Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods...Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods due to their short time scale. To address this issue of daily snowline and snow cover observations, a ground- based EOS 7D camera and four infrared digital hunting video cameras （LTL5210A） were installed around the Hulugou river basin （HRB） in the Qilian Mountains along northeastern margin of the Tibetan Plateau （38°15′54″N, 99°52′53″E） in September 2011. Pictures taken with the EOS 7D camera were georeferenced and the data from four LIL521oA cameras and snow depth sensors were used to assist snow cover estimation. The results showed that the time-lapse photography can be very useful and precise for monitoring snowline and snow cover in mountainous regions. The snowline and snow cover evolution at this basin can be precisely captured at daily scale. In HRB snow cover is mainly established after October, and the maximum snow cover appeared during February and March. The consistent rise of the snowline and decrease in snow cover appeared after middle part of March. This melt process is strongly associated with air temperature increase.展开更多
We investigate the behavior of the snowline in a protoplanetary disk and the relationship between the radius of the snowline and properties of molecular cloud cores.In our disk model,we consider mass influx from the g...We investigate the behavior of the snowline in a protoplanetary disk and the relationship between the radius of the snowline and properties of molecular cloud cores.In our disk model,we consider mass influx from the gravitational collapse of a molecular cloud core,irradiation from the central star,and thermal radiation from the ambient molecular cloud gas.As the protoplanetary disk evolves,the radius of the snowline increases first to a maximum value Rmax,and then decreases in the late stage of evolution of the protoplanetary disk.The value of Rmaxis dependent on the properties of molecular cloud cores(mass M;,angular velocity ω and temperature T;).Many previous works found that solid material tends to accumulate at the location of the snowline,which suggests that the snowline is the preferred location for giant planet formation.With these conclusions,we compare the values of R;with semimajor axes of giant planets in extrasolar systems,and find that Rmaxmay provide an upper limit for the locations of the formation of giant planets which are formed by the core accretion model.展开更多
The analysis of twenty five existent snowline elevation values in West China indicates that snowline elevationH (meter) presents zonality change declining from south to north with latitude φ(degree) and the change de...The analysis of twenty five existent snowline elevation values in West China indicates that snowline elevationH (meter) presents zonality change declining from south to north with latitude φ(degree) and the change declining from west to east with longitude which relates to the distance L (kilometer) to the east coastline. Therefore, the first order trend surface equation of the snowline in West China shows a plane incline from southwest to northeast. The second order trend surface equation of the snowline in West China truly represents the distribution law of the snowline in West China. Its form resembles a 'overturned anticline' from southwest to northeast. The 'raised axis' seems to be superimposed upon the first order trend surface.It reflects the effect of the relief. The snowline elevation in West China depends on horizontal zonality,distribution of ocean and land,and the relief.展开更多
Ⅰ. EVIDENCE FOR RESEARCHSnowlines, timber lines, the lower bounds of vertical permafrost zones and the upper bounds of alpine frozen soils are all important physical geographic elements and are controlled by the vert...Ⅰ. EVIDENCE FOR RESEARCHSnowlines, timber lines, the lower bounds of vertical permafrost zones and the upper bounds of alpine frozen soils are all important physical geographic elements and are controlled by the vertical (altitude)zonality, horizontal (latitude)zonality and regional climatic condition. From the analyses of global spatial distribution, the altitudes and latitudes展开更多
Unprecedented modern rates of warming are expected to advance alpine treelines to higher elevations,but global evidence suggests that current treeline dynamics are influenced by a variety of factors.Seasonal snow cove...Unprecedented modern rates of warming are expected to advance alpine treelines to higher elevations,but global evidence suggests that current treeline dynamics are influenced by a variety of factors.Seasonal snow cover has an essential impact on tree recruitment and growth in alpine regions,which may in turn influence current treeline elevation;however,little research has been conducted on its role in regional treeline formation.Based on 11,804treeline locations in the eastern Himalayas,we extracted elevation,climate,and topographic data for treeline and snowline.Specifically,we used linear and structural equation modelling to assess the relationship between these environmental factors and treeline elevation,and the climate-snow-treeline interaction mechanism.The results showed that the treeline elevation increased with summer temperature and permanent or seasonal snowline elevation,but decreased with snow cover days and spring temperature at the treeline positions(P<0.001).Importantly,spring snowline elevation(33.4%)and seasonal snow cover days(21.1%)contributed the most to treeline elevation,outperforming the permanent snowline,temperature,precipitation,and light.Our results support the assertion that the temperature-moisture interaction affects treeline elevation in the eastern Himalayas,but we also found that the effects were strongly mediated by seasonal snow cover patterns.The increasing tendency of snow cover governed by climate humidification observed in the eastern Himalayas,is likely to limit future treeline advancement and may even cause treeline decline due to the mortality of the remaining old trees.Together,our findings highlight the role of seasonal snow cover patterns in determining treeline elevation in the eastern Himalayas,which should be considered when assessing the potential for treeline ascent in snow-mediated alpine systems elsewhere.展开更多
