Engineering topics

Kayser, D.

Publications and source records attributed to Kayser, D..

3 records

NASA NTRS1995

Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the post midnight sector. A combination of chemical release rocket wind measurements, instrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of approximately 100 m/s developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of approximately 150 m/s developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nominally unstable with a Richardson number of approximately 0.08.

Larsen, M. F.↗

NASA NTRS1982

Thermospheric molecular oxygen

Thermospheric studies to date have relied heavily on model values of O2 concentration, which are in turn indirectly derived. This paper reports the results of a comparison of a large data base of directly measured O2 concentrations with the concentrations obtained from the MSIS model atmosphere. For concentrations of 10 billion/cu cm the direct measurements are larger than the model values by up to 50%. For concentrations of 100 million/cu cm the measured values are in agreement with the model to within 10%. A comparison is made of the computed major thermospheric species by using both the MSIS and the measured O2 concentrations. The impact is largest in the odd nitrogen species NO, N(S-4), and N(+), where the difference in concentration can be as much as 70%, and also on O2(+).

Torr, M. R.↗

NASA NTRS1979

Charge exchange of metastable 2D oxygen ions with molecular oxygen - A new source of thermospheric O2/+/ ions

Reactions involving metastable ions are difficult to study in the laboratory. Much new information on these reactions has been derived from satellite measurements of aeronomic parameters. In this paper, Atmosphere Explorer D data are used to study charge exchange of metastable O(+)(2D) ions with O2. Using direct measurements of the O2 at 200 km to compute O2 densities at 300 km and supporting ionic concentrations and temperature observations, we find the rate coefficient for this reaction to be 1 + or - 0.6 times 10 to the minus 9th cu cm/sec. The process constitutes a significant source of O2(+) ions in the F2 layer at times when the N2 and O2 densities are enhanced. This finding leads to the conclusion that charge exchange with O2 must be a major sink for O(+)(2D) and an important source of O2(+) ions in the E region, because of the increase in the O2 concentration/N2 concentration ratio with decreasing altitude. The results imply that 80% of all O(+) ions formed in the E region are converted to O2(+) and that only about 20% of the metastable O(+) ions are converted into N2(+) through charge exchange with N2.

Torr, D. G.↗