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| 1 | Influence of wave normal angle on gyroresonance between chorus waves and outer radiation belt electrons显示文摘In this paper,using a Gaussian distribution of wave normal angle X=tan,and considering contributions of harmonic resonances n up to±5,we analyze the effect of normal angle on diffusion coefficients induced by gyroresonance between chorus waves and electrons with energies 0.1 and 1.0 MeV on the dayside and nightside at L=4.5.When pitch angle e>10°,for 0.1and 1.0 MeV electrons on the dayside and nightside,diffusion coefficients of five orders(2,1,0,1,2)decrease with increasing normal angle peak,leading to the total diffusion coefficients decreasing with increasing peak.When e<10°,for 1.0MeV electrons on the dayside and 0.1 MeV electrons on the dayside and nightside,the positive order diffusion coefficients are generally smaller than the same negative order ones;in the meanwhile,diffusion coefficients of orders(2,1,2)are very small,the dominant order n=1 diffusion coefficients change very little,hence the total diffusion coefficients almost remain unchanged.However,for 1.0 MeV electrons on the nightside,diffusion coefficients of orders(2,1,2)which are larger than those of the order(1)resonance increase with increasing peak,hence the total diffusion coefficients increase with increasing peak.The current results show that the wave normal angle plays an important role in the quantitative analysis of gyroresonance between chorus waves and electrons in the outer radiation belt. | DING YuanHui HE ZhaoGuo ZHANG ZeLong XIAO FuLiang | 2013 | Science China(Technological Sciences)2013，56，11： | 5 |
| 2 | The influence of various frequency chorus waves on electron dynamics in radiation belts显示文摘Non-adiabatic behaviour induced by the chorus-electron interaction is an important contributor to the radiation belt dynamics,and largely relies on wave frequency distribution.During the geomagnetic storm on August 2,2016,upper-band,lower-band and extremely low frequency(ELF)chorus waves were simultaneously observed within one orbit period of the Van Allen Probe B.Numerical simulations are performed to investigate the electron evolution by the observed chorus with different frequencies.The results show that various frequency chorus waves have different effects on electron dynamics.For chorus in the range f≈0.3 fce–0.7 fce,energy diffusion is the dominant process in electron evolutions.For chorus in the range 0.1 fce≤f≤0.25 fce,the pitch angle diffusion tends to be comparable to energy diffusion for Ek>0.5 MeV.For ELF chorus below 0.1 fce,the pitch angle diffusion rate is much above the energy diffusion rate,leading to potential scattering losses. | HE JiaBei JIN Yu Yue XIAO FuLiang HE ZhaoGuo YANG Chang XIE YanQiong HE Qian WANG ChengZhi SHANG XiongJun LIU Si ZHOU QingHua ZHANG Sai | 2021 | Science China(Technological Sciences)2021，64，4： | 3 |
| 3 | Multi-satellite observations on the storm-time enhancements of energetic outer zone electron fluxes driven by chorus waves显示文摘The evolution of energetic outer zone electron fluxes during the strong magnetic storm on September 28, 2002 is investigated based on the observations of SAMPEX and GOES-10 satellites. The observations of both satellites showed that energetic electron fluxes increased significantly during the storm recovery phase, and reached the maximum on October 6. The 1.5–14 MeV and 2.5–14 MeV electron fluxes observed by SAMPEX peaked around L=3.5 with values of 6×10 2 cm -2 s -1 sr -1 keV -1 and 5×10 3 cm -2 s -1 sr -1 keV -1 , which were about 10 and 8 times the pre-storm values. At the geostationary orbit, the >0.6 MeV and >2 MeV electron fluxes observed by GOES-10 showed enhancement up to 50 and 30 times. The plasma parameters and whistler-mode chorus waves in the outer radiation belt are also analyzed based on the data from Cluster C3 satellite. Cluster C3 satellite went through the outer radiation belt twice from 1 October to 4 October, and observed whistler-mode chorus waves with high intensity (10 -5 –10 -4 nT 2 Hz -1 ). Numerical calculations indicated that the observed chorus waves were in gyro-resonance with the radiation belt electrons. The current observations and calculations provide new evidence for that the gyro-resonance with chorus waves contribute significantly to the buildup of energetic outer zone electron fluxes during storms. | HE ZhaoGuo XIAO FuLiang ZONG QiuGang WANG YongFu CHEN LiangXu YUE Chao ZHANG Sai | 2011 | Science China(Technological Sciences)2011，54，8： | 3 |
