Engineering topics

Glenar, D. A.

Publications and source records attributed to Glenar, D. A..

22 records · Page 2

NASA NTRS1981

Development of a diode laser heterodyne spectrometer and observations of silicon monoxide in sunspots

A state of the art, tunable diode laser infrared heterodyne spectrometer was designed and constructed for ground based observations throughout the 8 to 12 micron atmospheric window. The instrument was optimized for use with presently available tunable diode lasers, and was designed as a flexible field system for use with large reflecting telescopes. The instrument was aligned and calibrated using laboratory and astronomical sources. Observations of SiO fundamental (v = 1-0) and hot band (v = 2-1) absorption features were made in sunspots near 8 microns using the spectrometer. The data permit an unambiguous determination of the temperature pressure relation in the upper layers of the umbral atmosphere, and support the sunspot model suggested by Stellmacher and Wiehr.

Glenar, D. A.↗

NASA NTRS1978

The energy balance of the nighttime thermosphere

Energy balance considerations for the thermosphere are affected by the uncertainty of the solar EUV flux. The problem is simplified by investigating only the nighttime thermosphere. Vapor trail measurements provide wind data at the sunset and sunrise terminators and near the polar cap boundary. Temperature and density profiles were obtained from incoherent scatter and Ogo 6 measurements. Based on the available data the energy losses are estimated to be 8 times 10 to the 10th W due to downward conduction at 120 km and 3 times 10 to the 10th W due to infrared radiation. The energy carried by the measured winds from the polar cap is found to be 4.6 times 10 to the 10th W and that transported across the mid- and low-latitude terminators, 7.6 to 11 times 10 to the 10th W. The greatest uncertainty in this analysis was in the estimates of the differences in the densities and temperatures in the lower thermosphere at the dawn and dusk terminators. Because of the large rotational velocity of the earth, small differences in these parameters correspond to large amounts of energy transported to the night hemisphere.

Glenar, D. A.↗

NASA NTRS1977

The energy balance of the nighttime thermosphere

The discrepancy between the input from the day hemisphere and the observed loss rates is discussed in terms of ion-neutral processes and gravity wave inputs. There has been considerable speculation as to the energy balance of the thermosphere and in particular about the fraction of the total energy input supplied by ultraviolet radiation. The problem is considerably simplified by considering the energy balance of the nighttime hemisphere alone. Sunrise and sunset vapor trail measurements provide data on the wind systems at the terminator boundary, and temperature measurements provide information on the vertical energy conduction. North-south winds from high latitude vapor trail measurements provide a measure of the energy input from auroral processes.

Glenar, D. A.↗

NASA NTRS1977

Thermospheric meridional winds and atomic oxygen depletion at high latitudes

Rocket vapor trail measurements of the properties of the high latitude wind system are compared with Ogo 6 measurements, the atomic densities being studied as a function of geomagnetic local time at three seasons for three ranges of magnetic activity. It is found that the atomic oxygen densities at altitudes in the region of 120 km are about 35% lower in the post-midnight sector than in the afternoon and evening sectors, decrease with increasing magnetic activity, and are lower in summer than in winter. The variations are related to vertical velocities in the 95-150 km altitude range and to the meridional fluxes at 70 deg geomagnetic latitude. The upward average vertical velocity of atomic oxygen in the region poleward of 70 deg is calculated to be of the order of 0.3 m/s at 120 km and the energy transported by the winds out of this region is calculated to be of the order of 10 to the 10th W for Kp levels of 2.

Nisbet, J. S.↗