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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 127 records · Page 7
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NASA NTRS1994

Three-dimensional evolution of water vapor distributions in the Northern Hemisphere stratosphere as observed by the MLS

The three-dimensional evolution of stratospheric water vapor distributions observed by the Microwave Limb Sounder (MLS) during the period October 1991 - July 1992 is documented. The transport features inferred from the MLS water vapor distributions are corroborated using other dynamical fields, namely, nitrous oxide from the Cryogenic Limb Array Etalon Spectrometer instrument, analyzed winds from the U.K. Meteorological Office (UKMO), UKMO-derived potential vorticity, and the diabatic heating field. By taking a vortex-centered view and an along-track view, the authors observe in great detail the vertical and horizontal structure of the northern winter stratosphere. It is demonstrated that the water vapor distributions show clear signatures of the effects of diabatic descent through isentropic surfaces and quasi-horizontal transport along isentropic surfaces, and that the large-scale winter flow is organized by the interaction between the westerly polar vortex and the Aleutian high.

Lahoz, W. A.↗
NASA NTRS1988

In situ observations of ClO in the wintertime Northern Hemisphere: ER-2 aircraft results from 21 N to 61 N latitude

Measurements of lower stratospheric ClO taken during a NASA ER-2 flight between Moffett Field, CA (37 N, 122 W) and Great Slave Lake, Canada (61 N, 116 W) on 13 February 1988 are reported. Northbound, the aircraft was flown at about 20 km altitude from 39 N to 56 N, at 18 km from there to 58 N, in a descent to 15 km at 60 N, and in a rise and turn at the northernmost point. The southbound leg was flown in a gradual climb from 20 km to 21.5 km. On this day, the central position of the Arctic polar vortex, as determined by an NMC analysis of heights and temperatures at the 50 mb and 70 mb levels, was approximately 79 N, 100 W. Because the vortex was located on the North American side of the pole, the aircraft was able to reach a point slightly inside the maximum horizontal wind region where wind speeds were 80 to 90 knots. The general pattern for the observed ClO is that it increased with both latitude and altitude, and attained a maximum of about 55 pptv at 61 N latitude and 20.5 km altitude. This value is about 20 times smaller than the maxima observed over Antarctica, but is comparable to those seen just outside the chemical containment vessel located inside the Antarctic Polar vortex. On the other hand, in a comparison with northern midlatitude data taken on this and three other February flights, ClO mixing ratios observed north of 55 N latitude are 2 to 5 times larger at all flight altitudes (15 to 20 km). Possible reasons are discussed for this enhancement over midlatitude and the evidence is considered for whether or not the instruments sampled Arctic polar vortex air. A second feature of the data is the strong positive correlation between ClO and O3 during the entire flight.

Brune, W. H.↗
NASA NTRS1976

PECHCV, PECHFV, PEFHCV and PEFHFV: A set of atmospheric, primitive equation forecast models for the Northern Hemisphere, volume 3

As part of the SEASAT program of NASA, a set of four hemispheric, atmospheric prediction models were developed. The models, which use a polar stereographic grid in the horizontal and a sigma coordinate in the vertical, are: (1) PECHCV - five sigma layers and a 63 x 63 horizontal grid, (2) PECHFV - ten sigma layers and a 63 x 63 horizontal grid, (3) PEFHCV - five sigma layers and a 187 x 187 horizontal grid, and (4) PEFHFV - ten sigma layers and a 187 x 187 horizontal grid. The models and associated computer programs are described.

Wellck, R. E.↗
NASA NTRS1978

Lower stratosphere measurements of variation with latitude of CF2Cl2, CFCl3, CCl4, and N2O profiles in the northern hemisphere

Measurements were made from a U-2 aircraft of profiles of CF2Cl2, CFCl3, CCl4 and N2O in the lower stratosphere in a meridional survey at a longitude of 159 deg W during the period October 1 to November 14, 1976. The latitude distributions obtained show a marked decrease in mixing ratio with increasing latitude from about 7 deg N in the Intertropical Convergence Zone to about 79 deg N. The results suggest the importance of meridional transport and mixing in the stratosphere in accounting, at least in part, for the observed profile variation with latitude. The contaminants C2F4Cl2, C2F3Cl3, CHCCl3 and SF6 were also detected but their mixing ratios were small and no accurate standards were prepared for them.

