The equatorial and polar satellites of the Double Star Project (DSP) were launched successfully on December 29, 2003 and July 25, 2004, respectively, and both of them are operating smoothly. The DSP provides a good op...The equatorial and polar satellites of the Double Star Project (DSP) were launched successfully on December 29, 2003 and July 25, 2004, respectively, and both of them are operating smoothly. The DSP provides a good opportunity for investigat-ing the structure of the magnetosphere. Based on the DSP data collected during 2004, we have surveyed the distribution of the magnetic fields and plasmas in the magnetosphere. It is found that: (1) Near the Earth’s equatorial plane within geo-centric distances of less than 7 RE, the Earth’s magnetic field is dipolar. In the vi-cinity of the magnetopause, the magnetic field is enhanced by a factor of about 1.5, and on the nightside, the magnetic field can vary significantly from the Earth’s di-pole field, likely caused by the presence of the near-Earth tail current sheet. (2) In the day-side magnetosheath, the electron and ion densities are usually both in the range of 10―30 cm?3; the ion and electron temperatures are usually about 200 and 50 eV, respectively. The flow pattern is usually smooth, with a low velocity in the subsolar region and with significantly higher velocities in the dawn and dusk flanks. (3) In the region between the magnetopause and plasmasphere the density is low, approximately 0.5―5 cm?3, and the temperature is high, about 1―10 keV for ions and 0.1―5 keV for electrons. The ion temperature has an apparent anisotropy, with the ratio of the perpendicular and parallel temperatures being about 1.0―1.3 for the night- and dusk-side magnetosphere and about 1.3―2.0 for the day- and dawn-side magnetosphere. There is an evident sunward convection of about 50 km/s in the magnetosphere. On the dawn side, the flow becomes somewhat turbulent, and in the vicinity of the night-noon meridian plane, the convection is rather slow. (4) The high-energy electrons with energies higher than 2 MeV are mainly located in the regions with 3 < L < 4.5; the size of the high-energy electrons area varies with time, it may expand and shrink occasionally according to diff展开更多
The physical process in the Earth's polar region is very complex and still needs to be further studied.Using the data from Cluster satellite measurement,an analysis on field-aligned electrons in the mid-latitude c...The physical process in the Earth's polar region is very complex and still needs to be further studied.Using the data from Cluster satellite measurement,an analysis on field-aligned electrons in the mid-latitude cusp on 30 September 2001 has been performed.The satellite observed a down-flowing electron event in the low-latitude boundary and a sequential up-flowing electron event in the high-latitude boundary of the cusp region.The down-flowing electron had a velocity as high as 500 km/s and a flux of 2.0×10^(9) cm^(-2)-s^(-1).The up-flowing electron had a velocity up to 1200 km/s and a flux of 4.9×10^(9) cm^(-2)-s^(-1).Both the velocity and the flux observed in this event are the maximum values of the up-flowing electrons observed by all satellites to date.The electron is the main contributor for the field-aligned current in this event.The physical mechanism is also discussed.The down-flowing electron in the low-latitude boundary of the cusp region may result from solar wind injecting during the southward IMF,and the up-flowing electrons in the high-latitude boundary of cusp may result from mirroring of the solar wind,or from the ionospheric up-flowing electrons which have been accelerated.展开更多
A statistical study of the properties of ions (O+, He+ and H+) measured by the Cluster-II in cusp region as a function of the solar wind dynamic pressure and geomagnetic index Kp respectively was made dur-ing the summ...A statistical study of the properties of ions (O+, He+ and H+) measured by the Cluster-II in cusp region as a function of the solar wind dynamic pressure and geomagnetic index Kp respectively was made dur-ing the summer and fall of 2001-2003. The main results are that: (1) O+ ion density responds in a sig-nificant way to geomagnetic index Kp, and He+ ion density is not correlated with geomagnetic index Kp, both of them have a significant positive correlation with solar wind dynamic pressure; (2) H+ ion density is also observed to increase with solar wind dynamic pressure, and not correlated with geomagnetic index Kp.展开更多
