Last Glacial Maximum in Northeast Asia: Reconstructions From the Borehole Geotherms of the International Continental Scientific Drilling Program

AbstractPast ground surface temperature (GST), one of the important aspects of paleoclimate reconstructions, can be inverted from borehole temperature measurements. Here, we report continuous 6,100‐m temperature logs in the International Continental Scientific Drilling Program SK‐2e. We inverted the past GST changes from upper borehole temperature logging (<600 m). Below this depth, localized fluid flow masks the paleoclimate record. Inversions yield an approximately 2 K GST rise since 0.1–0.6 Kyr BP and an approximately 10 K rise since 20 Kyr BP. Assuming a ±5 K influence from the deep groundwater flow, the inverted temperature rise has varied between 8 and 12 K since 20 Kyr BP, which is consistent with previous reports since the Last Glacial Maximum. Our results emphasize the potential of borehole heat‐flow profiles as a record of climate changes and the importance of climate correction for heat‐flow determinations.

Simulated Trends in Land Surface Sensible Heat Flux on the Tibetan Plateau in Recent Decades

The spatial distribution and temporal variation of land surface sensible heat (SH) flux on the Tibetan Plateau (TP) for the period of 1981–2018 were studied using the simulation results from the Noah-MP land surface model. The simulated SH fluxes were also compared with the simulation results from the SEBS model and the results derived from 80 meteorological stations. It is found that, much larger annual mean SH fluxes occurred on the western and central TP compared with the eastern TP. Meanwhile, the inter-annual variations of SH fluxes on the central and western TP were larger than that on the eastern TP. The SEBS simulation showed much larger inter-annual variations than did the Noah-MP simulation across most of the TP. There was a trend of decrease in SH flux from the mid-1980s to the beginning of the 21st century in the Noah-MP simulations. Both Noah-MP and SEBS showed an increasing SH flux trend after this period of decrease. The increasing trend appeared on the eastern TP later than on the western and central TP. In the Noah-MP simulation, the western and central TP showed larger values of temperature difference between the ground surface and air (Ts–Ta) than did the eastern TP. Both mean Ts–Ta and wind speed decreased from the mid-1980s to approximately 2000, and then increased slightly. However, the Ts–Ta transition occurred later than that of wind speed. Changes in mean ground surface temperature (Ts) were the main cause of the decreasing and increasing trends in SH flux on the TP. Meanwhile, changes in wind speed contributed substantially to the decreasing trend in SH flux before 1998.

Analysis of Vegetation Coverage Evolution and Degradation under Coal Mine Construction in Permafrost Region

The ecological environment in permafrost regions is very sensitive to climate change and human activities. The effects of coal mining on the vegetation in permafrost regions have been poorly studied. Herein, on the basis of a field survey in the Juhugen mining area of Qilian Mountain, China, we investigated and quantified the influence of open-pit coal mining on vegetation coverage degradation in permafrost areas. According to the NDVI and field survey, the vegetation coverage was divided into five levels from low to high in the Arc GIS platform. Compared with the area not affected by coal mining, vegetation degradation was significant in the coal-mining-affected area, especially in the high-vegetation-coverage area. The vegetation coverage in Level 5 decreased from 51.99% to 21.35%. According to the conversion matrix, the transfer-out area in high coverage was larger, while the transfer-in area in low vegetation coverage was larger. The transfer-out area of five levels was significant in levels 2–5, accounting for 36.1% to 62.8% of the total area. The transfer-in area of five levels was significant in levels 1–4, accounting for 55.2% to 75.0% of the total area. Moreover, the ground surface temperature and water change were monitored in the vegetation degradation area. The results showed that the above degradation was related to an increase in the ground surface temperature and a decrease in the ground surface moisture.

