Preprints
https://doi.org/10.5194/angeo-2021-52
https://doi.org/10.5194/angeo-2021-52

  12 Oct 2021

12 Oct 2021

Review status: this preprint is currently under review for the journal ANGEO.

Intermediate Layers responses to Geomagnetic Activity During the 2009 Deep Solar Minimum Over the Brazilian Low Latitude Sector

Ângela Santos1, Christiano Brum2, Inez Batista1, José Sobral1, Mangalathayil Abdu1, and Jonas Souza1 Ângela Santos et al.
  • 1National Institute for Space Research, São José dos Campos, Brazil
  • 2Arecibo Observatory, University of Central Florida, Arecibo, Puerto Rico

Abstract. Intermediate layers (ILs) are regions of enhanced electron density located in the ionospheric valley that extends from the peak altitude of the daytime E-region to the bottom side of the F-region. This work presents the daytime behavior of the ILs parameters (the virtual height - h’IL, and the top frequency - ftIL) over the low latitude region of Cachoeria Paulista (CP, 22.42° S; 45° W, I: −34.4°) for the deepest solar minimum of the last 500 years. In such a unique condition, this research reveals for the first time the ILs' quiet state seasonal behavior as well as its responses to moderate changes in the geomagnetic activity. The main results show that even small variations of geomagnetic activity (quantified by the planetary Kp index) are able to modify the dynamics of the ILs parameters. For the first time, it was observed that during the summer, the h’IL decrease rapidly with the increase of geomagnetic activity mainly in the early morning hours. In the following hours, a smoothed rise of the IL was found in all seasons analyzed. Regarding to frequency, it was observed that after 12:00 LT, there is a tendency of it decreased with the increase of the magnetic disturbances, being this characteristic more intense after 16:00 LT, except in the equinox, when little or no response was found during all the interval analyzed. In addition, it stands out that the annual periodicity of the ftIL was observed while the h’IL presents semiannual component.

Ângela Santos et al.

Status: open (until 14 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on angeo-2021-52', Anonymous Referee #1, 15 Oct 2021 reply
    • CC1: 'Reply on RC1', Ângela Santos, 21 Oct 2021 reply
  • RC2: 'Comment on angeo-2021-52', Anonymous Referee #2, 24 Nov 2021 reply

Ângela Santos et al.

Ângela Santos et al.

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Short summary
Using the Digisonde data, this paper shows that the small variation in the geomagnetic activity during low solar activity can affect both the parameter of height and frequency of the intermediate layer (ILs) over the low latitude Brazilian sector. The most expressive responses of the ILs to geomagnetic activity were during the summer when the height of the ILs suffered a significant decrease with the increase of the magnetic activity magnetic in the first hours of the day.