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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

On the mean meridional mass motions of the stratosphere and mesosphere

Using a simplified, approximate 'Lagrangian-mean' dynamical formulation, the mean meridional mass circulation of the stratosphere and mesosphere is discussed. Under solstice conditions, it is shown that this Lagrangian-mean circulation may be inferred, as a first approximation, from the Eulerian-mean diabatic heating. Diabatic heating rates for the solstices, originally derived by Murgatroyd and Goody (1958), result in Lagrangian-mean rising motion at the tropical tropopause, subsidence across the extra-tropical tropopause, and a very strong summer-to-winter pole flow in the mesosphere. This circulation is exactly that obtained by Murgatroyd and Singleton (1961) for the solstices. Those authors, however, attempted to identify this circulation as the Eulerian-mean motion, and were later criticized for their neglect of the meridional eddy heat flux in the calculation, which proved to be extremely important in the winter hemisphere. The present study, nevertheless, indicates that Murgatroyd and Singleton's circulation may in fact be representative of actual air parcel motions in the stratosphere and mesosphere.

Dunkerton, T.↗
NASA NTRS1992

The coupling of the troposphere and stratosphere

A linear, time-dependent, primitive-equation, 3D numerical model is used to investigate the dynamical coupling between the troposphere and stratosphere through the vertical propagation of planetry waves. Attention is given to the roles of the tropopause in affecting the propagation of planetary waves and to the extent to which the stratosphere can determine its own wave driving, i.e., the sensitivity of the generation of the wave activity in the troposphere to the change of zonal wind in the stratosphere. Two maxima in Eliassen-Palm (EP) flux convergence are found for wave 1 in high latitudes, one in the upper stratosphere and the other in the upper troposphere. For wave 2 there is a third maximum north of the zero wind line in the tropical stratosphere. The formation of the maximum in EP-flux convergence in the upper troposphere is related to the dissipation of non-WKBJ waves near a local maximum of the refractive index. The existence of the local maximum in refractive index at the tropopause is a result of the great gradient of the buoyancy frequency as well as the vertical shear of the zonal flow there.

Chen, Ping↗
NASA NTRS1985

Effects of Rayleigh and Newtonian damping on wave-mean flow interaction

A theoretical study is made of the effects of mean damping on wave-mean flow interactions. A condition is derived for the Eliassen-Palm flux divergence to balance the steady-state residual circulations induced by eddies in the presence of mean damping. It is shown by a simple analytical model that this balance holds for stratospheric planetary waves when the Rayleigh friction coefficient is one order smaller than the Newtonian cooling coefficient, although the tall mean flow condition is not violated. In this case, the Eliassen-Palm flux divergence can be interpreted as approximating the steady residual circulation (approximately equal to Lagrangian-mean circulations) induced by eddies as well as the net mean acceleration in the absence of mean damping. This balance is consistent with the stratospheric circulations of a dynamical model.

Hayashi, Y.↗
NASA NTRS1986

October Antarctic temperature and total ozone trends from 1979-1985

The morphology of temperature trends in the south polar stratosphere from 1979-1985 is detailed. A significant cooling has occurred in the stratosphere over this period. South polar October mean temperatures have declined 18 K at 24 km over the seven-year period. A large fraction of this decline occurs as a result of including 1979 temperatures in the trend. The years 1979 and 1982 differ from other years in that they include large mid-October wave events which produce significantly warmer polar temperatures. Nevertheless, a significant temperature decline has still occurred in the stratosphere even when the dynamically active years are not included. Comparing two relatively dynamically quiet years, 1980 and 1985, the largest temperature decrease in the 30 mb temperature field occurs not at the pole but in the subpolar temperature maximum centered near 60 deg S. The changes in temperature of both the maximum and the polar low regions correlate fairly well with total ozone changes observed by the Total Ozone Mapping Spectrophotometer.

Newman, Paul A.↗
NASA NTRS1987

Climate-chemical interactions and effects of changing atmospheric trace gases

The paper considers trace gas-climate effects including the greenhouse effect of polyatomic trace gases, the nature of the radiative-chemical interactions, and radiative-dynamical interactions in the stratosphere, and the role of these effects in governing stratospheric climate change. Special consideration is given to recent developments in the investigations of the role of oceans in governing the transient climate responses, and a time-dependent estimate of the potential trace gas warming from the preindustrial era to the early 21st century. The importance of interacting modeling and observational efforts is emphasized. One of the problems remaining on the observational front is the lack of certainty in current estimates of the rate of growth of CO, O3, and NOx; the primary challenge is the design of a strategy that will minimize the sampling errors.

