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A new processing method for the AE index

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Science China(Technological Sciences) 2008年第10期51卷 1713-1720页

作者： W. BAUmJOHANN m. dunlop Space Research Institute Austrian Academy of Sciences Graz Austria Space Sciences Division Rutherford Appleton Laboratory Chilton Didcot United Kingdom

In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as a coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index and AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

关键词： AE index Dst index FIR filter substorm

The radial evolution of earthward BBFs during substorm

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Science China Earth Sciences 2010年第10期53卷 1542-1551页

作者： REmE H DANDOURAS I LUCEK E dunlop m Centre d'Etude Spatiale des Rayonnements Blackett Laboratory Imperial College London Rutherford Appleton Laboratory

We here study the occurrence rate,probability function of velocity and duration of earthward bursty bulk flows(BBFs) in the Inner Plasma Sheet(IPS,β>0.5) using the data of Cluster in 2001 and *** occurrence rate of earthward BBFs increases with distance from the Earth up to ?19 RE,which is in agreement with the previous observations of the radial evolution of *** 54% of earthward BBFs in expansion phase have a velocity larger than 600 km/s,whereas only 38% of earthward BBFs in growth and recovery phases have a velocity larger than 600 km/*** average velocity of earthward BBFs in expansion phase is 732 km/s,larger than those in growth phase(631 km/s) and recovery phase(617 km/s).The durations of earthward BBFs decrease with the decrease of downtail distance from Earth due to the braking of earthward *** duration of earthward BBFs in expansion phase is larger than that in growth and recovery *** average durations in growth,expansion,and recovery phases are respectively 49.3,71.5,and 47.6 ***,the ratios of transports of energy of earthward BBFs in growth,expansion,and recovery phases can be estimated to be 0.51:1:***,the earthward BBFs in the expansion phase have the largest capability of the transport of energy and can produce the largest braking effects,such as inertial currents and auroral activities.

关键词： substorm growth expansion recovery duration energy transport

Solar wind transport into magnetosphere caused by magnetic reconnection at high latitude magnetopause during northward ImF: Cluster-DSP conjunction observations

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Science China(Technological Sciences) 2008年第10期51卷 1677-1684页

作者： m. dunlop E. LUCEK H. RmE C. m. CARR Rutherford Appleton Laboratory Didcot United Kingdom Imperial College of Science Technology and Medicine London United Kingdom CESR BP4346 31028 Toulouse Cedex 4 France

An event of Cluster-Double Star conjunction observations of magnetic reconnec-tion at high latitude magnetopause nightside of both cusps and solar wind trans-port into magnetosphere caused by such reconnection process has been investi-gated. During northward ImF, Cluster/SC1 observed accelerated flows and ion heating associated with magnetic reconnection at high latitude magnetopause nightside of southern cusp. And Double Star observed cold dense solar wind plasma transported into dayside magnetosphere. The analysis on such conjunction observations shows that: (1) during northward ImF, magnetic reconnection occurs at high latitude nightside of southern cusp, accompanied by accelerated flows that are observed by Cluster/SC1; (2) the direction of the accelerated flows, with its sunward component Vx, dawnward component Vy, northward component Vz, is quite consistent with the theoretical anticipation under the condition of northward ImF with dawnward component By; (3) reconnection can heat plasma more in par-allel direction than in perpendicular direction, to a level of about 4 keV; (4) with reconnection taking place at high latitude magnetopause nightside of the southern cusp, TC-1 observed cold and dense plasma transported into magnetosphere; (5) by reconnection at high latitude magnetopause nightside of both cusps, solar wind flux tube can be captured by magnetosphere and pulled into dayside magneto-sphere. This event presents further observational evidence for magnetic reconnec-tion at high latitude magnetopause nightside of both cusps as an important mech-anism of sol-ar w-ind transport into magnetosphere.

关键词： transport process magnetic reconnection solar wind-magnetosphere interactions

Properties of Field Aligned Current in Plasma Sheet Boundary Layers in magnetotail： Cluster Observation

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Chinese Physics Letters 2009年第2期26卷 304-306页

作者：史建魁程征伟 T. L. Zhang m. dunlop 刘振兴 State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100190 Space Research Institute Austrian Academy of Sciences Graz Austria SSTD Rutherford Appleton Laboratory Chilton Didcot UK

Field aligned current （FAC） distribution in the plasma sheet boundary layers （PSBLs） in the magnetotail is studied statistically by analysing magnetic field data from the Cluster 4-point measurements. The results show that the FAC distribution on the dusk side is not the same as that on the dawn side in the magnetotail. On the each side earthward and tailward, FA C occurrences are different; occurrence and average current density of FA Cs in the northern hemisphere are different from those in the southern hemisphere. This implies that the FACs have dusk-dawn side asymmetry, polarity asymmetry and inter hemisphere difference in the magnetotail. The present results give a good observation evidence for study on the FAC mechanism.

关键词： field emission molybdenum dioxide enhancement factor

Solar wind entry via flux tube into magnetosphere observed by Cluster measurements at dayside magnetopause during southward ImF

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Science China(Technological Sciences) 2009年第7期52卷 2104-2111页

作者： m. dunlop A. Balogh H. Rème Y. V. Bogdanova A. Fazakerley Rutherford Appleton Laboratory Didcot United Kingdom Imperial College of Science Technology and Medicine London United Kingdom CESR BP4346 31028 Toulouse Cedex 4 France mullard Space Science Laboratory Dorkink United Kingdom Department of Physics La Trobe University Victoria 3086 Australia

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.

