Search NASA⌕ Search

SEARCH · Search NASA

Results for “winter”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

The causation and sensitivity of the northern winter planetary waves

High-resolution calculations of the wintertime stationary atmospheric response to planetary scale topographic and thermal forcings have been made using a numerical model that solves the spherical primitive equations linearized about observed zonal wind and temperature fields. The model equations are presented and their numerical implementation is discussed. The model inputs and parameters are presented and the model's response to relativistic forcing is analyzed. In middle latitudes the response to topographic forcing strongly dominates the response to thermal forcing. In the midlatitude troposphere, the topographic response is insensitive to changes in the zonal wind. In the stratosphere, both the variance and mean are dominated by the topographic response. In general, the sensitivity of the planetary waves to changes in the zonal wind is found to be much smaller than other recent calculations have indicated.

Jacqmin, D.↗
NASA NTRS1985

The middle atmosphere above Andoya Norway during the winter 1983/84 as derived from metrockets and OH nightglow observations

A total of 110 wind measurements were performed in the middle atmosphere above Andoya (69N, 16E) during the MAP/WINE Campaign from December 2, 1983 to February 23, 1984 using 57 inflatable passive falling spheres, 33 datasondes, 18 foil clouds and 2 instrumented active spheres. Temperature profiles were derived from 42 falling spheres, 26 datasondes and 2 active spheres. Near-mesopause temperatures were determined from OH nightglow observations. Synthesized charts of the temperatures as well as the zonal and meridional wind components between 0 and 90 km altitudes are presented. The temperature measurements indicate the occurrence of several minor and one major stratospheric warming, the latter being observed over Andoya at the end of the launch series.

Meyer, W.↗
NASA NTRS1985

Dynamical phenomena in the equatorial middle atmosphere during northern winter 1978-1979

Data from the Limb Infrared Monitor of the Stratosphere (LIMS) on the Nimbus-7 spacecraft were used to calculate the temperature and zonal wind structure of the equatorial stratosphere and lower mesosphere during the period October 25, 1978 to May 28, 1979. Interactions between the descending westerly shear zone of the semiannual oscillation and upward propagating Kelvin waves are described. Inertial instability may be influencing the zonal wind in midwinter.

Leovy, C. B.↗
NASA NTRS1985

Wave-mean flow interaction during the winter to summer transition in the Southern Hemisphere stratosphere

The evolution of the flow and wave-mean flow interactions in the Southern Hemisphere during the period when the final stratospheric warming and the associated reversal of the flow in the upper stratosphere occurred is described. The spring is the most interesting season as far as the wave mean flow interaction in the Southern Hemisphere is concerned. The data for this study are NMC analysis of temperature and geopotential fields between 1000 and 0.45 mb for the period August 31 to November 10, 1979.

Yamazaki, K.↗
NASA NTRS1986

Lower thermosphere densities of N2, O and Ar under high latitude winter conditions

Measurements of the neutral thermosphere were conducted in northern Scandinavia during the Energy Budget Campaign. These measurements included determinations of N2, O, and Ar densities using rocket-borne experiments. The results obtained in the experiments are presented, taking into account also details regarding the employed experimental methods, and an evaluation of the significance of the data. It is found that there are striking differences in thermospheric distributions of the neutral constituents under different geomagnetic conditions. Under quiet geomagnetic conditions there was reasonable agreement with the United States Standard Atmosphere. The concentrations of N2 and Ar were about 70 percent of the predicted values, while the O concentration was about 2.5 times greater.

Dickinson, P. H. G.↗
NASA NTRS1985

Aspects of the 40-50 day oscillation during the northern winter as inferred from outgoing longwave radiation

One-point correlation statistics and extended empirical orthogonal function analysis are used to show the existence of a principal mode of oscillation in the intraseasonal variability (ISV) of tropical convection. The data analyzed were derived from NOAA Outgoing Longwave Radiation data covering seven 6 mo periods from 1974-83. The data is filtered to remove fluctuations on time scales under 5 days and by subtracting a least-squares parabola to eliminate seasonal means. The previously-known 40-50 day oscillation is found to be the most prevalent component of the ISV of tropical convection. An E-W dipole forms and propagates over the equatorial Indian Ocean, then stalls and intensifies over Indonesia and the equatorial Indian Ocean, then stalls and intensifies over Indonesia and the equatorial central Pacific. Various anomalies generated in association with the dipole and dependent on its exact location when stalled are discussed.

Lau, K.-M.↗
NASA NTRS1985

Utilization of satellite-derived cloud cover to improve the estimation of latent heat release in a winter extratropical cyclone

A simple scheme for utilizing satellite cloud pattern information to improve the estimation of parameterized stable and convective latent heat release is proposed and tested for an extratropical cyclone occurring over the United States during January 9-11, 1975. Calculations are done over the standard North American rawinsonde data region and over a sparse data region simulated by ignoring one-third of the original rawinsonde stations. Results indicate 15 percent and 30 percent improvements in latent heating estimates derived from the total and sparse data sets, respectively. A larger improvement was found using the sparse data set because the parameterized latent heat release estimates obtained using these data were poorer than those obtained using the total data set.

Lin, S.-J.↗
NASA NTRS1986

Mean neutral circulation in the winter polar F region

A description of the mean global-scale circulation in the Northern Hemisphere F region has been synthesized by collating and averaging data from a global network of ground-based Fabry-Perot interferometers and from satellite sensors. An analysis of the results obtained shows that the combination of measurements made from multiple, strategically located ground-based observatories with satellite data provides a powerful technique for specifying the mean dynamic state of the earth's thermosphere. It is also found that a three-dimensional time-dependent numerical model with appropriate inputs for mean ionospheric convection can adequately predict the general characteristics observed in the mean thermospheric circulation.

Killeen, T. L.↗
NASA NTRS1986

Evolution of potential vorticity in the winter stratosphere of January-February 1979

This paper presents observations which are derived from Nimbus 7 LIMS data. Results at 850 K, January-February 1979 are considered, taking into account an overview of the period, January 19-30, January 31-February 11, February 12-23, and a postwarming sequence. Upper stratosphere diagnostics for early February 1979 are discussed, giving attention to the geopotential at 3 mbar, the 1200 K isentropic surface, the isentropic potential vorticity at 1200 K, and isentropic parcel trajectories. The vertical structure of potential vorticity is also examined. This paper helps also to interpret the area diagnostics of Butchart and Remsberg (1985). It is pointed out that the LIMS data allow calculation of the potential vorticity distribution at higher levels of the middle atmosphere.

Dunkerton, T. J.↗
NASA NTRS1985

Three dimensional flow phenomena in fluid machinery; Proceedings of the Winter Annual Meeting, Miami Beach, FL, November 17-22, 1985

For papers presented in this volume provide an overview of the latest developments in experimental measurements and analytical and numerical predictions of three-dimensional flows in fluid machinery. Topics discussed include three-dimensional cascade testing of turbine nozzles at high exit Mach number; the use of a secondary flow computation in the compressor design process; an experimental investigation of static propeller flow field; and calculation of three-dimensional boundary layers on rotating turbine blades. Papers are also presented on a three-dimensional solution method for turbomachinery analysis; analysis of rotational inviscid flows in curved passages; and a mathematical model for the analysis of fluid flow in a scroll.

Hamed, A.↗
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.↗