Numerical simulation of mid-latitude ionospheric <i>E</i>-region based on SEEK and SEEK-2 observations

Abstract

Abstract. Observational campaigns of the mid-latitude ionospheric E-region with sounding rockets and ground-based instruments were conducted in 1996 (SEEK) and 2002 (SEEK-2). Both of them were successfully conducted to bring important findings about the mid-latitude E-region and quasiperiodic (QP) VHF radar echoes. The observational results in the SEEK and the SEEK-2 are compared with numerical simulations and discussed in this paper. While sporadic-E (E s )-layers are actually formed by the observed neutral wind, it is difficult for the constant wind shear to produce the sharp E s -layer gradient. However, once they are formed in the lower E-region, they cannot easily be dissipated by the simple diffusive motion. The polarization electric field, calculated under the condition at the rocket launch time, shows similar amplitude and structure to the measurement around the E s -layer altitude. The structure of the plasma density and the electric field above the E s -layer observed in the SEEK-2 showed a wave-like pattern up to an altitude of 150 km. Considering a mapping of the polarization electric field generated within the E s -layers, gravity waves are the possible source of the wave-like structure of the measured electric fields and sub-peaks of the electron density above the main E s -layers. Fluctuation of the measured magnetic field is reproduced by Hall or field-aligned current driven by the polarization electric field. The current theoretical models for QP echoes and the polarization electric field are basically verified by the discussion in this paper.

The first coordinated observations of mid-latitude <i>E</i>-region quasi-periodic radar echoes and lower thermospheric 557.7-nm airglow

“…Yamamoto et al, 1991;Ogawa et al, 1995Ogawa et al, , 2002, which suggests that these fluctuations are invoked by AGWs and/or polarization electric fields in an E s (Huang and Kelley, 1996;Horinouchi et al, 2002;Horinouchi, 2004;Yokoyama et al, 2004bYokoyama et al, , 2005. Strong electric field fluctuations were actually found from the rocket flights during SEEK-1 (Pfaff et al, 1998) and SEEK-2 (Wakabayashi et al, 2005).…”

Multi-layer structure of mid-latitude sporadic-<i>E</i> observed during the SEEK-2 campaign

“…Therefore, the lower E s peak might be generated by the wind shear mechanism first, then the external electric field led to the formation of a higher E s . The numerical simulations by Yokoyama et al (2005;private communications) indicated the stability of the E s layer generated by only wind shears (although the actual E s layer has a "sporadic" nature). The present results are in agreement.…”

Muon radiography and deformation analysis of the lava dome formed by the 1944 eruption of Usu, Hokkaido -Contact between high-energy physics and volcano physics-

“…1000 C. The macroscpic viscosity of the 1944 lava dome is estimated at approx. 10 6 Pa.s (Yokoyama,6) Fig. 1).…”