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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Preliminary calculations concerning the maintenance of the zonal mean ozone distribution in the Northern Hemisphere

Results from a three-dimensional photochemical-dynamical model of ozone are presented and a qualitative description of the maintenance of the ozone distribution and its seasonal variations below 1 mb is given. The transition between photochemical and transport control of the ozone distribution is emphasized. Between 1 and 10 mb, transport by the eddies seems to play only a minor role at mid-latitudes in producing the observed ozone distribution despite the zero correlation between ozone and temperature which occurs in that region. In the lower stratosphere, mean and eddy contributions to ozone change generally strongly offset one another. The buildup and decay of the springtime ozone maximum is discussed. Emphasis is given to the mechanism of ozone transport by the mid-latitude eddies, which play an important role in the springtime accumulation of ozone.

Cunnold, D. M.↗
NASA NTRS1957

Statistical Study of Aircraft Icing Probabilities at the 700- and 500- Millibar Levels over Ocean Areas in the Northern Hemisphere

A statistical study is made of icing data reported from weather reconnaissance aircraft flown by Air Weather Service (USAF). The weather missions studied were flown at fixed flight levels of 500 millibars (18,000 ft) and 700 millibars (10,000 ft) over wide areas of the Pacific, Atlantic, and Arctic Oceans. This report is presented as part of a program conducted by the NACA to obtain extensive icing statistics relevant to aircraft design and operation. The thousands of in-flight observations recorded over a 2- to 4-year period provide reliable statistics on icing encounters for the specific areas, altitudes, and seasons included in the data. The relative frequencies of icing occurrence are presented, together with the estimated icing probabilities and the relation of these probabilities to the frequencies of flight in clouds and cloud temperatures. The results show that aircraft operators can expect icing probabilities to vary widely throughout the year from near zero in the cold Arctic areas in winter up to 7 percent in areas where greater cloudiness and warmer temperatures prevail. The data also reveal a general tendency of colder cloud temperatures to reduce the probability of icing in equally cloudy conditions.

Perkins, Porter J.↗
NASA NTRS1982

Northern Hemisphere 700 mb heights and Pacific Ocean temperatures for winter months

Mean monthly 700 mb height data are analyzed in relation to Pacific Ocean sea-surface temperatures (SST). Instead of treating the winter season as a unit, the data are analyzed separately for December, January and February; some results for November are also included. The associated pattern of the atmospheric circulation is most pronounced in January and February, especially over the Pacific. This indicates that time intervals of one month, and even shorter ones, are long enough to reveal the atmospheric relation to the sea-surface temperature. Moreover, an average of 700 mb data over the Pacific for January and February, would probably show a greater correlation with SST than the 'winter' average which commonly includes December. The differences between December and February observations are discussed with the aid of the theoretical model of Hoskins and Karoly (1981).

Fritz, S.↗
NASA NTRS1982

Cross correlation analysis of medium energy gamma rays for the Northern Hemisphere

In the cross correlation method the observed gamma rays are compared with the expected telescope response for a discrete celestial source. The background consists of the atmospheric flux with its maximum near the horizon, the cosmic diffuse flux, and neutron induced gamma rays in the telescope. In sharp contrast to the background, a celestial source produces an asymmetric azimuthal response which varies predictably in time as the source moves through the telescope's aperture. This contrast serves as the basis of the cross correlation technique. Continuous data of 47.5 hr were obtained during a balloon flight from Palestine, TX from 0930 UT on September 30, 1978 to 2300 UT on October 1, 1978. The Crab Nebula-Anticenter region was observed on two consecutive days. A number of other medium energy source candidates also crossed the field-of-view. The obtained results are discussed.

