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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Balloon-borne radio altimeter

Pulse radar altimeter design for balloon sounding, discussing flight tests, superregenerative stage, etc

Levanon, N.↗
NASA NTRS1974

Shortwave telemetric system

The application of frequency modulation when constructing a telemetric system in the shortwave band. The operating principles, the construction of the system and the decision making device are described and experimental data are presented. The equipment can be used on sounding balloons.

Valenchuk, K. K.↗
NASA NTRS1982

Dustsonde measurements of the Mount St. Helens volcanic dust cloud over Wyoming

Numerous balloon soundings of the aerosol and condensation nuclei (CN) concentrations were made over Laramie, Wyoming following the eruption of Mount St. Helens in May of 1980. On several occasions the volatility of the particles was tested. In addition, special instrumentation was used to observe the evolution of particle size after the eruption. The particles in the initial cloud were relatively large and nonvolatile. In a relatively short time, however, the aerosol began showing a dominant volatile component. Although there were probably no CN in the original cloud due to the expected very short coagulation life time, high concentrations of unusually small CN particles were observed about a month after the eruption. By the end of September the CN profiles and associated particle size were practically back to normal. At present the aerosol particles show about a three times larger concentration than before the eruption, most of the new material being in a layer centered around 19 km. The net effect of the more recent series of eruptions during the last half of October 1980 seems to be negligible.

Rosen, J. M.↗
NASA NTRS1983

Multi-anode microchannel arrays - New detectors for imaging and spectroscopy in space

Consideration is given to the construction and operation of multi-anode microchannel array detector systems having formats as large as 256 x 1024 pixels. Such arrays are being developed for imaging and spectroscopy at soft X-ray, ultraviolet and visible wavelengths from balloons, sounding rockets and space probes. Both discrete-anode and coincidence-anode arrays are described. Two types of photocathode structures are evaluated: an opaque photocathode deposited directly on the curved-channel MCP and an activated cathode deposited on a proximity-focused mesh. Future work will include sensitivity optimization in the different wavelength regions and the development of detector tubes with semitransparent proximity-focused photocathodes.

Timothy, J. G.↗
NASA NTRS1983

Stratospheric sulfuric acid fraction and mass estimate for the 1982 volcanic eruption of El Chichon

The stratospheric sulfuric acid fraction and mass for the 1982 volcanic eruptions of El Chichon are investigated using data from balloon soundings at Laramie (41 deg N) and in southern Texas (27-29 deg N). The total stratospheric mass of these eruptions is estimated to be approximately 8 Tg about 6.5 months after the eruption with possibly as much as 20 Tg in the stratosphere about 45 days after the eruption. Observations of the aerosol in Texas revealed two primary layers, both highly volatile at 150 C. Aerosol in the upper layer at about 25 km was composed of an approximately 80 percent H2SO4 solution while the lower layer at approximately 18 km was composed of a 60-65 percent H2SO4 solution aerosol. It is calculated that an H2SO4 vapor concentration of at least 3 x 10 to the 7th molecules/cu cm is needed to sustain the large droplets in the upper layer. An early bi-modal nature in the size distribution indicates droplet nucleation from the gas phase during the first 3 months, while the similarity of the large particle profiles 2 months apart shows continued particle growth 6.5 months after the explosion.

Hofmann, D. J.↗
NASA NTRS1984

The Ponape ST radar

In May, 1984, a 50-MHz ST radar was installed on the island of Ponape in the western equatorial Pacific (7 deg N, 158 deg E) by the Aeronomy Laboratory of NOAA. The radar consists of a 100 m x 100 m array with a single, vertically directed, beam and is initially transmitting micro sec. (2.25 km) pulses. The radar is operating continuously, with Doppler spectra being recorded at approximately 1 1/2 minute intervals and sent to Boulder for later analysis. One of the principal goals of the radar is to measure vertical motions in the troposphere and lower stratosphere at a location which is within the intertropical convergence zone during part of the year. First results, during generally fair weather conditions, show detectable echoes up to about 21 km with the tropopause at 17-18 km. Once daily balloon soundings are available locally from a NOAA Weather Service Office on the island, it is planned that this radar will be joined in the coming year by two others with oblique as well as vertical beams on two yet-to-be-selected equatorial islands as part of the TOGA (Tropical Oceans Global Atmosphere) program.

