Opening a new scientific frontier lying under the Antarctic ice, Russian researchers have drilled down and finally reached the surface of the gigantic freshwater lake, Lake Vostok. The mission chief likened the achiev...Opening a new scientific frontier lying under the Antarctic ice, Russian researchers have drilled down and finally reached the surface of the gigantic freshwater lake, Lake Vostok. The mission chief likened the achievement to placing a man on the moon. Drilling in the area of the lake began 22 years ago in 1990, but progressed slowly as a result of funding shortages, equipment breakdowns, difficulties of drilling in the ＂warm＂ ice, and environmental concerns. In 1996, six years after drilling was started, a group of Russian and British scientists discovered the lake believed to be one of the largest fresh water reservoirs on the planet. This lake is among the last unexplored places on Earth. Sealed from the Earth＇s atmosphere for millions of years, it may provide vital information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. Russian experts waited several years for international approval of their drilling technology before proceeding. As anticipated, lake water under pressure rushed up the borehole, pushing the drilling fluid up and away, then froze, forming a protective plug that prevented contamination of the lake. In December of the next Antarctic season, 2012--2013, researchers plan to re-drill the frozen sample of subglacial water for analysis.展开更多
Drilling operations in polar regions and mountainous areas are complicated by nature of the extreme environment. Yet conventional rotary drilling technologies can be used to drill ice for scientific samples and oth- e...Drilling operations in polar regions and mountainous areas are complicated by nature of the extreme environment. Yet conventional rotary drilling technologies can be used to drill ice for scientific samples and oth- er research. Due to such reasons as power consumption and weight complications, it is hard to apply a conven- tional rotary drilling rig for glacial exploration. Use of small, relatively lightweight, portable engine-powered drilling systems in which the drill lifting from the borehole is carried by the winch. It is reasonable enough for near-surface shallow ice-drilling down to 50 m. Such systems can be used for near-surface ablation-stakes in- stallation, also temperature measurements at the bottom of active strata layer, revealing of anthropogenie pollu- tion, etc. The specified used in this research is an auger ice drill powered by a gasoline engine. At this stage, it is crucial to choose effective drilling parameters such as weight on bit （WOB） and drill bit rotation rate. Sen- sors equipped on the rig have measured the main parameters of the drilling process, such as drill speed, WOB, drill rotation speed, torque and temperature. This paper addresses research on drilling parameters of engine powered auger ice drill and supplies some recommendations for optimization of any ice-core drilling process.展开更多
The firn aquifer beneath the Greenland Ice Sheet may play a significant role in rising sea level. Both traditional mechanical drilling and electric thermal drilling are poorly adapted for effective, low-disturbance sa...The firn aquifer beneath the Greenland Ice Sheet may play a significant role in rising sea level. Both traditional mechanical drilling and electric thermal drilling are poorly adapted for effective, low-disturbance sampling in firn aquifers. We propose using a vibrocoring technique for the undisturbed sampling of dry firn and firn aquifer layers. A remote-controlled vibrocorer is designed to obtain 1-m-long cores with a diameter of 100 mm. The depth capacity of the system is approximately 50 m. The total weight of the vibrocoring system with the surface auxiliary equipment is approximately 110 kg, and corer assembly itself weighs ~60 kg.展开更多
By using the ECMWF reanalysis daily data and daily precipitation data of 80 stations in Northeast China from 1961 to 2002, the impacts of moisture transport of East Asian summer monsoon on the summer precipitation ano...By using the ECMWF reanalysis daily data and daily precipitation data of 80 stations in Northeast China from 1961 to 2002, the impacts of moisture transport of East Asian summer monsoon on the summer precipitation anomaly in Northeast China, and the relationship between the variation of moisture budget and the establishment of East Asian summer monsoon in this region are studied. The results demonstrate that the moisture of summer precipitation in Northeast China mainly originates from subtropical, South China Sea, and South Asia monsoon areas. East China and its near coastal area are the convergent region of the monsoonal moisture currents and the transfer station for the currents continually moving northward. The monsoonal moisture transport, as an important link or bridge, connects the interaction between middle and low latitude systems. In summer half year, there is a moisture