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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Some initial ISEE-1 results on the ring current composition and dynamics during the magnetics storm of December 11, 1977

On December 11, 1977 the ISEE-1 spacecraft traversed the equatorial magnetosphere in the prenoon and dawn sectors during the early recovery phase of a magnetic storm with peak DST of -125 gamma. Along the dayside leg O(+) was comparable to or exceeded H(+) in number density in the energy range 0.1-17 keV. The velocity distribution of O(+) showed a characteristic dispersion, consistent with the ions being transported to the dayside from the dusk to midnight sector. The high-energy slope of the H(+) and O(+) distribution functions showed different radial dependence, with the slope of H(+) being consistent with a harder component carrying most of the energy density.

Lennartsson, W.↗
NASA NTRS1979

Radial deformation of the solar current sheet as a cause of geomagnetic storms

It is suggested that the solar current sheet, extending from a coronal streamer, develops a large-scale radial deformation, at times with a very steep gradient at the earth's distance. The associated magnetic field lines (namely, the interplanetary magnetic field (IMF) lines) are expected to have also a large gradient in the vicinity of the current sheet. It is also suggested that some of the major geomagnetic storms occur when the earth is located in the region where IMF field lines have a large dip angle with respect to the ecliptic plane for an extended period (6-48 h), as a result of a steep radial deformation of the current sheet.

Akasofu, S.-I.↗
NASA NTRS1979

On the connection of interplanetary shock wave parameters and energetic storm particle events

A series of energetic storm particle (ESP) events is investigated on the basis of observations of energetic solar protons by IMPs IV and V between 1967 and 1972. The total number and energy of particles associated with 20 ESP events are analyzed in connection with several plasma parameters at the shock surface; i.e., magnetic and thermal pressure, magnetic field and plasma mass flux. Correlation is established between the total energy of ESPs in the energy range of 1-80 MeV and the jump in the total pressure. It is pointed out that the amount of shock energy converted to the acceleration of ESP particles is not negligible and could, in principle, contribute to the deceleration of the shock wave.

Gombosi, T.↗
NASA NTRS1980

Storm hazards '79: F-106B operations summary

Preliminary flight tests with a F-106B aircraft were made on the periphery of isolated thunder cells using weather radar support. In addition to storm hazards correlation research, a direct-strike lightning measurement experiment and an atmospheric chemistry experiment were conducted. Two flights were made to close proximity to lightning generating cumulonimbus clouds; however, no direct lightning strikes were experienced. Although no discernible lightning transients were recorded, many operational techniques were identified and established.

Fisher, B. D.↗
NASA NTRS1979

Magnetic storm effects in electric power systems and prediction needs

Geomagnetic field fluctuations produce spurious currents in electric power systems. These currents enter and exit through points remote from each other. The fundamental period of these currents is on the order of several minutes which is quasi-dc compared to the normal 60 Hz or 50 Hz power system frequency. Nearly all of the power systems problems caused by the geomagnetically induced currents result from the half-cycle saturation of power transformers due to simultaneous ac and dc excitation. The effects produced in power systems are presented, current research activity is discussed, and magnetic storm prediction needs of the power industry are listed.

Albertson, V. D.↗
NASA NTRS1980

Severe storms forecast systems

Two research tasks are described: (1) the improvement and enhancement of an existing mesoscale numerical simulation system, and (2) numerical diagnostic studies associated with an individual case of severe storm development (April 10, 1979 in the Red River Valley of Texas and Oklahoma).

Kaplan, M.↗
NASA NTRS1980

A 94/183 GHz aircraft radiometer system for Project Storm Fury

A radiometer design suitable for use in NASA's WB-57F aircraft to collect data from severe storm regions was developed. The design recommended was a 94/183 GHz scanning radiometer with 3 IF channels on either side of the 183.3 GHz water vapor line and a single IF channel for a low loss atmospheric window channel at 94 GHz. The development and construction of the 94/183 GHz scanning radiometer known as the Advanced Microwave Moisture Sounder (AMMS) is presented. The radiometer scans the scene below the aircraft over an angle of + or - 45 degrees with the beamwidth of the scene viewed of approximately 2 degrees at 94 GHz and 1 degree at 183 GHz. The AMMS data collection system consists of a microcomputer used to store the radiometer data on the flight cartridge recorder, operate the stepper motor driven scanner, and collect housekeeping data such as thermistor temperature readings and aircraft time code.

