Preprints
https://doi.org/10.5194/angeo-2021-70
https://doi.org/10.5194/angeo-2021-70
 
03 Jan 2022
03 Jan 2022
Status: this preprint is currently under review for the journal ANGEO.

Time and Altitude spread F echoes distribution over the Christmas Island VHF radar

Ricardo Yvan de La Cruz Cueva1, Eurico Rodrigues de Paula2, and Acácio Cunha Neto2 Ricardo Yvan de La Cruz Cueva et al.
  • 1Physics Department, State University of Maranhão, São Luís, Maranhão, Brazil
  • 2DIHPA- Heliophysics, Planetary Sciences and Aeronomy Division, National Institute for Space Research, São José dos Campos, São Paulo, Brazil

Abstract. The goal of this work is to study the time and altitude echoes characteristics under different solar and seasonality conditions using the VHF radar RTI images. The occurrence of equatorial spread F depends on the existence of conditions that can seed the Raileight-Taylor instability, and these conditions can change with solar flux, seasonality, longitude distributions, and day-to-day variability. So, the equatorial spread F is observed as its time and altitude occurrence. The VHF radar of Christmas Island (2.0° N, 157.4° W, 2.9° N dip latitude) has been operational in the equatorial region for some time now, allowing long-term observations. The occurrence of echoes during solar minimum conditions are observed all throughout the night since the post reversal westward electric field is weaker than the solar maximum and the possibilities for the vertical plasma drift to become positive are larger. On other hand, echoes during solar maximum will be controlled by dynamics near the time of the Pre-reversal Peak (PRE). Our results indicate peak time occurrence of echoes along this period shows a well-defined pattern, with echoes being distributed as closer to local sunset during solar maximum and around/closer midnight during solar minimum conditions, meanwhile, the peak altitude occurrence of echoes shows a slightly regular pattern with higher altitude occurrences during solar maxima and lower altitudes during solar minimum conditions.

Ricardo Yvan de La Cruz Cueva et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on angeo-2021-70', Anonymous Referee #1, 18 Feb 2022
    • AC1: 'Reply on RC1', Ricardo Cueva, 11 Apr 2022
  • RC2: 'Comment on angeo-2021-70', Anonymous Referee #2, 21 Feb 2022
    • AC2: 'Reply on RC2', Ricardo Cueva, 11 Apr 2022

Ricardo Yvan de La Cruz Cueva et al.

Ricardo Yvan de La Cruz Cueva et al.

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Short summary
This paper brings analysis of spread-F echoes along the years of 2003 to 2012 from Christmas Island radar. We organize our data with the objective to observe the peak time and altitude distribution. Our results indicate peak time occurrence of echoes shows to be distributed closer to local sunset during solar maximum and around midnight during solar minimum, meanwhile, the peak altitude echoes show higher altitude occurrences during solar maxima and lower altitudes during solar minimum.