Increasing population density and development of mountainous terrain have brought human settlements within reach of landslide hazards.In recent years,due to the shortening of return period for severe natural events su...Increasing population density and development of mountainous terrain have brought human settlements within reach of landslide hazards.In recent years,due to the shortening of return period for severe natural events such as heavy rainfall,snowline retreating,great earthquake together with human activities,catastrophic landslides happened more frequently than before,resulting in large-scale casualties due to the increasing occurrences of rapid long-runout rock avalanches,especially in China.This paper presents some typical case histories related to the catastrophic landslides,including the Guanling rock avalanche,the Yigong rockslide-debris avalanche,the Wenchuan earthquake-induced landslides and the Danba landslide.They occurred in the last decade.Moreover,taking the Jiweishan catastrophic rockslide-fragment flow and the Yuhuangge landslide located in the new Wushan Town for examples,early-warning system and risk management on landslides are discussed in detail.展开更多
It is over 110 years since the term Mass Elevation Effect(MEE) was proposed by A. D. Quervain in 1904. The quantitative study of MEE has been explored in the Tibetan Plateau in recent years; however, the spatial distr...It is over 110 years since the term Mass Elevation Effect(MEE) was proposed by A. D. Quervain in 1904. The quantitative study of MEE has been explored in the Tibetan Plateau in recent years; however, the spatial distribution of MEE and its impact on the ecological pattern of the plateau are seldom known. In this study, we used a new method to estimate MEE in different regions of the plateau, and, then analyzed the distribution pattern of MEE, and the relationships among MEE, climate, and the altitudinal distribution of timberlines and snowlines in the Plateau. The main results are as follows:(1) The spatial distribution of MEE in the Tibetan Plateau roughly takes on an eccentric ellipse in northwestsoutheast trend. The Chang Tang Plateau and the middle part of the Kunlun Mountains are the core area of MEE, where occurs the highest MEE of above 11℃; and MEE tends to decreases from this core area northwestward, northeastward and southward;(2) The distance away from the core zone of the plateau is also a very important factor for MEE magnitude, because MEE is obviously higher in the interior than in the exterior of the plateau even with similar mountain base elevation(MBE).(3) The impacts of MEE on the altitudinal distribution of timberlines and snowlines are similar, i.e., the higher the MEE, the higher timberlines and snowlines. The highest timberline(4600–4800 m) appears in the lakes and basins north of the Himalayas and in the upper and middle reach valleys of the Yarlung Zangbo River, where the estimated MEE is 10.2822℃–10.6904℃. The highest snowline(6000–6200 m) occurs in the southwest of the Chang Tang Plateau, where the estimated MEE is 11.2059°C–11.5488℃.展开更多
Significant changes in the area and snowline altitude of two glacierized mountains - Nevado Champara (Cordillera Blanca,Peru) and Cerro Tilata (Cordillera Real,Bolivia)- in the tropical Andes,before and after the rece...Significant changes in the area and snowline altitude of two glacierized mountains - Nevado Champara (Cordillera Blanca,Peru) and Cerro Tilata (Cordillera Real,Bolivia)- in the tropical Andes,before and after the recent El Nino in 2015/16 period,have been analysed using Sentinel 2A and Landsat data.It is seen that the recent El Nino has been accompanied by higher fluctuation in glacier coverage on Nevado Champara and the loss of glacier coverage on Cerro Tilata was very high during the past 16 years.Rise in snowline altitude of selected glaciers was very high after the 2015/16 El Nino.Increase in the area covered by snow and ice during the La Nina periods were not enough to cover the ice loss occurred during the previous El Nino events and the strongest El Nino in 2015/ 16 was followed by a significant loss of ice-covered areas in the tropical Andes.Freshwater resources in this region will be affected in the near future if the current trends in glacier decline continue.Adaptation strategies needs to be implemented to reduce the impacts of the continuing loss of glacierized on regional communities in the tropical Andean region.展开更多
基金supported by the National Natural Sciences Foundation of China (Grant Nos. 41401078, 91025011, 41222001)National Basic Research Program of China (2013CBA01806)
