摘要
We investigate the flux evolution of geostationary orbit energetic electrons during a strong storm on 24 August 2005(event A,the storm index Dst<200 nT,the average substorm index AE=436 nT)and a weak storm on 28 October 2006(event B,Dst>50 nT,average AE=320 nT).Data collected by LANL and GOES-12 satellites show that energetic electron fluxes increase by a factor of 10 during the recovery phase compared to the prestorm level for both events A and B.As the substorm continued,the Cluster C4 satellite observed strong whistler-mode chorus waves(with spectral density approaching 10 5nT2/Hz).The wave amplitude correlates with the substorm AE index,but is less correlated with the storm Dst index.Using a Gaussian distribution fitting method,we solve the Fokker-Planck diffusion equation governing the wave-particle interaction.Numerical results demonstrate that chorus waves efficiently accelerate^1 MeV energetic electrons,particularly at high pitch angles.The calculated acceleration time scale and amplitude are comparable to observations.Our results provide new observational support for chorus-driven acceleration of radiation belt energetic electrons.
We investigate the flux evolution of geostationary orbit energetic electrons during a strong storm on 24 August 2005 （event A, the storm index Dst〈-200 nT, the average substorm index AE=436 nT） and a weak storm on 28 October 2006 （event B, Dst〉-50 nT, average AE=320 nT）. Data collected by LANL and GOES-12 satellites show that energetic electron fluxes in- crease by a factor of 10 during the recovery phase compared to the prestorm level for both events A and B. As the substorm continued, the Cluster C4 satellite observed strong whistler-mode chorus waves （with spectral density approaching 10-5 nT2/Hz）. The wave amplitude correlates with the substorm AE index, but is less correlated with the storm Dst index. Using a Gaussian distribution fitting method, we solve the Fokker-Planck diffusion equation governing the wave-particle interaction. Numerical results demonstrate that chorus waves efficiently accelerate -1 MeV energetic electrons, particularly at high pitch angles. The calculated acceleration time scale and amplitude are comparable to observations. Our results provide new observa- tional support for chorus-driven acceleration of radiation belt energetic electrons.
基金
supported by the National Natural Science Foundation of China(Grant Nos.40925014&41274165)
Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province
the Construct Program of the Key Discipline inHunan Province
