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1.
Permafrost warming in the Tien Shan Mountains, Central Asia   总被引：4，自引：0，他引：4  
The general features of alpine permafrost such as spatial distribution, temperatures, ice content, permafrost and active-layer thickness within the Tien Shan Mountains, Central Asia are described. The modern thermal state of permafrost reflects climatic processes during the twentieth century when the average rise in mean annual air temperature was 0.006–0.032 °C/yr for the different parts of the Tien Shan. Geothermal observations during the last 30 yr indicate an increase in permafrost temperatures from 0.3 °C up to 0.6 °C. At the same time, the average active-layer thickness increased by 23% in comparison to the early 1970s. The long-term records of air temperature and snow cover from the Tien Shan's high-mountain weather stations allow reconstruction of the thermal state of permafrost dynamics during the last century. The modeling estimation shows that the altitudinal lower boundary of permafrost distribution has shifted by about 150–200 m upward during the twentieth century. During the same period, the area of permafrost distribution within two river basins in the Northern Tien Shan decreased approximately by 18%. Both geothermal observations and modeling indicate more favorable conditions for permafrost occurrences and preservation in the coarse blocky material, where the ice-rich permafrost could still be stable even when the mean annual air temperatures exceeds 0 °C.  相似文献   

2.
Thirty borehole temperature–depth profiles in the central and southern Urals, Russia were scrutinized for evidence of ground surface temperature histories. We explored two inversion schemes: a simple ramp inversion in which solutions are parameterized in terms of an onset time and magnitude of change and a more sophisticated functional space inverse algorithm in which the functional form of the solution is left unspecified. To enhance and potentially identify latitudinal differences in the ground surface temperature signal, we subdivided the data into three groups based on geographic proximity and simultaneously inverted the borehole temperature–depth logs. The simultaneous inversions highlighted 13 temperature–depth logs that could not both fit a common ground surface temperature history and a priori models within reasonable bounds. Our results confirm that this is an effective way to reduce site-specific noise from an ensemble of boreholes. Each inversion scheme gives comparable results indicating locally variable warming on the order of 1°C starting between 1800 and 1900 AD. Similarly surface air temperature records from 12 nearby meteorological stations exhibit locally variable warming also on the order of 1°C of warming during the 20th century. To explore the degree to which borehole temperatures and surface air temperature (SAT) time series are responding to the same signal, we average the SAT data into the same three groups and used these averages as a forcing function at the Earth's surface to generate synthetic transient temperature profiles. Root mean square (RMS) misfits between these synthetic temperature profiles and averaged temperature–depth profiles are low, suggesting that first-order curvature in borehole temperatures and variations in SAT records are correlated.  相似文献   

3.
We analyzed data from 23 boreholes at 19 sites in central and eastern Canada, for the purpose of estimating ground surface temperature (GST) histories. These boreholes were logged down to at least 550 m depth with thermistor probes. Thermal conductivity measurements had been previously made at small depth intervals for the entire depth ranges of most of the boreholes. The temperature profiles of these boreholes do not indicate water disturbance. We estimated terrain effects for each borehole using a time dependent solid-angle method. The thermal perturbations caused by lakes or deforestation near the borehole sites are insignificant in most cases. However, four of the holes were found to be severely influenced by terrain effects. GSTs estimated from the borehole data less influenced by the terraineffects form two groups. The first group, which are generally from data of better quality, show a cold period near the end of the last century before the recent warming trend; the second show it 80–100 years earlier. We consider the former typical of the climate of the Boreal climatic region of Canada. The difference between the two groups may reflect the spacial variability of the climate. Four GST estimates do not belong to either type, and the reasons are discussed.  相似文献   

4.
An experimental air–ground climate station is operating in Pomquet, Nova Scotia, monitoring meteorological (surface air temperatures at three heights, wind velocity and direction, incoming solar radiation, precipitation, snow depth and relative humidity) and ground thermal variables (soil temperatures at depths of 0, 5, 10, 20, 50 and 100 cm). Readings are taken every 30 s and 5 min averages are stored, in order to characterize the energy exchanges at the air ground interface. Here, I report on the first year of operation. For spring, summer and fall, we find that soil temperatures track surface air temperatures with amplitude attenuation and phase lag with depth confirming that heat conduction adequately describe the soil thermal field at the Pomquet site. For winter conditions, we find that heat transfer is dominated by latent heat released during soil freezing and to a lesser extent by the insulating affect of snow cover. A numerical model of heat conduction was used in order to estimate the magnitude of the heat released by freezing during the winter months. I also show that there is an inverse correlation for the difference between soil (100 cm) and air temperatures and the incoming solar radiation at the site.  相似文献   

