As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North Am...As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North America as elsewhere in the world,changes in water resources strongly impact agriculture and animal husbandry.From a combination of Gravity Recovery and Climate Experiment（GRACE） gravity and Global Positioning System（GPS） data,it is recently found that water storage from August,2002 to March,2011 recovered after the extreme Canadian Prairies drought between 1999 and 2005.In this paper,we use GRACE monthly gravity data of Release 5 to track the water storage change from August,2002 to June,2014.In Canadian Prairies and the Great Lakes areas,the total water storage is found to have increased during the last decade by a rate of 73.8 ± 14.5 Gt/a,which is larger than that found in the previous study due to the longer time span of GRACE observations used and the reduction of the leakage error.We also find a long term decrease of water storage at a rate of-12.0 ± 4.2 Gt/a in Ungava Peninsula,possibly due to permafrost degradation and less snow accumulation during the winter in the region.In addition,the effect of total mass gain in the surveyed area,on present-day sea level,amounts to-0.18 mm/a,and thus should be taken into account in studies of global sea level change.展开更多
A one-dimensional hybrid model was developed to study the electrical asymmetry effect（EAE） caused by the fourthorder harmonic in a dual-frequency capacitively coupled Ar plasma.The self-bias voltage caused by the fo...A one-dimensional hybrid model was developed to study the electrical asymmetry effect（EAE） caused by the fourthorder harmonic in a dual-frequency capacitively coupled Ar plasma.The self-bias voltage caused by the fourth-order frequency changes periodically with the phase angle,and the cycle of self-bias with the phase angle is π/2,which is half of that in the second-order case.The influence of the phase angle between the fundamental and its fourth-order frequency on the ion density profiles and the ion energy distributions（IEDs） were studied.Both the ion density profile and the IEDs can be controlled by the phase angle,which provides a convenient way to adjust the sheath characters without changing the main discharge parameters.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.41431070,41174016,41274026,41274024,41321063)National Key Basic Research Program of China(973 Program,2012CB957703)+1 种基金CAS/SAFEA International Partnership Program for Creative Research Teams(KZZD-EW-TZ-05)The Chinese Academy of Sciences
文摘As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North America as elsewhere in the world,changes in water resources strongly impact agriculture and animal husbandry.From a combination of Gravity Recovery and Climate Experiment（GRACE） gravity and Global Positioning System（GPS） data,it is recently found that water storage from August,2002 to March,2011 recovered after the extreme Canadian Prairies drought between 1999 and 2005.In this paper,we use GRACE monthly gravity data of Release 5 to track the water storage change from August,2002 to June,2014.In Canadian Prairies and the Great Lakes areas,the total water storage is found to have increased during the last decade by a rate of 73.8 ± 14.5 Gt/a,which is larger than that found in the previous study due to the longer time span of GRACE observations used and the reduction of the leakage error.We also find a long term decrease of water storage at a rate of-12.0 ± 4.2 Gt/a in Ungava Peninsula,possibly due to permafrost degradation and less snow accumulation during the winter in the region.In addition,the effect of total mass gain in the surveyed area,on present-day sea level,amounts to-0.18 mm/a,and thus should be taken into account in studies of global sea level change.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11305032,11305028,11375163,and 11275039)the Scientific Foundation of Ministry of Education of China(Grant No.N130405008)
文摘A one-dimensional hybrid model was developed to study the electrical asymmetry effect（EAE） caused by the fourthorder harmonic in a dual-frequency capacitively coupled Ar plasma.The self-bias voltage caused by the fourth-order frequency changes periodically with the phase angle,and the cycle of self-bias with the phase angle is π/2,which is half of that in the second-order case.The influence of the phase angle between the fundamental and its fourth-order frequency on the ion density profiles and the ion energy distributions（IEDs） were studied.Both the ion density profile and the IEDs can be controlled by the phase angle,which provides a convenient way to adjust the sheath characters without changing the main discharge parameters.
