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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
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NASA NTRS2019

Martian Dust Storm Impact on Atmospheric H2o and D/H Observed By Exomars Trace Gas Orbiter

Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.

Ann Carine Vandaele↗
NASA NTRS1992

A new numerical model of the middle atmosphere. I - Dynamics and transport of tropospheric source gases

Attention is given to a new model of the middle atmosphere which includes, in addition to the equations governing the zonal mean state, a potential vorticity equation for a single planetary-scale Rossby wave, and an IR radiative transfer code for the stratosphere and lower mesosphere, which replaces the Newtonian cooling parameterization used previously. It is shown that explicit computation of the planetary-scale wave field yields a more realistic representation of the zonal mean dynamics and the distribution of trace chemical species. Wave breaking produces a well-mixed 'surf zone' equatorward of the polar night vortex and drives a meridional circulation with downwelling on the poleward side of the vortex. This combination of mixing and downwelling produces shallow meridional gradients of trace gases in the subtropics and middle latitudes, and very steep gradients at the edge of the polar vortex. Computed distributions of methane and nitrous oxide are shown to agree well with observations.

Garcia, Rolando R.↗
NASA NTRS1981

Solar terrestrial observatory

Eight basic solar-terrestrial scientific objectives that benefit from the Shuttle/Platform approach and a program of measurements for each are discussed. The objectives are to understand: (1) solar variability, (2) wave-particle processes, (3) magnetosphere-ionosphere mass transport, (4) the global electric circuit, (5) upper atmospheric dynamics, (6) middle atmospheric chemistry and energetics, (7) lower atmospheric turbidity, and (8) planetary atmospheric waves. A two stage approach to a multidisciplinary payload is developed: an initial STO, that uses a single platform in a low-Earth orbit, and an advanced STO that uses two platforms in differing orbits.

Source record↗
NASA NTRS1998

Solid State Laser Technology Development for Atmospheric Sensing Applications

NASA atmospheric scientists are currently planning active remote sensing missions that will enable global monitoring of atmospheric ozone, water vapor, aerosols and clouds as well as global wind velocity. The measurements of these elements and parameters are important because of the effects they have on climate change, atmospheric chemistry and dynamics, atmospheric transport and, in general, the health of the planet. NASA will make use of Differential Absorption Lidar (DIAL) and backscatter lidar techniques for active remote sensing of molecular constituents and atmospheric phenomena from advanced high-altitude aircraft and space platforms. This paper provides an overview of NASA Langley Research Center's (LaRC's) development of advanced solid state lasers, harmonic generators, and wave mixing techniques aimed at providing the broad range of wavelengths necessary to meet measurement goals of NASA's Earth Science Enterprise.

Barnes, James C.↗
NASA NTRS2022

Constraining Venus and Mars Internal Structures from the Gravity Response to Atmospheric Loading

The gravity fields of celestial bodies that possess an atmosphere are periodically perturbed by the redistribution of fluid mass associated with the atmospheric dynamics. A component of this perturbation is due to the gravitational response of the body to the deformation of its surface induced by the atmospheric pressure loading. The magnitude of this effect depends on the relation between the loading and the response in terms of geopotential variations measured by the load Love numbers. In this work, we simulate and analyze the gravity field generated by the atmospheres of Venus and Mars by accounting for different models of their internal structure. By precisely characterizing the phenomena that drive the mass transportation in the atmosphere through general circulation models, we determine the effect of the interior structure on the response to the atmospheric loading. An accurate estimation of the time-varying gravity field, which measures the atmospheric contribution, may provide significant constraints on the interior structure through the measurement of the load Love numbers. A combined determination of tidal and load Love numbers would enhance our knowledge of the interior of planetary bodies, providing further geophysical constraints in the inversion of internal structure models.The gravity fields of celestial bodies that possess an atmosphere are periodically perturbed by the redistribution of fluid mass associated with the atmospheric dynamics. A component of this perturbation is due to the gravitational response of the body to the deformation of its surface induced by the atmospheric pressure loading. The magnitude of this effect depends on the relation between the loading and the response in terms of geopotential variations measured by the load Love numbers. In this work, we simulate and analyze the gravity field generated by the atmospheres of Venus and Mars by accounting for different models of their internal structure. By precisely characterizing the phenomena that drive the mass transportation in the atmosphere through general circulation models, we determine the effect of the interior structure on the response to the atmospheric loading. An accurate estimation of the time-varying gravity field, which measures the atmospheric contribution, may provide significant constraints on the interior structure through the measurement of the load Love numbers. A combined determination of tidal and load Love numbers would enhance our knowledge of the interior of planetary bodies, providing further geophysical constraints in the inversion of internal structure models.

