XIAO Chao,
LIU WenLong,
ZHANG DianJun et al
.2020.Formation of the high-density cusp Chinese Journal of Geophysics(in Chinese),63(9): 3231-3239,doi: 10.6038/cjg2020N0424
高密度极尖区的形成原因
肖超, 刘文龙, 张典钧, 张钊
北京航空航天大学空间与环境学院, 北京 102206
Formation of the high-density cusp
XIAO Chao, LIU WenLong, ZHANG DianJun, ZHANG Zhao
School ofSpace and Environment, Beihang University, Beijing 102206, China
Abstract:The cusp region is an important window for solar wind particles entering the magnetosphere. Its density is a key parameter for understanding this physical process. Generally, the density of cusp region is about 1~10 cm-3, but sometimes the satellites can observe cusp density greater than 40 cm-3, which is called high-density cusp region in this paper. Based on the observations of Cluster satellite from 2001 to 2009, we find 28 high-density cusp crossing events in all the 470 cusp crossing events. We further discuss the favorable conditions of the formation of high-density cusp region, and the external conditions for solar wind efficiently entering cusp region. The results show that the smaller the |MLT-12|, the higher the solar wind density, the existence of low latitude magnetopause reconnection and the positive dipole tilt are favorable conditions for the occurrence of high-density cusp events. When the above-mentioned four conditions are met at the same time, the occurrence rate of high-density cusp events is 100%. The low latitude magnetopause reconnection and large positive dipole tilt are considered as important conditions for the solar wind efficiently entering the cusp region. These results will help us to further understand the physical mechanism of the solar wind entering the cusp region.
Aparicio B, Thelin B, Lundin R. 1991. The polar cusp from a particle point of view:A statistical study based on Viking data. Journal of Geophysical Research:Space Physics, 96(A8):14023-14031. Chapman S, Ferraro V C A. 1930. A new theory of magnetic storms. Nature, 126(3169):129-130. Connor H J, Raeder J, Trattner K J. 2012. Dynamic modeling of cusp ion structures. Journal of Geophysical Research:Space Physics, 117(A4):A04203, doi:10.1029/2011JA017203. Dungey J W. 1961. Interplanetary magnetic field and the auroral zones. Physical Review Letters, 6(2):47-48. Escoubet C P, Smith M F, Fung S F, et al. 1992. Staircase ion signature in the polar cusp:A case study. Geophysical Research Letters, 19(17):1735-1738. Escoubet C P, Berchem J, Bosqued J M, et al. 2008. Effect of a northward turning of the interplanetary magnetic field on cusp precipitation as observed by Cluster. Journal of Geophysical Research:Space Physics, 113(A7):A07S13, doi:10.1029/2007JA012771. Farrell W M, Van Allen J A. 1990. Observations of the Earth's polar cleft at large radial distances with the Hawkeye 1 Magnetometer. Journal of Geophysical Research, 95(A12):20945-20958. Frank L A. 1971. Plasma in the Earth's polar magnetosphere. Journal of Geophysical Research, 76(22):5202-5219. Fu H S, Cao J B, Vaivads A, et al. 2016. Identifying magnetic reconnection events using the FOTE method. Journal of Geophysical Research:Space Physics, 121(2):1263-1272. Fu H S, Vaivads A, Khotyaintsev Y V, et al. 2017. Intermittent energy dissipation by turbulent reconnection. Geophysical Research Letters, 44(1):37-43. Fu S Y, Sun W J. 2016. Models of the Earth's plasmapause position. Science China Earth Sciences, 59(4):871-872. Fujimoto R, Mitsuda K, McCammon D, et al. 2007. Evidence for solar-wind charge-exchange X-Ray emission from the earth's magnetosheath. Progress of Theoretical Physics Supplement, 169:71-74,doi:10.1143/PTPS.169.71. Guo J G, Shi J K, Cheng Z W, et al. 2013. Variation of dependence of the cusp location at different altitude on the dipole tilt. Chinese Science Bulletin, 58(28-29):3541-3545. Haerendel G, Paschmann G, Sckopke N, et al. 1978. The frontside boundary layer of the magnetosphere and the problem of reconnection. Journal of Geophysical Research:Space Physics, 83(A7):3195-3216. Heikkila W J, Winningham J D. 1971. Penetration of magnetosheath plasma to low altitudes through the dayside magnetospheric cusps. Journal of Geophysical Research, 76(4):883-891. Heikkila W J. 1985. Definition of the Cusp.//Holtet J A, Egeland A eds. The Polar Cusp. Dordrecht:Springer Netherlands, 387-395. Kremser G, Woch J, Mursula K, et al. 1995. Origin of energetic ions in the polar cusp inferred from ion composition measurements by the Viking satellite. Annales Geophysicae, 13(6):595-607. Kuntz K D, Collado-Vega Y M, Collier M R, et al. 2015. The solar wind charge-exchange production factor for hydrogen. The Astrophysical Journal, 808(2):143. Lavraud B, Fedorov A, Budnik E, et al. 2004. Cluster survey of the high-altitude cusp properties:A three-year statistical study. Annales Geophysicae, 22(8):3009-3019. Liu W L, Tu W C, Li X L, et al. 2016. On the calculation of electric diffusion coefficient of radiation belt electrons with in situ electric field measurements by THEMIS. Geophysical Research Letters, 43(3):1023-1030. Liu W L. 2016. Kinetic features of bursty bulk flows and dipolarization fronts. Science China Earth Sciences, 59(12):2463-2464. Lockwood M, Smith M F. 1989. Low-altitude signatures of the cusp and flux transfer events. Geophysical Research Letters, 16(8):879-882. Lockwood M, Smith M F. 