Growin: Modeling ionospheric instability growth rates

Abstract

Seasonal and zonal climatologies of Rayleigh-Taylor growth rates under geomagnetically quiet conditions during solar minimum and solar moderate conditions as a function of local time and altitude are calculated using open source data and software. It is under the action of the Rayleigh-Taylor instability that plumes of depleted plasma, or plasma bubbles, are understood to develop in the bottomside of the equatorial ionosphere. The growin python module utilizes other Heliophysics python modules to collate and process vertical plasma drift to drive the SAMI2 is Another Model of the Ionosphere (SAMI2) model and subsequently calculate the flux tube integrated Rayleigh-Taylor growth rate. The process is repeated for two different types of drift inputs: the Fejer-Scherliess model and measured drifts from the Communication/Navigation Outage Forecasting System (C/NOFS). These growth rates are compared to bubble occurrence frequencies obtained from a dataset of bubbles detected by the C/NOFS satellite. There is agreement between periods of strong positive instability growth and high frequencies of bubble occurrence in both low and moderate solar activity conditions when using C/NOFS drifts. Fejer-Scherliess drifts are only in agreement with bubble occurrence frequencies during moderate solar activity conditions. Bubble occurrence frequencies are often above 25% even when growth rates in the bottomside F region are negative. The climatological nature of the growth rates discussed here begs further study into the day-to-day variability of the growth rate and its drivers.

A system science perspective of the drivers of equatorial plasma bubbles

“…Modeling techniques that incorporate growth rate analysis from a global perspective can be used to determine the relative importance of each energy path that modifies the equatorial regions (e.g., Carter et al, 2014b;10.3389/fspas.202210.3389/fspas. .1064150 Hysell et al, 2022Smith and Klenzing, 2022). Another path forward is to incorporate variable grid scale ionosphere in a global model (Huba and Liu, 2020).…”

sami2py—Overview and applications

“…Similar to the previous application, the broader ionospheric research community is the user and will benefit from a Python version of growin and the inclusion of sami2py within it. The feasibility, viability, and expected improvements can all be found within Smith and Klenzing (2022). Thus many of the milestones have been completed for this application through the previously discussed application in Section 4.1.…”

“…This allows users with direct measurements to create a localized drift model. Examples of this type of usage are presented in Klenzing et al (2013) and Smith and Klenzing (2022). An additional input file to the FORTRAN code names exb.inp was added so that the localized model can be changed without recompiling the FORTRAN engine.…”

“…Subsequently the produced ionospheric plasma densities, drifts, and winds are used to compute flux-tube integrated quantities necessary to compute the RTI growth rate. These growth rates have been previously used to discuss bubble occurrence frequencies obtained from the CINDI (Smith and Klenzing, 2022) and Global Observations of the Limb and Disk (GOLD) (Martinis et al, 2021) missions.…”

A height-dependent climatological model of the equatorial ionospheric zonal plasma drifts (EZDrifts): Description and application to an analysis of the longitudinal variations of the zonal drifts

“…This has motivated various experimental and theoretical studies of the vertical drifts, including the development of a climatological global model of the vertical drifts (Scherliess and Fejer, 1999). This drift model is commonly used to drive numerical models of the ionosphere (Zhan and Rodrigues, 2018;Smith and Klenzing, 2022), to evaluate plasma drift measurements (Stoneback et al, 2011;Rodrigues et al, 2013), and to assess the results of simulations of the ionospheric electrodynamics (Liu et al, 2018;Shidler and Rodrigues, 2022).…”