关键词： transport process magnetic reconnection solar wind-magnetosphere interactions

Rapid and Asymmetric Response of the Earth＇s Bow Shock： multipoint Observations

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空间科学学报 2017年第2期37卷 129-139页

作者： LIU Bing dunlop m W CAO Jinbin LAVRAUD B LI Liuyuan YANG Junying School of Astronautics Beihang University Beijing 100191 Space Science Department Rutherford-Appleton Laboratory Chilton Didcot UK Research Institute in Astrophysics and Planetology 31028 Toulouse France

We analyze observations of three bow shock crossings which occurred during *** upstream data from STEREO A/*** and WIND,combined with multi-point THEmIS and Cluster data,and TC-1 data located near *** the crossing of 7 may *** find that following a rapid reduction in solar wind ram pressure and subsequent pressure pulse seen by ACE and WIND upstream,the bow shock responds asymmetrically from dawn to *** data on the dawn-side suggest the bow shock is significantly flared and responds rapidly to the pulse arrival,while TC-1 at noon,and THEmIS on the dusk-side,are well matched to the model bow shock,but show a delayed *** crossings observed on 21 may and 2 June show contrasting response matching the model boundary for northward Interplanetary magnetic Field(ImF).The ImF and solar wind plasma data suggest that,the bow shock crossing at dawn-dusk side and subsolar point were mainly caused by large and smaller scale features of the solar wind ram pressure rise rather than the influence of ImF.

关键词：空间科学问题工作研究

Double Star ＆ Cluster Observations of magnetic Reconnection at the Dayside magnetopause

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Double Star ＆ Cluster Observations of Magnetic Reconnection...

Surveys on magnetospheric plasmas based on the Double Star Project (DSP) exploration

第十一届全国日地空间物理学术讨论会

作者： m.dunlop Space Sciences Division RAL Oxford UK

＜正＞Coordinate Double Star and Cluster measurements have brought new results concerning the physics of the magnetopause. We can see for the first time, the evolution of structures at small scales within the Cluster tetrahedron, and then at large scales with Cluster and Double Star conjunction. This paper presents a part of Double Star and Cluster observations of magnetic reconnection at the dayside magnetopause by introducing a few interesting events. These include: （a） TC-1 observations of the magnetic shear angle across the magnetopause near/at the reconnection site which was considerably smaller than 180 degree and observations of noticeable guide field near/in the diffusion region. （b） TC-1 observations of magnetic reconnection at the dayside low-latitude magnetopause for northward ImF when a strong By component exists. （c） Observations of plasma jets simultaneously at the subsolar point and near the cusp, suggesting that reconnection is preferentially initiated near the subsolar point and then propagates to the high-latitudes. （d） Almost simultaneous observations of an FTE by Cluster and TC-1 at different positions of the flux rope. This allows us to infer the large-scale configuration of the reconnected magnetic tube near the dayside magnetopause. （e） Simultaneous multi-spacecraft observations of reconnection signatures by Cluster at the northern high-latitude magnetopause, TC-1 in the low-latitude region and TC-2 in the southern low-altitude cusp, together with ImAGE in the southern hemisphere. The possible implications of these observations are discussed. New challenges to the present theories of magnetic reconnection and magnetopause reconnection models are addressed.

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Science China(Technological Sciences) 2008年第10期51卷 1639-1647页

作者： C. P. ESCOUBET C. m. CARR H. RmE A. FAZAKERLEY H. LAAKSO I. DANDOURAS m. dunlop ESA/ESTEC SCI-SH Keplerlaan 1 2200 AG Noordwijk The Netherlands Imperial College of Science Technology and Medicine London SW7 2BZ United Kingdom CESR BP4346 31028 Toulouse Cedex 4 France mullard Space Science Laboratory Univ. College London Dorking Surrey RH5 6NT United Kingdom Imperial College of Science Technology and Medicine London SW7 2BZ United Kingdom Rutherford Appleton Laboratory Didcot Oxon OX11 0QX United Kingdom

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 me, it may expand and shrink

关键词： Earth’s magnetosphere space exploration geomagnetic field space plasmas

Cluster observations of high-altitude cusp during multiple fast-turning ImF

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Chinese Science Bulletin 2010年第22期55卷 1178-1185页

作者： CAI HongTao mA ShuYing dunlop m W BOGDANOVA Y DAVIES J A PITOUT F School of Electronic Information Wuhan University Wuhan 430079 China Key Lab of Geospace Environment and Geodesy CNEM Wuhan 430079 China SSTD Rutherford Appleton Laboratory Chilton OX11 OQX UK Department of Physics La Trobe University Melbourne Victoria 3086 Australia max-Planck-lnstitut fiir Extraterrestrische Physik Garching D-37191 Germany

Using coordinated observations from the Cluster,DmSP and ESR radar,high-altitude cusp was investigated for a time period characterized by four fast reversals of the ImF *** February 12,2003,Cluster was flying sunward at duskside over the Northern Hemisphere,across the high-altitude northern cusp *** the two crossings are during steady northward ImF interval,whereas ion fluxes detected during the time period are quite *** cusp in the first crossing is a "typical" northward-ImF one,with short-lived ion injections of evident "reversed" dispersion *** the second crossing,however,the cusp appears to be a region reminiscent of the Stagnant Exterior Cusp (SEC).In addition,evident upward-flowing O+ ion bursts,possibly original from polar ionosphere,are also detected during the second cusp crossing,together with enhancement of trapped magnetospheric-like electron *** suggest that the SEC-like cusp is likely on newly closed field lines,which were first reconnected (being opened) at low latitudes and later reconnected again (being closed) poleward of the northern cusp.

关键词：国际货币基金组织高海拔群集观测十字路口离子检测低纬度地区气象卫星

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