Vedder, J. F.↗
NASA NTRS1978

Stratospheric NO and HNO3 observations in the Northern Hemisphere for three seasons

NO, HNO3, and O3 levels and air temperature were measured as a function of latitude in the 18 to 21 km region of the stratosphere, and the sum of odd nitrogen, equal to NO + NO2 + HNO3, was calculated and compared with model predictions. (NO2 values were inferred from photochemical equilibrium characteristics.) The data show that NO measurements generally exhibit good agreement with model predictions for low and midlatitudes but poor agreement at high latitudes. The experimental sum of odd nitrogen mixing ratios and model predictions agree within a factor of 2-1/2 or better at both 20 and 40 deg N, and show excellent agreement for latitudinal dependence.

Loewenstein, M.↗
NASA NTRS1977

Lunar spectral units - A northern hemispheric mosaic

The distribution of lunar spectral units has been studied with the aid of multispectral imaging using silicon vidicons. The employed method has been developed over the last few years. The lunar observations used in the study had been made on May 7, 1974 (UT) at the Table Mountain Observatory. Four narrow bandpass interference filters centered at 0.38, 0.56, 0.85, and 1.05 micrometers were used. In the data displays presented the large differences (as in visual albedo) between the mare and the uplands have been deliberately minimized to allow small variations between these two major regions to be studied. Most of the spectral units are quite distinct, with relatively sharp boundaries. Attention is given to the general characteristics of spectral units, the distribution of mare basalt types, and the distribution of orange glass and dark mantling material.

Johnson, T. V.↗
NASA NTRS1978

The relationship of air temperature variations over the northern hemisphere during the secular and 11-year solar cycles

A comparison was made of air temperature anomaly maps for the months of January and July against a background of high and low secular solar activity, with and without regard for the 11 year cycle. By comparing temperature variations during the 11 year and secular cycles, it is found that the 11 year cycle influences thermal conditions more strongly than the secular cycle, and that temperature differences between extreme phases of the solar cycles are greater in January than in July.

Ryzhakov, L. Y.↗
NASA NTRS1978

Arecibo radar observations of Mars surface characteristics in the Northern Hemisphere

Mars surface characteristics at and near the Viking Chryse and Tritonis Lacus landing areas were determined by radio scatter using the 12.6-cm radar at the Arecibo Observatory during 1975-76. Interpretation of each power spectrum suggests rms surface tilts of 4 deg at the final A1WNW (47.9 deg W, 22.5 deg N) site, 5 deg near the original A1 site, and 6 deg between the two. At the back-up site (A2) surface-roughness estimates were about 4 deg. Striking changes in surface texture have been found near the eastern bases of Tharsis Montes and Albor Tholus, each volcanic feature marking the western boundary of very smooth surface units. The roughness sensed at 1- to 100-m scales by radar appears to be relatively independent of the surface units defined at large scale lengths by photogeologists. Radar properties thus provide an additional means by which planetary surfaces may be characterized.

Simpson, R. A.↗
NASA NTRS1979

Horizontal eddy diffusivities in the Northern Hemispheric stratosphere and lower mesosphere

Meteorological rocket soundings, launched between 1969-74 at six locations representative of low, middle, and high altitudes, are employed with the use of the statistical theory of diffusion, to determine the zonal and meridional component of eddy diffusivity between 30 and 55 km as a function of season, latitude, and altitude. A comparison is also made between annually-averaged eddy diffusivities above and below 30 km. It is shown that the zonal component of eddy diffusivity is approximately three to five times as large as the meridional component, in most cases. Both components of eddy diffusivity vary greatly with season, latitude, and altitude. Highest eddy diffusivities, found in the vicinity of the winter westerly jet, are approximately one order of magnitude higher than those present during the summer. Tropical eddy diffusivities, however, remain relatively small throughout the year. Annually, a minimum is indicated near 25 km between maximums located at the stratopause and tropopause.

Kao, S. K.↗