Formula omitted] as a proxy for the variations of [formula omitted] drift and plasma irregularity over East Africa

Abstract

This paper demonstrates that real-time, dip-equatorial, daytime, vertical E×B drift velocities can be derived from ground-based magnetometers over an understudied Eastern African longitude sector. An integrated third order periodic mean partial least square (PMPLS) technique is introduced for vertical drift estimation. The vertical drift data sets, obtained from Communication/Navigation Outage Forecasting Systems (C/NOFS) during an extended period of 2008–2013 on quiet geomagnetic storm conditions were used. The paper also characterizes the influence of daytime horizontal magnetic field perturbations for the vertical E×B drift velocity and therefore for the evening time plasma irregularities over Addis Ababa, Ethiopia (9.03° N, 38.7° E, dip latitude 2.09°). Linear and non-linear coefficients of the C/NOFS E×B drift variations were calculated in order to capture the trend of the variation on the temporal basis. Furthermore amplified (07:00–10:00 LT), saturated (10:00–16:00 LT) and linear (16:00–1900 LT) variations of vertical drift are found. Results are compared with independent vertical ion drift estimates of International Reference Ionosphere 2012 (IRI-2012) and partial least square (PLS). PMPLS performance was better in terms of capturing the daytime trends of observed C/NOFS E×B drift. Overall, PMPLS results showed better agreement with the observation C/NOFS E×B drift with maximum and minimum root-mean-square errors (RMSEs) of 12.67 m/s and 9.2 m/s during noontime and post noontimes respectively. Despite ΔH are weaker-positive for most of our observations during prereversal enhancement (PRE) hours the strength of the daytime ΔH are somewhat related to the formation of the post-sunset irregularities.