Vertical Thermospheric Density Profiles from EUV Solar Occultations made by PROBA2 LYRA for Solar Cycle 24

TL;DR

This paper presents a new dataset of thermospheric neutral density profiles from EUV solar occultations by PROBA2 LYRA, analyzing their variability and correlation with solar EUV irradiance during Solar Cycle 24.

Contribution

It introduces a novel dataset of neutral density profiles from PROBA2 LYRA measurements and assesses their response to solar EUV variability, with detailed uncertainty analysis.

Findings

Density profiles are consistent with NRLMSISE-00 model.

Maximum correlation between density and EUV occurs near 300 km at dusk.

Thermospheric temperature sensitivity to EUV decreases above 300 km.

Abstract

A new dataset of summed neutral N2 and O number density profiles, spanning altitudes between 150 and 400 km, and observed during Northern Winter from 2010 through 2016 is presented. The neutral density profiles are derived from solar occultation measurements made by the 0.1-20 nm Zr channel on the LYRA instrument onboard 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 is 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. The sensitivity of thermospheric temperature to EUV irradiance decreases with altitude above 300 km at both terminators.