Tree rings reveal changes in the temperature pattern in eastern China before and during the Anthropocene

A comprehensive understanding of the spatial characteristics of warming trends and temperature variability is important given global warming. Paleoclimate reconstruction has played an important role in evaluating warming and extreme climactic events in recent decades. Using the ring width of Pinus tabulaeformis, we reconstructed the ground surface temperature changes at Mengshan Mountain, in the central part of eastern China (EC), from 1667 to 2019. There were 3 extremely low-temperature years, 42 low-temperature years, 256 normal years, 37 high-temperature years and 15 extremely high-temperature years over the past 353 years. High and extremely high temperatures mainly occurred in the first half of the 19th century, the end of the 20th century and the beginning of the 21st century; low and extremely low temperatures occurred in almost all periods except for the last 50 years. By combining the past temperature reconstructions from the Great Xing’an Mountains in northern EC and Taiwan in southern EC, we also found that after the start of the Anthropocene, there were strong positive correlations among the temperatures of the northern, central and southern parts of EC. However, before the Anthropocene, these correlations were weak, and there was even a significant negative correlation during some periods. Additionally, the temperature in EC exhibited different change patterns before and during the Anthropocene. Before the Anthropocene, the temperature in southern EC showed an upward trend; in central EC, the temperature first rose and then began to decline in the 1820s; there was no obvious trend in the temperature changes in northern EC. The spatial consistency of temperature changes during the Anthropocene might be related to the fact that greenhouse gases emitted by human activities diffuse evenly withatmospheric circulation and absorb longwave radiation to directly heat the atmosphere.

Land Development and Role of Evapotranspiration in Climate Change

Analyses of underground temperatures have been used to obtain ground surface temperature (GST) histories. At individual sites, changes in the GST over time are synchronous with development which altered the evapotranspiration. At different, closely spaced sites, measured differences in GST between sites depend on the relative amounts of evaporation and transpiration at each site. These observations prove that a significant portion of the climate change observed on land is caused by changes in the amounts of evapotranspiration at each location. The magnitudes of GST changes vary from 0.6 to 2.6 C, for developments occurring from 8 to 52 years ago. In the temperate zone of Canada, these differences occur primarily in the summer. Our development, including urbanization and development of agricultural land, has produced a significant warming. It is best defined from underground temperature data.

Long-term global ground heat flux and continental heat storage from geothermal data

Abstract. Energy exchanges among climate subsystems are of critical importance to determine the climate sensitivity of the Earth's system to greenhouse gases, to quantify the magnitude and evolution of the Earth's energy imbalance, and to project the evolution of future climate. Thus, ascertaining the magnitude of and change in the Earth's energy partition within climate subsystems has become urgent in recent years. Here, we provide new global estimates of changes in ground surface temperature, ground surface heat flux, and continental heat storage derived from geothermal data using an expanded database and new techniques. Results reveal markedly higher changes in ground heat flux and heat storage within the continental subsurface than previously reported, with land temperature changes of 1 K and continental heat gains of around 12 ZJ during the last part of the 20th century relative to preindustrial times. Half of the heat gain by the continental subsurface since 1960 has occurred in the last 20 years.

Seasonal sensitivity to atmospheric and ground surface temperature changes of an open earth-air heat exchanger in Canadian climates

Open earth-air heat exchangers (EAHE) have an inherent relationship with their surrounding environment, relying on the natural contrast between ambient air and subsurface temperatures. This work explored the seasonal sensitivity of open earth air heat exchanger systems to variations in these temperatures. Utilizing 492 weather files in Canada, the heating and cooling potential of open earth air heat exchangers computed using a climate-based approach were compared for different seasonal variation scenarios. Heightened sensitivity to seasonal changes in ground temperatures relative to air temperatures were observed. These effects expectedly decreased with depth. Heating and cooling potential sensitivity to seasonal variations in air temperatures are dependent on the timing, often observing the greatest influence during peak demand periods. Binning by climates identified that regions with a greater mix of heating and cooling potential were more susceptible to seasonal variations. These results also suggest improvements to the heating potential in Canada can be improved by increasing ground surface temperatures outside the summer season, with little influence on the cooling potential. Understanding the interaction between open earth air heat exchanger systems and their environments can ultimately help outline limitations and design solutions specific to their implementation in Canadian climates.

