The operational and research DTM-2020 thermosphere models

Abstract

Aims - The semi-empirical Drag Temperature Models (DTM) predict temperature, density and composition of the Earth's thermosphere, especially for orbit computation purposes. Twonew models were developed in the framework of the H2020 Space Weather Atmosphere Models and Indices project (SWAMI). The operational model is driven by the trusted and established F10.7 and Kp indices for solar and geomagnetic activity, respectively. The so-called research model is more accurate, but it uses the indices F30 and the hourly Hpo, which are not yet accredited operationally. Methods - The backbone of the DTM2020 models is made up of GOCE, CHAMP and Swarm A densities, processed by TU Delft, and Stella processed in-house. They constitute the standards for absolute densities, and they are 20-30% smaller than the datasets used in the fit of DTM2013. Also, the global daily mean TLE densities at 250 km, spanning four solar cycles, were now used in the fit to improve solar cycle variations. The operational model, which employs the same algorithm as DTM2013, was obtained through fitting to all data in our database from 1967-2019. Because of the Hpo index, which is not available before 1995, the coefficients linked to geomagnetic activity of the research model are fitted to data from 2000-2019. The algorithm was updated to take advantage of the higher cadence of Hpo. Both models are assessed with independent data and compared with the COSPAR International Reference Atmosphere models NRLMSISE-00, JB2008, and DTM2013. The bias and precision of the models are assessed through comparison with observations according to published metrics on several time scales. Secondly, binning of the density ratios is used in order to detect specific model errors. Results –The DTM2020 densities are on average 20-30% smaller than those of DTM2013, NRLMSISE-00 and JB2008. The assessment shows that the research DTM2020 is the least biased and most precise model compared to assimilated data. It is a significant improvement over DTM2013 under all conditions and at all altitudes. This is confirmed by the comparison with independent SET HASDM density data. The operational DTM2020 is always less accurate than the research model except at 800 km altitude. It has comparable or slightly higher precision than DTM2013, despite using F10.7 instead of F30 as solar activity driver. DTM, and semi-empirical models in general, can still be significantly improved on the condition of setting up a more complete and consistent total density, composition and temperature database than available at this time by means of a well-conceived observing system.

Machine‐Learned HASDM Thermospheric Mass Density Model With Uncertainty Quantification

“…Uncertainties in density modeling can result in large discrepancies between expected and observed satellite positions (Bussy‐Virat et al., 2018; R. Licata et al., 2020, 2021). The most recent Drag Temperature Model (DTM‐2020) became the first prominent thermosphere model to provide uncertainty estimates (Bruinsma & Boniface, 2021). They determined 1‐ σ uncertainties as a function of the inputs (Boniface & Bruinsma, 2021).…”

Geomagnetic Activity Index Hpo

“…The high‐cadence output of Hpo enables a more accurate selection of quiet‐time data than the three‐hourly Kp index. Bruinsma and Boniface (2021) used Hp60 to drive a recent version of the Drag Temperature Model, DTM‐2020, which is a semi‐empirical model of the Earth's thermosphere, developed for orbit determination and prediction of spacecraft and debris. They showed that the use of Hpo leads to the improvement of the model compared with the predecessor model DTM‐2013 (Bruinsma, 2015) that is driven by Kp .…”

Space Weather Environment During the SpaceX Starlink Satellite Loss in February 2022

“…Simulations using multiple empirical neutral atmosphere models including NRLMSISE‐00 (Picone et al., 2002, hereinafter referred as MSIS‐00), the updated version of MSIS‐00 model the NRLMSIS v2.0 (Emmert et al., 2021, hereinafter referred as MSIS v2.0), and Drag Temperature Model (DTM2020, Bruinsma & Boniface, 2021) are also examined. These empirical models describe atmospheric temperature, composition, and mass density based on various in‐situ or remote sensing observations of the neutral atmosphere.…”