sink in Northeast China where the moisture influx is greater than outflux. The advance transport and accumulation of moisture are of special importance to pentad time scale summer precipitation. The onset, retreat, and intensity change of the monsoonal rainy season over Northeast China are mainly signified by the moisture input condition along the southern border of this area. The establishment of East Asian summer monsoon in this area ranges from about 10 July to 20 August and the onset in the west is earlier than that in the east. The latitude that the monsoon can reach is gradually northward from west to east, reaching 50°N within longitude 120°-135°E. In summer, the difference of air mass transport between summers with high and low rainfall mainly lies in whether more air masses originating from lower latitudes move northward through East China and its coastal areas, consequently transporting large amounts of hot and humid air into Northeast China.展开更多
A novel embedded sensor network records changes in key climatic-environmental variables over a range of altitude in the BaekduDaegan Mountain （BDM） of Gangwon Province in Korea, a protected mountain region with uniq...A novel embedded sensor network records changes in key climatic-environmental variables over a range of altitude in the BaekduDaegan Mountain （BDM） of Gangwon Province in Korea, a protected mountain region with unique biodiversity undergoing climate change research. The investigated area is subdivided into three horizontal north-south study areas. Three variables, temperature （T, °C）, relative humidity （RH, %）, and light intensity （LI, lumens m-2, or lux, lx）, have been continuously measured at hourly intervals from June, 2olo to September, 2011 using HOBO H8 devices at lO fixed study sites. These hourly observations are aggregated to monthly, seasonal and annual mean values, and results are summarized to inaugurate a long-term climate change investigation. A region wide T difference in accordance with altitude, or lapse rate, over the interval is calculated as o.4°C l00 m-1. T lapse rates change seasonally, with winter lapse rates being greater than those of summer. RH is elevated in summer compared to other seasons. LI within forestland is lower during summer and higher during other seasons. The obtained results could closely relate to the vegetation type and structure and the terrain state since data loggers were located in forestland.展开更多
Ages determined with the 40Ar/39Ar isotopic system affirms the Early Cretaceous volcanic activity in the Barton Peninsula, King George Island, Antarctica. Two specimens of basaltic andesite collected from the lower-mo...Ages determined with the 40Ar/39Ar isotopic system affirms the Early Cretaceous volcanic activity in the Barton Peninsula, King George Island, Antarctica. Two specimens of basaltic andesite collected from the lower-most volcanic sequence of the peninsula were irradiated and analyzed in different experiments, yielding an identical age spectrum, and two magmatic thermal events of the Early Cretaceous (120.4±1.6 Ma, 119±1 Ma) and Early Tertiary (53.1±1.5 Ma, 52±1 Ma) are distinguished. The former is interpreted to represent the primary cooling age of basaltic andesite, whereas the latter is the thermal reset age caused by the intrusion of granitic pluton. These new ages clearly indicate that volcanism was active during the Early Cretaceous on the Barton Peninsula and that intensive hydrothermal alteration and mineralization of Mesozoic volcanic rocks resulted from Tertiary magmatism.展开更多
Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International ...Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International Polar Year （IPY） during August 2007. In this paper two data processing methods are used together to generate two 100-m cell size digital elevation models （DEMs） of the Dome A region （Dome A-DEM） by using Cokriging method to interpolate the ICESat GLAS data, with Ihde-DEM as a constraint. It provides fundamental data to glaciological and geophysical investigation in this area. The Dome A-DEM was applied to determining the ice-sheet surface elevations and coordinates of the south and north summits, defining boundaries of basins and ice ftowlines, deducing subglacial topography, and mapping surface slope and aspect in Dome A region. The DEM shows there are two （north and south） summits in Dome A region. The coordinate and the surface elevation of the highest point （the north summit） are 80°21＇29.86＂S, 77°21＇50.29＂E and 4092.71±1.43m, respectively. The ice thickness and sub-ice bedrock elevation at north summit are 2420m and 1672m, respectively. Dome A region contains four drainage basins that meet together near the south summit. Ice ftowlines, slope and aspect in detail are also derived using the DEM.展开更多
