The desert and permafrost conditions of the Qinghai-Tibet Plateau are unique.However,the effects of desertification on the ground temperature of permafrost are currently unclear.Recently,understanding this problem has...The desert and permafrost conditions of the Qinghai-Tibet Plateau are unique.However,the effects of desertification on the ground temperature of permafrost are currently unclear.Recently,understanding this problem has become more urgent because of increasing desertification on the plateau.For this reason,an observational field experiment was undertaken by the authors at Honglianghe on the Qinghai-Tibet Plateau.Thermistor ground temperature probes were used,and synchronized contrasting observations were made in an open area.Observations of the ground temperature of permafrost below sand layers with a range of thicknesses were made from May 2010 to April 2011.The sand layers were found to play a key role in the protection of the underlying permafrost.The ground temperature below a permafrost table overlain by a thick sand layer was lower than that of the average annual temperature for the natural ground surface,and the temperature drop was roughly constant at 0.2°C.During the warmer part of the year (May to September),the maximum temperature drops over the five months were 3.40,3.72,4.85,3.16,and 1.88°C,respectively.The ground temperature near a permafrost table overlain by a thin sand layer was also lower than that of the average annual temperature for the natural ground surface.However,in this case the average of the annual maximum temperature drop was significantly less,0.71°C.The scientific significance of our preliminary conclusions is not only to present an exploration of the interaction between desertification and permafrost,but also to provide new engineering ideas for protecting the permafrost in regions where construction is required on the Qinghai-Tibet Plateau.展开更多
Electric discharge phenomenon is often observed during the passage of sandstorms over desert regions and sometimes does great damage to human beings. Based on previous researches on the electrification of sandstorms b...Electric discharge phenomenon is often observed during the passage of sandstorms over desert regions and sometimes does great damage to human beings. Based on previous researches on the electrification of sandstorms by the scholars both at home and aboard,the authors conducted the simulation experiments on the electric fields of sandstorm-triggered creeping-saltating sand, suspending sand and watered suspending sand in the large-scale wind tunnel. According to the experimental results the electric field structure and its formation mechanism were analysed and discussed, the quantity of electric charges and electric field strengthwere measured and calculated, and finally several conclusions were drawn.展开更多
Pulsatory characteristics of wind velocity in sand flow over Gobi and mobile sand surface have been investigated experimentally in the wind tunnel. The primary goal of this paper is to reveal the relation- ship betwee...Pulsatory characteristics of wind velocity in sand flow over Gobi and mobile sand surface have been investigated experimentally in the wind tunnel. The primary goal of this paper is to reveal the relation- ship between pulsatory characteristics of instantaneous wind speed in sand flow and the motion state of sand grains. For a given underlying surface, pulsation of wind velocities in sand flow on different heights has a good correlation. As the space distance among different heights increases, fluctuation of instantaneous wind speed presents a decreasing trend and its amplitude is closely related to the mo- tion state of sand grains and their transport. Pulsatory intensity increases with the indicated wind speed, but its relative value does not depend on it, only agrees with height.展开更多
基金supported by the National Natural Science Foundation of China (40930741 and 41071009)the Knowledge Innovation Program of Chinese Academy of Sciences (KZCX2-YW-329)
文摘The desert and permafrost conditions of the Qinghai-Tibet Plateau are unique.However,the effects of desertification on the ground temperature of permafrost are currently unclear.Recently,understanding this problem has become more urgent because of increasing desertification on the plateau.For this reason,an observational field experiment was undertaken by the authors at Honglianghe on the Qinghai-Tibet Plateau.Thermistor ground temperature probes were used,and synchronized contrasting observations were made in an open area.Observations of the ground temperature of permafrost below sand layers with a range of thicknesses were made from May 2010 to April 2011.The sand layers were found to play a key role in the protection of the underlying permafrost.The ground temperature below a permafrost table overlain by a thick sand layer was lower than that of the average annual temperature for the natural ground surface,and the temperature drop was roughly constant at 0.2°C.During the warmer part of the year (May to September),the maximum temperature drops over the five months were 3.40,3.72,4.85,3.16,and 1.88°C,respectively.The ground temperature near a permafrost table overlain by a thin sand layer was also lower than that of the average annual temperature for the natural ground surface.However,in this case the average of the annual maximum temperature drop was significantly less,0.71°C.The scientific significance of our preliminary conclusions is not only to present an exploration of the interaction between desertification and permafrost,but also to provide new engineering ideas for protecting the permafrost in regions where construction is required on the Qinghai-Tibet Plateau.
基金This project was supported by the InnovationProject of the Chinese Academy of Sciences (Grant No. 210027) the Knowledge Innovation Project of Chinese Academy of Sciences (GrantNo. KZCX2-304)+1 种基金the National Natural Science Foundation of China(Grant No.39971013) the State Key Basic Research Development Planning (Grnat No.20000487).
文摘Electric discharge phenomenon is often observed during the passage of sandstorms over desert regions and sometimes does great damage to human beings. Based on previous researches on the electrification of sandstorms by the scholars both at home and aboard,the authors conducted the simulation experiments on the electric fields of sandstorm-triggered creeping-saltating sand, suspending sand and watered suspending sand in the large-scale wind tunnel. According to the experimental results the electric field structure and its formation mechanism were analysed and discussed, the quantity of electric charges and electric field strengthwere measured and calculated, and finally several conclusions were drawn.
基金Supported by the National Key Basic Research Project (Grant No. G1999043504) the National Science and Technology Key Task Project (Grant No. 2002BA517A11)
文摘Pulsatory characteristics of wind velocity in sand flow over Gobi and mobile sand surface have been investigated experimentally in the wind tunnel. The primary goal of this paper is to reveal the relation- ship between pulsatory characteristics of instantaneous wind speed in sand flow and the motion state of sand grains. For a given underlying surface, pulsation of wind velocities in sand flow on different heights has a good correlation. As the space distance among different heights increases, fluctuation of instantaneous wind speed presents a decreasing trend and its amplitude is closely related to the mo- tion state of sand grains and their transport. Pulsatory intensity increases with the indicated wind speed, but its relative value does not depend on it, only agrees with height.