Mars↗
NASA NTRS1992

Stratospheric turbulence measurements and models for aerospace plane design

Progress in computational atmospheric dynamics is exhibiting the ability of numerical simulation to describe instability processes associated with turbulence observed at altitudes between 15 and 25 km in the lower stratosphere. As these numerical simulation tools mature, they can be used to extend estimates of atmospheric perturbations from the present gust database for airplane design at altitudes below 15 km to altitudes between 25 and 50 km where aerospace plane operation would be at hypersonic speeds. The amount of available gust data and number of temperature perturbation observations are limited at altitudes between 15 and 25 km. On the other hand, in-situ gust data at higher altitudes are virtually nonexistent. The uncertain potential for future airbreathing hypersonic flight research vehicles to encounter strong turbulence at higher altitudes could penalize the design of these vehicles by undue cost or limitations on performance. Because the atmospheric structure changes markedly with altitude, direct extrapolation of gust magnitudes and encounter probabilities to the higher flight altitudes is not advisable. This paper presents a brief review of turbulence characteristics observed in the lower stratosphere and highlights the progress of computational atmospheric dynamics that may be used to estimate the severity of atmospheric transients at higher altitudes.

Ehernberger, L. J.↗
NASA NTRS1992

Stratospheric turbulence measurements and models for aerospace plane design

Progress in computational atmospheric dynamics is exhibiting the ability of numerical simulation to describe instability processes associated with turbulence observed at altitudes between 15 and 25 km in the lower stratosphere. As these numerical simulation tools mature, they can be used to extend estimates of atmospheric perturbations from the present gust database for airplane design at altitudes below 15 km to altitudes between 25 and 50 km where aerospace plane operation would be at hypersonic speeds. The amount of available gust data and number of temperature perturbation observations are limited at altitudes between 15 and 25 km. On the other hand, in-situ gust data at higher altitudes are virtually nonexistent. The uncertain potential for future airbreathing hypersonic flight research vehicles to encounter strong turbulence at higher altitudes could penalize the design of these vehicles by undue cost or limitations on performance. Because the atmospheric structure changes markedly with altitude, direct extrapolation of gust magnitudes and encounter probabilities to the higher flight altitudes is not advisable. This paper presents a brief review of turbulence characteristics observed in the lower stratosphere and highlights the progress of computational atmospheric dynamics that may be used to estimate the severity of atmospheric transients at higher altitudes.

Ehernberger, L. J.↗
NASA NTRS1984

Cloud and ice in the planetary scale circulation and in climate

The roles of the cryosphere, and of cloud-radiative interactions are investigated. The effects clouds and ice have in the climate system are examined. The cloud radiation research attempts explain the modes of interaction (feedback) between raditive transfer, cloud formation, and atmospheric dynamics. The role of sea ice in weather and climate is also discussed. Models are used to describe the ice and atmospheric dynamics under study.

Herman, G. F.↗
NASA NTRS1973

The hydroperoxyl radical in atmospheric chemical dynamics - Reaction with carbon monoxide.

Discussion of laboratory measurements which indicate that the reaction of the thermalized HO(2) radical with CO is exceedingly slow and that this reaction should not, therefore, be of any significance in atmospheric chemistry. The large discrepancy between the new results and data obtained earlier by Westenberg and de Haas (1972) is explained in terms of the reacting hydroperoxyl radical being in a non-Boltzmann distribution in the former study. It appears that the most important reactions of thermalized HO(2) in the atmosphere are those involving the trace gases of NO and sulfur dioxide.

