Nelson W. Spencer

TL;DR: In this article, the authors combined ground-based incoherent scatter radar and Fabry-Perot optical interferometers to generate a revision (HWM90) of the HWM87 empirical model and extend its applicability to 100 km.

TL;DR: In this article, mass spectrometers on five satellites (AE-B, Ogo 6, San Marco 3, Aeros A, and AE-C) and neutral temperatures inferred from incoherent scatter measurements at four ground stations are combined to produce a model of thermospheric neutral temperatures and nitrogen densities similar to the Ogo6 empirical model (Hedin et al., 1974).

TL;DR: In this paper, the MSIS (mass spectrometer and incoherent scatter data) model is compared with the Ogo 6 model (Hedin et al., 1974) for the time period from mid-1969 to mid-1975.

TL;DR: An empirical global model for magnetically quiet conditions has been derived from longitudinally averaged N2, O, and He densities by means of an expansion in spherical harmonics as mentioned in this paper.

TL;DR: The neutral gas composition and density in the thermosphere of Venus is measured with a quadrupole mass spectrometer on the Pioneer Venus orbiter as discussed by the authors, where data are obtained near periapsis once per day approximately 150-250 km above the surface.