极区夏季中间层顶尘埃颗粒的生长及数密度分布
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摘要
中间层顶部是大气层温度最低的区域,过饱和水汽凝结成冰晶(尘埃)颗粒,进而吸附电子形成非均匀密度分布层,造成雷达波的强烈回波.对此现象起因的研究曾引起众多探讨但尚无定论.这里以外大气层下落的微陨石颗粒和以中层底部随气流上升的烟尘颗粒为凝结核,根据尘埃颗粒与水汽分子的碰撞吸附效应建立颗粒的生长模型,研究变质量的颗粒在重力和中性气流拖曳力作用下的运动和生长过程.结果表明,颗粒半径随时间线性增长,颗粒的运动速度与半径之间存在复杂的关系,对于半径在一定范围的初始凝结核,颗粒在运动过程中可以反弹,即速度方向逆转.根据通量守恒计算了尘埃颗粒的粒子数密度随高度的分布,结果表明,由于初始凝结核大小具有一定的分布以及存在反弹效应,边界层附近可形成陡峭的密度分布(小尺度密度结构).该结构有利于形成强的雷达回波.
Mesopause is the region of the lowest temperature in the atmosphere,where supersaturated water vapor condenses into ice(dust)particulates that absorb electrons and result in the non-uniform density layer,causing strong echoes of radar signals.This phenomenon has sparkled a great number of studies but is still not fully understood.Based on the effect of collisional attachment of water vapor on the surface of the dust grains,a model of dust growth was developed,in which the grains of micrometeoroid showering from the outer atmosphere and the grains ascending with the upward neutral wind from the bottom of the mesosphere serve as the nucleation cores.The motion of the ice grains under the gravity and the neutral drag forces was studied.It is shown that the radius of the ice grains increases linearly with time.The velocity of the grains exhibits a complicated relation with the radius.For a certain range of the radius of the initial condensation core,the grain bounces at a certain height with its velocity reversing in direction.Based on the flux conservation,the variation of the number density of the grains with respect to the height is numerically calculated.The results show that a steep density distribution(i.e.,a small-scale density structure)appears near the boundary layer because of the bounce effect as well as the effect of the finite spread of the radius of the initial condensation core.The so-formed small scale structure is a possible explanation of the formation of strong radar echoes.
Mesopause is the region of the lowest temperature in the atmosphere,where supersaturated water vapor condenses into ice(dust)particulates that absorb electrons and result in the non-uniform density layer,causing strong echoes of radar signals.This phenomenon has sparkled a great number of studies but is still not fully understood.Based on the effect of collisional attachment of water vapor on the surface of the dust grains,a model of dust growth was developed,in which the grains of micrometeoroid showering from the outer atmosphere and the grains ascending with the upward neutral wind from the bottom of the mesosphere serve as the nucleation cores.The motion of the ice grains under the gravity and the neutral drag forces was studied.It is shown that the radius of the ice grains increases linearly with time.The velocity of the grains exhibits a complicated relation with the radius.For a certain range of the radius of the initial condensation core,the grain bounces at a certain height with its velocity reversing in direction.Based on the flux conservation,the variation of the number density of the grains with respect to the height is numerically calculated.The results show that a steep density distribution(i.e.,a small-scale density structure)appears near the boundary layer because of the bounce effect as well as the effect of the finite spread of the radius of the initial condensation core.The so-formed small scale structure is a possible explanation of the formation of strong radar echoes.
引文
[1]Fortov V E,Ivlev A V,Khrapak S A,et al.Complex(dusty)plasmas:Current status,open issues,perspectives[J].Phys Rep,2005,421:1-103.
[2]Shukla P K,Mamum A A.Introduction to DustyPlasma Physics[M].Bristol:Institute of PhysicsPublishing,2002:Chapter 2.
[3]Li Y F,Ma J X,Li J J.Dust-ion-acoustic soliton in aninhomogeneous collisional plasma[J].Phys Plasmas,2004,11(4):1 366-1 371.
[4]Xiao D L,Ma J X,Li Y F.Dust-acoustic shockwaves:Effect of plasma density gradient[J].PhysPlasmas,2005,12:052314.
