Authors: Justyna Sokol (SwRI)

Solar wind dynamic pressure varies with the solar cycle as measured in the ecliptic plane. The in-ecliptic solar wind speed and density do not show a solar cycle variation typical for the variation of the sunspot number or solar EUV radiation. Despite this, the solar wind dynamic pressure increases rapidly every solar maximum, as recently studied by Sokol et al. 2021 (ApJ 922:250). The abrupt change in the solar wind pressure affects the global heliosphere and the processes at its boundaries causing an increase in the production of energetic neutral atoms as observed by the Interstellar Boundary Explorer (IBEX). The reason for the periodic changes in the solar wind dynamic pressure remains unclear. We look closer to the long-term variations of the solar wind in the ecliptic plane over the last solar cycles and to the hydrogen ENA variations of the solar cycle as measured by IBEX.