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Turner, R. E.

Publications and source records attributed to Turner, R. E..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Mars 2001 Cruise Phase Radiation Measurments

Mars 2001 presents an exciting opportunity for advances in radiation risk management of a future human mission to Mars. The mission timing is particularly fortuitous, coming just after solar maxinuun, when there will be a high probability to observe significant solar particle events (SPEs). A major objective of this mission is to characterize the Martian radiation environment to support future human missions to Mars. In addition, the MARIE instruments on the Lander and Orbiter, designed to measure the energetic particle flux at Mars, can be used during the cruise phase to provide multipoint observations of SPEs in the critical region of the heliosphere (1 to 1.5 AU) needed to reduce the in-flight radiation risk to a future Mars-bound crew.

Turner, R. E.↗
NASA NTRS1998

Orbit selection and its impact on radiation warning architecture for a human mission to Mars

With the recent announcement of the discovery of the possibility of life on Mars, there is renewed interest in Mars missions, perhaps eventually in human missions. Astronauts on such missions are at risk to occasional periods of enhanced high energy particle flux from the sun known as Solar Particle Events. These events can pose a substantial risk to the health of the astronauts and to the on-board electronics. Effective forecast and warning of these events could provide time to take steps to minimize the risk (retreating to a safe haven, shutting down sensitive equipment, etc.) Providing that forecast capability, will require additional monitoring capability. The extent of this architecture is sensitive to the orbit selected for the transfer to and from Mars. This paper looks at the major classes of Mars missions (Conjunction and Opposition) and sub-categories of these classes and draws conclusions on the number of monitoring satellites needed for each, with a goal to reducing total system cost through optimum orbit selection.

Non-NASA Center↗
NASA NTRS1998

Solar particle events and the International Space Station

The high inclination orbit for the International Space Station poses a risk to astronauts on EVA during occasional periods of enhanced high energy particle flux from the sun known as Solar Particle Events. We are currently unable to predict these events within the few-hour lead time required for evasive action. Compounding the threat is the fact that station construction occurs during increasing solar activity and through the peak of the solar cycle. In this paper we present an overview of the risk, the current methods to provide forecasts of SPEs, and potential risk mitigation options.

NASA Discipline Radiation Health↗
NASA NTRS1993

The interaction of radiative and dynamical processes during a simulated sudden stratospheric warming

An analysis of a spontaneous sudden stratospheric warming that occurred during a 2-year integration of the Langley Research Center (LaRC) Atmospheric Simulation Model is presented. The simulated warming resembles observed 'wave 1' warmings in the Northern Hemisphere stratosphere and provides an opportunity to investigate the radiative and dynamical processes occurring during the warming event. Isentropic analysis of potential vorticity sources and sinks indicates that dynamically induced departures from radiative equilibrium play an important role in the warming event. Enhanced radiative cooling associated with a series of upper stratospheric warm pools leads to radiative dampening within the polar vortex. Within the 'surf zone' large-scale radiative cooling leads to diabatic advection of high potential vorticity air from aloft. Lagrangian area diagnostics of the simulated warming agree well with Limb Infrared Monitor of the Stratosphere (LIMS) analyses. Dynamical mixing is shown to account for the majority of the decrease in the size of the polar vortex during the simulated warming. An investigation of the nonlinear deformation of material lines that are initially coincident with diagnosed potential vorticity isopleths is conducted to clarify the relationship between the Lagrangian area diagnostics and potential vorticity advection during wave breaking events.

Pierce, R. B.↗
NASA NTRS1993

Some aspects of the interaction between chemical and dynamic processes relating to the Antarctic ozone hole

Observational and modeling studies have been conducted to examine the interaction between the chemical and dynamical processes that occur during springtime in the lower stratosphere of the Southern Hemisphere. The temporal evolution of the ozone distribution and the circulation during 1987 is contrasted with that for 1988 as an illustrative example of how dynamical processes and the resulting meteorological conditions modulate the ozone depletion. Concurrently with the observational analysis, an effort was initiated to simulate the ozone depletion during austral spring using a 3D chemical/transport model. The model includes a parameterized representation of the heterogeneous processes thought to be important in this region. The simulation indicates that the inclusion of this additional chemistry, which results in the release of free chlorine and the redistribution of odd nitrogen into reservoir species, reproduces many aspects of the observations.

