Characteristics of energetic electron precipitation into the earthʹs polar atmosphere and geomagnetic conditions Original Research Article

A number of energetic electron precipitation events (EPEs) were observed in the Earthʹs polar atmosphere (Murmansk region, geographical coordinates 68.57 N, 33.03 E and Mirny, Antarctica, 66.34 S, 92.55 E) during the long-term cosmic ray balloon experiment from 1957 up to now. During geomagnetic storms significant X-ray fluxes caused by precipitating electrons at the top of the atmosphere sometimes penetrated to the atmospheric depth of 60 gcm−2. We show that (1) there is a quasi-11-year cycle in EPE occurrence shifted with respect to solar activity cycle, and (2) the yearly rate of EPE occurrence has an ascending trend during the period 1965–1999. The EPE characteristics evaluated from the balloon experiment are compared with the available data on geomagnetic activity and the possible relations between the features of EPE events and geomagnetic conditions are discussed.