[5]Xie Baisong,He Kaifen,Chen Yanping.Dust-acousticshock waves in the sheath of dusty plasmas[J].ChinPhys B,2000,9:922-926.
[6]Wang H Y,Duan W S.Theoretical investigation ofproperties of soliton in hot dusty plasma with non-thermal ions[J].Acta Phys Sin,2007,56:3 977-3 983.王红艳,段文山.对含有非热力学平衡离子的尘埃等离子体中孤波特性的理论研究[J].物理学报,2007,56:3 977-3 983.
[7]Hong X R,Duan W S,Sun J A,et al.Thepropagation of solitons in an inhomogeneousdusty plasma[J].Acta Phys Sin,2003,52:2 671-2 677.洪学仁,段文山,孙建安,等.非均匀尘埃等离子体中孤子的传播[J].物理学报,2003,52:2 671-2 677.
[8]Yang Xuefeng,Wang Xiaogang,Liu Yue.Dispersionrelations of lattice waves in three-dimensional stronglycoupled complex plasma crystals[J].Chin Phys B,2009,18(11):4 938-4 943
[9]Hou L J,Wang Y N.Theoretical study on nonlinearresonances of a charged micro-particle in a RF sheath[J].Acta Phys Sin,2003,52(2):434-441.侯璐景,王友年.尘埃颗粒在射频等离子体鞘层中的非线性共振现象的理论研究[J].物理学报,2003,52(2):434-441.
[10]Wang Y N,Hou L J,Wang X.Self-consistentnonlinear resonance and hysteresis of a chargedmicroparticle in a RF sheath[J].Phys Rev Lett,2002,89:155001.
[11]Ma J X,Liu J,Yu M Y.Fluid theory of the boundaryof a dusty plasma[J].Phys Rev E,1997,55(4):4 627-4 633
[12]Duan P,Liu J Y,Gong Y,et al.The distribution ofdust particles in the plasma sheath[J].Acta Phys Sin,2007,56:7 090-7 099.段萍,刘金远,宫野,等.等离子体鞘层中尘埃粒子的分布特性[J].物理学报,2007,56:7 090-7 099.
[13]Huang Feng,Ye Maofu,Wang Long,et al.Influenceof gas pressure on the pattern evolutions of dustclusters and fractals in a dusty plasma system[J].ChinPhys B,2004,13(11):1 896-1 901.
[14]Thomas H,Morfill G E,Demmel V,et al.Plasmacrystal:Coulomb crystallization in a dusty plasma[J].Phys Rev Lett,1994,75:652-655
[15]Wu J,Zhang P Y,Song Q L,et al.Investigation ofvoid in dust clouds in reactive plasma[J].Acta PhysSin,2005,54(10):4 794-4 798.吴静,张鹏云,宋巧丽,等.反应等离子体中尘埃空洞形成的实验研究[J].物理学报,2005,54(10):4 794-4 798.
[16]Shi Y X,Wu J,Ge D B.The research on the dielectrictensor of weakly ionized dust plasma[J].Acta PhysSin,2009,58(8):5 507-5 512.石雁祥,吴健,葛德彪.弱电离尘埃等离子体的介电张量研究[J].物理学报,2009,58(8):5 507-5 512.
[17]Shi Y X,Ge D B,Wu J.Influence of charge anddischarge processes of dust particles on the dust plasmaconductivity[J].Acta Phys Sin,2006,53(10):5 318-5 324.石雁祥,葛德彪,吴健.尘埃粒子充放电过程对尘埃等离子体电导率的影响[J].物理学报,2006,53(10):5 318-5 324.
[18]Klumov B A,Morfill G E,Popel S I.Formation ofstructures in a dusty ionosphere[J].Journal ofExperimental and Theoretical Physics,2005,100(1):152-164.
[19]Kopin S I,Popel S I,Yu M Y.Phenomena associatedwith complex(dusty)plasmas in the ionosphere duringhigh-speed meteor showers[J].Phys Plasmas,2009,16:063705.
[20]Havnes O,MelandsF,Hoz C L,et al.Charged dustin the Earth's mesopause:Effects on radar backscatter[J].Phys Scr,1992,45:535-554.
