Leonovich L.A., Tashchilin A.V., Lunyushkin S.B., Karavaev Yu.A., Penskikh Yu.V. «Studying 630 nm atomic oxygen emission sources during strong magnetic storms in the night mid-latitude ionosphere» Солнечно-земная физика, 5, № 2, с. 35-41 (2019)

We analyze significant increases in 630 nm atomic oxygen night emissions during very strong geomagnetic storms, using optical measurements, theoretical modeling, and magnetogram inversion technique (MIT) data. It is shown that during strong magnetic storms when electron precipitation equatorial boundary at the night sector expands up to ∼40°, the interaction of energetic electron flux with thermospheric components may cause extreme increases in the 630 nm emission intensity. Model calculations of the red line intensity show good agreement with observational data. Using the November 20, 2003 magnetic storm as an example, we have found that oxygen atom collisions with thermal Maxwell and superthermal electrons make a major contribution to the integral emission intensity. Thermospheric density variations during the magnetic storm significantly affect the red line generation.

Dali Ya., Tiemin Zh., Jihong W., Jianqing Wu., Linmao W., Xu Z., Hongyan P. «Characteristics of double sodium layer over Haikou, China (20.0°N, 110.1°E)» Солнечно-земная физика, 5, № 2, с. 30-34 (2019)

We study the property of double sodium layer structures (DSLs) in the mesosphere and lower thermosphere (MLT) by a lidar at the low-latitude location of Haikou (20.0°N, 110.1°E), China. From April 2010 to December 2013, 21 DSLs were observed within a total of 377 observation days. DSLs were recorded at middle latitudes of Beijing and Wuhan, China, but were rarely observed at low latitudes. We analyze and discuss characteristics of DSLs such as time of occurrence, peak altitude, FWHM, duration time, etc. At the same time, the critical frequency f_oE_s and the virtual height h E_s of the sporadic E layer E_s were observed by an ionosonde over Danzhou (19.0°N, 109.3°E). We discuss such their characteristics as differences of time, differences of altitude compared to DSLs. We used an Nd:YAG laser pumped dye laser to generate the probing beam. The wavelength of the dye laser was set to 589 nm by a sodium fluorescence cell. The backscattered fluorescence photons from the sodium layer were collected by a telescope with the ∼1000 mm primary mirror.