The seasonal variations in the mesopause densities, especially with regard to its global structure, are still unclear. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars from Arctic to Antarctic latitudes. The results reveal a significant AO and SAO in mesopause density, an asymmetry between the two polar regions and evidence of intraseasonal oscillations (ISOs), perhaps associated with the ISOs of the troposphere.

It reports the long-term climatology of the intensity of E_s layers from COSMIC satellites. The global E_s maps present high-resolution spatial distributions and seasonal dependence. It mainly occurs at mid-latitudes and polar regions. Based on wind shear theory, simulation results indicate the convergence of vertical ion velocity could partially explain the E_s seasonal dependence and some disagreements between observations and simulations suggest other processes play roles in the E_s variations.

Two traveling ionospheric disturbances (TIDs) were observed by the GPS network in Asia following the large meteorite blast over Chelyabinsk, Russia. No TIDs propagating in a global range were found. Features of TIDs were compared with those excited by early nuclear explosion tests. It is inferred from our analysis that the energy release of the Chelyabinsk meteorite blast may not be large enough to excite such ionospheric disturbances in a global range as some nuclear explosions have done.