1. 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

2. 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)

3. 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

4. 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

5. 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

6. 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

7. 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?

8. 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.

9. 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

10. 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).

11. 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

12. 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 ?!!

13. 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.

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