Ionospheric Response to the Space Weather Events of 4-10 September 2017: First Chilean Observations

Manuel Bravo,Pedro Vega-Jorquera,Elías Ovalle,Carlos Villalobos,Luis Tamblay,Alberto Foppiano,Rodrigo Leiva

doi:10.2174/1874282301812010001

Abstract

Objective: The diurnal variations of several ionospheric characteristics during the Space Weather Events of 4-10 September 2017, for Chilean latitudes, will be reported. Materials and Methods: Observations were made using a recently installed ionosonde at the Universidad de La Serena field station (29°52'S; 71°15’W). Also, reported is the total electron content determined using the upgraded Chilean network of dual-frequency Global Navigation Satellite Systems (GNSS) receivers. Results: Sudden ionospheric disturbances are described in terms of the minimum reflection frequency determined from ionosonde records. An attempt to derive the extent of the effect on high frequency propagation paths in the region is made using simultaneous ionosonde observations at other locations. The geomagnetic storm ionospheric effects are discussed in detail using the observed diurnal variation of maximum electron concentration (NmF2), virtual height of the F-region (h’F/F2) and Total Electron Content (TEC). These are complemented with the time-latitude variation of TEC for the 70°W meridian. Conclusion: It is found that large increases of NmF2, h’F/F2 and TEC observed during 8 September 2017 storm are well described in terms of the evolution of the Equatorial Ionospheric Anomaly (EIA) over the same time interval. Known physical mechanisms are suggested to explain most of the observations.

Highlights

It is well known that geomagnetic storms generate ionospheric disturbances
Diurnal variations of global geomagnetic indices, ionospheric characteristics for La Serena (LS), GOES X-ray flux and vertical TEC (vTEC) for 6 and 10 September 2017 are shown in Fig. (3)
SIDs are observed at La Serena (29°52'S; 71°15’W) following most significant solar flares of 6 to 10 September 2017, in spite of some observations gaps

Summary

Introduction

It is well known that geomagnetic storms generate ionospheric disturbances. Reports of regional studies of the effects of geomagnetic storms have been made (e.g. Italy, North Africa and Brazil), as multi instrument ionospheric observations have become available [3 - 8]. One regional study relates the increases of maximum electron concentration (NmF2), Total Electron Content (TEC) and airglow intensity for several hours during a geomagnetic storm (13-15 November 2012) associated with northward evolution of the Equatorial Ionospheric Anomaly (EIA) in the northern hemisphere [3]. Other reports [4] on the generation of traveling ionospheric/thermospheric perturbations by a geomagnetic storm (27-28 February 2014). They found anti-correlation between observed NmF2 and the height of the maximum of maximum electron concentration (hmF2)

Methods

Results

Discussion

Conclusion