By analyzing hot ion and electron parameters together with magnetic field measurements from Cluster, an event of magnetopause crossing of the spacecraft has been investigated. At the latitude of about 40° and mag...By analyzing hot ion and electron parameters together with magnetic field measurements from Cluster, an event of magnetopause crossing of the spacecraft has been investigated. At the latitude of about 40° and magnetic local time (MLT) of 13:20 during the southward interplanetary magnetic field (IMF), a transition layer was observed, with the magnetospheric field configuration and cold dense plasma features of the magnetosheath. The particle energy-time spectrograms inside the layer were similar to but still a little different from those in the magnetosheath, obviously indicating the solar wind entry into the magnetosphere. The direction and magnitude of the accelerated ion flow implied that reconnection might possibly cause such a solar wind entry phenomenon. The bipolar signature of the normal magnetic component BN in magnetopause coordinates further supported happening of reconnection there. The solar wind plasma flowed toward the magnetopause and entered the magnetosphere along the reconnected flux tube. The magnetospheric branch of the reconnected flux tube was still inside the magnetosphere after reconnection and supplied the path for the solar wind entry into the dayside magnetosphere. The case analysis gives observational evidence and more details of how the reconnection process at the dayside low latitude magnetopause caused the solar wind entry into the magnetosphere.展开更多
From a sustainability perspective, achieving greater efficiencies in environmental waste management is at the heart of current academic discussion on climate change science. Over the last few decades the tourism indus...From a sustainability perspective, achieving greater efficiencies in environmental waste management is at the heart of current academic discussion on climate change science. Over the last few decades the tourism industry has developed exponentially and is now considered one of the most dynamic economic activities worldwide. Solid waste is a commonly identified and ever increasing aspect of tourism;the improper management of which can lead to substantial and irreversible direct and indirect environmental, economic and social impacts. However, the management of solid waste in tourism dominated island communities is particularly problematic due to climatic conditions, topography, financial restraints, planning issues, changing consumption patterns, transient population, and seasonal variations in solid waste quantity and composition. In addition, there is often a lack of momentum to implement new initiatives and programs as stakeholders involved in the design, construction and operation of tourist resorts have conflicts of interest. Using information gathered from key informant interviews, participation observations and literature reviews, this article appraises current waste management practices in four European tourist destinations, namely: Mallorca, Tenerife, Kefalonia and Rhodes. Findings indicate that, although there are signs of compliance with global best practice, a variety of locally-based measures need to be implemented to enhance sustainability.展开更多
In this review,we discuss the structure and dynamics of the magnetospheric LowLatitude Boundary Layer(LLBL)based on recent results from multi-satellite missions Cluster and Double Star.This boundary layer,adjacent to ...In this review,we discuss the structure and dynamics of the magnetospheric LowLatitude Boundary Layer(LLBL)based on recent results from multi-satellite missions Cluster and Double Star.This boundary layer,adjacent to the magnetopause on the magnetospheric side,usually consists of a mixture of plasma of magnetospheric and magnetosheath origins,and plays an important role in the transfer of mass and energy from the solar wind into the magnetosphere and subsequent magnetospheric dynamics.During southward Interplanetary Magnetic Field(IMF)conditions,this boundary layer is generally considered to be formed as a result of the reconnection process between the IMF and magnetospheric magnetic field lines at the dayside magnetopause,and the structure and plasma properties inside the LLBL can be understood in terms of the time history since the reconnection process.During northward IMF conditions,the LLBL is usually thicker,and has more complex structure and topology.Recent observations confirm that the LLBL observed at the dayside can be formed by single lobe reconnection,dual lobe reconnection,or by sequential dual lobe reconnection,as well as partially by localized cross-field diffusion.The LLBL magnetic topology and plasma signatures inside the different sub-layers formed by these processes are discussed in this review.The role of the Kelvin-Helmholtz instability in the formation of the LLBL at the flank magnetopause is also discussed.Overall,we conclude that the LLBL observed at the flanks can be formed by the combination of processes,(dual)lobe reconnection and plasma mixing due to non-linear Kelvin-Helmholtz waves.展开更多