| 4 | Bidirectional electron conic observations for photoelectrons in the Martian ionosphere显示文摘Electron pitch angle distributions similar to bidirectional electron conics(BECs)have been reported at Mars in previous studies based on analyses of Mars Global Surveyor measurements.BEC distribution,also termed“butterfly”distribution,presents a local minimum flux at 90°and a maximum flux before reaching the local loss cone.Previous studies have focused on 115 eV electrons that were produced mainly via solar wind electron impact ionization.Here using Solar Wind Electron Analyzer measurements made onboard the Mars Atmosphere and Volatile Evolution spacecraft,we identify 513 BEC events for 19-55 eV photoelectrons that were generated via photoionization only.Therefore,we are investigating electrons observed in regions well away from their source regions,to be distinguished from 115 eV electrons observed and produced in the same regions.We investigate the spatial distribution of the 19-55 eV BECs,revealing that they are more likely observed on the nightside as well as near strong crustal magnetic anomalies.We propose that the 19-55 eV photoelectron BECs are formed due to day-to-night transport and the magnetic mirror effect of photoelectrons moving along cross-terminator closed magnetic field lines. | YuTian Cao Jun Cui BinBin Ni XiaoShu Wu Qiong Luo ZhaoGuo He | 2020 | Earth and Planetary Physics2020，4，4： | 1 |
| 5 | A MAVEN investigation of O++ in the dayside Martian ionosphere显示文摘O^++ is an interesting species in the ionospheres of both the Earth and Venus. Recent measurements made by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on board the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft provide the first firm detection of O^++ in the Martian ionosphere. This study is devoted to an evaluation of the dominant O^++ production and destruction channels in the dayside Martian ionosphere, by virtue of NGIMS data accumulated over a large number of MAVEN orbits. Our analysis reveals the dominant production channels to be double photoionization of O at low altitudes and photoionization of O^+ at high altitudes, respectively, in response to the varying degree of O ionization. O^++ destruction is shown to occur mainly via charge exchange with CO2 at low altitudes and with O at high altitudes. In the dayside median sense, an exact balance between O^++ production and destruction is suggested by the data below 200 km. The apparent discrepancy from local photochemical equilibrium at higher altitudes is interpreted as a signature of strong O^++ escape on Mars, characterized by an escape rate of 6×10^22s^-1. | Hao Gu Jun Cui ZhaoGuo He JiaHao Zhong | 2020 | Earth and Planetary Physics2020，4，1： | 1 |
| 6 | Correlated observations linking loss of energetic protons to EMIC waves显示文摘Electromagnetic ion cyclotron(EMIC)emission is an efficient mechanism for scattering loss of energetic protons.Here,we report an event that provides both in-situ observation of energetic proton differential fluxes in the inner magnetosphere and precipitation of protons at ionospheric altitudes.During the 7-8 September 2015 geomagnetic storm the Van Allen Probes observed strong EMIC waves around L=5 and a distinct decrement in fluxes of tens of keV protons around pitch angles 0°-45°.Meanwhile,precipitating protons at ionospheric altitudes were found to significantly enhanced(by several orders of magnitude),measured by NOAA 18 and 19 when they magnetically linked to the Van Allen Probe-A.By solving the Fokker-Planck diffusion equation,we show that EMIC waves can efficiently produce loss of energetic protons within about 2 h in the pitch angle range of~0°-45°,comparable to the satellite observations. | YANG Chang WANG ZongQiang XIAO FuLiang HE ZhaoGuo XIE YanQiong ZHANG Sai HE YiHua LIU Si ZHOU QingHua | 2022 | Science China(Technological Sciences)2022，65，1： | 0 |
| 7 | Quasi-linear modeling of gyroresonance between different MLT chorus and geostationary orbit electrons显示文摘The contributions of dayside and nightside gyroresonance of chorus waves to electron radiation belt evolution at L = 6.6 are detailedly differentiated via fully solving the two-dimensional Fokker-Plank equation.The numerical results show that the chorus waves at different regions play signiffcantly different roles.The dayside chorus waves can cause obvious loss of energetic electrons at lower pitch angles and weak energization at larger pitch angles.The nightside chorus waves can yield significant energization at larger pitch angles,but cannot efficiently resonate with the energetic electrons at lower pitch angle.Due to the numerical difficulty in fully solving Fokker-Planck equation,the cross diffusion terms are often ignored in the previous work.Here the effect of cross diffiusion at different regions is further analyzed.On the dayside,ignoring cross diffusion overestimates the electron phase space density by several orders of magnitude at lower pitch angles,and consequently the dayside chorus waves are incorrectly regarded as an effective energization mechanism.On the nightside,ignoring cross diffusion overestimates the electron phase space density(PSD) by about one order of magnitude at larger pitch angles.These numerical results suggest that cross diffusion terms can significantly affect gyroresonance of chorus waves on both the dayside and nightside,which should be included in the future radiation belt models. | ZHANG ZeLong XIAO FuLiang HE YiHua HE ZhaoGuo YANG Chang ZHOU XiaoPing TANG LiJun | 2012 | Science China(Information Sciences)2012，55，11： | 0 |
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