Carter, D. A.↗
NASA NTRS1985

Balloon measurements of aerosol in the Antarctic stratosphere

Three balloon soundings of aerosol were conducted from Syowa Station, Antarctica in April, June and October 1983. Number concentration and the size distribution of aerosol particles with diameter greater than 0.3 microns were measured by using a light scattering aerosol particle counter. The influence of the eruption of Mt. El Chichon on the aerosol concentration in the stratosphere was observed on October 16. Very high aerosol concentration at stratospheric heights was obtained from the first successful aerosol sounding in winter Antarctic stratosphere. The result gives direct evidence of winter enhancement in the Antarctic stratosphere.

Morita, Y.↗
NASA NTRS1985

The upper atmosphere research satellite

The Upper Atmosphere Research Satellite (UARS) will provide, for the first time, data on a global basis for the study of the physical processes acting witin and upon the stratosphere, mesosphere, and lower thermosphere. Specifically, the areas of scientifc study to be addressed are energy input and loss, photochemistry, dynamics, and the coupling among processes and between atmospheric regions. The UARS is a single observatory consisting of a multimission modular spacecraft (MMS) and an instrument module containing 10 scientific instruments. The satellite will be Shuttle launched and placed in a 57 deg inclined orbit at 600 km altitude. A Central Data Handling Facility (CDHF) will receive data from the satellite and process these data into atmospheric quantities for use by the science team. The 'processed' data will be stored at the CDHF and will be available via communication lines for analysis by the investigators at their home laboratories using remote computers. Together with other satellite programs, balloons, sounding rockets, and laboratory efforts, UARS will make available the opportunity for extensive coordination of data devoted to solar terrestrial study.

Burr, P. T.↗
NASA NTRS1985

Observation of lower-atmospheric moisture structure and its evolution using a Raman lidar

Observations of the water-vapor mixing ratio in the lower atmosphere and its temporal evolution have been made with a Raman lidar. Comparison with an independent radiosonde measurement indicated excellent agreement. The moisture structure, observed up to an altitude of 5 km and over an 80-min period during the early morning of April 30, 1985 (the present lidar is limited to night operation), showed temporal variations of several atmospheric features which could not be resolved by balloon soundings. Application of the lidar should provide the opportunity to study details of atmospheric moisture, its structure, and its evolution in a manner never before realized.

Melfi, S. H.↗
NASA NTRS1986

Effect of backscatter-to-extinction ratio on lidar inversions

One way of deriving the atmospheric extinction coefficient from lidar measurements is to start from the single scattering lidar equation. Simulations of lidar experiments and extinction coefficient calculation were conducted and the resulting errors examined. In order to make the simulation realistic, the volume backscatter coefficients and extinction coefficients used in the simulation were based on measured particle distributions, in this case on the particle size distributions measured in Meppen, Germany in the fall of 1980. In that experiment particle size distributions were measured with a balloon-borne particle spectrometer during balloon descents from about 600 meters above ground to the surface. Each particle spectrum represented a layer of at most a few meter thickness, so an altitude resolved profile of particle size spectra is measured. A Mie code was used to compute linear extinction coefficient and volume backscatter coefficient profiles from the particle size spectra for each balloon sounding.

Measure, E. M.↗
NASA NTRS1986

Climatology of tropospheric vertical velocity spectra

Vertical velocity power spectra obtained from Poker Flat, Alaska; Platteville, Colorado; Rhone Delta, France; and Ponape, East Caroline Islands using 50-MHz clear-air radars with vertical beams are given. The spectra were obtained by analyzing the quietest periods from the one-minute-resolution time series for each site. The lengths of available vertical records ranged from as long as 6 months at Poker Flat to about 1 month at Platteville. The quiet-time vertical velocity spectra are shown. Spectral period ranging from 2 minutes to 4 hours is shown on the abscissa and power spectral density is given on the ordinate. The Brunt-Vaisala (B-V) periods (determined from nearby sounding balloons) are indicated. All spectra (except the one from Platteville) exhibit a peak at periods slightly longer than the B-V period, are flat at longer periods, and fall rapidly at periods less than the B-V period. This behavior is expected for a spectrum of internal waves and is very similar to what is observed in the ocean (Eriksen, 1978). The spectral amplitudes vary by only a factor of 2 or 3 about the mean, and show that under quiet conditions vertical velocity spectra from the troposphere are very similar at widely different locations.

Ecklund, W. L.↗