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Rees, D.

Publications and source records attributed to Rees, D..

27 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

A comparison of wind observations of the upper thermosphere from the Dynamics Explorer satellite with the predictions of a global time-dependent model

Experimental and theoretical investigations of high-latitude circulation in the upper thermosphere are reported. Vector-wind plots constructed by combining remotely sensed meridional-wind and in situ zonal-wind data obtained during four south-polar and three north-polar passes of the NASA Dynamics Explorer satellite in October and December, 1981, are presented and analyzed, taking the geomagnetic activity level and local solar time into account. The results are then compared with the predictions of 3D time-dependent global models of thermospheric neutral winds (Fuller-Rowell and Rees, 1980, 1981, 1983) adjusted to account for both solar-UV/EUV heating and ionization effects and quiet (Kp from 1 to 2) or moderately disturbed (Kp from 3 to 4) geomagnetic conditions (models Q and MD). An MD model incorporating a self-consistent description of the high-latitude ionosphere and a Q model excluding high-latitude effects are found to give the most accurate predictions for the respective geomagnetic conditions.

Rees, D.↗
NASA NTRS1982

Stable and rugged etalon for the Dynamics Explorer Fabry-Perot interferometer. II - Performance

The etalon is shown to remain stable to less than 5-m/sec equivalent wind over one orbit and less than 100 m/sec over several months in orbit. The thermal stability considerations for the highly stable etalon are discussed, including the passive thermal control used in flight. The various physical processes which give rise to drifts in the peak transmission wavelength are quantified, and the kinematic mount used to isolate the etalon from large incremental forces caused by changes in the thermal environment is presented. The performance of the etalon in its flight configuration is evaluated.

Killeen, T. L.↗
NASA NTRS1982

Wind structure and small-scale wind variability in the stratosphere and mesosphere during the November 1980 Energy Budget Campaign

Rocket observations made from two sites in northern Scandinavia between November 6 and December 1, 1980, as part of the Energy Budget Campaign are discussed. It was found that significant vertical and temporal changes in the wind structure were present and that they coincided with different geomagnetic conditions, that is, quiet and enhanced. Before November 16, the meridional wind component above 60 km was found to be positive (southerly), whereas the magnitude of the zonal wind component increased with altitude. After November 16 the meridional component became negative (northerly), and the magnitude of the zonal wind component was observed to decrease with altitude. Time sections of the perturbations of the zonal wind reveal the presence of vertically propagating waves, suggesting gravity wave activity. The waves are found to increase in wavelength from 3-4 km near 40 km to more than 12 km near 80 km. The observational techniques made use of chaff foil, chemical trails, inflatable spheres, and parachutes.

Schmidlin, F. J.↗
NASA NTRS1980

Observations of neutral wind profiles between 115- and 175-km altitude in the dayside auroral oval

Lithium trail neutral wind measurements have been made in the morning dayside auroral oval as a function of altitude. During all four experiments the winds displayed a large altitude shear. In the most extreme case the wind at 135-km altitude was toward the south at 210 m/s, and at 185-km altitude toward the northwest at 170 m/s. A one-dimensional numerical solution to the Navier Stokes equation including an initial steady-state wind profile, viscosity, pressure gradient, Lorenz force and the Coriolis force was made in order to study the effect of auroral processes on the neutral atmosphere. Since electric fields and plasma density were measured, the Lorenz force could be modeled with reasonable accuracy. The pressure gradient was determined in an iterative way as a best fit to the observations. Within the limitations of a one-dimensional model the numerical solution is in reasonable agreement with one of the observations, which is applicable to such a modeling, and indicates that both Lorenz forces and pressure gradients due to auroral processes are required to explain the observation.

Pereira, E.↗
NASA NTRS1980

Midlatitude measurements of the ionospheric electric field during the ALADDIN programme

Three measurements of ionospheric electric field were made during the 24-h ALADDIN rocket program at Wallops Island on June 29-30, 1974. The first of these used a double probe instrument, flown at 1500 Local Solar Time, and the second and third measurements were made by barium cloud releases at evening and morning twilight. These three electric field vectors have been compared with the predictions of a number of models of electric field due to the dynamo effects of various atmospheric tides, and also of a possible magnetospheric origin. On the assumption that the measurements were made at a location equatorward of the afternoon convergence and poleward of the morning divergence in the electric field patterns related to the Sq current system, Stening's (1973) model of the diurnal variation of the electric field induced by the (1, -2) tidal model at the time of the summer solstice correctly predicts the directions of the observed electric field. Forbes and Lindzen's (1976, 1977) model, incorporating the three major propagating tidal modes as well as the evanescent (1, -2) mode, also bears an acceptable relationship to the ALADDIN electric field directions. The ALADDIN E-field magnitudes are comparable with those obtained by ground-based observations from Millstone Hill and from Saint Santin but are about half of Stening's model values, and three times those of Forbes and Lindzen. Saint Santin E-field directions, at the same latitude but 75 deg difference in longitude, are distinctly different from ALADDIN, implying that longitudinal differences are significant.

Rees, D.↗
NASA NTRS1973

Investigation of mid-latitude ionospheric currents by combined rocket techniques.

A comprehensive range of neutral atmospheric and simultaneous ionospheric structure measurements were obtained from a Skylark rocket launched at Woomera during evening twilight on a quiet magnetic day. Above 150 km, good agreement was found between the results obtained from three different methods of electric field measurement despite the low field strength (about 1.5 mV/m). In the immediate vicinity of an intense sporadic E layer, the probe measurements indicated large excursions of the electrostatic field amounting to 6.5 mV/m at 105.3 km and 2.7 mV/m at 104.8 km. The calculated ionospheric current system in the vicinity of the rocket trajectory was of similar magnitude to that indicated by local ground-based magnetometers, but was diametrically opposed in direction.

Rees, D.↗
NASA NTRS1972

Thermospheric observations combining chemical seeding and ground-based techniques. I - Winds, turbulence and the parameters of the neutral atmosphere.

Two Skylark sounding rockets carrying chemical seeding payloads were launched from Woomera, South Australia (31 S, 137 E) in October 1969. In conjunction with these firings, the University of Adelaide conducted ground-based experiments on the upper atmosphere using the radio meteor and spaced receiver drift methods. This paper presents the measurements of properties of the neutral atmosphere above 90 km which were obtained from these experiments.

Lloyd, K. H.↗