Inversion of thermal conductivity and heat flow from borehole temperature data affected by recent variation in ground surface temperature

We inverted the thermal conductivity of earth material, heat flow, and ground surface temperature (GST) history from borehole temperature data obtained at the carbon dioxide capture and storage demonstration project site in Tomakomai, Japan, by Bayesian inverse analysis. Past GST change that had disturbed the underground temperature was treated as a heat source in inversion analysis to determine thermal conductivity of the earth material from borehole temperature and underground structure data. The inverted past GST change suggested an increase of GST by 3 K from 1800 to the present. The inverted thermal conductivity of the earth material appeared to correspond to lithology in the borehole. The inverted heat flow was consistent with those measured around the site. To invert these model parameters from borehole temperature data, underground structure data are required. For inverse analysis of borehole temperature data without underground structure data, we propose a simple method for inferring underground structure related to thermal conductivity of the earth material and report the effectiveness of this method for the inversion of model parameters from borehole temperature data only.

Atmospheric Radiative Processes Accelerate Ground Surface Warming over the Southeastern Tibetan Plateau during 1998–2013

AbstractThe Tibetan Plateau (TP), known as the world’s “Third Pole,” plays a vital role in regulating the regional and global climate and provides freshwater for about 1.5 billion people. Observations show an accelerated ground surface warming trend over the southeastern TP during the global warming slowdown period of 1998–2013, especially in the summer and winter seasons. The processes responsible for such acceleration are under debate as contributions from different radiative processes are still unknown. Here we estimate for the first time the contributions of each radiative component to the ground surface warming trend before and after 1998 by analyzing multisource datasets under an energy balance framework. Results show that declining cloud cover caused by the weakening of both the South Asian summer monsoon and local-scale atmospheric upward motion mainly led to the accelerated ground surface warming during the summers of 1998–2013, whereas the decreased surface albedo caused by the snow melting was the major warming factor in winter. Moreover, increased clear-sky longwave radiation induced by the warming middle and upper troposphere was the second largest factor, contributing to about 21%–48% of the ground surface warming trend in both the summer and winter seasons. Our results unravel the key processes driving the ground surface warming over the southeastern TP and have implications for the development of climate and Earth system models in simulating ground surface temperature change and other related complex cryosphere–hydrosphere–atmosphere interactions over high-altitude land areas.

Regional climate change signals inferred from a borehole temperature profile in Muli, Qilian Mountain, using the Tikhonov method

ABSTRACT Within the gas hydrate drilling project in the Qilian Mountain permafrost region, a temperature–depth profile measured from borehole DK-12 in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, China, was analyzed to infer recent climate changes. The long-term surface temperature and thermal gradient were retrieved from borehole temperature measurements. The ground surface temperature (GST) changes were reconstructed by inversion of transient temperature perturbations through solving an inverse heat conduction problem using the Tikhonov method. Based on the instability of this kind of inverse problem and the nature of method-dependent features of borehole paleothermometry, we initially applied the Tikhonov regularization technique to obtain a stable past GST variation pattern with relatively low resolution. The inversion results showed that this region experienced temperature fluctuation with a total warming of 3°C (±1.6°C) from 1400 to the 2010s and a more exacerbated warming starting from the 1960s. The GST trend fit the surface air temperature observation trend from the nearest Yeniugou meteorological station. This work fills the gap created by limited meteorological records in the Muli area and extends knowledge of ground surface temperature trends going back more than ten centuries.

Influence of radiative forcing factors on ground–air temperature coupling during the last millennium: implications for borehole climatology

