NRLMSISE-00 is an empirical, global model of the Earth's atmosphere from ground to space. It models the temperatures and densities of the atmosphere's components. A primary use of this model is to aid predictions of satellite orbital decay due to atmospheric drag. This model has also been used by astronomers to calculate the mass of air between telescopes and laser beams in order to assess the impact of laser guide stars on the non-lasing telescopes.

The model, developed by Mike Picone, Alan Hedin, and Doug Drob, is based on the earlier models MSIS-86 and MSISE-90, but updated with actual satellite drag data. It also predicts anomalous oxygen.

NRL stands for the US Naval Research Laboratory.MSIS stands for Mass Spectrometer and Incoherent Scatter Radar respectively, the two primary data sources for development of earlier versions of the model.E indicates that the model extends from the ground through exosphere and 00 is the year of release.

According to the NRL website, NRLMSISE-00 is the standard for international space research.

The inputs for the model are;
Year and day
time of day
geodetic altitude
geodetic latitude
longitude
local apparent solar time
81 day average of F10.7 solar flux
daily F10.7 solar flux for previous day
Daily magnetic index

Output of the model is;
Helium Number density
Oxygen(O) Number density
Oxygen (O₂) Number density
Nitrogen (N) Number density
Nitrogen (N₂) Number density
Argon Number density
H Hydrogen Number density
total mass density
Anomalous oxygen Number density
Exospheric temperature
temperature at altitude