Seminars

Lecturer: Asta Pellinen-Wannberg
Date: 2014-04-03 10:00
Place: Aniara

Collective E region ionization caused by the 1767 trail during the 2002 Leonids

Intensive E region ionization extending up to 140 km altitude and lasting for several hours was observed with the EISCAT UHF radar during the 2002 Leonids meteor shower maximum. The level of global geomagnetic disturbance as well as the local geomagnetic and auroral activity in northern Scandinavia were low during the event. Thus the ionization cannot be explained by intensive precipitation. The layer was 30-40 km thick, so it cannot be classified as a sporadic E-layer which are typically just about km-wide and associated to ions of meteoric origin.

Incoherent scatter radars have never so far reported any notable meteor shower-related increases in the average background ionization. The 2002 Leonids storm flux, however, was so high that it, if any, might be able to induce such an event. Whether meteors in general can cause such an excess E region ionization during an intensive shower is discussed. Predicted flux values in free space are used to estimate how much ionization can be induced. The University of Leeds CABMOD model is used to estimate deposition rates of in dividual meteors and to relate the results to the predicted Leonid flux values in free space and observed ionization on November 19, 2002. The high latitude electrodynamic conditions between the EISCAT UHF and EISCAT Svalbard Radar (ESR) some 1000 km further north, which did not observe any excess ionization during the event, are compared to evaluate what kind of circumstances can feed such collective ionization.

Created 2014-01-30 15:22:24 by Uwe Raffalski
Last changed 2014-03-27 14:00:59 by Uwe Raffalski