As an important component of the cryosphere, sea ice is very sensitive to climate change. The study of sea ice physics needs accurate sea ice thickness. This paper presents an electromagnetic induction （EM） techniqu...As an important component of the cryosphere, sea ice is very sensitive to climate change. The study of sea ice physics needs accurate sea ice thickness. This paper presents an electromagnetic induction （EM） technique which can be used to measure the sea ice thickness distribution efficiently and its successful application in the Antarctic Neila Fjord. Based on the electrical properties of sea ice and seawater and the application of electromagnetic field theory, this technique can accurately detect the distance between the EM instrument and the ice/water interface to measure the sea ice thickness. Analyzing the apparent conductivity data obtained by the electromagnetic induction technique and drill-hole measurements at same location allows the construction of a transform equation for the apparent conductivity and sea ice thickness. The verification of the calculated sea ice thickness using this equation indicates that the electromagnetic induction technique is able to determine reliable sea ice thickness with an average relative error of only 5.5%. The ice thickness profiles show the sea ice distribution in Neila Fjord is basically level with a thickness of 0.8 - 1.4 m.展开更多
Thermobaric conditions of subglacial Antarctic environment remain poorly understood, despite recent advances in radar and seismic surveying. The direct accessing to the largest subglacial lake, Lake Vostok, was carrie...Thermobaric conditions of subglacial Antarctic environment remain poorly understood, despite recent advances in radar and seismic surveying. The direct accessing to the largest subglacial lake, Lake Vostok, was carried out twice by Russian scientists in February 2012 and January 2015, opening new opportunities for assessing the thermobaric conditions at ice-water interface. According to the assumption that ice sheet is “floating” on the lake, it was predicted that the water would rise 30 - 40 m in the bottom part of the borehole, but in fact the water rose from the lake to a height of more than 500 m. To explain this phenomenon we assume that the pressure in Lake Vostok results from the external pressure of the entire mass of ice above it and the pressure of the water column that is overlaid above the point being considered. Extrapolation of temperature measurements from the deep bore-holes drilled at Vostok Station also confirmed that the bed of the ice sheet is at pressure melting point. As a result of accessing Lake Vostok, the pressure in the lake is reduced that would lead to the formation of a new additional layer of accretion ice on the lower ice sheet surface.展开更多
Ice cores contain an abundance of information about the Earth＇s climate in the past, and recovered from shallow drilling down to 300-350 m give sufficient information for reconstructing of the last climatic changes a...Ice cores contain an abundance of information about the Earth＇s climate in the past, and recovered from shallow drilling down to 300-350 m give sufficient information for reconstructing of the last climatic changes and for monitoring of pollution from human being. Cable-suspended core auger drills use an armored cable with a winch to provide power to the down-hole motor system and to retrieve the down-hole unit. Because of their lightweight, convenient transportation and installation, high penetration rates and low power consumption, core auger drills are widely used for shallow drilling in ice. Nowadays at least 14 types of auger electromechani- cal drills were designed and tested in different foreign and national glaciological laboratories. However, auger options were usually determined by experience, and the main parameters （ helix angle of the fights and rotational speed） are varied in a wide range from drill to drill. If parameters of auger are not chosen properly, poorly en- gineered drills had troubles with low efficiency of cuttings transportation, jam of ice cuttings, repeated fragmen- tation, cutters icing and stop penetration, abnormal power consumption, high rotation torques, and so on. Thus, this paper presents the method of optimization of iee cuttings transportation of cable-suspended core auger drill on the base of the theory of rotary auger. As the result, the optimal helix angle was determined correspond- ing to the rotational speed from the transportation efficiency point of view.展开更多
Evaluation on a regional climate model was made with five-month atmospheric simulations over the Arctic river basins. The simulations were performed with a modified mesoscale model, Polar MM5 coupled to the NCAR Land ...Evaluation on a regional climate model was made with five-month atmospheric simulations over the Arctic river basins. The simulations were performed with a modified mesoscale model, Polar MM5 coupled to the NCAR Land Surface Model （LSM） to illustrate the skill of the coupled model （Polar MM5＋LSM） in simulating atmospheric circulation over the Arctic river basins. Near-surface and upper-air observations were used to verify the simulations. Sensitivity studies between the Polar MM5 and Polar MM5＋LSM simulations revealed that the coupled model could improve the forecast skill for surface variables at some sites. In addition, the extended evaluations of the coupled model simulations on the North American Arctic domain during December 15, 2002 to May 15, 2003 were carried out. The time series plots and statistics of the observations and Polar MM5＋LSM simulations at six stations for near-surface and vertical profiles at 850 hPa and 500 hPa were analyzed. The model was found capable of reproducing the observed atmospheric behavior in both magnitude and variability, especially for temperature and near-surface wind direction.展开更多