文摘Snowline change and snow cover distribution patterns are still poorly understood in steep alpine basins of the Qilian Mountainous region because fast changes in snow cover cannot be observed by current sensing methods due to their short time scale. To address this issue of daily snowline and snow cover observations, a ground- based EOS 7D camera and four infrared digital hunting video cameras （LTL5210A） were installed around the Hulugou river basin （HRB） in the Qilian Mountains along northeastern margin of the Tibetan Plateau （38°15′54″N, 99°52′53″E） in September 2011. Pictures taken with the EOS 7D camera were georeferenced and the data from four LIL521oA cameras and snow depth sensors were used to assist snow cover estimation. The results showed that the time-lapse photography can be very useful and precise for monitoring snowline and snow cover in mountainous regions. The snowline and snow cover evolution at this basin can be precisely captured at daily scale. In HRB snow cover is mainly established after October, and the maximum snow cover appeared during February and March. The consistent rise of the snowline and decrease in snow cover appeared after middle part of March. This melt process is strongly associated with air temperature increase.
基金supported by the National Natural Science Foundation of China (Grant No. 11504150)
文摘We investigate the behavior of the snowline in a protoplanetary disk and the relationship between the radius of the snowline and properties of molecular cloud cores.In our disk model,we consider mass influx from the gravitational collapse of a molecular cloud core,irradiation from the central star,and thermal radiation from the ambient molecular cloud gas.As the protoplanetary disk evolves,the radius of the snowline increases first to a maximum value Rmax,and then decreases in the late stage of evolution of the protoplanetary disk.The value of Rmaxis dependent on the properties of molecular cloud cores(mass M;,angular velocity ω and temperature T;).Many previous works found that solid material tends to accumulate at the location of the snowline,which suggests that the snowline is the preferred location for giant planet formation.With these conclusions,we compare the values of R;with semimajor axes of giant planets in extrasolar systems,and find that Rmaxmay provide an upper limit for the locations of the formation of giant planets which are formed by the core accretion model.
文摘The analysis of twenty five existent snowline elevation values in West China indicates that snowline elevationH (meter) presents zonality change declining from south to north with latitude φ(degree) and the change declining from west to east with longitude which relates to the distance L (kilometer) to the east coastline. Therefore, the first order trend surface equation of the snowline in West China shows a plane incline from southwest to northeast. The second order trend surface equation of the snowline in West China truly represents the distribution law of the snowline in West China. Its form resembles a 'overturned anticline' from southwest to northeast. The 'raised axis' seems to be superimposed upon the first order trend surface.It reflects the effect of the relief. The snowline elevation in West China depends on horizontal zonality,distribution of ocean and land,and the relief.
文摘Ⅰ. EVIDENCE FOR RESEARCHSnowlines, timber lines, the lower bounds of vertical permafrost zones and the upper bounds of alpine frozen soils are all important physical geographic elements and are controlled by the vertical (altitude)zonality, horizontal (latitude)zonality and regional climatic condition. From the analyses of global spatial distribution, the altitudes and latitudes
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program of China(No.2019QZKK0301)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA26010101)the National Natural Science Foundation of China(Nos.31860123,31560153)。
文摘Unprecedented modern rates of warming are expected to advance alpine treelines to higher elevations,but global evidence suggests that current treeline dynamics are influenced by a variety of factors.Seasonal snow cover has an essential impact on tree recruitment and growth in alpine regions,which may in turn influence current treeline elevation;however,little research has been conducted on its role in regional treeline formation.Based on 11,804treeline locations in the eastern Himalayas,we extracted elevation,climate,and topographic data for treeline and snowline.Specifically,we used linear and structural equation modelling to assess the relationship between these environmental factors and treeline elevation,and the climate-snow-treeline interaction mechanism.The results showed that the treeline elevation increased with summer temperature and permanent or seasonal snowline elevation,but decreased with snow cover days and spring temperature at the treeline positions(P<0.001).Importantly,spring snowline elevation(33.4%)and seasonal snow cover days(21.1%)contributed the most to treeline elevation,outperforming the permanent snowline,temperature,precipitation,and light.Our results support the assertion that the temperature-moisture interaction affects treeline elevation in the eastern Himalayas,but we also found that the effects were strongly mediated by seasonal snow cover patterns.The increasing tendency of snow cover governed by climate humidification observed in the eastern Himalayas,is likely to limit future treeline advancement and may even cause treeline decline due to the mortality of the remaining old trees.Together,our findings highlight the role of seasonal snow cover patterns in determining treeline elevation in the eastern Himalayas,which should be considered when assessing the potential for treeline ascent in snow-mediated alpine systems elsewhere.