Eckman, R. S.↗
NASA NTRS1992

Characteristics of 3-D transport simulations of the stratosphere and mesosphere

A 3D mechanistic, primitive-equation model of the stratosphere and mesosphere is coupled to an offline spectral transport model. The dynamics model is initialized with and forced by observations so that the coupled models may be used to study specific episodes. Results are compared with those obtained by transport online in the dynamics model. Although some differences are apparent, the results suggest that coupling of the models to a comprehensive photochemical package will provide a useful tool for studying the evolution of constituents in the middle atmosphere during specific episodes.

Fairlie, T. D. A.↗
NASA NTRS1992

A three-dimensional model simulation of atmospheric nitrous oxide

The NASA Langley 3D GCM chemical transport model is used to investigate the distribution of atmospheric N2O up to 60 km altitude. The transport characteristics of the model is evaluated without the complications of a detailed chemical formulation for all of the relevant stratospheric minor constituents. Interpretation of the yearly average zonal mean N2O distribution in terms of transport by the yearly averaged meridional circulation and stratospheric photochemical loss indicates large regions in the Northern Hemisphere stratosphere where dynamical mixing apparently plays a large role in maintaining the N2O distribution. In these regions, slopes of the N2O mixing ratio isopleths are maintained by competition between advection by the meridional circulation acting to steepen and dynamical mixing acting to flatten the slopes.

Turner, R. E.↗
NASA NTRS1990

Stratospheric dynamics and transport studies

A three dimensional General Circulation Model/Transport Model is used to simulate stratospheric circulation and constituent distributions. Model simulations are analyzed to interpret radiative, chemical, and dynamical processes and their mutual interactions. Concurrent complementary studies are conducted using both global satellite data and other appropriate data. Comparisons of model simulations and data analysis studies are used to aid in understanding stratospheric dynamics and transport processes and to assess the validity of current theory and models.

Grose, William L.↗
NASA NTRS1987

Simulated sudden stratospheric warming - Synoptic evolution

An analysis is presented of a sudden stratospheric warming event which occurred spontaneously during a general circulation model simulation of the global atmospheric circulation. Two separate warming pulses exhibit the same dynamical evolution with a 'cycle' of about two weeks. Two distinct phases of the warming cycle are apparent: (1) the generation of an intense localized warm cell in conjunction with significant adiabatic heating associated with cross-isobar flow which has been induced by vertically propagating long wave disturbances; and (2) the northward transport of that warm cell via advection by the essentially geostrophic windfield corresponding to an intense, offset polar cyclone, in conjunction with a strong Aleutian anticyclone. During the first warming pulse in January, a moderate Aleutian anticyclone was in place prior to the warming cycle and was intensified by interaction with an eastward traveling anticyclone induced by the differential advection of the warm cell. The second warming pulse occurred in early February with a strong Aleutian anticyclone already established. In contrast to the January event, the warming in February culminated with reversal of the zonal westerlies to easterlies over a significant depth of the stratosphere.

Blackshear, W. T.↗
NASA NTRS1985

Transport processes in the stratosphere: Model simulations and comparisons with satellite observations

A three dimensional atmospheric model was used to study transport processes and to simulate the distribution of chemically active species in the stratosphere. The present results are part of a long term simulation of the seasonally varying structure of stratospheric trace constituents. The occurrence of a midwinter stratospheric warming and the associated transport of O3 and HNO3 during the simulation are described. Comparison of the simulated distributions of O3 and HNO3 are made with data from the Limb Infrared Monitor of the Stratosphere (LIMS) experiment. In addition, distributions of Ertel's potential vorticity on isentropic surfaces (IPV) are evaluated as a diagnostic for interpreting transport processes. Comparisons are made with IPV distributions inferred from LIMS temperature data.

