Fig. 7From: Occurrence features of intermediate descending layer and Sporadic E observed over the higher mid-latitude ionospheric station of MoscowLomb periodograms of ionogram numerical data corresponding to IDLs over Moscow. The observed periodicities on Es occurrence for all winter months (December, January, February) during the period 2011–2019 are shown. The 4- and 4.8- hour periodicities are indicated within the orange boxBack to article page