Institution: | a Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), Troitsk, Moscow Region 142092, Russia b Radiophysical Research Institute (NIRFI), B. Pecherskaya 25/14, Nizhniy Novgorod 603600, Russia c Space Research Institute (IKI), Profsoyuznaya 84/32, Moscow 117810, Russia |