NRLMSIS 2.0: A Whole‐Atmosphere Empirical Model of Temperature and Neutral Species Densities

Abstract

NRLMSIS  2.0 is an empirical atmospheric model that extends from the ground to the exobase and describes the average observed behavior of temperature, 8 species densities, and mass density via a parametric analytic formulation. The model inputs are location, day of year, time of day, solar activity, and geomagnetic activity. NRLMSIS 2.0 is a major, reformulated upgrade of the previous version, NRLMSISE-00. The model now couples thermospheric species densities to the entire column, via an effective mass profile that transitions each species from the fully mixed region below ~70 km altitude to the diffusively separated region above ~200 km. Other changes include the extension of atomic oxygen down to 50 km and the use of geopotential height as the internal vertical coordinate. We assimilated extensive new lower and middle atmosphere temperature, O, and H data, along with global average thermospheric mass density derived from satellite orbits, and we validated the model against independent samples of these data. In the mesosphere and below, residual biases and standard deviations are considerably lower than NRLMSISE-00. The new model is warmer in the upper troposphere and cooler in the stratosphere and mesosphere. In the thermosphere, N2 and O densities are lower in NRLMSIS 2.0; otherwise, the NRLMSISE-00 thermosphere is largely retained. Future advances in thermospheric specification will likely require new in situ mass spectrometer measurements, new techniques for species density measurement between 100 and 200 km, and the reconciliation of systematic biases among thermospheric temperature and composition datasets, including biases attributable to long-term changes.

New Measurement of the Vertical Atmospheric Density Profile From Occultations of the Crab Nebula With X‐Ray Astronomy Satellites Suzaku and Hitomi

“…However, we cannot yet rule out a possibility that the NRL model overestimated the density at altitudes around 100 km. In fact, a new model of MSIS, that is, NRLMSIS 2.0 (Emmert et al., 2020), was released during the preparation of this paper. By using the python package pymsis (available at https://pypi.org/project/pymsis/), we calculated updated density profiles expected on March 26, 2016, and found that the new model gives 20%–30% lower densities at altitudes 70–110 km.…”

Testing the electrodynamic method to derive height-integrated ionospheric conductances

“…Data used in the development of the fieldaligned current model are available through Edwards et al (2020). The electric potential model (Edwards, 2019) was developed with the Swarm cross-track ion drift data available at https://swarm-diss.eo.esa.int/#swarm/Advanced/Plasma_Data/ 2Hz_TII_Cross-track_Dataset (Burchill and Knudsen, 2020) and Dynamics Explorer 2 Vector Electric Field measurements at https://cdaweb.gsfc.nasa.gov/pub/data/de/de2/electric_fields_vefi/ (last access: 12 January 2021, Maynard et al, 1981 Frandsen et al, 1978;Coplan et al, 1978), and data from ACE are available at https://cdaweb.gsfc.nasa.gov/pub/data/ace/mag/level_2_cdaweb/ and https://cdaweb.gsfc.nasa.gov/pub/data/ace/swepam/level_2_ cdaweb/swe_h0 (last access: August 2019, Smith et al, 1998;McComas et al, 1998).…”

New Measurement of the Vertical Atmospheric Density Profile from Occultations of the Crab Nebula with X-Ray Astronomy Satellites Suzaku and Hitomi

“…However, we cannot yet rule out a possibility that the NRL model overestimated the density at altitudes around 100 km. In fact, a new model of MSIS, i.e., NRLMSIS 2.0 (Emmert et al, 2020), was released during the preparation of this paper. By using the python package pymsis (available at https://pypi.org/project/pymsis/), we calculated updated density profiles expected on 2016-03-26, and found that the new model gives 20-30% lower densities at altitudes 70-110 km.…”