Abstract | The Solar Wind Anisotropy (SWAN) instrument on SOHO has been measuring the solar Lyman-alpha line emission backscattered by interplanetary hydrogen atoms for 22 years, allowing to study the 3D neutral hydrogen distribution and the effect of solar wind charge exchange and photoionization processes upon it. We present an updated analysis of the SWAN dataset comparing the last two solar cycles and discuss the evolution of the instrument's performance in the last years, with respect to in-situ solar wind flux measurements in the ecliptic and global photoionization rates. |