[21]Thomas G E.Mesospheric clouds and the physics ofthe mesopause region[J].Rev Geophys,1991,29(4):553-575.
[22]Rapp M,Lübken F J.Polar mesosphere summerechoes(PMSE):Review of observations and currentunderstanding[J].Atmos Chem Phys,2004,4:2 601-2 633.
[23]Czechowsky P,Ruster R,Schmidt G.Variations ofmesospheric structures in different seasons[J].Geophys Res Lett,1979,6(6):459-462.
[24]Ecklund W L,Balsley B B.Long-term observations ofthe Arctic mesosphere with the MST radar at PokerFlat,Alaska[J].J Geophys Res,1981,86:7 775-7 780.
[25]Rottger J,Hoz C L,Kelley M C,et al.The structureand dynamics of polar mesosphere summer echoesobserved with the EISCAT 224 MHz radar[J].Geophys Res Lett,1988,15:1 353-1 356.
[26]Rottger J,Rietveld M T,LaHoz C,et al.Polarmesosphere summer echoes observed with the EISCAT933-MHz radar and the CUPRI 46.9-MHz radar,theirsimilarity to 224-MHz radar echoes,and their relationto turbulence and electron density profiles[J].RadioSci,1990,25:671-687.
[27]Ulwick J C,Baker K D,Kelley M C,et al.Comparison of simultaneous MST radar and electrondensity probe measurements during STATE[J].JGeophys Res,1988,93:6 989-7 000.
[28]Havnes O,Trim J,Blix T,et al.First detection ofcharged dust particles in the Earth's mesosphere[J].JGeophys Res,1996,101:10 839-10 847.
[29]Czechowsky P,Reid I M,Rüster R.VHF radarmeasurements of the aspect sensitivity of the summerpolar mesospaus echoes over Andenes(69°N,16°E),norway[J].Geophys Res Lett,1988,15:1 259-1 262.
[30]Zhang W G,Ma J X,Li Y R,et al.Small scalestructures of a mesospheric dusty plasma[J].PlanetSpace Sci,2010,58:801-806.
[31]Havnes O,Nasheim L I,Hartquist T W,et al.Meter-scale variations of the charge carried bymesospheric dust[J].Planet Space Sci,1996,44:1 191-1 198.
[32]Rapp M,Lübken F J.On the nature of PMSE:Electron diffusion in the vicinity of chargedparticles revisited[J].J Geophys Res,2003,108:8 437.
[33]LI Fang.Electron density fluctuation in a dusty plasma[J].Chin Phys Lett,2002,19(2):214-216.
[34]Li H,Wu J,Wu J,et al.Study on the sharp boundaryof layered dust structure in the summer polarmesopause[J].Chinese Journal of Polar Research,2009,21(4):272-278.李辉,吴健,吴军,等.极区夏季中层顶尘埃分层的锐边界结构研究[J].极地研究,2009,21(4):272-279.
[35]Kopnin S I,Kosarev I N,Popel S I,et al.Localizedstructures of nanosize charged dust grains in Earth'smiddle atmosphere[J].Planet Space Sci,2004,52(13):1 187-1 194.
[36]Lie-Svendsen,Blix T A,Hoppe U P,et al.Modeling the plasma response to small-scale aerosolparticle perturbations in the mesopause region[J].JGeophys Res,2003,108:8 442.
[37]Jensen E J,Thomas G E.Charging of mesosphericparticles:Implications for electron density and particlecoagulation[J].J Geophys Res,1991,96:18 603-18 615.
[38]Pfaff R,Holzworth R,Goldberg R,et al.Rocketprobe observations of electric field irregularities in thepolar summer mesosphere[J].Geophys Res Lett,2001,28:1 431-1 434.
[39]Hill R J,Gibson-Wilde D E,Werne J A,et al.Turbulence-induced fluctuations in ionization andapplication to PMSE[J].Earth Plan Space,1999,51:499-513.
[2]Shukla P K,Mamum A A.Introduction to DustyPlasma Physics[M].Bristol:Institute of PhysicsPublishing,2002:Chapter 2.
[3]Li Y F,Ma J X,Li J J.Dust-ion-acoustic soliton in aninhomogeneous collisional plasma[J].Phys Plasmas,2004,11(4):1 366-1 371.
