Middle Atmosphere Climatology using LIDAR for the evaluation of atmospheric conditions during man-made object reentry

Atmospheric reentry impact on the atmosphere is an increasingly important topic today as the number of objects entering the atmosphere continues to rise (e.g. nanosats, cubesats, missiles, …) Modelling the way those artificial objects both enter the atmosphere and disaggregate requires precise knowledge of the medium conditions (e.g. temperature, density, …) However,current atmospheric models like MSIS 2.0 or ERA-5 reanalyses have been proven to lack accuracy at higher altitudes, limiting their use for this application. Therefore, this study aims at proposing an updated middle-atmospheric climatology using the NDACC and our Rayleigh LIDAR. We evaluate the bias between LIDAR observations and models (MSIS 2.0 and ERA 5), and explore the impact of mesospheric events on the temperature climatology. We also demonstrate how both the general daily variability and the input of some extreme events can influence the density and temperature at those altitudes. Climatologies were developed using 40 years of Lidar data, then compared to a climatology obtained with the calling of models. MSIS 2.0, while reliable in terms of seasonal trends, is less accurate daily: it shows high biases with the lidar at high altitudes (1.25% at 60 km, up to 6% at 80km). The European Climate and Weather Forecast model ERA-5 agrees with the lidar at 98.9% in the upper stratosphere but shows a larger statistical bias of 7 to 10% in the mesosphere. We removed extreme events  such as Sudden Stratospheric Warmings (SSWs), Mesospheric Inversion Layers (MILs) and Double Stratopause (DSs) to create a “Steady-State” Climatology at different lidar stations. Observing the densities corresponding to the temperature profiles, we could evaluate the annual mean density in the OHP and the impact of those different events on the mean density profile. Density disturbances caused by SSWs and MILs were quantified, revealing deviations of up to 12% and 25%, respectively, from MSIS density profiles, with impacts spanning 10–20 km in altitude. Our study provided important basis for the study of atmospheric reentry. Re-actualisation of temperature and density above lidar station and expected bias for the most commonly used middle-atmosphere model will help set the ground for future evaluation of heating, ablation and trajectory computation in this medium.