Gagliano, J. A.↗
NASA NTRS1980

Evaluation and development of satellite inferences of convective storm intensity using combined case study analysis and thunderstorm model simulations

Major research accomplishments which were achieved during the first year of the grant are summarized. The research concentrated in the following areas: (1) an examination of observational requirements for predicting convective storm development and intensity as suggested by recent numerical experiments; (2) interpretation of recent 3D numerical experiments with regard to the relationship between overshooting tops and surface wind gusts; (3) the development of software for emulating satellite-inferred cloud properties using 3D cloud model predicted data; and (4) the development of a conceptual/semi-quantitative model of eastward propagating, mesoscale convective complexes forming to the lee of the Rocky Mountains.

Cotton, W. R.↗
NASA NTRS1980

Analysis and prediction of severe storms environment

Using the special data set collected in Project SESAME (1979), an analysis and modeling efforts to test the hypothesis that a unique combination of terrain, boundary layer processes, and synoptic-scale circulations result in a preferred region of latent instability that determines the location of severe thunderstorm outbreaks are described. Because the relevant circulations are large scale, it is hypothesized that a model that contains the necessary physics will be able to predict the location of these severe storms at least 24 h in advance. Through detailed analysis of the SESAME data set and a series of numerical forecasts, the above hypothesis is being tested and it is hoped that quantitative understanding of the processes leading to the development of severe thunderstorms in the midwestern United States will be gained.

Carlson, T. N.↗
NASA NTRS1980

Coincident particle observations from AE-C and ATS 6 during the October 28, 1977, geomagnetic storm

Simultaneous measurements of ion and electron energy spectra recorded during the October 28, 1977 geomagnetic storm by the AE-C and ATS 6 spacecraft when both were nearly on the same L shell are evaluated and compared. The orbit of the AE-C generates wide longitudinal coverage of the auroral oval, whereas the ATS 6, which is located at geosynchronous orbit, samples the equatorial particle population. It is shown that the coincident electron energy spectra obtained by the two satellites agree well above 5 keV and the spectra of electrons peak near 1 keV at ionospheric altitudes, while no peaks in energy appear at synchronous altitude.

Zanetti, L. J.↗
NASA NTRS1980

Short-interval SMS wind vector determinations for a severe local storms area

Short-interval SMS-2 visible digital image data are used to derive wind vectors from cloud tracking on time-lapsed sequences of geosynchronous satellite images. The cloud tracking areas are located in the Central Plains, where on May 6, 1975 hail-producing thunderstorms occurred ahead of a well defined dry line. Cloud tracking is performed on the Goddard Space Flight Center Atmospheric and Oceanographic Information Processing System. Lower tropospheric cumulus tracers are selected with the assistance of a cloud-top height algorithm. Divergence is derived from the cloud motions using a modified Cressman (1959) objective analysis technique which is designed to organize irregularly spaced wind vectors into uniformly gridded wind fields. The results demonstrate the feasibility of using satellite-derived wind vectors and their associated divergence fields in describing the conditions preceding severe local storm development. For this case, an area of convergence appeared ahead of the dry line and coincided with the developing area of severe weather. The magnitude of the maximum convergence varied between -10 to the -5th and -10 to the -14th per sec. The number of satellite-derived wind vectors which were required to describe conditions of the low-level atmosphere was adequate before numerous cumulonimbus cells formed. This technique is limited in areas of advanced convection.

Peslen, C. A.↗
NASA NTRS1981

Thunderstorm hazards flight research: Storm hazards 1980 overview

A highly instrumented NASA F-106B aircraft, modified for the storm hazards mission and protected against direct lightning strikes, was used in conjunction with various ground based radar and lightning measurement systems to collect data during thunderstorm penetration flights. During 69 thunderstorm penetrations, there were 10 direct lightning strikes to the aircraft. No problems were encountered with any of the aircraft's systems as a result of the strikes and the research instrumentation performed as designed. Electromagnetic characteristics of nine strikes were recorded, and the results of other experiments confirm the theory that X-ray radiation and nitrous oxide gas are being produced by processes associated directly with thunderstorm electric fields and lightning discharges. A better understanding of aircraft lightning attachment mechanisms and strike zones is being accomplished by careful inspection, identification, and documentation of lightning attachment points and swept stroke paths following each strike to the aircraft.

