Coordinated measurements of low-energy electron precipitation and scintillations/TEC in the auroral oval


  • Sunanda Basu,

  • Eileen MacKenzie,

  • Santimay Basu,

  • H. C. Carlson,

  • D. A. Hardy,

  • F. J. Rich,

  • R. C. Livingston


A case study of coordinated observations of low-energy (<500 eV) electron precipitation in the auroral oval from DMSP/F2 and phase and amplitude scintillations from Goose Bay, using a geostationary satellite transmitting at 244 MHz, is presented. The precipitation event took place during the expansion phase of an intense evening substorm, when the equatorward boundary of the diffuse aurora reached 59° invariant latitude. Particularly large phase scintillations (>10 radians for fluctuation frequencies >0.0067 Hz) were found to be well correlated with intense fluxes (>109 particles (cm2 s sr)−1) of precipitated low-energy electrons. Total electron content and magnetometer measurements indicate that the onset of the precipitation event was about 10 min prior to the DMSP pass. Within this time scale, the ionization generated in the F region could reach the topside so that the thermal sensor on board the DMSP satellite was able to measure a factor of 2–3 density enhancement at 840 km. The latitudinal width of these density structures is consistent with that of F region blobs observed at Chatanika. The gradient scale length measured in the topside was only 30 km, which was probably responsible for the fast growth rate of the scintillation-producing irregularities. The phase to amplitude scintillation ratio changed rather drastically compared to quiet magnetic times, however, implying that increased convection velocities during these magnetic disturbances were partially responsible for the enhanced phase scintillation.