5.
Gases locked in hydrates or trapped beneath a gas hydrate cap within the earth are potential contributors to the greenhouse effect, and therefore both thermal conditions of and occurrences of the methane hydrates should be considered in the study of past climate change and of future global warming. The decomposition of methane hydrates triggered by an increase in near surface temperatures and the subsequent upward migration of released gases is occurring at present in the Beauffort-Mackenzie area of northern Canada. In addition to surface warming, the warming effect of the upward flow of the deep fluids, recharged in high elevation areas bordering the Alaska and Yukon coastal plain, may also be a factor in the release of methane directly from deeper buried hydrates in the fluid discharge zones. Any assessment of the total methane contribution to the atmosphere and the rate of the release requires a knowledge of the distribution, spatially and with depth, the temperature and composition of the gas hydrates. In this study the zones of methane hydrate stability are predicted by a thermal method and compared with the distribution of hydrates detected on well logs. An extensive hydrate prone layer extending to as deep as 1400±200 m over an area of 50,000 km2 is predicted by the thermal data and hydrate stability field. Comparison of the predicted maximum depths of methane hydrate stability with the maximum depths of hydrate occurrences in 52 wells shows general agreement in the areas of thick offshore and onshore permafrost. Differences in several areas of up to 400 m between the thermally predicted hydrate base and the deepest detected hydrates (detected hydrates are deeper than the predicted ones) can be explained by changes in gas composition. Otherwise low near-surface thermal gradients of approximately 15 mK/m to 20 mK/m (in comparison with observed deep thermal gradients of 25–40 mK/m) would be needed to explain the existence of deep hydrates in the area of the southern Mackenzie Delta trough and offshore north of 71° N latitude. Unfortunately there is no reliable industrial temperature observation from wells to support the latter. Such regional studies of the distribution of gas hydrates, including the stability of those deposits, form a crucial component of an assessment of the influence of gas hydrate formation and decomposition on the proportion of methane present in the earth's atmosphere. Current estimates suggest that between 10.E18 and 10.E21 tonnes of methane may be presently locked in gas hydrate deposits. To fully assess the total amount and the potential contribution to global warming, similar regional assessments are needed for each of the major areas of occurrence, especially in the circumpolar regions which are subject to the greatest increase in temperature conditions.  相似文献   

6.
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7.
Geothermal observations from a suite of boreholes in western Utah, USA, combined with meteorologic data at nearby weather stations are used to test the hypothesis that temperatures in the earths subsurface contain an accurate record of recent climate change. The change in air temperature over the last hundred years successfully predicts detailed subsurface temperature profiles to better than ±0.05°C, indicating that ground temperatures tract air temperatures over long periods and that climate change signals are conducted into, and recorded in, the solid earth by the process of heat conduction. We combine borehole temperature data with meteorologic data from the nearest weather station to determine the time averaged difference between surface ground temperature and surface air temperature for borehole-weather station pairs and to infer the long term mean air temperature prior to the observational record. For our western Utah sites the preobservational mean temperature is close to the average surface air temperature for this century suggesting that up to 0.5°C of warming deduced from the last 100 years of weather station data may be attributed to recovery from a cool period at the turn of the century.  相似文献   