[4]Xiao D L,Ma J X,Li Y F.Dust-acoustic shockwaves:Effect of plasma density gradient[J].PhysPlasmas,2005,12:052314.
[5]Xie Baisong,He Kaifen,Chen Yanping.Dust-acousticshock waves in the sheath of dusty plasmas[J].ChinPhys B,2000,9:922-926.
[6]Wang H Y,Duan W S.Theoretical investigation ofproperties of soliton in hot dusty plasma with non-thermal ions[J].Acta Phys Sin,2007,56:3 977-3 983.王红艳,段文山.对含有非热力学平衡离子的尘埃等离子体中孤波特性的理论研究[J].物理学报,2007,56:3 977-3 983.
[7]Hong X R,Duan W S,Sun J A,et al.Thepropagation of solitons in an inhomogeneousdusty plasma[J].Acta Phys Sin,2003,52:2 671-2 677.洪学仁,段文山,孙建安,等.非均匀尘埃等离子体中孤子的传播[J].物理学报,2003,52:2 671-2 677.
[8]Yang Xuefeng,Wang Xiaogang,Liu Yue.Dispersionrelations of lattice waves in three-dimensional stronglycoupled complex plasma crystals[J].Chin Phys B,2009,18(11):4 938-4 943
[9]Hou L J,Wang Y N.Theoretical study on nonlinearresonances of a charged micro-particle in a RF sheath[J].Acta Phys Sin,2003,52(2):434-441.侯璐景,王友年.尘埃颗粒在射频等离子体鞘层中的非线性共振现象的理论研究[J].物理学报,2003,52(2):434-441.
[10]Wang Y N,Hou L J,Wang X.Self-consistentnonlinear resonance and hysteresis of a chargedmicroparticle in a RF sheath[J].Phys Rev Lett,2002,89:155001.
[11]Ma J X,Liu J,Yu M Y.Fluid theory of the boundaryof a dusty plasma[J].Phys Rev E,1997,55(4):4 627-4 633
[12]Duan P,Liu J Y,Gong Y,et al.The distribution ofdust particles in the plasma sheath[J].Acta Phys Sin,2007,56:7 090-7 099.段萍,刘金远,宫野,等.等离子体鞘层中尘埃粒子的分布特性[J].物理学报,2007,56:7 090-7 099.
[13]Huang Feng,Ye Maofu,Wang Long,et al.Influenceof gas pressure on the pattern evolutions of dustclusters and fractals in a dusty plasma system[J].ChinPhys B,2004,13(11):1 896-1 901.
[14]Thomas H,Morfill G E,Demmel V,et al.Plasmacrystal:Coulomb crystallization in a dusty plasma[J].Phys Rev Lett,1994,75:652-655
[15]Wu J,Zhang P Y,Song Q L,et al.Investigation ofvoid in dust clouds in reactive plasma[J].Acta PhysSin,2005,54(10):4 794-4 798.吴静,张鹏云,宋巧丽,等.反应等离子体中尘埃空洞形成的实验研究[J].物理学报,2005,54(10):4 794-4 798.
[16]Shi Y X,Wu J,Ge D B.The research on the dielectrictensor of weakly ionized dust plasma[J].Acta PhysSin,2009,58(8):5 507-5 512.石雁祥,吴健,葛德彪.弱电离尘埃等离子体的介电张量研究[J].物理学报,2009,58(8):5 507-5 512.
[17]Shi Y X,Ge D B,Wu J.Influence of charge anddischarge processes of dust particles on the dust plasmaconductivity[J].Acta Phys Sin,2006,53(10):5 318-5 324.石雁祥,葛德彪,吴健.尘埃粒子充放电过程对尘埃等离子体电导率的影响[J].物理学报,2006,53(10):5 318-5 324.
[18]Klumov B A,Morfill G E,Popel S I.Formation ofstructures in a dusty ionosphere[J].Journal ofExperimental and Theoretical Physics,2005,100(1):152-164.
[19]Kopin S I,Popel S I,Yu M Y.Phenomena associatedwith complex(dusty)plasmas in the ionosphere duringhigh-speed meteor showers[J].Phys Plasmas,2009,16:063705.
