Permafrost distribution modelling in the mountains of the Mediterranean: Corral del Veleta,Sierra Nevada,Spain

A statistical model for automated mapping of the spatial distribution of permafrost in the area of Corral del Veleta in south-east Spain (3703' N, 322' W; 3398 m a.s.l.) was developed and applied. The model uses a relationship between permafrost occurrence as indicated by BTS measurements, and variables such as altitude, solar radiation and summer snow cover. The model was implemented within a geographical information system (GIS) and determines the spatial distribution of probable permafrost in Corral del Veleta. Validation was achieved by comparing the predicted permafrost distribution with the results of recent fieldwork, such as geomorphic mapping, geophysical soundings and ground temperature logging.     

A model of permafrost formation and occurrences in the intracontinental mountains

The proposed method of permafrost distribution mapping entails the use of a computer-based model that takes into account the specific conditions of arid mountains for permafrost formation and occurrence. In the intracontinental arid mountains, incoming short-wave solar radiation, mean annual temperature and evaporation are the main influences on the distribution of permafrost. Coarse debris is widespread in the high mountains and greatly influences the thermal state of the ground. The model can compute heat transfer in the coarse debris, which is considered a porous body, and it can be used for permafrost distribution mapping with various degrees of spatial resolution. As a result, the GIS-based map of permafrost distribution for the Bolshaya Almatinka River basin, Kazakhstan, was generated.     

Using relict rockglaciers in GIS-based modelling to reconstruct Younger Dryas permafrost distribution patterns in the Err-Julier area,Swiss Alp

Differences in mean annual air temperature between the Younger Dryas period and today were estimated at the fronts of 32 relict rockglaciers in the Err-Julier area, eastern Swiss Alps. The analyses were based on a case-by-case calculation of direct incoming solar radiation and mean annual air temperature using a digital elevation model (DEM) and meteo data of recent years. Our results suggest that mean annual air temperature during the Younger Dryas was lowered by c. 3C to 4C, and that the lower limit of permafrost occurrence was depressed considerably more than glacier equilibrium lines. This indicates strongly reduced precipitation (30% to 40% reduction) and much larger abundance of mountain permafrost at that time. A model simulation of the corresponding spatial permafrost distribution during the Younger Dryas indicates that glaciers in the study area were mostly surrounded by permafrost at that time and probably had a polythermal structure of englacial temperatures.     

Regional modelling of present,past and future potential distribution of discontinuous permafrost based on a rock glacier inventory in the Bagnes‐Hérémence area (Western Swiss Alps)

A regional model was used to draw the permafrost distribution in the 200 km 2 of the Bagnes-Hérémence area (Western Swiss Alps). The model is based on the fact that permafrost distribution depends mainly on altitude and orientation and that the minimal altitude of active/inactive rock glaciers can be used as an indicator of the lower limit of discontinuous permafrost. The lower limit of relict rock glaciers is also used as an indicator of past distribution of permafrost. An inventory of rock glaciers was therefore made in the study area. The lower limit of permafrost during the Younger Dryas was determined by comparing the position of relict rock glaciers and glacier extension during the Older Dryas. The model was then applied to four periods (Younger Dryas, Little Ice Age, current period and future) in order to show the temporal evolution of permafrost distribution and glacier extension.     

GIS-simulation of the spatial distribution of snow cover and observed ground temperatures in the Daisetsu Mountains,Japan

This paper describes one geometrical method of simulating the spatial distribution of snow cover. Geographical Information Systems (GIS) and precise Digital Elevation Model (DEM) were used in the simulation. The model is based on empirical parameters called coefficients depending on slope aspect and inclination. As a result, this model predicts that windward convex terrains remain snow-free during winter. This snow cover distribution was validated by usage of an air photograph taken in early spring, and the distribution of vegetation patches which represent the outer fringes of snow covered areas. Low ground temperatures together with high DC resistivities, which suggest the presence of permafrost, were identified in simulated snow-free areas.     