Ramanathan, V.↗
NASA NTRS1988

Millimeter-Wave Atmospheric Sounder (MAS)

MAS is a remote sensing instrument for passive sounding (limb sounding) of the earth's atmosphere from the Space Shuttle. The main objective of the MAS is to study the composition and dynamic structure of the stratosphere, mesosphere, and lower thermosphere in the height range 20 to 100 km, the region known as the middle atmosphere. The MAS will be flown on the Atmospheric Laboratory for Applications and Science (ATLAS 1) NASA mission scheduled for late 1990. The Millimeter-Wave Atmospheric Sounder will provide, for the first time, information obtained simultaneously on the temperature and on ozone concentrations in the 20 to 90 km altitude region. The information will cover a large area of the globe, will have high accuracy and high vertical resolution, and will cover both day and night times. Additionally, data on the two important molecules, H2O and ClO, will also be provided.

Hartmann, G. K.↗
NASA NTRS1989

Middle Atmosphere Program. Handbook for MAP, volume 27

The proceedings are presented from the MAP program of July 1988. It is intended to be a quick synopsis of the symposium. General topics include: New International Equatorial Observatory; Dynamics of the Middle Atmosphere in Winter (DYNAMICS); Global Budget of Stratospheric Trace Constituents (GLOBUS); Gravity Waves and Turbulence in the Middle Atmosphere Program (GRATMAP); Middle Atmosphere Electrodynamics (MAE); Winter in Northern Europe (WINE); Atmospheric Tides Middle Atmosphere Program (ATMAP); and many others.

Edwards, Belva↗
NASA NTRS1989

Global budget of stratospheric trace constituents (GLOBUS). MAP/GLOBUS 1983: A review

MAP/GLOBUS 1983 was a project for the study of stratospheric trace gases and dynamics. A respective field campaign was performed in September/October 1983 in Western Europe. A large number of measurements were taken by instruments based on the ground, on airplane, balloons, and satellite. The structure of the campaign is described, and a survey of the results are given.

Offermann, D.↗
NASA NTRS1989

Nonlinear Hadley circulation driven by asymmetric differential heating

The dynamical state of the stratosphere influenced by radiative heating, with no internal sources or sinks of angular momentum, is examined. It is shown that there exists a nonlinear Hadley regime driven by antisymmetric (or more generally, asymmetric) thermal equilibria typical of the middle atmosphere at the solstices. This regime consists of a single mean meridional cell, equatorial easterlies, and strong winter westerlies. Outside of the circulation region the flow is in thermal equilibrium. The effect of one-sided friction, acting as a drag on midlatitude westerlies only, is to expand the Hadley cell into the winter hemisphere and increase the magnitude of cross-equatorial flow. This result is possible even in the steady state when the advection of angular momentum in the tropics is made small by reducing the gradient of angular momentum in this region instead of the advecting velocity.

Dunkerton, Timothy J.↗
NASA NTRS1990

Rocket temperature soundings

The purpose was to provide rocket-borne measurements of temperature and wind. These data are used to: obtain a better understanding of the processes that control the chemical and dynamic behavior of the stratospheric region; monitor temperature trends and detect changes; verify and monitor remote measurements (ground- and satellite-based); and provide density measurements for large space vehicle operations.

Schmidlin, Francis J.↗
NASA NTRS1992

A reexamination of the radiative balance of the stratosphere

The radiative balance of the stratosphere is examined in the light of the possible sensitivity of tracers to small changes in the diabatic heating. A comprehensive radiative transfer algorithm is developed on the basis of accurate and efficient methods for use in coupled stratospheric models of chemistry, dynamics, and radiative transfer, and the individual components of the code are validated against available line-by-line calculations. Finally, the results of different approximations commonly employed in radiative transfer algorithms are compared, and their effects on tracer transport are evaluated using a 2D ozone model.

Olaguer, Eduardo P.↗
NASA NTRS1994

Local fluctuations of ozone from 16 km to 45 km deduced from in situ vertical ozone profile

A vertical ozone profile obtained by an in situ ozone sonde from 16 km to 45 km, has allowed to observe local ozone concentration variations. These variations can be observed, thanks to a fast measurement system based on a UV absorption KrF excimer laser beam in a multipass cell. Ozone standard deviation versus altitude calculated from the mean is derived. Ozone variations or fluctuations are correlated with the different dynamic zones of the stratosphere.