Davis, D. D.↗
NASA NTRSDate not supplied

An Overview of the NASA ADM-Aeolus Cal/Val Test Flight Campaign

Lidars are uniquely capable of collecting high precision and high spatio-temporal observations that have been used for atmospheric process studies from the ground, aircraft, and space for over 30 years. The Atmospheric Dynamics Mission Aeolus (ADM-Aeolus), the first-ever spaceborne Doppler wind lidar, was developed by the European Space Agency and launched in August 2018. The ADM-Aeolus Atmospheric Laser Doppler Instrument (ALADIN) observes profiles of the component of the wind vector and aerosol optical properties along the instrument’s line-of-sight direction on a global scale. Two airborne lidar systems have been developed at NASA Langley Research Center in recent years that collect measurements in support of several NASA Earth Science Division focus areas. The Doppler Aerosol WiNd (DAWN) lidar measures vertical profiles of horizontal wind speed and direction. The High Altitude Lidar Observatory (HALO) measure high resolution profiles of atmospheric water vapor (WV) and aerosol and cloud optical properties. Though new space-based missions with advanced capabilities such as Aeolus are continuously being conceived and developed, there are limitations in terms of spatial and vertical detail and measurement precision that can be accomplished from space, thus airborne remote sensing observations like those from DAWN and HALO are required to fill these observational gaps as well as to calibrate and validate space-based measurements. Over a two-week period in April 2019 during their Aeolus Cal/Val Test Flight campaign, NASA conducted five research flights over the Eastern Pacific Ocean with the DC-8 aircraft to 1) demonstrate the DAWN Doppler wind lidar, HALO high spectral resolution lidar aerosol/cloud measurement and differential absorption lidar WV measurement capabilities across a range of atmospheric conditions, 2) demonstrate Aeolus Cal/Val flight strategies and compare DAWN and HALO measurements with Aeolus to gain an initial perspective of Aeolus performance, and 3) demonstrate how atmospheric dynamic processes can be resolved and better understood through simultaneous observations of wind, WV, and aerosol profile observations, coupled with numerical model and other remote sensing observations. This paper provides a brief description of the DAWN and HALO instruments, discusses the synergistic observations collected across a wide range of atmospheric conditions sampled during the DC-8 flights, and a summary of the validation of DAWN, HALO, and Aeolus observations and comparisons.

Kristopher M. Bedka↗
NASA NTRS1984

Research Review, 1983

The Global Modeling and Simulation Branch (GMSB) of the Laboratory for Atmospheric Sciences (GLAS) is engaged in general circulation modeling studies related to global atmospheric and oceanographic research. The research activities discussed are organized into two disciplines: Global Weather/Observing Systems and Climate/Ocean-Air Interactions. The Global Weather activities are grouped in four areas: (1) Analysis and Forecast Studies, (2) Satellite Observing Systems, (3) Analysis and Model Development, (4) Atmospheric Dynamics and Diagnostic Studies. The GLAS Analysis/Forecast/Retrieval System was applied to both FGGE and post FGGE periods. The resulting analyses have already been used in a large number of theoretical studies of atmospheric dynamics, forecast impact studies and development of new or improved algorithms for the utilization of satellite data. Ocean studies have focused on the analysis of long-term global sea surface temperature data, for use in the study of the response of the atmosphere to sea surface temperature anomalies. Climate research has concentrated on the simulation of global cloudiness, and on the sensitivities of the climate to sea surface temperature and ground wetness anomalies.

Source record↗
NASA NTRS2013

Probability of US Heat Waves Affected by a Subseasonal Planetary Wave Pattern

Heat waves are thought to result from subseasonal atmospheric variability. Atmospheric phenomena driven by tropical convection, such as the Asian monsoon, have been considered potential sources of predictability on subseasonal timescales. Mid-latitude atmospheric dynamics have been considered too chaotic to allow significant prediction skill of lead times beyond the typical 10-day range of weather forecasts. Here we use a 12,000-year integration of an atmospheric general circulation model to identify a pattern of subseasonal atmospheric variability that can help improve forecast skill for heat waves in the United States. We find that heat waves tend to be preceded by 15-20 days by a pattern of anomalous atmospheric planetary waves with a wavenumber of 5. This circulation pattern can arise as a result of internal atmospheric dynamics and is not necessarily linked to tropical heating.We conclude that some mid-latitude circulation anomalies that increase the probability of heat waves are predictable beyond the typical weather forecast range.