基金the National Natural Science Foundation of China (Grant Nos. 40621003, 40728005,40674094, and 40390150)Ministry of Science and Technology of China (Grant No. 2006CB806305)Hundred Talents Program of the CAS
文摘The equatorial and polar satellites of the Double Star Project (DSP) were launched successfully on December 29, 2003 and July 25, 2004, respectively, and both of them are operating smoothly. The DSP provides a good opportunity for investigat-ing the structure of the magnetosphere. Based on the DSP data collected during 2004, we have surveyed the distribution of the magnetic fields and plasmas in the magnetosphere. It is found that: (1) Near the Earth’s equatorial plane within geo-centric distances of less than 7 RE, the Earth’s magnetic field is dipolar. In the vi-cinity of the magnetopause, the magnetic field is enhanced by a factor of about 1.5, and on the nightside, the magnetic field can vary significantly from the Earth’s di-pole field, likely caused by the presence of the near-Earth tail current sheet. (2) In the day-side magnetosheath, the electron and ion densities are usually both in the range of 10―30 cm?3; the ion and electron temperatures are usually about 200 and 50 eV, respectively. The flow pattern is usually smooth, with a low velocity in the subsolar region and with significantly higher velocities in the dawn and dusk flanks. (3) In the region between the magnetopause and plasmasphere the density is low, approximately 0.5―5 cm?3, and the temperature is high, about 1―10 keV for ions and 0.1―5 keV for electrons. The ion temperature has an apparent anisotropy, with the ratio of the perpendicular and parallel temperatures being about 1.0―1.3 for the night- and dusk-side magnetosphere and about 1.3―2.0 for the day- and dawn-side magnetosphere. There is an evident sunward convection of about 50 km/s in the magnetosphere. On the dawn side, the flow becomes somewhat turbulent, and in the vicinity of the night-noon meridian plane, the convection is rather slow. (4) The high-energy electrons with energies higher than 2 MeV are mainly located in the regions with 3 < L < 4.5; the size of the high-energy electrons area varies with time, it may expand and shrink occasionally according to diff
基金Supported by the National Natural Science Foundation of China under Grant Nos 41074114,40804031 and 40921063the Specialized Research Fund for State Key Laboratory in China.
文摘The physical process in the Earth's polar region is very complex and still needs to be further studied.Using the data from Cluster satellite measurement,an analysis on field-aligned electrons in the mid-latitude cusp on 30 September 2001 has been performed.The satellite observed a down-flowing electron event in the low-latitude boundary and a sequential up-flowing electron event in the high-latitude boundary of the cusp region.The down-flowing electron had a velocity as high as 500 km/s and a flux of 2.0×10^(9) cm^(-2)-s^(-1).The up-flowing electron had a velocity up to 1200 km/s and a flux of 4.9×10^(9) cm^(-2)-s^(-1).Both the velocity and the flux observed in this event are the maximum values of the up-flowing electrons observed by all satellites to date.The electron is the main contributor for the field-aligned current in this event.The physical mechanism is also discussed.The down-flowing electron in the low-latitude boundary of the cusp region may result from solar wind injecting during the southward IMF,and the up-flowing electrons in the high-latitude boundary of cusp may result from mirroring of the solar wind,or from the ionospheric up-flowing electrons which have been accelerated.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40621003, 40674091 and 40523006)the International Collaboration Research Team Program of the Chinese Academy of Sciences
文摘A statistical study of the properties of ions (O+, He+ and H+) measured by the Cluster-II in cusp region as a function of the solar wind dynamic pressure and geomagnetic index Kp respectively was made dur-ing the summer and fall of 2001-2003. The main results are that: (1) O+ ion density responds in a sig-nificant way to geomagnetic index Kp, and He+ ion density is not correlated with geomagnetic index Kp, both of them have a significant positive correlation with solar wind dynamic pressure; (2) H+ ion density is also observed to increase with solar wind dynamic pressure, and not correlated with geomagnetic index Kp.