8.
The occurrence of permafrost in bedrock in northern Fennoscandia and its dependence on past and presently ongoing climatic variations was investigated with one- (1D) and two-dimensional (2D) numerical models by solving the transient heat conduction equation with latent heat effects included. The study area is characterized by discontinuous permafrost occurrences such as palsa mires and local mountain permafrost. The ground temperature changes during the Holocene were constructed using climatic proxy data. This variation was used as a forcing function at the ground surface in the calculations. Several versions of the present ground temperature were applied, resulting in different subsurface freezing–thawing conditions in the past depending on the assumed porosity and geothermal conditions.Our results suggest that in high altitude areas with a cold climate (present mean annual ground temperature between 0°C and −3°C), there may have been considerable variations in permafrost thickness (ranging from 0 to 150 m), as well as periods of no permafrost at all. The higher is the porosity of bedrock filled with ice, the stronger is the retarding effect of permafrost against climatic variations.Two-dimensional models including topographic effects with altitude-dependent ground temperatures and slope orientation and inclination dependent solar radiation were applied to a case of mountain permafrost in Ylläs, western Finnish Lapland, where bedrock permafrost is known to occur in boreholes to a depth of about 60 m. Modelling suggests complicated changes in permafrost thickness with time as well as contrasting situations on southern and northern slopes of the mountain.Extrapolating the climatic warming of the last 200 years to the end of the next century when the anticipated increase in the annual average air temperature is expected to be about 2 K indicates that the permafrost occurrences in bedrock in northern Fennoscandia would be thawing rapidly in low-porosity formations. However, already a porosity of 5% filled with ice would retard the thawing considerably.  相似文献   

9.
Because the Khumbu Himal of the Nepal Himalayas lacks long-term climate records from weather stations, mountain permafrost degradation serves as an important indicator of climate warming. In 1973, the permafrost lower limit was estimated to be 5200–5300 m above sea level (ASL) on southern-aspect slopes in this region. Using ground-temperature measurements, we examined the mountain permafrost lower limit on slopes with the same aspect in 2004. The results indicate that the permafrost lower limit was 5400–5500 m ASL in 2004. The permafrost lower limit was estimated to be 5400 to 5500 m on slopes with a southern aspect in the Khumbu Himal in 1991 using seismic reflection soundings. Thus, it is possible that the permafrost lower limit has risen 100–300 m between 1973 and 1991, followed by a stable limit of 5400 to 5500 m over the last decade. An increase in mean annual air temperature of approximately 0.2 to 0.4 °C from the 1970s to the 1990s has indicated a rise in the permafrost lower limit of 40 to 80 m at the Tibetan Plateau. The rise in the mountain permafrost lower limit in the Khumbu Himal exceeds that of the Tibetan Plateau, suggesting the possibility of greater climate warming in the Khumbu Himal.  相似文献   

10.
Permafrost and climatic change in China   总被引：8，自引：0，他引：8  
The permafrost area in China is about 2.15×106 km2, and is generally characterized by altitudinal permafrost. Permafrost in China can be divided into latitudinal and altitudinal types, the latter can be further divided into plateau and alpine permafrost. Altitudinal permafrost also can be divided into five thermal stability types. The permafrost environment has changed significantly since the Late Pleistocene. In northeastern China, the southern limit of permafrost extended to 41–42°N during the last glaciation maximum; in the Holocene megathermal, it retreated northward. The ice wedges and permafrost formed during the Late Pleistocene are still present in the northern part of the Da-Xing'anling Mountains. The inactive ice wedges at Yitulihe indicate a cooling and subsequent permafrost expansion during the Late Pleistocene. The lower limit of altitudinal permafrost in western China has elevated from 800 to 1500 m since the last glaciation maximum. Compared with that in northern Europe and North America, latitudinal permafrost in northeastern China is less sensitive to climatic warming, but altitudinal permafrost, especially permafrost on the Qinghai–Tibet Plateau (QTP), is sensitive to climatic warming. Since the early 20th century, significant permafrost degradation has occurred and is occurring in most permafrost regions in China. Due to the combined influence of climatic warming and increasing anthropogenic activities, substantial retreat of permafrost is expected on the QTP and in northeastern China during the 21st century. Permafrost degradation has and will cast great influence on engineering construction, water resources and environments in the cold regions of China. The wetlands in the cold regions of China emit significant amounts of CH4 and N2O to the atmosphere and uptake atmospheric CO2 at a considerable rate, which might contribute to the global atmospheric carbon budget and feedback to climatic systems. However, uncertainties about permafrost changes, rates of changes and their environmental impacts are still large and call for intensive studying.  相似文献   

