An electrodynamics model for Data Interpretation and Numerical Analysis of ionospheric Missions and Observations (DINAMO)

Samuel A Shidler,Fabiano S Rodrigues

doi:10.1186/s40645-021-00462-3

Abstract

We introduce a new numerical model developed to assist with Data Interpretation and Numerical Analysis of ionospheric Missions and Observations (DINAMO). DINAMO derives the ionospheric electrostatic potential at low- and mid-latitudes from a two-dimensional dynamo equation and user-specified inputs for the state of the ionosphere and thermosphere (I–T) system. The potential is used to specify the electric fields and associated F-region E × B plasma drifts. Most of the model was written in Python to facilitate the setup of numerical experiments and to engage students in numerical modeling applied to space sciences. Here, we illustrate applications and results of DINAMO in two different analyses. First, DINAMO is used to assess the ability of widely used I–T climatological models (IRI-2016, NRLMSISE-00, and HWM14), when used as drivers, to produce a realistic representation of the low-latitude electrodynamics. In order to evaluate the results, model E × B drifts are compared with observed climatology of the drifts derived from long-term observations made by the Jicamarca incoherent scatter radar. We found that the climatological I–T models are able to drive many of the features of the plasma drifts including the diurnal, seasonal, altitudinal and solar cycle variability. We also identified discrepancies between modeled and observed drifts under certain conditions. This is, in particular, the case of vertical equatorial plasma drifts during low solar flux conditions, which were attributed to a poor specification of the E-region neutral wind dynamo. DINAMO is then used to quantify the impact of meridional currents on the morphology of F-region zonal plasma drifts. Analytic representations of the equatorial drifts are commonly used to interpret observations. These representations, however, commonly ignore contributions from meridional currents. Using DINAMO we show that that these currents can modify zonal plasma drifts by up to ~ 16 m/s in the bottom-side post-sunset F-region, and up to ~ 10 m/s between 0700 and 1000 LT for altitudes above 500 km. Finally, DINAMO results show the relationship between the pre-reversal enhancement (PRE) of the vertical drifts and the vertical shear in the zonal plasma drifts with implications for equatorial spread F.

Highlights

We use DINAMO to evaluate the ability of current climatological drivers (HWM14, IRI-2016, and NRLMSISE-00) to produce realistic ionospheric electrodynamics for different seasons and solar flux conditions (Sect. 3.1)
Focus is given to results for the Peruvian longitude sector (∼ 284◦E), which allows a comparison of model drift results with mean plasma drifts derived from long-term Jicamarca incoherent scatter radar (ISR) observations
The left column in each Figure corresponds to low solar flux (LSF) conditions, and the right column corresponds to high solar flux (HSF) conditions

Summary

Introduction

(ESF) ionospheric irregularities (Abdu et al 1983; Fejer et al 1999; Huang 2018; Huang and Hairston 2015; Smith et al 2015; Sultan 1996) which can affect signals used for communication, navigation and remote sensing systems (Basu et al 1988; Carrano et al 2012; Kintner et al 2007). The more recent studies (e.g., Eccles 1998; Eccles et al 2015; Haerendel et al 1992; Huba et al 2010) have successfully used a field line integrated, two-dimensional model to describe the electrodynamics of the low-latitude ionosphere. We use DINAMO to evaluate the contribution of the integrated vertical current ( JL ) to the morphology of the equatorial F-region zonal drifts. With the exception of Haerendel et al (1992), which considered a few different values of JL , these studies neglected the contribution of the vertical integrated current to the morphology of the zonal drifts.

Model description

Collision frequency and conductivity

Results and discussion

Conclusions