Abstract. Past climate variations may be uncovered via reconstruction methods that use proxy data as predictors. Among them, borehole reconstruction is a well-established technique to recover the long-term past surface air temperature (SAT) evolution. It is based on the assumption that SAT changes are strongly coupled to ground surface temperature (GST) changes and transferred to the subsurface by thermal conduction. We evaluate the SAT–GST coupling during the last millennium (LM) using simulations from the Community Earth System Model LM Ensemble (CESM-LME). The validity of such a premise is explored by analyzing the structure of the SAT–GST covariance during the LM and also by investigating the evolution of the long-term SAT–GST relationship. The multiple and single-forcing simulations in the CESM-LME are used to analyze the SAT–GST relationship within different regions and spatial scales and to derive the influence of the different forcing factors on producing feedback mechanisms that alter the energy balance at the surface. The results indicate that SAT–GST coupling is strong at global and above multi-decadal timescales in CESM-LME, although a relatively small variation in the long-term SAT–GST relationship is also represented. However, at a global scale such variation does not significantly impact the SAT–GST coupling, at local to regional scales this relationship experiences considerable long-term changes mostly after the end of the 19th century. Land use land cover changes are the main driver for locally and regionally decoupling SAT and GST, as they modify the land surface properties such as albedo, surface roughness and hydrology, which in turn modifies the energy fluxes at the surface. Snow cover feedbacks due to the influence of other external forcing are also important for corrupting the long-term SAT–GST coupling. Our findings suggest that such local and regional SAT–GST decoupling processes may represent a source of bias for SAT reconstructions from borehole measurement, since the thermal signature imprinted in the subsurface over the affected regions is not fully representative of the long-term SAT variations.

Spatio-Temporal Variations of Soil Active Layer Thickness in Chinese Boreal Forests from 2000 to 2015

The soil active layer in boreal forests is sensitive to climate warming. Climate-induced changes in the active layer may greatly affect the global carbon budget and planetary climatic system by releasing large quantities of greenhouse gases that currently are stored in permafrost. Ground surface temperature is an immediate driver of active layer thickness (ALT) dynamics. In this study, we mapped ALT distribution in Chinese boreal larch forests from 2000 to 2015 by integrating remote sensing data with the Stefan equation. We then examined the changes of the ALT in response to changes in ground surface temperature and identified drivers of the spatio-temporal patterns of ALT. Active layer thickness varied from 1.18 to 1.3 m in the study area. Areas of nonforested land and low elevation or with increased air temperature had a relatively high ALT, whereas ALT was lower at relatively high elevation and with decreased air temperatures. Interannual variations of ALT had no obvious trend, however, and the ALT changed at a rate of only −0.01 and 0.01 m year−1. In a mega-fire patch of 79,000 ha burned in 2003, ΔALT (ALTi − ALT2002, where 2003 ≤ i ≤ 2015) was significantly higher than in the unburned area, with the influence of the wildfire persisting 10 years. Under the high emission scenario (RCP8.5), an increase of 2.6–4.8 °C in mean air temperature would increase ALT into 1.46–1.55 m by 2100, which in turn would produce a significant positive feedback to climate warming.

Spurious Additional Warming Reconstructed From Borehole Temperatures Corrected for the Effect of the Last Glacial Cycle

AbstractReconstructions of past ground surface temperature changes from temperature logs conducted in several hundred meter deep boreholes have proved to be a valuable independent source of information on climate variations over the last millennium. The reconstruction techniques have been evolving for more than two decades to extract optimally the climate signal of the last millennium contained in the temperature logs of different length performed in sites with different histories of the Last Glacial Cycle. This paper analyzes the method of the Last Glacial Cycle thermal effect removal from such borehole temperature profiles used by Beltrami et al. (2017, https://doi.org/10.1002/2016GL071317) in reconstructing the last 500 year history. I show that the reported results of additional warming in this period reconstructed from the corrected borehole data for North America are an artifact generated by the correction.

Impacts of the Last Glacial Cycle on ground surface temperature reconstructions over the last millennium

AbstractBorehole temperature profiles provide robust estimates of past ground surface temperature changes, in agreement with meteorological data. Nevertheless, past climatic changes such as the Last Glacial Cycle (LGC) generated thermal effects in the subsurface that affect estimates of recent climatic change from geothermal data. We use an ensemble of ice sheet simulations spanning the last 120 ka to assess the impact of the Laurentide Ice Sheet on recent ground surface temperature histories reconstructed from borehole temperature profiles over North America. When the thermal remnants of the LGC are removed, we find larger amounts of subsurface heat storage (2.8 times) and an increased warming of the ground surface over North America by 0.75 K, both relative to uncorrected borehole estimates.