青藏高原地气温差变化及空间分布

The difference between ground soil and air temperature （Ts-Ta） was studied by using the data of ground and air temperature of 99 stations over the Qinghai-Xizang （Tibet） Plateau from 1960 to 2000,and its spatial distribution and time changing tendency have been diagnosed by principal component analysis and power spectral analysis methods. The results show that the values of （Ts-Ta） are the maximum in June and the minimum in December. The first three loading eigenvectors, which reflect the main spatially anomalous structure of （Ts-Ta） over the Qinghai-Xizang Plateau, contain the contrary changing pattern between the northwestern and the southeastern regions, the pattern response of the sea level elevation and the geography, and the pattern response of the distribution of the permafrost. There are four patterns of time evolution including the patterns of monotonous increasing or decreasing trends, the basic stability pattern and the parabola pattern with the minimum value. （Ts-Ta） has a periodic variation about 2 years. According to the spatial distribution of the third loading eigenvectors of （Ts-Ta） over the Qinghai-Xizang Plateau in cold season, the permafrost response region and the seasonal frozen ground response region are identified.     

Mountain permafrost distribution modeling using Multivariate Adaptive Regression Spline (MARS) in the Wenquan area over the Qinghai-Tibet Plateau

In high mountainous areas, the development and distribution of alpine permafrost is greatly affected by macro- and micro-topographic factors. The effects of latitude, altitude, slope, and aspect on the distribution of permafrost were studied to understand the distribution patterns of permafrost in Wenquan on the Qinghai-Tibet Plateau. Cluster and correlation analysis were performed based on 30 m Global Digital Elevation Model (GDEM) data and field data obtained using geophysical exploration and borehole drilling methods. A Multivariate Adaptive Regression Spline model (MARS) was developed to simulate permafrost spatial distribution over the studied area. A validation was followed by comparing to 201 geophysical exploration sites, as well as by comparing to two other models, i.e., a binary logistic regression model and the Mean Annual Ground Temperature model (MAGT). The MARS model provides a better simulation than the other two models. Besides the control effect of elevation on permafrost distribution, the MARS model also takes into account the impact of direct solar radiation on permafrost distribution.     

气候变化下的祁连山地区近40 年多年冻土分布变化模拟

冻土是一种对气候变化极为敏感的土体介质,故气候的变化过程能反映和模拟冻土的分布及变化趋势。基于高程-响应模型,运用高分辨率的高程数据（DEM）、经度数据（Longitude）、纬度数据（Latitude）、年平均气温数据（MAAT）和气温垂直递减率数据（VLRT）对祁连山地区近40 年的多年冻土分布状况进行了数值模拟。分析表明：① 该高程-响应模型模拟的冻土范围和变化趋势与相关研究所引入逻辑回归模型的模拟结果基本一致。② 该模型模拟的1970s、1980s、1990s,2000s 的祁连山地区冻土分布面积分别为9.75×10⁴ km²、9.35×10⁴ km²、8.85×10⁴ km²、7.66×10⁴ km²。在这40 年中,冻土的分布范围呈现出明显减少的趋势。③ 从1970s 到1980s、1980s 到1990s、1990s 到2000s 三个时间段内,冻土分布范围的退缩速率分别为4.1%、5.3%、13.4%,其呈现逐渐增速的趋势,1990s 到2000s 出现了跳跃式增长。本研究可为分析长时间序列祁连山地区的多年冻土变化提供科学参考依据。     

Investigation of mountain permafrost in the Kozia Dolinka valley,Tatra Mountains,Poland

The Kozia Dolinka valley lies at an altitude above 1900 m a.s.l. on the northern slope of the main ridge of the High Tatra Mountains. Mountain permafrost occurrences were studied with the use of BTS, infrared imaging, water and ground temperature measurements and DC resistivity soundings. The data suggest the existence of isolated patches of permafrost. The lowest observed bottom temperature of winter snow values was in the order of-10C. DC soundings revealed the existence of a high resistivity layer of limited extent. Permafrost seasonal monitoring was conducted with resistivity soundings. Measurements were carried out in spring-autumn 1999, when a distinct change in permafrost thickness was observed.     