Long, J.↗
NASA NTRS1982

Linear trends in Northern Hemisphere tropospheric geopotential height and temperature patterns

Gridded National Meteorological Center data for 500 mb geopotential height and 300-500 mb and 500-700 mb thickness for the period 1951-1978 are subjected to linear trend analyses. The analyses are carried out for each calendar month. Significant geographical and seasonal distributions of cooling and warming patterns are found. An atmospheric cooling trend over the North Pacific during the winter months is seen in a region where oceanic cooling has also been observed, but planetary-wave adjustments rather than ocean-atmosphere feedback mechanisms appear to be dominant in the atmospheric cooling on climatic time scales. Consistently large temperature trends are also seen over the continent of Asia. Comparisons between thickness trends in the layer 300-500 mb and those in the layer 500-700 mb reveal pronounced patterns of stabilization and destabilization.

Reiter, E. R.↗
NASA NTRS1983

Documentation for the machine-readable version of the Lowell Proper Motion Survey, Northern Hemisphere, the G numbered stars

This catalog contains a summary of many individual papers published in the Lowell Observatory Bulletins in the years 1958 to 1970. The data in the machine-readable version include observed positions, proper motions, estimated photographic magnitudes and colors, and references to identifications in other catalogs. Photoelectric data on the UBV system are included for many stars, but no attempt was made to find all existing photometry. The machine version contains all data of the published catalog, except the Lowell Bulletin numbers where finding charts can be found. A separate file contains the notes published in the original catalog.

Warren, W. H., Jr.↗
NASA NTRS1983

Spectral study of wintertime kinetic energy of the Northern Hemisphere in the troposphere

Characteristics of the kinetic energy of wind fields at various pressure levels were analyzed, and significant wavenumbers in the wavenumber-frequency domain were identified. The nonlinear interaction terms of the kinetic energy equation were examined, and the distribution of the kinetic energy at the 850 mb, 500 mb, and 200 mb levels was calculated. A 5 deg latitude-longitude square grid was used, with NMC data for the 1975-1976 winter in the 20-60 deg N at 500 mb and 20-85 deg N for the 200 mb and 850 mb levels. The kinetic energy distribution was determined to be geography-dependent, with wavenumbers 6-9 westerly waves in the midfrequency range contributing significantly to kinetic energy maxima over the North Pacific and the east coast of North America. The contribution of the nonlinear interactions of these waves, which correspond to the longitudinal convergence of the kinetic energy flux, was found to be larger than the meridional convergence of the kinetic energy flux, and to occur mainly between 30-50 deg N. The nonlinear interactions were a negative contribution over the North Pacific at the 200 mb level.

Lee, H. N.↗
NASA NTRS1983

Large-scale energy transformations in the high latitudes of the Northern Hemisphere

The kinetic energy balance and kinetic energy sources are studied for high latitudes north of 55 deg N with twice daily upper air observations during a seven-year period from 1973 to 1979. Energy variables are presented for 5 deg latitudinal zones from 55 to 75 deg N and for the polar cap north of 75 deg N. Spatial distributions of important energy variables are also presented. The upper level maximum of the cross-isobaric generation in high latitudes is observed in th lower stratosphere above the tropopause level in the winter and becomes insignificant during the summer. The flux convergence of potential energy from the source in lower latitudes is identified as the single major source for kinetic energy in higher latitudes. The contribution of the baroclinic conversion is minor. Examination during the First GARP Global Experiment winter indicates that the cold air outbreaks of the Asian winter monsoon are associated with noticeable changes in the hemispherical distributions of the fields of vertical motion and energetics in the high latitudes.

Kung, E. C.↗
NASA NTRS1983

Seeing Halley's Comet: A guide for observers in the Northern Hemisphere

A guide for the observation of Halley's comet is presented. The path of the comet is described for the fly by dates and charts are provided for location of the comet in the morning or evening skies. Suggestions for visual observation and photography of Halley's comet are included.