文摘Increasing population density and development of mountainous terrain have brought human settlements within reach of landslide hazards.In recent years,due to the shortening of return period for severe natural events such as heavy rainfall,snowline retreating,great earthquake together with human activities,catastrophic landslides happened more frequently than before,resulting in large-scale casualties due to the increasing occurrences of rapid long-runout rock avalanches,especially in China.This paper presents some typical case histories related to the catastrophic landslides,including the Guanling rock avalanche,the Yigong rockslide-debris avalanche,the Wenchuan earthquake-induced landslides and the Danba landslide.They occurred in the last decade.Moreover,taking the Jiweishan catastrophic rockslide-fragment flow and the Yuhuangge landslide located in the new Wushan Town for examples,early-warning system and risk management on landslides are discussed in detail.
基金supported by the Natural Science Foundation of China (Grant Nos. 41401111 and 41601091)National Key R&D Program of China (2017FY100900)
文摘It is over 110 years since the term Mass Elevation Effect(MEE) was proposed by A. D. Quervain in 1904. The quantitative study of MEE has been explored in the Tibetan Plateau in recent years; however, the spatial distribution of MEE and its impact on the ecological pattern of the plateau are seldom known. In this study, we used a new method to estimate MEE in different regions of the plateau, and, then analyzed the distribution pattern of MEE, and the relationships among MEE, climate, and the altitudinal distribution of timberlines and snowlines in the Plateau. The main results are as follows:(1) The spatial distribution of MEE in the Tibetan Plateau roughly takes on an eccentric ellipse in northwestsoutheast trend. The Chang Tang Plateau and the middle part of the Kunlun Mountains are the core area of MEE, where occurs the highest MEE of above 11℃; and MEE tends to decreases from this core area northwestward, northeastward and southward;(2) The distance away from the core zone of the plateau is also a very important factor for MEE magnitude, because MEE is obviously higher in the interior than in the exterior of the plateau even with similar mountain base elevation(MBE).(3) The impacts of MEE on the altitudinal distribution of timberlines and snowlines are similar, i.e., the higher the MEE, the higher timberlines and snowlines. The highest timberline(4600–4800 m) appears in the lakes and basins north of the Himalayas and in the upper and middle reach valleys of the Yarlung Zangbo River, where the estimated MEE is 10.2822℃–10.6904℃. The highest snowline(6000–6200 m) occurs in the southwest of the Chang Tang Plateau, where the estimated MEE is 11.2059°C–11.5488℃.
文摘Significant changes in the area and snowline altitude of two glacierized mountains - Nevado Champara (Cordillera Blanca,Peru) and Cerro Tilata (Cordillera Real,Bolivia)- in the tropical Andes,before and after the recent El Nino in 2015/16 period,have been analysed using Sentinel 2A and Landsat data.It is seen that the recent El Nino has been accompanied by higher fluctuation in glacier coverage on Nevado Champara and the loss of glacier coverage on Cerro Tilata was very high during the past 16 years.Rise in snowline altitude of selected glaciers was very high after the 2015/16 El Nino.Increase in the area covered by snow and ice during the La Nina periods were not enough to cover the ice loss occurred during the previous El Nino events and the strongest El Nino in 2015/ 16 was followed by a significant loss of ice-covered areas in the tropical Andes.Freshwater resources in this region will be affected in the near future if the current trends in glacier decline continue.Adaptation strategies needs to be implemented to reduce the impacts of the continuing loss of glacierized on regional communities in the tropical Andean region.
