TY - JOUR

T1 - Polarization electric field and Farley-Buneman instability during a precipitation event.

AU - del Pozo, C. F.

PY - 1994/3

Y1 - 1994/3

N2 - An anomalous polarization electric field may be set-up in the lower auroral E-region in response to an electron precipitation event during unstable electrojet conditions. For instance, observations during post-midnight to early morning hours on 06–07 June 1990, using the EISCAT radar facility in Scandinavia, show that the in-situ dynamics of the E-region ionization may be radically affected by the presence of the Farley-Buneman instability. In this case, the measured ion drifts at 105 km height are exceptionally strong and comparable in magnitude with the E × B-drift in the F-region, mapped along the same magnetic fieldline. In this paper we present a model to explain the main features of these observations. We assume a simple relaxation model for the E-region ionization generated by an instantaneous electron precipitation event during diffuse aurora conditions and in the presence of the Farley-Buneman instability. In these conditions and for times smaller than the ionization lifetime (tens of seconds to a few minutes), the induced polarization electric field to restore charge quasi-neutrality may radically increase the ion drift velocity, and effectively decouple the ion motion from the dynamics of the neutral atmosphere.

AB - An anomalous polarization electric field may be set-up in the lower auroral E-region in response to an electron precipitation event during unstable electrojet conditions. For instance, observations during post-midnight to early morning hours on 06–07 June 1990, using the EISCAT radar facility in Scandinavia, show that the in-situ dynamics of the E-region ionization may be radically affected by the presence of the Farley-Buneman instability. In this case, the measured ion drifts at 105 km height are exceptionally strong and comparable in magnitude with the E × B-drift in the F-region, mapped along the same magnetic fieldline. In this paper we present a model to explain the main features of these observations. We assume a simple relaxation model for the E-region ionization generated by an instantaneous electron precipitation event during diffuse aurora conditions and in the presence of the Farley-Buneman instability. In these conditions and for times smaller than the ionization lifetime (tens of seconds to a few minutes), the induced polarization electric field to restore charge quasi-neutrality may radically increase the ion drift velocity, and effectively decouple the ion motion from the dynamics of the neutral atmosphere.

KW - Polar ionosphere

KW - Ionospheric E region

KW - Electric field

KW - Polarization

KW - Buneman Farley instability

KW - Particle precipitation

KW - Drift velocity

U2 - 10.1016/0021-9169(94)90200-3

DO - 10.1016/0021-9169(94)90200-3

M3 - Journal article

VL - 56

SP - 509

EP - 523

JO - Journal of Atmospheric and Terrestrial Physics

JF - Journal of Atmospheric and Terrestrial Physics

IS - 4

ER -