11.
Abstract— The Marquez Dome, Leon County, Texas represents a 13 km diameter Paleocene/Eocene impact structure formed in largely unconsolidated sediments in a near-shore environment. The present study is an analysis of samples from cores taken from boreholes drilled separately on the edge of the central uplift and in the surrounding annular basin. The borehole drilled in the annular basin of the structure penetrated a sequence of interbedded sands, silts, and shales that is typical of the stratigraphy of the surrounding area. In contrast, the borehole drilled on the edge of the central uplift penetrated material that is relatively homogeneous in chemical composition and texture and may represent a mixture of sand, silt, clay, and minor carbonate derived from deeper levels in the preimpact stratigraphy. Veins containing pseudotachylitic breccias are not found and are not expected in this environment because low-strength target materials are not conducive to frictional melting. Similarly, the low strength and unconsolidated nature of these target materials are not conducive to the formation of other types of typical impact breccias (e.g., melt rocks or suevites). The absence of such lithologies results either from explosive ejection of these materials caused by the water-rich character of the target sediments or, more probably, from removal of these materials by deeper postimpact erosion than has been suggested previously. Planar deformation features (PDFs) were not found in quartz grains from any of these samples. The scarcity of quartz grains with PDFs, which have only been reported in rare impact breccias from the central uplift, and the large amount of vertical displacement indicated for the central uplift of this structure may also be a consequence of the low strength of target materials.  相似文献   

12.
Seasonal snow covers the tundra surface for up to nine months of each year on the Alaskan North Slope. Variations in the snow thickness could strongly influence the thermal regime of the underlying soil and permafrost, and the surface energy balance. The impacts of increases and decreases in the tundra snow thickness on the thermal regime of snow surface, active layer, and permafrost, and on the conductive heat flow to the atmosphere were investigated numerically, by using an improved surface energy balance approach based one-dimensional heat transfer model. The baseline inputs for the numerical model are mean daily meteorological data and surface albedos collected at Barrow, Alaska from 1995 through 1999. Based on a study for the long-term mean daily maximum and minimum snow thickness distributions at Barrow in the snow season of 1948 through 1997, a snow thickness factor was defined and five simulation cases were run for the snow season of 1997–1998 by changing the snow thickness factor. The modeled results indicate that changes in snow thickness have significant impacts on ground thermal regimes and conductive heat flow to the atmosphere. Decreasing the snow thickness by 50% led to the maximum ground temperature decrease of 1.48 °C at 0.29 m depth, and 0.72 °C at 3.0 m depth; the magnitude of the mean conductive heat flow to the atmosphere for December increase of 4.3 Wm− 2. Increasing the snow thickness by 50% resulted in the maximum ground temperature increase of 1.44 °C at 0.29 m depth, and 0.66 °C at 3.0 m depth; the magnitude of the mean conductive heat flow to the atmosphere for December decrease of 1.57 W m− 2. On an annual basis, variation in the snow thickness by 50%, the ground temperature variations of more than 0.25 °C occurred as deep as 8.0 m below the ground surface. The modeled results also show that changes in snow thickness have a relatively small influence on the snow surface temperature.  相似文献   

13.
The snow cover of the Northern Patagonia Icefield (NPI) was monitored after applying the Normalized Difference Snow Index (NDSI) and the Red/NIR band ratio to 134 Moderate Resolution Imaging Spectroradiometer (MODIS) images captured between 2000 and 2006. The final results show that the snow cover extent of the NPI fluctuates a lot in winter, in addition to its seasonal behaviour. The minimum snow cover extent of the period (3600 km2) was observed in March 2000 and the maximum (11,623 km2) in August 2001. We found that temperature accounts for approximately 76% of the variation of the snow cover extent over the entire icefield. We also show two different regimes of winter snow cover fluctuations corresponding to the eastern and the western sides of the icefield. The seasonality of the snow cover on the western side was determined by temperature rather than precipitation, while on the east side the seasonality of the snow cover was influenced by the seasonal behaviour of both temperature and precipitation. This difference can be explained by the two distinct climates: coastal and continental. The fluctuations in the winter snow cover extent were more pronounced and less controlled by temperature on the western side than on the eastern side of the icefield. Snow cover extent was correlated with temperature R2 = 0.75 and R2 = 0.74 for the western and eastern sides, respectively. Since limited meteorological data are available in this region, our investigation confirmed that the change in snow cover is an interesting climatic indicator over the NPI providing important insights in mass balance comprehension. Since snow and ice were distinguished snow cover fluctuations can be associated to fluctuations in the snow accumulation area of the NPI. In addition, days with minimum snow covers of summer season can be associated to the period in which Equilibrium Line Altitude (ELA) is the highest.  相似文献   

