“…By assimilating observed density data to estimate model parameter corrections, the process that called density model calibration is able to effectively improve model accuracy. Many studies have been carried out on the calibration method, such as high accuracy satellite drag model (HASDM) (Storz et al, 2005), parameterization method (Doornbos et al, 2005;Doornbos, 2012), the scale calibration (Shi et al, 2015;Ren and Shan, 2018), the neural network-based calibration (Perez and Bevilacqua, 2015) and the inter-calibration approach (Weimer et al, 2016). Significant progress has already been made on the HASDM and the research presented by Doornbos. In HASDM, a weighted least-squares algorithm, which is called dynamic calibration atmosphere (DCA) (Casali and Barker, 2002), is used to estimate the corrections of satellite states and Jacchia-70 density model parameters.…”