1994. Low and middle altitude cusp particle signatures for general magnetopause reconnection rate variations:1. Theory. Journal of Geophysical Research:Space Physics, 99(A5):8531-8553. Lockwood M. 1995. Overlapping cusp ion injections:An explanation invoking magnetopause reconnection. Geophysical Research Letters, 22(9):1141-1144. Lv X, Liu W L. 2018. Measurements of convection electric field in the inner magnetosphere. Science China Technological Sciences, 61(12):1866-1871. Newell P T, Meng C I. 1988. The cusp and the cleft/boundary layer:Low-altitude identification and statistical local time variation. Journal of Geophysical Research:Space Physics, 93(A12):14549-14556. Newell P T, Meng C I. 1991. Ion acceleration at the equatorward edge of the cusp:Low altitude observations of patchy merging. Geophysical Research Letters, 18(10):1829-1832. Perry C H, Grande M, Zurbuchen T H, et al. 2000. Use of Fe charge state changes as a tracer for solar wind entry to the magnetosphere. Geophysical Research Letters, 27(16):2441-2444. Pitout F, Escoubet C P, Klecker B, et al. 2009. Cluster survey of the mid-altitude cusp-Part 2:Large-scale morphology. Annales Geophysicae, 27(5):1875-1886. Rème H, Aoustin C, Bosqued J M, et al. 2001. First multispacecraft ion measurements in and near the Earth's magnetosphere with the identical Cluster ion spectrometry (CIS) experiment. Annales Geophysicae, 19(10-12):1303-1354. Reiff P H, Hill T W, Burch J L. 1977. Solar wind plasma injection at the dayside magnetospheric cusp. Journal of Geophysical Research, 82(4):479-491. Robertson I P, Collier M R, Cravens T E, et al. 2006. X-ray emission from the terrestrial magnetosheath including the cusps. Journal of Geophysical Research:Space Physics, 111(A12):A12105, doi:10.1029/2006JA011672. Rosenbauer H, Grünwaldt H, Montgomery M D, et al. 1975. Heos 2 plasma observations in the distant polar magnetosphere:The plasma mantle. Journal of Geophysical Research, 80(19):2723-2737. Russell C T, Elphic R C. 1979. ISEE observations of flux transfer events at the dayside magnetopause. Geophysical Research Letters, 6(1):33-36. Russell C T. 2000. The polar cusp. Advances in Space Research, 25(7-8):1413-1424. Shelley E G, Sharp R D, Johnson R G. 1976. He++ and H+ flux measurements in the day side cusp:Estimates of convection electric field. Journal of Geophysical Research, 81(13):2363-2370. Shen C, Dunlop M, Ma Y H, et al. 2011. The magnetic configuration of the high-latitude cusp and dayside magnetopause under strong magnetic shears. Journal of Geophysical Research:Space Physics, 116(A9):A09228, doi:10.1029/2011JA016501. Shi Q Q, Zong Q G, Zhang H, et al. 2009. Cluster observations of the entry layer equatorward of the cusp under northward interplanetary magnetic field. Journal of Geophysical Research:Space Physics, 114(A12):A12219, doi:10.1029/2009JA014475. Shi Q Q, Zong Q G, Fu S Y, et al. 2013. Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times. Nature Communications, 4(1):1466. Tao D, Liu W L, Ma Y D. 2018. Plasma perturbations in the coexisting environment of VLF transmitter emission, lightning strokes and seismic activity. Science China Technological Sciences, 61(5):678-686. Trattner K J, Coates A J, Fazakerley A N, et al. 1998. Overlapping ion populations in the cusp:polar/TIMAS results. Geophysical Research Letters, 25(10):1621-1624. Walsh B M, Niehof J, Collier M R, et al. 2016. Density variations in the Earth's magnetospheric cusps. Journal of Geophysical Research:Space Physics, 121(3):2131-2142. Wang T Y, Cao J B, Fu H S, et al. 2014. Turbulence in the Earth's cusp region:The k-filtering analysis. Journal of Geophysical Research:Space Physics, 119(12):9527-9542. Woch J, Lundin R. 1992. Magnetosheath plasma precipitation in the polar cusp and its control by the interplanetary magnetic field. Journal of Geophysical Research:Space Physics, 97(A2):1421-1430. Xiao C, Liu W L, Shen C, et al. 2018. Study on the curvature and gradient of the magnetic field in earth's cusp region based on the magnetic curvature analysis method. Journal of Geophysical Research:Space Physics, 123(5):3794-3805. Yu Y Q, Ridley A J. 2013. Exploring the influence of ionospheric O+ outflow on magnetospheric dynamics:dependence on the source location. Journal of Geophysical Research:Space Physics, 118(4):1711-1722. Zhang D J, Liu W L, Li X L, et al. 2018. Observations of impulsive electric fields induced by interplanetary shock. Geophysical Research Letters, 45(15):7287-7296. Zhang H, Fritz T A, Zong Q G, et al. 2005. Stagnant exterior cusp region as viewed by energetic electrons and ions:A statistical study using Cluster Research with Adaptive Particle Imaging Detectors (RAPID) data. Journal of Geophysical Research:Space Physics, 110(A5):A05211, doi:10.1029/2004JA010562. Zhang H, Dunlop M W, Zong Q G, et al. 2007. Geometry of the high-latitude magnetopause as observed by Cluster. Journal of Geophysical Research:Space Physics, 112(A2):A02204, doi:10.1029/2006JA011774. Zhou X W, Russell C T, Le G, et al. 2000. Solar wind control of the polar cusp at high altitude. Journal of Geophysical Research:Space Physics, 105(A1):245-251. Zong Q G, Fritz T A, Zhang H, et al. 2004. Triple cusps observed by Cluster-Temporal or spatial effect? Geophysical Research Letters, 31(9):L09810, doi:10.1029/2003GL019128.