基金Supported by the Ministry of Science and Technology of China(Grant No.2006CB806305)the National Natural Science Foundation of China(Grant Nos.40621003,40620130094,40674094and40731054)the Hundred Talents Program of the CAS,and the Specialized Research Fund for State Key Laboratories
文摘By analyzing hot ion and electron parameters together with magnetic field measurements from Cluster, an event of magnetopause crossing of the spacecraft has been investigated. At the latitude of about 40° and magnetic local time (MLT) of 13:20 during the southward interplanetary magnetic field (IMF), a transition layer was observed, with the magnetospheric field configuration and cold dense plasma features of the magnetosheath. The particle energy-time spectrograms inside the layer were similar to but still a little different from those in the magnetosheath, obviously indicating the solar wind entry into the magnetosphere. The direction and magnitude of the accelerated ion flow implied that reconnection might possibly cause such a solar wind entry phenomenon. The bipolar signature of the normal magnetic component BN in magnetopause coordinates further supported happening of reconnection there. The solar wind plasma flowed toward the magnetopause and entered the magnetosphere along the reconnected flux tube. The magnetospheric branch of the reconnected flux tube was still inside the magnetosphere after reconnection and supplied the path for the solar wind entry into the dayside magnetosphere. The case analysis gives observational evidence and more details of how the reconnection process at the dayside low latitude magnetopause caused the solar wind entry into the magnetosphere.
文摘From a sustainability perspective, achieving greater efficiencies in environmental waste management is at the heart of current academic discussion on climate change science. Over the last few decades the tourism industry has developed exponentially and is now considered one of the most dynamic economic activities worldwide. Solid waste is a commonly identified and ever increasing aspect of tourism;the improper management of which can lead to substantial and irreversible direct and indirect environmental, economic and social impacts. However, the management of solid waste in tourism dominated island communities is particularly problematic due to climatic conditions, topography, financial restraints, planning issues, changing consumption patterns, transient population, and seasonal variations in solid waste quantity and composition. In addition, there is often a lack of momentum to implement new initiatives and programs as stakeholders involved in the design, construction and operation of tourist resorts have conflicts of interest. Using information gathered from key informant interviews, participation observations and literature reviews, this article appraises current waste management practices in four European tourist destinations, namely: Mallorca, Tenerife, Kefalonia and Rhodes. Findings indicate that, although there are signs of compliance with global best practice, a variety of locally-based measures need to be implemented to enhance sustainability.
文摘In this review,we discuss the structure and dynamics of the magnetospheric LowLatitude Boundary Layer(LLBL)based on recent results from multi-satellite missions Cluster and Double Star.This boundary layer,adjacent to the magnetopause on the magnetospheric side,usually consists of a mixture of plasma of magnetospheric and magnetosheath origins,and plays an important role in the transfer of mass and energy from the solar wind into the magnetosphere and subsequent magnetospheric dynamics.During southward Interplanetary Magnetic Field(IMF)conditions,this boundary layer is generally considered to be formed as a result of the reconnection process between the IMF and magnetospheric magnetic field lines at the dayside magnetopause,and the structure and plasma properties inside the LLBL can be understood in terms of the time history since the reconnection process.During northward IMF conditions,the LLBL is usually thicker,and has more complex structure and topology.Recent observations confirm that the LLBL observed at the dayside can be formed by single lobe reconnection,dual lobe reconnection,or by sequential dual lobe reconnection,as well as partially by localized cross-field diffusion.The LLBL magnetic topology and plasma signatures inside the different sub-layers formed by these processes are discussed in this review.The role of the Kelvin-Helmholtz instability in the formation of the LLBL at the flank magnetopause is also discussed.Overall,we conclude that the LLBL observed at the flanks can be formed by the combination of processes,(dual)lobe reconnection and plasma mixing due to non-linear Kelvin-Helmholtz waves.
