Vertical Thermospheric Density Profiles From EUV Solar Occultations Made by PROBA2 LYRA for Solar Cycle 24
A new data set of summed neutral N2 and O number density profiles, spanning altitudes between 150 and 400 km, and observed during Northern Winter from 2010 to 2016 is presented. The neutral density profiles are derived from solar occultation measurements made by the 0.1-20 nm Zr channel on the Large Yield Radiometer (LYRA) instrument on board Project for Onboard Autonomy 2 (PROBA2). The climatology derived from the vertical profiles is consistent with that predicted by the NRLMSISE-00 model, and the systematic error and random uncertainty of the measurements are less than 13% and 6%, respectively. The density profiles are used to characterize the response of thermospheric density to solar EUV irradiance variability. Peak correlation coefficients between neutral density and EUV irradiance occur near 300 km at the dusk terminator and 220 km at the dawn terminator. Density variability is higher at dawn than it is at dusk, and temperature variability increases with increasing altitude at both terminators.