The Amery Ice Shelf is the largest ice shelf in East Antarctica. A new DEM was generated for this ice shelf, using kriging to interpolate the data from ICE- Sat altimetry and the AIS-DEM. The ice thickness distributio...The Amery Ice Shelf is the largest ice shelf in East Antarctica. A new DEM was generated for this ice shelf, using kriging to interpolate the data from ICE- Sat altimetry and the AIS-DEM. The ice thickness distribution map is converted from the new DEM, assuming hydrostatic equilibrium. The Amery Ice Shelf marine ice, up to 230 m thick, is concentrated in the northwest of the ice shelf. The volume of the marine ice is 2.38 × 10^3 km^3 and accounts for about 5.6% of the shelf volume.展开更多
Paramo is a term used to describe tropical alpine vegetation between the continuous timberline and the snow line in tbe Northern Andes. Paramo environments provide important species habitat and ecosystem services. Cha...Paramo is a term used to describe tropical alpine vegetation between the continuous timberline and the snow line in tbe Northern Andes. Paramo environments provide important species habitat and ecosystem services. Changes in spatial extent of the paramo ecosystem at Pambamarca in the Central Cordillera of the northern Ecuadorian Andes were analysed using multi-temporal Landsat TM/ETM＋ satellite data. The region suffered a loss of 1826.6 ha or 20% of the total area at a rate of 100 ha/annum during 1988-2007 period. It is found that permanent paramo cover decreased from 8350 ha in 1988 to 5864 ha in 2007 at a fairly constant rate （R^2=0.94）. This loss is attributed to expansion of commercial agriculture and floriculture in the valleys coupled with increased population pressure. Land at higher elevations has been cleared for small scale agriculture. Loss of the paramo ecosystem will exert a number of negative impacts on ecosystem services and livelihoods of the local population at Pambamarca.展开更多
Deep ice drilling in Polar Regions plays a key role in paleo-climate, microbiological and glaciological researches. For deep ice and subglacial coring the special purpose-built electromechanical cable-suspended drills...Deep ice drilling in Polar Regions plays a key role in paleo-climate, microbiological and glaciological researches. For deep ice and subglacial coring the special purpose-built electromechanical cable-suspended drills with bottom-hole circulation are designed and explored. Used at present drilling fluid circulation systems are specified by very high fluid wastes during processing. Measurements in deep drilling projects in Antarctic and Greenland ice sheets showed that 25%-40% of the drilling fluid, pumped into the hole, is retrieved to the surface with cable and drill, and up to 45% of retrieved fluid goes to waste. This leads not only to increasing of the fluid consumption and cost of the project in general but also to severe contamination of air, surface and near-surface snow-firn layers at the drilling site. In order to reduce wastes and environmental impact, it is proposed to modify drilling fluid processing system by avoiding of evaporation and leakages of fluid as far as practicable. Drilling fluid is prepared and pumped into the hole according to predetermined program on semiautomatic mode, and volume and density of blended and pumped into the hole drilling fluid are measured continuously. Components of the drilling fluid are stored and mixed in the special closed containers equipped by pressure relief valves. Separation of drilling fluid from ice cuttings is carried out by two steps: firstly, fluid is separated with hydro extractor and then with thermal separator. To reduce the amount of removed drilling fluid with cable special squeezing collar is installed on the borehole mouth. All these arrangements are able to decrease drilling fluid wastes in many times.展开更多
First let me say that I am honored to be asked for advice and suggestions as a Foreign Member of the Chinese Academy of Sciences.I have been working in China since 1984, first with the Institute of Glaciology and Geoc...First let me say that I am honored to be asked for advice and suggestions as a Foreign Member of the Chinese Academy of Sciences.I have been working in China since 1984, first with the Institute of Glaciology and Geocryology located展开更多
Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's ...Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's life forms.Despite various approaches to access and directly sample subglacial water and sediments,clean access and exploration of subglacial lakes remain challenging.To address this concern,Jilin University has developed the RECoverable Autonomous Sonde(RECAS)prototype.This technology enables sampling and in-situ detection of subglacial lake water while being isolated from the surface,thus minimizing the risk of pollution.Laboratory tests,including downward and upward drilling,long-running,remote-control,and cold-environment assessments,were conducted to validate the sonde's principle and functionality.During the 38th Chinese National Antarctic Research Expedition,CHINARE(2021–2022 season),the RECAS prototype underwent testing on the flank region of Dalk glacier,10 km from Zhongshan Station in Antarctica.Three boreholes with depths of 200.3,183.2,and 133.5 m were successfully drilled,with the refrozen meltwater sealing the boreholes during the process.Approximately 600 mL of melted water samples were collected from each hole.Throughout the drilling tests,all systems of the RECAS prototype performed within the expected ranges.展开更多
文摘Opening a new scientific frontier lying under the Antarctic ice, Russian researchers have drilled down and finally reached the surface of the gigantic freshwater lake, Lake Vostok. The mission chief likened the achievement to placing a man on the moon. Drilling in the area of the lake began 22 years ago in 1990, but progressed slowly as a result of funding shortages, equipment breakdowns, difficulties of drilling in the ＂warm＂ ice, and environmental concerns. In 1996, six years after drilling was started, a group of Russian and British scientists discovered the lake believed to be one of the largest fresh water reservoirs on the planet. This lake is among the last unexplored places on Earth. Sealed from the Earth＇s atmosphere for millions of years, it may provide vital information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. Russian experts waited several years for international approval of their drilling technology before proceeding. As anticipated, lake water under pressure rushed up the borehole, pushing the drilling fluid up and away, then froze, forming a protective plug that prevented contamination of the lake. In December of the next Antarctic season, 2012--2013, researchers plan to re-drill the frozen sample of subglacial water for analysis.
基金Supported by projects of National Science Foundation of China(No.41327804)the Geological Survey of China(No.3R212W324424)
文摘Drilling operations in polar regions and mountainous areas are complicated by nature of the extreme environment. Yet conventional rotary drilling technologies can be used to drill ice for scientific samples and oth- er research. Due to such reasons as power consumption and weight complications, it is hard to apply a conven- tional rotary drilling rig for glacial exploration. Use of small, relatively lightweight, portable engine-powered drilling systems in which the drill lifting from the borehole is carried by the winch. It is reasonable enough for near-surface shallow ice-drilling down to 50 m. Such systems can be used for near-surface ablation-stakes in- stallation, also temperature measurements at the bottom of active strata layer, revealing of anthropogenie pollu- tion, etc. The specified used in this research is an auger ice drill powered by a gasoline engine. At this stage, it is crucial to choose effective drilling parameters such as weight on bit （WOB） and drill bit rotation rate. Sen- sors equipped on the rig have measured the main parameters of the drilling process, such as drill speed, WOB, drill rotation speed, torque and temperature. This paper addresses research on drilling parameters of engine powered auger ice drill and supplies some recommendations for optimization of any ice-core drilling process.
基金supported the by the National Key R&D Program of China (Grant no. 2021YFC2801400)。
文摘The firn aquifer beneath the Greenland Ice Sheet may play a significant role in rising sea level. Both traditional mechanical drilling and electric thermal drilling are poorly adapted for effective, low-disturbance sampling in firn aquifers. We propose using a vibrocoring technique for the undisturbed sampling of dry firn and firn aquifer layers. A remote-controlled vibrocorer is designed to obtain 1-m-long cores with a diameter of 100 mm. The depth capacity of the system is approximately 50 m. The total weight of the vibrocoring system with the surface auxiliary equipment is approximately 110 kg, and corer assembly itself weighs ~60 kg.
基金the National Natural Science Foundation of China under Grant Nos. 40633016 , 40575047 the Special Social Public Welfare Foundation of the Ministry of Science and Technology of China+1 种基金 the Open Foundation of Wuhan Institute of Heavy Rain under Grant No. IHR2006K05 the Special Foundation of Climate Change of China Meteorological Administration under Grant CCSF2006-18.
