Protons of radiation belts as a source of hydrogen in the Earth’s atmosphere

A scenario is proposed for replenishing the Earth’s exosphere with atomic hydrogen of cosmic origin. An assessment was made and the coincidence of the total atomic hydrogen content in the exosphere with the number of protons (after thermolization converted into hydrogen ions) precipitated in the SAA zone during the year according to the data of the Meteor M and NOAA‑19 satellites was confirmed. The observed coincidence indicates that the rates of replenishment of hydrogen due to precipitation from radiation belts and dissipation into outer space coincide in order of magnitude. It is concluded that the exosphere hydrogen is mainly of cosmic origin and its main source is the thermalized protons of galactic cosmic rays, solar cosmic rays and partially solar wind.