Mid-Latitude Daytime F2-Layer Disturbance Mechanism under Extremely Low Solar and Geomagnetic Activity in 2008–2009

Andrey V. Mikhailov,Anatoly A. Nusinov,Loredana Perrone

doi:10.3390/rs13081514

Andrey V. Mikhailov, Anatoly A. Nusinov + Show 1 more

Open Access

https://doi.org/10.3390/rs13081514

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Journal: Remote sensing	Publication Date: Apr 14, 2021
Citations: 5	License type: CC BY 4.0

Affiliation: Istituto Nazionale di Geofisica e Vulcanologia

Abstract

European near-noontime ionosonde observations were considered during the period of deep solar minimum in 2008–2009 to analyze foF2 perturbations not related to solar and geomagnetic activity. Sudden stratospheric warming (SSWs) events in January 2008 and 2009 were analyzed. An original method was used to retrieve aeronomic parameters from observed electron concentration in the ionospheric F-region. Atomic oxygen was shown to be the main aeronomic parameter responsible both for the observed day-to-day and long-term (during SSWs) foF2 variations. Atomic oxygen rather than neutral temperature mainly controls the decrease of thermospheric neutral gas density in the course of the SSW events. Day-to-day variations of thermospheric circulation and an intensification of eddy diffusion during SSWs are suggested to be the processes changing the atomic oxygen abundance in the upper atmosphere for the periods in question. Recent Global-Scale Observations of the Limb and Disk (GOLD) observations of O/N2 column density confirm the depletion of the atomic oxygen abundance not related to geomagnetic activity during SSWs.

Highlights

Quiet time F2 -layer disturbances (Q-disturbances) present a special class of Nm F2 perturbations occurring under magnetically quiet conditions
Geomagnetic and solar activity was at extremely low levels with small day-to-day variations
One may think that pure meteorological effects in day-to-day fo F2 variations related to planetary and gravity waves do exist, but a special selection of days with zero 3h-ap indices are required for such analysis and this is a task for future

Summary

Introduction

Quiet time F2 -layer disturbances (Q-disturbances) present a special class of Nm F2 perturbations occurring under magnetically quiet conditions. Their morphology and the formation mechanism differ from F2 -layer storm effects related to enhanced geomagnetic activity [1,2,3,4]. Such day-to-day Nm F2 variations may be considered in the framework of F2 layer variability [5,6,7]. Solar EUV radiation is a slowly varying parameter and its contribution to

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