Daytime mid-latitude F2-layer Q-disturbances: A formation mechanism

Loredana Perrone,Anatoly A Nusinov,Andrey V Mikhailov

doi:10.1038/s41598-020-66134-2

Loredana Perrone, Anatoly A Nusinov + Show 1 more

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https://doi.org/10.1038/s41598-020-66134-2

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Abstract

Negative and positive near noontime prolonged (≥3 hours) F2-layer Q-disturbances with deviations in NmF2 > 35% occurred at Rome have been analyzed using aeronomic parameters inferred from fp180 (plasma frequency at 180 km height) and foF2 observations. Both types of NmF2 perturbations occur under quiet (daily Ap < 15 nT) geomagnetic conditions. Day-to-day atomic oxygen [O] variations at F2-region heights specify the type (positive or negative) of Q-disturbance. The [O] concentration is larger on positive and is less on negative Q-disturbance days compared to reference days. This difference takes place not only on average but for all individual Q-disturbances in question. An additional contribution to Q-disturbances formation is provided by solar EUV day-to-day variations. Negative Q-disturbance days are characterized by lower hmF2 while positive – by larger hmF2 compared to reference days. This is due to larger average Tex and vertical plasma drift W on positive Q-disturbance days, the inverse situation takes place for negative Q-disturbance days. Day-to-day changes in global thermospheric circulation may be considered as a plausible mechanism. The analyzed type of F2-layer Q-disturbances can be explained in the framework of contemporary understanding of the thermosphere-ionosphere interaction based on solar and geomagnetic activity as the main drivers.

Highlights

Negative and positive near noontime prolonged (≥3 hours) F2-layer Q-disturbances with deviations in NmF2 > 35% occurred at Rome have been analyzed using aeronomic parameters inferred from fp[180] and foF2 observations
F2-layer disturbances are related to geomagnetic activity variations but there is a class of F2-layer perturbations which occur under quiet geomagnetic conditions (Q-disturbances), their magnitude being comparable to moderate F2-layer storm effects
Day-to-day NmF2 variability is 15–20% at middle latitudes[1,2] while we are speaking about NmF2 deviations with the magnitude >35% occurring near noontime with a duration more than three hours, i.e. longer than two characteristic e-fold times of the daytime F2-layer. Such long-lasting NmF2 deviations imply either changes in the ionizing solar EUV radiation or changes in the production/recombination rate or/and changes in vertical plasma drift mainly related to thermospheric winds

Summary

Introduction

Negative and positive near noontime prolonged (≥3 hours) F2-layer Q-disturbances with deviations in NmF2 > 35% occurred at Rome have been analyzed using aeronomic parameters inferred from fp[180] (plasma frequency at 180 km height) and foF2 observations Both types of NmF2 perturbations occur under quiet (daily Ap < 15 nT) geomagnetic conditions. Day-to-day NmF2 variability is 15–20% at middle latitudes[1,2] while we are speaking about NmF2 deviations with the magnitude >35% occurring near noontime with a duration more than three hours, i.e. longer than two characteristic e-fold times of the daytime F2-layer (the e-fold time is the time required for a parameter to change by 2.72 times) Such long-lasting NmF2 deviations imply either changes in the ionizing solar EUV radiation or changes in the production/recombination rate (i.e. thermospheric neutral composition) or/and changes in vertical plasma drift mainly related to thermospheric winds. Www.nature.com/scientificreports today we have direct solar EUV observations and satellite neutral gas density measurements which can be successfully used to control the obtained results

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