Source record↗
NASA NTRS1985

On the Latitudinal Distribution of Debris in the Northern Hemisphere of Mars

Examination of Mariner 9 images showed evidence of debris mantling on Mars. The evidence included craters that appeared to be filled with debris and an apparent lack of small craters. Based on such data, it was suggested that a circumpolar debris mantle exists poleward of about 30N and 30S latitudes. The presence of a debris layer has important implications for the modulation over time of atmospheric pressure by the cap-regolith-atmosphere system. Preliminary efforts in providing constraints on the thickness and distribution of debris are discussed. The initial approach is to examine crater size-frequency data for selected regions on Mars, later expanding the study to include an inventory of aeolian features and other direct indicators of debris deposition. The crater size-frequency distributions for ten regions between latitudes 20N and 80N and covering a range of longitudes were discovered. Crater data were derived from Viking Orbiter images with resolutions of between 26 and 75 meters/pixel.

Guinness, E. A.↗
NASA NTRS1985

All sky Northern Hemisphere 10(15) EV gamma-ray survey

Flux limits in the range 10 to the minus 13th power-10 to the minus 12 power/sq cm/s have been obtained by observing Cerenkov flashes from small air showers. During 1983, a 3.5 sigma excess of showers was observed during the phase interval 0.2 to 0.3 of the 4.8h period of Cygnus X-3, but no excess was found in 1984 observations.

Baltrusaitis, R. M.↗
NASA NTRS1985

Comparisons of the North Polar Cap of Mars and the Earth's Northern Hemisphere snow cover

The boundaries of the polar caps of Mars have been measured on more than 3000 photographs since 1905 from the plate collection at the Lowell Observatory. For the Earth the polar caps have been accurately mapped only since the mid 1960's when satellites were first available to synoptically view the polar regions. The polar caps of both planets wax and wane in response to changes in the seasons, and interannual differences in polar cap behavior on Mars as well as Earth are intimately linked to global energy balance. In this study data on the year to year variations in the extent of the polar caps of Mars and Earth were assembled and analyzed together with data on annual variations in solar activity to determine if associations exist between these data. It was found that virtually no correlation exists between measurements of Mars north polar cap and solar variability. An inverse relationship was found between variations in the size of the north polar caps of Mars and Earth, although only 6 years of concurrent data were available for comparison.

Foster, J.↗
NASA NTRS1986

Circulation regime-dependent nonlinear interactions during northern hemisphere winter

Data of 500 mb geopotential heights, obtained in Januaries from 1963-1977 are used to study the relationship between the interaction of different scales of motion and the circulation regime characterizing the large-scale pattern. Geostrophic and 500 mb height streamfunctions and energy and enstrophy spectra are computed. Differences in the height variance, kinetic energy, and enstrophy spectra of the large positive anomaly events are compared to normal circulation. Systematic differences in the nonlinear cascading are examined. The data reveal that transient eddies perform a regime-dependent function in the interactions with atmospheric circulation modes on the scale of the persistent anomalies.

Brown, P. S.↗
NASA NTRS1986

Optical observations of the AMPTE artificial comet from the Northern Hemisphere

The AMPTE artificial comet of Dec. 27, 1984, developed a well-defined core (maximum size about 160 x 100 km) of cold barium ions, surrounded by a diffuse coma, 500 km in diameter, consisting of ions extracted from the core. A plasma tail extended from the core, mainly directed away from the sun. The plasma tail and diffuse coma consisted of energetic ions (above 200 eV). Confounding predictions, the artificial comet survived for barely five minutes, and the core of the comet moved southward, rather than in the direction of the solar wind.

Rees, D.↗
NASA NTRS1986

Measurements of the north polar cap of Mars and the earth's Northern Hemisphere ice and snow cover

The boundaries of the polar caps of Mars have been measured on more than 3000 photographs since 1905 from the plate collection at the Lowell Observatory. For the earth, the polar caps have been accurately mapped only since the mid 1960s when satellites were first available to synoptically view the polar regions. The polar caps of both planets wax and wane in response to changes in the seasons, and interannual differences in polar cap behavior on Mars as well as earth are intimately linked to global energy balance. Data on the year to year variations in the extent of the north polar caps of Mars and earth have been assembled and compared, although only 6 years of concurrent data were available for comparison.

Foster, J.↗