Engineering topics

Zipoy, David

Publications and source records attributed to Zipoy, David.

5 records

NASA NTRS1993

Solar magnetic field studies using the 12 micron emission lines. II - Stokes profiles and vector field samples in sunspots

Polarimetric observations at 12 microns of two sunpots are reported. The horizontal distribution of parameters such as magnetic field strength, inclination, azimuth, and magnetic field filling factors are presented along with information about the height dependence of the magnetic field strength. Comparisons with contemporary magnetostatic sunspot models are made. The magnetic data are used to estimate the height of 12 micron line formation. From the data, it is concluded that within a stable sunspot there are no regions that are magnetically filamentary, in the sense of containing both strong-field and field-free regions.

Hewagama, Tilak↗

NASA NTRS1991

Absolute wind velocities in the lower thermosphere of Venus using infrared heterodyne spectroscopy

NASA's IR Telescope Facility and the McMath Solar Telescope have yielded absolute wind velocities in the Venus thermosphere for December 1985 to March 1987 with sufficient spatial resolution for circulation model discrimination. A qualitative analysis of beam-integrated winds indicates subsolar-to-antisolar circulation in the lower thermosphere; horizontal wind velocity was derived from a two-parameter model wind field of subsolar-antisolar and zonal components. A unique model fit common to all observing periods possessed 120 m/sec subsolar-antisolar and 25 m/sec zonal retrograde components, consistent with the Bougher et al. (1986, 1988) hydrodynamical models for 110 km.

Goldstein, Jeffrey J.↗

NASA NTRS1991

Ground-based infrared measurements of the global distribution of ozone in the atmosphere of Mars

Doppler-limited IR spectroscopy measurements of the Mars atmosphere's global ozone distribution have been obtained for June 3-7, 1988; surface pressures and temperature profiles are retrieved through inversion of the fully-resolved (C-12)(O-16)2 line. The total O3 column abundance at each position has been retrieved at each of eight positions over a range of Martian latitudes by fitting the lines with synthetic spectra generated by a radiative transfer program: column burdens of O3 are less than 2.2 microns-atm for all latitudes sampled.

Espenak, Fred↗

NASA NTRS1990

Ethane abundance on Neptune

IR spectroscopic measurements of the C2H6 RR (4,5) emission line at 840.9764/cm have been used to infer Neptune's ethane mole fractions; while the resulting value is lower than that obtained by Orton et al. (1987), it lies within their 2-sigma error bounds. The present results are also found to require 2.0-5.8 times more ethane in the 0.02-2 mbar pressure region than predicted by the Romani and Atreya (1989) photochemical model. Better agreement is obtainable through a reduction of eddy mixing in the lower stratosphere and/or an increase of stratospheric temperature by more than 10 K above the 6-mbar level.

Kostiuk, Theodor↗

NASA NTRS1987

Variability of ethane on Jupiter

Varying stratospheric temperature profiles and C2H6 altitude distributions furnish contexts for the evaluation of ethane abundances and distributions in the Jupiter stratosphere. Substantial ethane line emission and retrieved mole fraction variability is noted near the footprint of Io's flux tube, as well as within the auroral regions. It is suggested that this and other observed phenomena are due to the modification of local stratospheric chemistry by higher-order effects, which are in turn speculated to be due to the precipitation of charged particles along magnetic field lines.

Kostiuk, Theodor↗