Topographic radiation balance models: Sensitivity and application in periglacial geomorphology

Direct solar radiation integrated over one year is a function of latitude and time of year, and topographic slope , aspect and shadowing control the local distribution. Recently, several spatial models have been developed which estimate the radiation balance based on digital elevation models, taking into account aspect, slope and shadowing effects. For the periglacial realm, these models are integrated both in models estimating possible occurrence of mountain permafrost and in studies of active layer dynamics. In this article our aim is to assess and discuss sensitivity and validations of the radiation balance model SRAD, in comparison with two other topographic-based radiation models. The study site and field data are from Finse, Southern Norway.     

Permafrost distribution in the Posets massif,Central Pyrenees

The Posets massif is located in the Central Pyrenees and reaches a height of 3363 m a.s.l. at the Posets peak, the second highest massif in the Pyrenees. Geomorphological maps of scales 1:25000 and 1:10000, BTS (bottom temperature of winter snow), ground measurements and snow poles were used to observe the more representative periglacial active landform association, ground thermal regime, the winter snow cover evolution and basal temperatures of snow. The main active periglacial landforms and processes related to the ground thermal regime and snow cover were studied. Mountain permafrost up to 2700 m a.s.l. on northexposed slopes and up to 2900 m a.s.l. on south-exposed slopes were detected. Three permafrost belts were differentiated: sporadic permafrost between 2700 and 2800 m a.s.l. and between 2850 and 3000 m a.s.l., discontinuous permafrost between 2800 and 2950 and between 2950 and 3050, and continuous permafrost up to 2900 m a.s.l. and up to 3050 m a.s.l. on northern and southern slopes, respectively.     

Meteorological observations 1998 at the arctic station,Qeqertarsuaq (69°15'N), Central West Greenland/Active layer monitoring in two Greenlandic permafrost areas: Zackenberg and Disko Island

An automatic meteorological station has been operating at the Arctic Station (69°15'N, 53°31'W) in West Greenland since 1990. This paper summarises meteorological parameters during 1998, including snow cover, ground temperatures and active layer development, and presents comments on the local permafrost thickness.

Abstract

Active layer monitoring in Greenland was started in 1996 and 1997, and forms part of the Circumpolar Active Layer Monitoring (CALM) Network of the International Permafrost Association (IPA). The results of the first years of this monitoring of thaw progression and maximum active layer thickness in two Greenlandic permafrost areas are presented. Two sites are in the continuous permafrost zone at Zackenberg in NE Greenland (74 °N), and one at Disko Island in W Greenland (69 °N), at the border between discontinuous and continuous permafrost.

The data collected at Zackenberg demonstrate interannual variation in the timing of thaw progression in the monitoring grid holding a seasonal snowpatch, while there is less variation in the horizontal grid without a snowpatch. The maximum active layer thickness for the two Zackenberg grids is more or less consistent for the first three years with averages from 58 to 66 cm in mid and late August. At Disko the active layer reached 71 cm in mid August 1998. Spatially the distribution of the maximum, annual active layer thickness within the grids is concordant.     

A comparison of permafrost prediction models along a section of Trail Ridge Road, Rocky Mountain National Park, Colorado, USA

The distribution of mountain permafrost along Trail Ridge Road (TRR) in Rocky Mountain National Park, Colorado, was modeled using ‘frost numbers’ and a ‘temperature of permafrost model’ (TTOP) in order to assess the accuracy of prediction models. The TTOP model is based on regional observations of air temperature and heat transfer functions involving vegetation, soil, and snow; whereas the frost number model is based on site-specific ratios of ground temperature measurements of frozen and thawed degree-days. Thirty HOBO© temperature data loggers were installed near the surface as well as at depth (30 to 85 cm). From mid-July 2008 to 2010, the mean annual soil temperature (MAST) for all surface sites was − 1.5 °C. Frost numbers averaged 0.56; TTOP averaged − 1.8 °C. The MAST was colder on western-facing slopes at high elevations. Surface and deeper probes had similar MASTs; however, deeper probes had less daily and seasonal variation. Another model developed at the regional scale based on proxy indicators of permafrost (rock glaciers and land cover) classified 5.1 km² of permafrost within the study area, whereas co-kriging interpolations of frost numbers and TTOP data indicated 2.0 km² and 4.6 km² of permafrost, respectively. Only 0.8 km² were common among all three models. Three boreholes drilled within 2 m of TRR indicate that permafrost does not exist at these locations despite each borehole being classified as containing permafrost by at least one model. Addressing model uncertainty is important because nutrients stored within frozen or frost-affected soils can be released and impact alpine water bodies. The uncertainty also exposes two fundamental problems: empirical models designed for high latitudes are not necessarily applicable to mountain permafrost, and the presence of mountain permafrost in the alpine tundra of the Colorado Front Range has not been validated.     