[20]Havnes O,MelandsF,Hoz C L,et al.Charged dustin the Earth's mesopause:Effects on radar backscatter[J].Phys Scr,1992,45:535-554.
[21]Thomas G E.Mesospheric clouds and the physics ofthe mesopause region[J].Rev Geophys,1991,29(4):553-575.
[22]Rapp M,Lübken F J.Polar mesosphere summerechoes(PMSE):Review of observations and currentunderstanding[J].Atmos Chem Phys,2004,4:2 601-2 633.
[23]Czechowsky P,Ruster R,Schmidt G.Variations ofmesospheric structures in different seasons[J].Geophys Res Lett,1979,6(6):459-462.
[24]Ecklund W L,Balsley B B.Long-term observations ofthe Arctic mesosphere with the MST radar at PokerFlat,Alaska[J].J Geophys Res,1981,86:7 775-7 780.
[25]Rottger J,Hoz C L,Kelley M C,et al.The structureand dynamics of polar mesosphere summer echoesobserved with the EISCAT 224 MHz radar[J].Geophys Res Lett,1988,15:1 353-1 356.
[26]Rottger J,Rietveld M T,LaHoz C,et al.Polarmesosphere summer echoes observed with the EISCAT933-MHz radar and the CUPRI 46.9-MHz radar,theirsimilarity to 224-MHz radar echoes,and their relationto turbulence and electron density profiles[J].RadioSci,1990,25:671-687.
[27]Ulwick J C,Baker K D,Kelley M C,et al.Comparison of simultaneous MST radar and electrondensity probe measurements during STATE[J].JGeophys Res,1988,93:6 989-7 000.
[28]Havnes O,Trim J,Blix T,et al.First detection ofcharged dust particles in the Earth's mesosphere[J].JGeophys Res,1996,101:10 839-10 847.
[29]Czechowsky P,Reid I M,Rüster R.VHF radarmeasurements of the aspect sensitivity of the summerpolar mesospaus echoes over Andenes(69°N,16°E),norway[J].Geophys Res Lett,1988,15:1 259-1 262.
[30]Zhang W G,Ma J X,Li Y R,et al.Small scalestructures of a mesospheric dusty plasma[J].PlanetSpace Sci,2010,58:801-806.
[31]Havnes O,Nasheim L I,Hartquist T W,et al.Meter-scale variations of the charge carried bymesospheric dust[J].Planet Space Sci,1996,44:1 191-1 198.
[32]Rapp M,Lübken F J.On the nature of PMSE:Electron diffusion in the vicinity of chargedparticles revisited[J].J Geophys Res,2003,108:8 437.
[33]LI Fang.Electron density fluctuation in a dusty plasma[J].Chin Phys Lett,2002,19(2):214-216.
[34]Li H,Wu J,Wu J,et al.Study on the sharp boundaryof layered dust structure in the summer polarmesopause[J].Chinese Journal of Polar Research,2009,21(4):272-278.李辉,吴健,吴军,等.极区夏季中层顶尘埃分层的锐边界结构研究[J].极地研究,2009,21(4):272-279.
[35]Kopnin S I,Kosarev I N,Popel S I,et al.Localizedstructures of nanosize charged dust grains in Earth'smiddle atmosphere[J].Planet Space Sci,2004,52(13):1 187-1 194.
[36]Lie-Svendsen,Blix T A,Hoppe U P,et al.Modeling the plasma response to small-scale aerosolparticle perturbations in the mesopause region[J].JGeophys Res,2003,108:8 442.
[37]Jensen E J,Thomas G E.Charging of mesosphericparticles:Implications for electron density and particlecoagulation[J].J Geophys Res,1991,96:18 603-18 615.
[38]Pfaff R,Holzworth R,Goldberg R,et al.Rocketprobe observations of electric field irregularities in thepolar summer mesosphere[J].Geophys Res Lett,2001,28:1 431-1 434.
[39]Hill R J,Gibson-Wilde D E,Werne J A,et al.Turbulence-induced fluctuations in ionization andapplication to PMSE[J].Earth Plan Space,1999,51:499-513.