Impact of borehole depths on reconstructed estimates of ground surface temperature histories and energy storage

AbstractEstimates of ground surface temperature changes and continental energy storage from geothermal data have become well‐accepted indicators of climatic changes. These estimates are independent contributions to the ensemble of paleoclimatic reconstructions and have been used for the validation of general circulation models, and as a component of the energy budget accounting of the global climate system. Recent global and hemispheric analyses of geothermal data were based on data available in the borehole paleoclimatology database, which contains subsurface temperature profiles from a minimum depth of 200 m to about 600 m. Because of the nature of heat conduction, different depth ranges contain the record of past and persistent changes in the energy balance between the lower atmosphere and the ground for different time periods. Here we examine the dependency of estimated ground surface temperature histories and the magnitude of the subsurface heat content on the depth of borehole temperature profiles. Our results show that uncertainties in the estimates of the long‐term surface temperature are in the range of ±0.5K. We conclude that previous estimates of ground surface temperature change remain valid for the period since industrialization, but longer‐term estimates are subject to considerable uncertainties. The subsurface heat content shows a larger range of variability arising from differences in depth of the borehole temperature profiles, as well as from differences in the time of data acquisition, spanning four decades. These results indicate that estimates of subsurface heat should be carried out with caution to decrease cumulative errors in any spatial analysis.

Late Pleistocene–Holocene ground surface heat flux changes reconstructed from borehole temperature data (the Urals, Russia)

Abstract. We use geothermal reconstruction of the ground surface temperature (GST) history early obtained in the Middle Urals to determine the surface heat flux (SHF) history over the past 35 kyr. A new algorithm of GST–SHF transformation was applied to solve this problem. The timescale of geothermal reconstructions has been corrected by comparing the estimated heat flux and annual insolation at the latitude of 60° N. The consistency of SHF and insolation changes on the interval 35–6 kyr BP with the linear correlation coefficient R = 0.99 points to orbital factors as the main cause of climatic changes during the Pleistocene–Holocene transition. The amplitude of SHF variations is about 1.3% of the insolation change amplitude. The increase of carbon dioxide concentrations lagged by 2–3 kyr from the SHF increase and occurred synchronously with GST changes.

Spatiotemporal variations of climate warming in northern Northeast China as indicated by freezing and thawing indices

As the thermal state of the upper boundary conditions of the soil layer, ground surface and air temperatures sensitively indicate the heat transferring process between atmosphere and land surface. Due to the combined effects of high latitude and elevation, northern northeast (NNE) China is the second largest permafrost region in China. Based on the daily ground surface and air temperatures at 21 selected stations in NNE China, the Mann–Kendall test and Sen's slope estimate were used to detect changes in the mean annual ground surface temperature (MAGST), mean annual air temperature (MAAT), annual ground surface freezing index (GFI), annual air freezing index (AFI), annual ground surface thawing index (GTI), annual air thawing index (ATI), and surface offset of MAGST–MAAT for the period between 1972 and 2005. The results show a significant warming in NNE China during the past three decades. The MAGST and MAAT averaged 0.72 and −0.50 °C, with mean increasing rates of 0.61 and 0.72 °C/10y, respectively. The lowest MAGST and MAAT were observed in the northernmost and middle parts of the Da Xing'anling Mountains. The multiyear average GFI is 2822.1 C°/y with a range between 1827.6 and 3919.6 C°·d. The multiyear average AFI is 2688.8 C°/y with a range between 1729.5 and 3606.1 C°·d. Over the same period, the multiyear average GTI ranged between 2451.8 and 3705.5 C°·d, with an average of 2514.0 C°/y, and the multiyear average of ATI ranged from 1902.7 to 2990.1 C°·d, with an average of 2508.3 C°. Trend analyses show a significant decline in annual GFI (−13.5 C°·d/y) and annual AFI (−13.4 C°·d/y), and a significant increase in annual GTI (9.96 C°·d/y) and annual ATI (8.71 C°·d/y). The most pronounced warming has occurred in sporadic permafrost regions of NNE China. However, in continuous permafrost, and discontinuous permafrost regions with extensive presence of taliks, such as at Ta'he and Xinlin stations, no significant trend is detected. Study of the variations of freezing and thawing indices may provide some implications of spatiotemporal changes in the thermal regimes of active layer and permafrost soils, and facilitate better understanding of cold environment changes in permafrost regions of Northeast China.