Numerical simulations of the influence of the seasonal snow cover on the occurrence of permafrost at high latitudes

It has repeatedly been reported that snow cover is a dominating factor in determining the presence or absence of permafrost in the discontinuous and sporadic permafrost regions. The temperature at the snow-soil interface by the end of winter, known as the bottom temperature of winter snow (BTS) method, has been used to detect the existence of permafrost in European alpine regions when the maximum snow depth is about 1.0 m or greater. A critical snow thickness of about 50 cm or greater can prevent the development of permafrost in eastern Hudson Bay, Canada. The objective of this study is to investigate the impact of snow cover on the presence or absence of permafrost in cold regions through numerical simulations. A one-dimensional heat transfer model with phase change and a snow cover regime is used to simulate energy exchange between deep soils and the atmosphere. The model has been validated against the in situ data in the Arctic. The simulation results indicate that both snow depth and the onset date of snow cover establishment are important parameters in relation to the presence or absence of permafrost. Early establishment of snow cover can make permafrost disappear, even with a relatively thin snow cover. Permafrost may survive when snow cover starts after the middle of December even with a snow thickness >1.0 m. This effect of snow cover on the ground thermal regime can be explained with reference to the pattern of seasonal temperature variation. Early establishment of snow cover enhances the insulating impact over the entire cold season, thus warming and eventually thawing the permafrost. The insulating effect is substantially reduced when snow cover starts relatively late and snowmelt in the spring creates a huge heat sink, resulting in a favorable combination for permafrost existence.     

近50年来黑龙江省冻土厚度的时空变化特征

基于MK检验、滑动t检验、EOF分析方法,使用近50年（1961-2012年）黑龙江省32个气象基准台站逐日冻土观测数据、气温观测数据,对黑龙江省冻土厚度时空变化特征进行了分析。结果表明：① 近50年黑龙江省冻土厚度减少了12.86 cm,下降速率为-0.53 cm/a,以2001年为界发生了突变。② 冻土厚度空间分布呈现由北厚南薄格局,中部地区冻土厚度较同纬度其他区域偏低;空间变化呈现南部冻土厚度降低快,北部降低慢,中部与西部、东南部呈相反变化的特征,伊春、铁力、漠河观测点为冻土变化敏感区。③ 气温是影响黑龙江省冻土厚度变化的主要因素,与冻土厚度相关系数为-0.611。本文的主要贡献为揭示了黑龙江省冻土厚度的空间变化特征,为相关研究及各级政府规划提供了依据。     

Size and spatial distribution of loess slides on the Chinese Loess Plateau

ABSTRACT

The size and spatial distribution of loess slides are important for estimating the yield of eroded materials and determining the landslide risk. While previous studies have investigated landslide size distributions, the spatial distribution pattern of landslides at different spatial scales is poorly understood. The results indicate that the loess slide distribution exhibits a power-law scaling across a range of the size distribution. The mean landslide size and size distribution in the different geomorphic types are different. The double Pareto and inverse gamma functions can coincide well with the empirical probability distribution of the loess slide areas and can quantitatively reveal the rollover location, maximum probability, and scaling exponents. The frequency of loess slides increases with mean monthly precipitation. Moreover, point distance analysis showed that > 80% of landslides are located < 3 km from other loess slides. We found that the loess slides at the two study sites (Zhidan and Luochuan County) in northern Shaanxi Province, China show a significant clustered distribution. Furthermore, analysis results of the correlated fractal dimension show that the landslides exhibit a dispersed distribution at smaller spatial scales and a clustered distribution at larger spatial scales.     

