Coronal signatures of accelerated electrons

Whereas hard X-rays, microwaves and gamma-rays trace flare accelerated electrons and ions interacting in the low corona and the chromosphere, imaging and spectral radio observations in the decimetric-dekametric domain provide signatures of non thermal electrons in the middle and upper corona. These latter radio observations, combined with X-ray, EUV and optical measurements, contain unique information on the various circumstances of electron acceleration whether they are associated with flares or not. In this paper we outline the results of multiwavelength studies which provide: (i) information on the magnetic structure at various spatial scales into which flare accelerated electrons are injected/accelerated and (ii) evidence for various sites of electron acceleration outside flares which are located in the corona at altitudes ranging typically from ∼ 0.1 to ∼ 1 Ro above the photosphere. © 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.