A comparison of ionospheric vertical drift velocities measured by Digisonde and Incoherent Scatter Radar at the magnetic equator

Using data acquired with a Digisonde DPS-4 and an Incoherent Scatter Radar both from Jicamarca Radio Observatory, Peru, comparisons of ionospheric vertical drift velocities derived from these two instruments are carried out in this work. They show good agreement during sunset and evening hours (around sunset, up to approximately 22 LT), and also, during the post-midnight (between 02 and 03 LT) and sunrise hours (until 08 LT), when the F-layer bottom side height is around and above 300 km, as well as during events of magnetically disturbed periods when the ionospheric plasma drift may be influenced by the perturbation electric fields arising from (1) direct penetration from high to low magnetic latitudes, and (2) disturbance winds dynamo action driven by Joule heating due to increased energy and momentum deposition into the high-latitude thermosphere-ionosphere system. The results of this study lend confidence to using Digisonde drift data to study phenomena related to night-time magnetically disturbed periods. (c) 2006 Elsevier Ltd. All rights reserved.