Deal, P. L.↗
NASA NTRS1981

Interplanetary ions during an energetic storm particle event - The distribution function from solar wind thermal energies to 1.6 MeV

An ion velocity distribution function of the postshock phase of an energetic storm particle (ESP) event is obtained from data from the ISEE 2 and ISEE 3 experiments. The distribution function is roughly isotropic in the solar wind frame from solar wind thermal energies to 1.6 MeV. The ESP event studied (8/27/78) is superposed upon a more energetic particle event which was predominantly field-aligned and which was probably of solar origin. The observations suggest that the ESP population is accelerated directly out of the solar wind thermal population or its quiescent suprathermal tail by a stochastic process associated with shock wave disturbance. The acceleration mechanism is sufficiently efficient so that approximately 1% of the solar wind population is accelerated to suprathermal energies. These suprathermal particles have an energy density of approximately 290 eV cubic centimeters.

Gosling, J. T.↗
NASA NTRS1981

VISSR Atmospheric Sounder (VAS) simulation experiment for a severe storm environment

Radiance fields were simulated for prethunderstorm environments in Oklahoma to demonstrate three points: (1) significant moisture gradients can be seen directly in images of the VISSIR Atmospheric Sounder (VAS) channels; (2) temperature and moisture profiles can be retrieved from VAS radiances with sufficient accuracy to be useful for mesoscale analysis of a severe storm environment; and (3) the quality of VAS mesoscale soundings improves with conditioning by local weather statistics. The results represent the optimum retrievability of mesoscale information from VAS radiance without the use of ancillary data. The simulations suggest that VAS data will yield the best soundings when a human being classifies the scene, picks relatively clear areas for retrieval, and applies a "local" statistical data base to resolve the ambiguities of satellite observations in favor of the most probable atmospheric structure.

Chesters, D.↗
NASA NTRS1982

Microwave radiometric observations near 19.35, 92 and 183 GHz of precipitation in tropical storm Cora

Observations of rain cells in the remains of a decaying tropical storm were made by Airborne Microwave Radiometers at 19.35,92 and three frequencies near 183 GHz. Extremely low brightness temperatures, as low as 140 K were noted in the 92 and 183 GHz observations. These can be accounted for by the ice often associated with raindrop formation. Further, 183 GHz observations can be interpreted in terms of the height of the ice. The brightness temperatures observed suggest the presence of precipitation sized ice as high as 9 km or more.

Wilheit, T. T.↗
NASA NTRS1981

Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes

Computations concerning variations of the geomagnetic field at MAGSAT altitudes were investigated. Using MAGSAT data for the X, Y, and Z components of the geomagnetic field, a computer conversion to yield the H component was performed. Two methods of determining delta H normalized to a constant geocentric distance R sub 0 = 6800 were investigated, and the utility of elta H at times of magnetic storms was considered. Delta H at a geographical latitude of 0 at dawn and dusk, the standard Dst, and K sub p histograms were plotted and compared. Magnetic anomalies are considered. Examination of data from the majority of the 400 passes of MAGSAT considered show a reasonable delta H versus latitude variation. Discrepancies in values are discussed.

Kane, R. P.↗
NASA NTRS1982

Research study: Severe storms Doppler lidar signal processing

Four tasks related to the signal processing aspects of the severe-storms Doppler lidar program are discussed. The development of algorithms for windfield retrieval from Doppler lidar measurements are discussed. Signal processor installation on a CV-990 aircraft is discussed.

Lee, R. W.↗
NASA NTRS1982

Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes, part 2

Geomagnetic field variations were studied by considering the parameter delta H which indicated H(observed) minus H(model), where H = (X squared + Y squared) (1/2) where X, Y, and Z are the components actually observed. Quiet time base values for 5 deg longitude belts were estimated. After subtracting these from the observed values, the residual delta H (dawn) and delta H (dusk) were studied for the two major storms. It was noticed that the dusk values attained larger (negative) values for a longer time, than the dawn value. Some changes in delta Y and delta Z were also noticed, indicating possibilities of either meridional currents and/or noncoincidence of the central plane of the ring current with the equatorial plane of the Earth. Other details are described.

Dejesusparada, N.↗