Conjugate observations of power line harmonic radiation onboard DEMETER

Abstract The effects of power line harmonic radiation (PLHR) on near-Earth space have been debated for many years. Since some ultrahigh voltage AC and DC projects were added to the Chinese grid, increasingly numerous radiations at 50 Hz their harmonics caught by microsatellite DEMETER in geomagnetically conjugate topside ionosphere during daytime winter spring. Distribution SYM-H index has studied, showing geomagnetic disturbances may be unnecessary occurrence PLHR. propagation PLHR between hemispheres without much attenuation illustrates that can amplified when crosses equatorial zone. Eliminating seasonal diurnal factors, dependence change plasma density is disclosed. abrupt variation electron gradient create a favored condition waves propagating hemispheres. Graphical