# Contribution of solar hydrogen Ly{\alpha} line emission in total ionization rate in ionospheric D-region during the maximum of solar X-flare

## TL;DR

This study quantifies the contribution of solar Lyα line emission to ionization in the ionospheric D-region during solar X-flares, highlighting its significance amidst other energetic impacts.

## Contribution

It provides analytical expressions and numerical simulations to assess Lyα's role in ionospheric ionization during solar X-flare disturbances.

## Key findings

- Lyα emission significantly influences ionization during X-flares
- Analytical models for ionization rates are developed
- Numerical simulations confirm the importance of Lyα in disturbed conditions

## Abstract

The solar Ly{\alpha} line emission can be considered as the dominant source of ionization processes in the ionospheric D-region at altitudes above 70 km during unperturbed conditions. However, large sudden impacts of radiation in some other energy domains can also significantly influence the ionization rate and, in this paper, we present a study on the contribution of Ly {\alpha} radiation to the ionization rate when the ionosphere is disturbed by solar X-flares. We give relevant analytical expressions and make calculations and numerical simulations for the low ionosphere using data collected by the VLF receiver located in Serbia for the VLF radio signal emitted by the DHO transmitter in Germany.