文摘By using the ECMWF reanalysis daily data and daily precipitation data of 80 stations in Northeast China from 1961 to 2002, the impacts of moisture transport of East Asian summer monsoon on the summer precipitation anomaly in Northeast China, and the relationship between the variation of moisture budget and the establishment of East Asian summer monsoon in this region are studied. The results demonstrate that the moisture of summer precipitation in Northeast China mainly originates from subtropical, South China Sea, and South Asia monsoon areas. East China and its near coastal area are the convergent region of the monsoonal moisture currents and the transfer station for the currents continually moving northward. The monsoonal moisture transport, as an important link or bridge, connects the interaction between middle and low latitude systems. In summer half year, there is a moisture sink in Northeast China where the moisture influx is greater than outflux. The advance transport and accumulation of moisture are of special importance to pentad time scale summer precipitation. The onset, retreat, and intensity change of the monsoonal rainy season over Northeast China are mainly signified by the moisture input condition along the southern border of this area. The establishment of East Asian summer monsoon in this area ranges from about 10 July to 20 August and the onset in the west is earlier than that in the east. The latitude that the monsoon can reach is gradually northward from west to east, reaching 50°N within longitude 120°-135°E. In summer, the difference of air mass transport between summers with high and low rainfall mainly lies in whether more air masses originating from lower latitudes move northward through East China and its coastal areas, consequently transporting large amounts of hot and humid air into Northeast China.
文摘A novel embedded sensor network records changes in key climatic-environmental variables over a range of altitude in the BaekduDaegan Mountain （BDM） of Gangwon Province in Korea, a protected mountain region with unique biodiversity undergoing climate change research. The investigated area is subdivided into three horizontal north-south study areas. Three variables, temperature （T, °C）, relative humidity （RH, %）, and light intensity （LI, lumens m-2, or lux, lx）, have been continuously measured at hourly intervals from June, 2olo to September, 2011 using HOBO H8 devices at lO fixed study sites. These hourly observations are aggregated to monthly, seasonal and annual mean values, and results are summarized to inaugurate a long-term climate change investigation. A region wide T difference in accordance with altitude, or lapse rate, over the interval is calculated as o.4°C l00 m-1. T lapse rates change seasonally, with winter lapse rates being greater than those of summer. RH is elevated in summer compared to other seasons. LI within forestland is lower during summer and higher during other seasons. The obtained results could closely relate to the vegetation type and structure and the terrain state since data loggers were located in forestland.
基金This work was financially supported by the National Natural Science Foundation of China(49672107)CAS(KZ951-A1-205-02)+2 种基金the Ministry of Science and Technology of China(98-927-01-06-05)This work was also supported by the Ministry of Maritime Affairs and Fisheries,Korea through KORDI(PP98001 04)The 9th Korean Antarctic Re-search Program and the King Sejong Station headedby Dr.Yeadong Kim provided logistic support duringthe expedition.
文摘Ages determined with the 40Ar/39Ar isotopic system affirms the Early Cretaceous volcanic activity in the Barton Peninsula, King George Island, Antarctica. Two specimens of basaltic andesite collected from the lower-most volcanic sequence of the peninsula were irradiated and analyzed in different experiments, yielding an identical age spectrum, and two magmatic thermal events of the Early Cretaceous (120.4±1.6 Ma, 119±1 Ma) and Early Tertiary (53.1±1.5 Ma, 52±1 Ma) are distinguished. The former is interpreted to represent the primary cooling age of basaltic andesite, whereas the latter is the thermal reset age caused by the intrusion of granitic pluton. These new ages clearly indicate that volcanism was active during the Early Cretaceous on the Barton Peninsula and that intensive hydrothermal alteration and mineralization of Mesozoic volcanic rocks resulted from Tertiary magmatism.
基金Under the auspices of the National Natural Science Foundation of China (No. 40471028, No. 40476005)ShanghaiShu Guang Project (No. 05SG46)
文摘Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International Polar Year （IPY） during August 2007. In this paper two data processing methods are used together to generate two 100-m cell size digital elevation models （DEMs） of the Dome A region （Dome A-DEM） by using Cokriging method to interpolate the ICESat GLAS data, with Ihde-DEM as a constraint. It provides fundamental data to glaciological and geophysical investigation in this area. The Dome A-DEM was applied to determining the ice-sheet surface elevations and coordinates of the south and north summits, defining boundaries of basins and ice ftowlines, deducing subglacial topography, and mapping surface slope and aspect in Dome A region. The DEM shows there are two （north and south） summits in Dome A region. The coordinate and the surface elevation of the highest point （the north summit） are 80°21＇29.86＂S, 77°21＇50.29＂E and 4092.71±1.43m, respectively. The ice thickness and sub-ice bedrock elevation at north summit are 2420m and 1672m, respectively. Dome A region contains four drainage basins that meet together near the south summit. Ice ftowlines, slope and aspect in detail are also derived using the DEM.