Moreau, G.↗
NASA NTRS1995

Determination of hydrocarbon abundances and the strength of eddy mixing in the stratosphere of Neptune: Analysis of UVS solar occultation lightcurves

Work on completing our analysis of the Voyager UVS solar occultation data acquired during Neptune encounter is essentially complete, as testified by the attached poster materials. The photochemical modeling addresses the recent revision in branching ratios for radical production in the photolysis of methane at H Lyman alpha implied by the lab measurements of Mordaunt et al. (1993). The software generated in this effort has been useful for checking the degree to which photochemical models addressing other datasets (mainly infrared) are consistent with the UVS data. This work complements the UVS modeling results in that the IR data refer to deeper pressure levels; as regards the modeling of UVS data, the most significant result is the convincing support for the presence of a stagnant lower stratosphere. Evidence for strong dynamical (mixing) transport of minor constituents at shallower pressures is provided by the UVS data analysis.

Bishop, James↗
NASA NTRS1999

Observations of Convective and Dynamical Instabilities in Tropopause Folds and their Contribution to Stratosphere-Troposphere Exchange

SONEX has provided a number of opportunities to learn more about the fine-scale structure of the atmosphere. Coupled with the MOZAIC work on layers we can synthesize a new 3-D view of the fine scales that influence atmospheric chemistry. As a side issue we are also relating the features to clear air turbulence which would be, we think, a useful connection for commercial aviation.

Newell, Reginald E.↗
NASA NTRS2004

A Mechanism For Solar Forcing of Climate: Did the Maunder Minimum Cause the Little Ice Age?

The mechanism we wish to demonstrate exploits chemical, radiative, and dynamical sensitivities in the stratosphere to affect the climate of the troposphere. The sun, while its variability in total radiative output over the course of the solar cycle is on the order of 0.1%, exhibits variability in the UV output on the order of 5%. We expect to show that a substantially decreased solar UV output lessened the heating of the Earth's stratosphere during the Maunder Minimum, through decreased radiative absorption by ozone and oxygen. These changes in stratospheric heating would lead to major changes in the stratospheric zonal wind pattern which would in turn affect the propagation characteristics of planetary-scale waves launched in the winter hemisphere. Until recently, there was no quantitative data to relate the changes in the stratosphere to those at the surface. There is now empirical evidence from the NCEP Reanalysis data that a definitive effect of the solar cycle on climate in the troposphere exists. Our recent work is summarized as follows (see complete list of publications in later part of this report).

Yung, Yuk L.↗
NASA NTRS2009

The GEOS-Chemistry-Climate Model (CCM), Versions 1,2 and 3

This paper examines evolution of key ozone and climate aspects in our range of Goddard Earth Observing System Models, Versions 1-3. Version 1 (Pawson et al., 2008; )GR) used GSFC stratospheric ozone chemistry in GEOS-4 GCM. A chronic high bias in polar ozone at low chlorine loading persisted into Version 2, which used the GEQS-5 GCM and the same chemistry. This is much improved in Version 3, which uses the GMI-COMBO stratosphere-troposphere chemistry. A dynamical problem with Version 1, the overactive nature of the Antarctic polar vortex, is corrected in Versions 2 and 3, when GEQS-5 replaces GEO5-4. Other changes between the various model versions will be documented.

Pawson, Steven↗
NASA NTRS1983

Numerical studies of major and minor stratospheric warmings caused by orographic forcing

A primitive equation spectral model using spherical harmonics is formulated to study dynamic interactions between the troposphere and stratosphere in association with sudden stratospheric warmings. Using sigma coordinates for five tropospheric layers and log-pressure coordinates for 26 stratospheric and mesospheric layers, separate model equations for each system are combined to form single matrix governing equations. The gradual introduction of large scale topography to balanced initial states representative of observed mean winter conditions in the Northern Hemisphere is used for the generation of planetary waves during 40-day time integrations. Results of these integrations indicate that stratospheric warmings can be simulated by this orographic forcing and that mean momentum flux divergence due to zonal mean motion appears to be an essential mechanism of these simulated sudden warmings. It was found that the strength of the polar night jet can be a determining factor whether a warming becomes 'major' or 'minor'.

Koermer, J. P.↗