14.
The parameterization scheme SPONSOR (Semi-distributed ParameterizatiON Scheme of the ORography-induced hydrology) participating in PILPS (Project for Intercomparison of Land-surface Parameterization Schemes) experiments since 1993 is described in more detail than before, taking into account a range of recent modifications. Improvement of the scheme in several aspects (e.g., soil water movement) resulted in significantly improved results for the Cabauw site (used for PILPS (2a) experiments). Then, parameterization of cold seasons/regions processes (water phase transformations within soil and snow cover) was developed for PILPS (2d) experiments carried out with Valdai data. Testing of the scheme against the data of Kolyma water balance station shows that it is able to reproduce the main features of heat and water exchange at the land surface in the permafrost zone quite satisfactorily. It was found that the scheme results are rather sensitive to the soil heat conductivity, especially in the cold seasons. The original method for the calculation of this parameter was developed using a square root function. The surface temperature and dates of crossing the 0°C temperature threshold for Kolyma station were reproduced with satisfactory accuracy. The temporal variation of the deep soil layers' temperatures was modelled satisfactorily too, but the seasonal amplitude of deep soil temperatures was overestimated by the scheme. This disadvantage can possibly be improved by inclusion of vertical inhomogeneity of soil thermal and hydraulic properties in the model.  相似文献   

15.
Most general circulation models (GCMs) project that climate will be warmer in the 21st century, especially in high latitudes. Climate warming will induce permafrost degradation, which would have great impacts on hydrology, ecosystems and soil biogeochemistry, and could destabilize the foundations of infrastructure. In this study, we simulated transient changes of permafrost distribution in Canada in the 21st century using a process-based permafrost model driven by six GCM-generated climate scenarios. The results show that the area underlain by permafrost in Canada would be reduced by 16.0–19.7% from the 1990s to the 2090s. This estimate was smaller than equilibrium projections because the ground thermal regime was in disequilibrium at the end of the 21st century and permafrost degradation would continue. The simulation shows significant permafrost thaw from the top: On average for the area where permafrost exists in all the years during 1990–2100, active-layer thickness increased by 0.3–0.7 m (or 41–104%), the depth to permafrost table increased by 1.9–5.0 m, and the area with taliks increased exponentially. Permafrost was also thawed from the bottom in southern regions.  相似文献   

16.
The effect of vegetation on the Younger Dryas (YD) climate is studied by comparing the results of four experiments performed with the ECHAM-4 atmospheric general circulation model (AGCM): (1) modern control climate, (2) simulation with YD boundary conditions, but with modern vegetation, (3 and 4) identical to (2), but with paleo-vegetation. Prescribing paleo-vegetation instead of modern vegetation resulted in temperature anomalies (both positive and negative) of up to 4°C in the Northern Hemisphere mid-latitudes, mainly as an effect of changes in forest cover (change in albedo). Moreover, changes in precipitation and evaporation were found, most notably during December–January–February (DJF) in the tropics and were caused by the replacement of forests by grasslands. These results are consistent with other model studies on the role of vegetation changes on climate and they suggest that it is important in paleoclimate simulation studies to prescribe realistic vegetation types, belonging to the period of interest. However, in our case the addition of YD vegetation did not improve the agreement with proxy data in Europe, as the temperatures were increasing during winter compared to the YD simulation with modern vegetation. It must be noted that this increase was not statistically significant. The model-data mismatch suggests that other factors probably played an important role, such as permafrost and atmospheric dust. We infer that during the last glacial-interglacial transition, the time lag between the first temperature increase and the northward migration of trees, estimated at 500–1000 years, could have delayed the warming of the Eurasian continent. The relatively open vegetation that existed during the early stages of the last glacial-interglacial transition had a relatively high albedo, thus tempering warming up of the Eurasian land surfaces.  相似文献   