基金This work was supported by National Natural Science Foundation of China （Grant No. 40476005 and 40233032）, the Ministry of Science and Technology, China （Grant No. 2005DIB3J114）, and the ＂863 Project＂ （Grant No. 2006AA04Z206 and 2006AA09Z152）.
文摘As an important component of the cryosphere, sea ice is very sensitive to climate change. The study of sea ice physics needs accurate sea ice thickness. This paper presents an electromagnetic induction （EM） technique which can be used to measure the sea ice thickness distribution efficiently and its successful application in the Antarctic Neila Fjord. Based on the electrical properties of sea ice and seawater and the application of electromagnetic field theory, this technique can accurately detect the distance between the EM instrument and the ice/water interface to measure the sea ice thickness. Analyzing the apparent conductivity data obtained by the electromagnetic induction technique and drill-hole measurements at same location allows the construction of a transform equation for the apparent conductivity and sea ice thickness. The verification of the calculated sea ice thickness using this equation indicates that the electromagnetic induction technique is able to determine reliable sea ice thickness with an average relative error of only 5.5%. The ice thickness profiles show the sea ice distribution in Neila Fjord is basically level with a thickness of 0.8 - 1.4 m.
文摘Thermobaric conditions of subglacial Antarctic environment remain poorly understood, despite recent advances in radar and seismic surveying. The direct accessing to the largest subglacial lake, Lake Vostok, was carried out twice by Russian scientists in February 2012 and January 2015, opening new opportunities for assessing the thermobaric conditions at ice-water interface. According to the assumption that ice sheet is “floating” on the lake, it was predicted that the water would rise 30 - 40 m in the bottom part of the borehole, but in fact the water rose from the lake to a height of more than 500 m. To explain this phenomenon we assume that the pressure in Lake Vostok results from the external pressure of the entire mass of ice above it and the pressure of the water column that is overlaid above the point being considered. Extrapolation of temperature measurements from the deep bore-holes drilled at Vostok Station also confirmed that the bed of the ice sheet is at pressure melting point. As a result of accessing Lake Vostok, the pressure in the lake is reduced that would lead to the formation of a new additional layer of accretion ice on the lower ice sheet surface.
基金Supported by Project of the National Science Foundation of China(No.41327804)
文摘Ice cores contain an abundance of information about the Earth＇s climate in the past, and recovered from shallow drilling down to 300-350 m give sufficient information for reconstructing of the last climatic changes and for monitoring of pollution from human being. Cable-suspended core auger drills use an armored cable with a winch to provide power to the down-hole motor system and to retrieve the down-hole unit. Because of their lightweight, convenient transportation and installation, high penetration rates and low power consumption, core auger drills are widely used for shallow drilling in ice. Nowadays at least 14 types of auger electromechani- cal drills were designed and tested in different foreign and national glaciological laboratories. However, auger options were usually determined by experience, and the main parameters （ helix angle of the fights and rotational speed） are varied in a wide range from drill to drill. If parameters of auger are not chosen properly, poorly en- gineered drills had troubles with low efficiency of cuttings transportation, jam of ice cuttings, repeated fragmen- tation, cutters icing and stop penetration, abnormal power consumption, high rotation torques, and so on. Thus, this paper presents the method of optimization of iee cuttings transportation of cable-suspended core auger drill on the base of the theory of rotary auger. As the result, the optimal helix angle was determined correspond- ing to the rotational speed from the transportation efficiency point of view.
基金Supported by the Polar Stratagem Fund of China (No.JD07-6).
文摘Evaluation on a regional climate model was made with five-month atmospheric simulations over the Arctic river basins. The simulations were performed with a modified mesoscale model, Polar MM5 coupled to the NCAR Land Surface Model （LSM） to illustrate the skill of the coupled model （Polar MM5＋LSM） in simulating atmospheric circulation over the Arctic river basins. Near-surface and upper-air observations were used to verify the simulations. Sensitivity studies between the Polar MM5 and Polar MM5＋LSM simulations revealed that the coupled model could improve the forecast skill for surface variables at some sites. In addition, the extended evaluations of the coupled model simulations on the North American Arctic domain during December 15, 2002 to May 15, 2003 were carried out. The time series plots and statistics of the observations and Polar MM5＋LSM simulations at six stations for near-surface and vertical profiles at 850 hPa and 500 hPa were analyzed. The model was found capable of reproducing the observed atmospheric behavior in both magnitude and variability, especially for temperature and near-surface wind direction.