Mid-Latitude Circulation↗
NASA NTRS1994

Investigation of atmospheric waves on Neptune

This document constitutes the final report for grant NAGW-2442 of the Neptune Data Analysis Program, which supported research concerning atmospheric dynamics on Neptune. Professor Von R. Eshleman was the principal investigator. David P. Hinson was a Co-Investigator. The grant covered the period 1 March 1991 through 31 August 1994, including a six month no-cost extension. Funding from this grant resulted in publication of one journal article and one book chapter as well as presentation of results at two conferences and in numerous seminars. A complete bibliography is given below. A copy of the journal article is attached along with abstracts from the book chapter and the conference presentations. With support from this grant we extended our analysis and interpretation of the Voyager Project. This research contributed to an improvement in our basic understanding of atmospheric dynamics on Neptune. The highlight was the discovery and characterization of inertio-gravity waves in the troposphere and stratosphere. Results include measures of basic wave properties, such as amplitudes and vertical wavelengths, as well as estimates of the effect of the waves on the photochemistry and momentum balance of the stratosphere. This investigation also yielded a better understanding of the potential of radio occultation experiments for studies of atmospheric waves. At the same time we developed new methods of data analysis for exploiting these capabilities. These are currently being applied to radio occultation data obtained with the Magellan spacecraft to study waves in the atmosphere of Venus. Future planetary missions, such as Mars Global Surveyor and Cassini, will benefit from these accomplishments.

Eshleman, Von R.↗
NASA NTRS2010

Multiyear Statistics of 2-D Shortwave Radiative Effects at Three ARM Sites

This study examines the importance of horizontal photon transport effects, which are not considered in the 1-D calculations of solar radiative heating used by most atmospheric dynamical models. In particular, the paper analyzes the difference between 2-D and 1-D radiative calculations for 2-D vertical cross-sections of clouds that were observed at three sites over 2- to 3-year periods. The results show that 2-D effects increase multiyear 24-hour average total solar absorption by about 4.1 W/sq m, 1.2 W/sq m, and 0.3 W/sq m at a tropical, mid-latitude, and arctic site, respectively. However, 2-D effects are often much larger than these average values, especially for high sun and for convective clouds. The results also reveal a somewhat unexpected behavior, that horizontal photon transport often enhances solar heating even for oblique sun. These findings underscore the need for fast radiation calculation methods that can allow atmospheric dynamical simulations to consider the inherently multidimensional nature of shortwave radiative processes.

Varnai, Tamas↗
NASA NTRS1979

Martian meteorology

Viking mission results concerning the structure and dynamics of the Martian atmosphere are reviewed. The large-scale variability of pressure, temperature, and zonally averaged wind at the Lander sites is described, and small-scale phenomena involving the boundary layer and internal gravity waves are discussed. Observational evidence for the existence of transient planetary-scale waves, forced quasi-stationary waves, and thermal tides on Mars is examined. Atmospheric dynamics and properties of dust storms are considered, with emphasis on dust properties and distribution, the time evolution of planetwide dust storms, and dust-storm genesis and decay. Attention is also given to the nature of past Martian climates, the sizes and composition of volatile reservoirs, and volatile escape from the atmosphere.

Leovy, C. B.↗
NASA NTRS1971

Dynamic upper atmospheric force model on stabilized vehicles for a high-precision trajectory computer program

The upper atmosphere model draws heavily on the behavior of the earth's upper atmosphere which exhibits cyclic as well as irregular variations in density profile, temperature, pressure, and composition in unison with solar activities as deduced from the more recent land-based and satellite observations. The lift and drag model is designed specifically for inertially stabilized vehicles of the Mariner class, with possible extension to gravity gradient stabilized vehicles of the GEOS class. The model considers operation in the free molecular flow regimes with large Knudsen numbers. The vehicle is considered a composite structure with basic components having well-defined shapes, each with its own surface characteristics in terms of temperature, reflectivity, and accommodation of free stream molecules. The model takes into account both the calculation of precise aerodynamic force coefficients in terms of expansion of modified Bessel functions in speed ratios and angle of attack, and approximate force coefficients when the speed ratios approach infinity. Other considerations include specular and diffused reflectivity, shielding, and shadow effects.

Khatib, A. R.↗