Delayed response of the global total electron content to solar EUV variations

Christoph Jacobi,Norbert Jakowski,Thomas N. Woods,Gerhard Schmidtke

doi:10.5194/ars-14-175-2016

Abstract

Abstract. The ionospheric response to solar extreme ultraviolet (EUV) variability during 2011–2014 is shown by simple proxies based on Solar Dynamics Observatory/Extreme Ultraviolet Variability Experiment solar EUV spectra. The daily proxies are compared with global mean total electron content (TEC) computed from global TEC maps derived from Global Navigation Satellite System dual frequency measurements. They describe about 74 % of the intra-seasonal TEC variability. At time scales of the solar rotation up to about 40 days there is a time lag between EUV and TEC variability of about one day, with a tendency to increase for longer time scales.

Highlights

The solar extreme ultraviolet (EUV) radiation varies on different time scales, including the 27-day Carrington rotation as one of the primary sources of variability at the intraseasonal time scale
We analyzed the correlation between global mean total electron content (TEC) and solar EUV variability, the latter described by 2 different proxies, namely the integrated EUV flux measured by Solar Dynamics Observatory (SDO)/Extreme Ultraviolet Variability Experiment (EVE), and the EUV-TEC proxy that describes primary ionization based on EUV spectra
There is an ionospheric delay at the solar rotation and longer time scale of 1–2 days, such that TEC variations lag EUV ones

Summary

Introduction

The solar extreme ultraviolet (EUV) radiation varies on different time scales, including the 27-day Carrington rotation as one of the primary sources of variability at the intraseasonal time scale. Unglaub et al (2011, 2012) have introduced a proxy, termed EUV-TEC, which is based on the vertically and globally integrated primary ionization rates. It has been calculated from spectral EUV fluxes measured by the Solar EUV Experiment (SEE) on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite (Woods et al, 2000, 2005). We shall use data from 2011 through early spring 2014, and analyze the correlation between EUV proxies and global TEC variability, as well as the ionospheric delay at different time scales

Data and analysis

Correlation of EUV parameters and global TEC

Findings

Conclusions