基于MODIS温度的青藏高原多年冻土活动层厚度变化研究

基于MODIS温度数据,采用TTOP模型和Stefan公式模拟了青藏高原地区的冻土分布并计算了活动层厚度,并与地面观测结果进行了对比。结果表明：2003—2019年青藏高原多年冻土面积为1.01×10⁶ km²;多年冻土活动层厚度区域平均值为1.79 m, 活动层厚度区域平均的变化率为3.67 cm/10a,且草甸地区的变化率明显大于草原地区,5100~5300 m高程带的活动层厚度变化速率最大。     

Research progress in cold region wetlands, China

China has some of the most abundant wetland resources in the world. Cold region wetlands cover more than 60% of the total natural wetlands in China and play an indispensable role in global climate regulation, water holding, uptake and emission of greenhouse gases, and biodiversity conservation. Because cold region wetlands are sensitive to climatic and environmental changes, it is important for ecological conservation and environmental management to summarize and analyze current research progress on these specific ecosystems. This paper reviews the focus of present studies on the typical cold region wetlands in the northeast region and the Qinghai-Tibet Plateau of China from several aspects as follows: types and distribution, responses of permafrost to climatic changes, uptake and emission of greenhouse gas, eco-hydrological processes, and vegetation succession. Our conclusions are: global warming has a long-term and serious impact on cold region permafrost; emission of greenhouse gases has great temporal and spatial heterogeneity; and hygrophytes in the cold region wetlands have been generally replaced by xerophytes, although it is still unclear whether the vegetation diversity index has increased or decreased. Based on this review, some key topics for future study are recommended as follows: (1) the response of degeneration of cold region permafrost at various spatial and temporal scales; (2) prediction of wetland degeneration tendency by coupling weather, soil, and hydrological models; (3) evaluation of carbon storage; (4) the actual response mechanisms of greenhouse gases to climatic changes; and (5) development of water requirement calculation methods tailored to the unique ecosystems of cold region wetlands.     

The Geography of Fish: The Use of Remote Sensing and Spatial Analysis Tools in Fisheries Research

Rather than seeing the oceans as an expansive void, researchers using acoustic technologies can detect the heterogeneity of biological resources and view the marine environment as a three-dimensional landscape. Underwater remote sensing, using acoustics, provides high resolution maps of the spatial distribution of organisms in aquatic ecosystems. Analyzing the spatial pattern of species distribution within the water column and the impact of that organization on ecological processes bridges the fields of fisheries and spatial analysis. Tools and concepts familiar to geographers, such as remote sensing, GIS, and landscape ecology, contribute to the investigation of large lake and marine ecosystems.     

青藏高原西部区域多年冻土分布模拟及其下限估算

准确评估青藏高原西部多年冻土的空间分布及多年冻土下限深度情况对该区地下水资源利用、生态环境保护有重要意义.本文依托科技基础性工作专项“青藏高原多年冻土本底调查”在该区及周边取得的冻土调查资料,利用遥感数据和扩展地面冻结数模型模拟了该区多年冻土的空间分布,调查区的模拟验证表明该方法有较高的精度.在此基础上,根据有限的地温实测资料建立了地温与位置、高程、坡向和太阳辐射的关系,并根据地温-下限关系估算了该区多年冻土下限深度的分布情况.研究表明,该区有多年冻土约占36.9%,季节冻土占57.5%,多年冻土主要分布在34°N~36.5°N范围的喀喇昆仑、西昆仑一带,季节冻土主要分布在塔里木盆地和34°N以南地区.阿里高原及以南是岛状多年冻土分布区域,其多年冻土分布面积少于此前出版的冻土图所绘制的.青藏高原西部区域的多年冻土下限深度整体表现为由东南-西北逐渐加深.