17.
Air and ground temperatures measured in Eastern Siberia has been compiled and analyzed. The analysis of mean annual air temperatures measured at 52 meteorological stations within and near the East-Siberian transect during the period from 1956 through 1990 demonstrates a significant and statistically significant (at 0.05 level) positive trend ranging from 0.065 to 0.59 °C/10 yr. A statistically significant (at 0.05 level) positive trend was also observed in mean annual ground temperatures for the same period. The permafrost temperature reflects changes in air temperature on a decadal time scale much better than on an interannual time scale. Generally, positive trends in mean annual ground temperatures are slightly smaller in comparison with trends in mean annual air temperatures, except for several sites where the discordance between the air and ground temperatures can be explained by the winter snow dynamics. The average trend for the entire region was 0.26 °C/10 yr for ground temperatures at 1.6 m depth and 0.29 °C/10 yr for the air temperatures. The most significant trends in mean annual air and ground temperatures were in the southern part of the transect, between 55° and 65° N. Numerical modeling of ground temperatures has been performed for Yakutsk and Tiksi for the last 70 yr. Comparing the results of these calculations with a similar time series obtained for Fairbanks and Barrow in Alaska shows that similar variations of ground temperatures took place at the same time periods in Yakutsk and Fairbanks, and in Tiksi and Barrow. The decadal and longer time scale fluctuations in permafrost temperatures were pronounced in both regions. The magnitudes of these fluctuations were on the order of a few degrees centigrade. The fluctuations of mean annual ground temperatures were coordinated in Fairbanks and Yakutsk, and in Barrow and Tiksi. However, the magnitude and timing of these fluctuations were slightly different for each of the sites.  相似文献   

18.
We present results on the ability of microturbulence, LTE line formation, and a homogeneous thermal model to realistically represent the center-limb variation of temporally and spacially averaged solar line profiles. We have used three somewhat similar semi-empirical thermal models in combination with five current microturbulence models which cover the gamut of homogeneous-isotropic to nonhomogeneous-anisotropic. From high resolution photoelectric data for λ λ5000–6000 at five μ-values (1, 0.63, 0.4, 0.25, 0.16) obtained at KPNO, we selected 17 Fe i and 5 Fe ii line profiles to unblend and symmetrize for study. An iterative scheme has been developed to calculate theoretical profiles for the various combination of models and compare them to the observed profile using the abundance at each limb position and the magnitude of the pressure broadening at the center of the disc as parameters. We find that a microturbulence model, for which the radial and tangential components increase into deeper layers with ξtan>ξrad, produces a reasonable good center-limb fit for lines less than 100 mÅ. However, for lines stronger than 140 mÅ, microturbulence models with no depth dependence produce the best match between theory and observation. Thus, there is reason to question the uniqueness of the microturbulence concept.  相似文献   

19.
The effect of glaciation on the temperature regime in a sedimentary basin has been estimated. Four modeling cases, representing glaciation with cold (permafrost) glaciers and temperate glaciers as well as non-glaciation, were undertaken. The thermal consequences of taking the glaciation into account can be significant. Subsurface temperatures during a cold (permafrost) glaciation were as much as 25°C lower than the subsurface temperatures in a non-glaciated case. Increased conductivities due to frozen pore water contributed significantly to the cooling of the subsurface. Given two cases of cold glaciation, the first with increased thermal conductivities due to freezing of pore water and the second with no effect of freezing, the first case results in up to 10°C lower subsurface temperatures than the second one. A temperate glacier with a temperature of 0°C at the ice/sediment boundary is, as expected, less significant compared to a cold glacier. In this case subsurface temperatures were up to 7°C lower than the subsurface temperatures in the non-glaciated case. Thus it is crucial to know which type of glacier is present at which time as well as the effect of frozen pore water on thermal conductivity in order to have a good estimation of subsurface temperatures in glaciated areas.  相似文献   

20.
Accurate temperature–depth profiles may help to assess the temperature variations associated with the climate changes in the past. Ninety-eight ground surface temperature histories inverted from the temperature–depth borehole logs drilled on the territory of the Czech Republic [Bodri, L., ermák, V., 1995. Climate changes of the last millennium inferred from borehole temperatures: results from the Czech Republic — Part I. Global Planet. Change 11, pp. 111–125; Bodri, L., ermák, V., 1997. Climate changes of the last two millennia inferred from borehole temperatures: results from the Czech Republic — Part II. Global Planet. Change 14, pp. 163–173.] are used to reconstruct the regional patterns of the respective climate change. The climate was mapped for the following periods: 1100–1300 A.D. (Little Climatic Optimum), 1400–1500 A.D., 1600–1700 A.D. (main phase of the Little Ice Age), and for the most recent climate trend after year 1960. Comparison of the obtained maps with the meteorological observations and proxy climatic reconstructions confirmed good applicability of the “geothermal” paleoclimatic reconstructions for the regional studies.  相似文献   

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