文摘The Amery Ice Shelf is the largest ice shelf in East Antarctica. A new DEM was generated for this ice shelf, using kriging to interpolate the data from ICE- Sat altimetry and the AIS-DEM. The ice thickness distribution map is converted from the new DEM, assuming hydrostatic equilibrium. The Amery Ice Shelf marine ice, up to 230 m thick, is concentrated in the northwest of the ice shelf. The volume of the marine ice is 2.38 × 10^3 km^3 and accounts for about 5.6% of the shelf volume.
文摘Paramo is a term used to describe tropical alpine vegetation between the continuous timberline and the snow line in tbe Northern Andes. Paramo environments provide important species habitat and ecosystem services. Changes in spatial extent of the paramo ecosystem at Pambamarca in the Central Cordillera of the northern Ecuadorian Andes were analysed using multi-temporal Landsat TM/ETM＋ satellite data. The region suffered a loss of 1826.6 ha or 20% of the total area at a rate of 100 ha/annum during 1988-2007 period. It is found that permanent paramo cover decreased from 8350 ha in 1988 to 5864 ha in 2007 at a fairly constant rate （R^2=0.94）. This loss is attributed to expansion of commercial agriculture and floriculture in the valleys coupled with increased population pressure. Land at higher elevations has been cleared for small scale agriculture. Loss of the paramo ecosystem will exert a number of negative impacts on ecosystem services and livelihoods of the local population at Pambamarca.
基金Supported by the National Natural Science Foundation of China(No.41276189)
文摘Deep ice drilling in Polar Regions plays a key role in paleo-climate, microbiological and glaciological researches. For deep ice and subglacial coring the special purpose-built electromechanical cable-suspended drills with bottom-hole circulation are designed and explored. Used at present drilling fluid circulation systems are specified by very high fluid wastes during processing. Measurements in deep drilling projects in Antarctic and Greenland ice sheets showed that 25%-40% of the drilling fluid, pumped into the hole, is retrieved to the surface with cable and drill, and up to 45% of retrieved fluid goes to waste. This leads not only to increasing of the fluid consumption and cost of the project in general but also to severe contamination of air, surface and near-surface snow-firn layers at the drilling site. In order to reduce wastes and environmental impact, it is proposed to modify drilling fluid processing system by avoiding of evaporation and leakages of fluid as far as practicable. Drilling fluid is prepared and pumped into the hole according to predetermined program on semiautomatic mode, and volume and density of blended and pumped into the hole drilling fluid are measured continuously. Components of the drilling fluid are stored and mixed in the special closed containers equipped by pressure relief valves. Separation of drilling fluid from ice cuttings is carried out by two steps: firstly, fluid is separated with hydro extractor and then with thermal separator. To reduce the amount of removed drilling fluid with cable special squeezing collar is installed on the borehole mouth. All these arrangements are able to decrease drilling fluid wastes in many times.
文摘First let me say that I am honored to be asked for advice and suggestions as a Foreign Member of the Chinese Academy of Sciences.I have been working in China since 1984, first with the Institute of Glaciology and Geocryology located
基金supported by the National Key Research and Development Project of the Ministry of Science and Technology of China(Grant Nos.2016YFC1400302,2023YFC2812602)the National Natural Science Foundation of China(Grant No.41941005)。
文摘Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's life forms.Despite various approaches to access and directly sample subglacial water and sediments,clean access and exploration of subglacial lakes remain challenging.To address this concern,Jilin University has developed the RECoverable Autonomous Sonde(RECAS)prototype.This technology enables sampling and in-situ detection of subglacial lake water while being isolated from the surface,thus minimizing the risk of pollution.Laboratory tests,including downward and upward drilling,long-running,remote-control,and cold-environment assessments,were conducted to validate the sonde's principle and functionality.During the 38th Chinese National Antarctic Research Expedition,CHINARE(2021–2022 season),the RECAS prototype underwent testing on the flank region of Dalk glacier,10 km from Zhongshan Station in Antarctica.Three boreholes with depths of 200.3,183.2,and 133.5 m were successfully drilled,with the refrozen meltwater sealing the boreholes during the process.Approximately 600 mL of melted water samples were collected from each hole.Throughout the drilling tests,all systems of the RECAS prototype performed within the expected ranges.
