Lower thermosphere factor in formation York University Lower thermosphere factor in formation of sporadic E under influence of horizontal wind and AGWs Goderdzi DIDEBULIDZE, Giorgi DALAKISHVILI, Lekso TORIASHVILI Abastumani Astrophysical Observatory Tbilisi, Georgia

Theory of sporadic E formation by atmospheric waves Windshear theory (Axford, 1963): is geomagnetic field, is ions velocity, is neutrals velocity, is ion-neutral collisions frequency Windshear theory developed for atmospheric waves: is background horizontal wind velocity, is neutrals velocity caused by atmospheric waves (particulary AGWs or vortical type of perturbations)

Ions vertical convergence by AGWs For simplicity the isothermal model (Hines, 1960) of AGWs is used and dispersion equation have the following form: Z λz λz H is atmospheric scale height, kx,y,z=2π/λx,y,z are the horizontal and vertical wave numbers AGW velocity

Ions vertical convergence by AGWs For simplicity the isothermal model (Hines, 1960) of AGWs is used and dispersion equation have the following form: Z B λz B λz H is atmospheric scale height, kx,y,z=2π/λx,y,z are the horizontal and vertical wave numbers B AGW velocity

Ions vertical convergence by AGWs For simplicity the isothermal model (Hines, 1960) of AGWs is used and dispersion equation have the following form: Z Ions convergence B λz Ions convergence B λz Ions convergence H is atmospheric scale height, kx,y,z=2π/λx,y,z are the horizontal and vertical wave numbers B AGW velocity

Atmospheric gravity waves Ions vertical distribution under an influence of AGWs and background meridional wind Ions production and loss rates Meridional wind Atmospheric gravity waves Ambipolar diffusion

Simultaneous horizontal wind velocity and electron density rocket measurements in the lower thermosphere Bishop, Earle, Larson, Swenson, Carlson, Roddy, Fish, and Bullet, JGR, 2005. Atmospheric wave plus background wind structure?

Heavy metallic ions (Fe+) diffusive displacement in the lower thermosphere The initial distribution of the ions is described by the Gaussian type function: Nom is maximal ions density, zm=95;135 km. Heff =16 km.

Horizontal wind influences on electron/ions density height profile behavior Electron density, Ne/Nom Electron density, Ne/Nom The case of presence of westward Directed wind The case of presence of Eastward Directed wind

Electron density, Ne/Nom The formation of Es layers under influence of AGWs Electron density, Ne/Nom X,Z frame. Uon=-Vph=-31m/s H=10 km, λx =120 km, λz =12 km, (Didebulidze et al., JASTP, 2015).

Electron density, Ne/Nom The ions convergence regions in some cases are shifted from the point of AGWs velocity polarization changes Electron density, Ne/Nom λz λz λz AGWs velocity amplitude 60m/s, λx =120 km, λz =10 km

Electron density, Ne/Nom The ions convergence regions in some cases are shifted from the point of AGWs velocity polarization changes Electron density, Ne/Nom λz λz λz The convergence point shipment also depends on vertical wavelength ?!!

CONCLUSIONS Horizontal background wind influence on ions vertical distribution in the mid-latitude lower thermosphere and can effect on their convergence height. The horizontal wind speed close to AGWs phase velocity is convenient for ions vertical convergence and formation multilayered sporadic E. The ions convergence points caused by the AGWs can be shifted from the regions of its horizontal velocity polarization changes. Acknowledgement: G. Dalakishvili is supported by Georgian Shota Rustaveli National Science Foundation Grant no. FR/51/6-300/14.

14th Quadrennial Solar-Terrestrial Physics Symposium Thank you! 14th Quadrennial Solar-Terrestrial Physics Symposium Toronto, July 9, 2018