Grose, W. L.↗
NASA NTRS1984

The response of a nonlinear, time-dependent, baroclinic model of the atmosphere to tropical thermal forcing

A multi-level, sigma coordinate, primitive equation atmospheric model has been utilized to study both the tropical and extratropical response to an isolated region of steady thermal forcing in the tropics. The nonlinear response during the first 28 days of the simulation is described. The response can be generally characterized by two distinct components. The first component is a quasi-stationary disturbance which extends eastward and poleward away from the source region along a 'great circle' path. The structure of this disturbance is essentially barotropic away from the source region. The second component is a growing baroclinic wave propagating zonally at mid-latitudes. Significantly, this disturbance is apparently the result of baroclinic instability induced by the quasi-stationary wavetrain. The discussion is predominantly heuristic in form and relies heavily on graphical presentation and quasi-geostrophic theory to interpret the response and individual components of the thermodynamic energy and momentum equations.

Grose, W. L.↗
NASA NTRS1983

NASA/MSFC FY-83 Atmospheric Research Review

Atmospheric research conducted at the Marshall Space Flight Center in FY 1983 is discussed. Clear air turbulence, gusts, and fog dispersal near airports is discussed. The use of Doppler Lidar signals in discussed, as are low level flow conditions that are hazardous to aircraft.

Turner, R. E.↗
NASA NTRS1983

Atmospheric environment for space shuttle (STS-8) launch

Selected atmospheric conditions observed near Space Shuttle STS-8 launch time on August 30, 1983, at Kennedy Space Center, Florida are summarized. Values of ambient pressure, temperature, moisture, ground winds, visual observations (cloud), and winds aloft are included. The sequence of prelaunch Jimsphere measured vertical wind profiles is given. Also presented are wind and thermodynamic parameters representative of surface and aloft conditions in the SRB descent/impact ocean area. Final meteorological tapes, which consist of wind and thermodynamic parameters versus altitude, for STS-8 vehicle ascent and SRB descent/impact were constructed. The STS-8 ascent meteorological data tape was constructed.

Johnson, D. L.↗
NASA NTRS1983

NASA/MSFC FY-83 Atmospheric Processes Research Review

The atmospheric processes research program was reviewed. Research tasks sponsored by the NASA Office of Space Science and Applications, Earth Sciences and Applications Division in the areas of upper atmosphere, global weather, and mesoscale processes are discussed. The are: the research project summaries, together with the agenda and other information about the meeting.

Turner, R. E.↗
NASA NTRS1983

A stochastic atmospheric model for remote sensing applications

There are many factors which reduce the accuracy of classification of objects in the satellite remote sensing of Earth's surface. One important factor is the variability in the scattering and absorptive properties of the atmospheric components such as particulates and the variable gases. For multispectral remote sensing of the Earth's surface in the visible and infrared parts of the spectrum the atmospheric particulates are a major source of variability in the received signal. It is difficult to design a sensor which will determine the unknown atmospheric components by remote sensing methods, at least to the accuracy needed for multispectral classification. The problem of spatial and temporal variations in the atmospheric quantities which can affect the measured radiances are examined. A method based upon the stochastic nature of the atmospheric components was developed, and, using actual data the statistical parameters needed for inclusion into a radiometric model was generated. Methods are then described for an improved correction of radiances. These algorithms will then result in a more accurate and consistent classification procedure.

Turner, R. E.↗
NASA NTRS1983

NASA's AVE/VAS program

A discussion is presented concerning the Atmospheric Variability Experiment (AVE) which was conducted during the spring of 1982 as part of NASA's Visible and Infrared Spin-Scan Radiometer (VISSR) Atmospheric Sounder (VAS) demonstration. The AVE/VAS Ground Truth Field Experiment is examined in detail, which comprised the obtaining of rawinsonde observations during various meteorological conditions on four different days when VAS data were obtained. These experiments were performed over 24 hr periods in a mesoscale network of 24 National Weather Service rawinsonde sites and 13 NASA and NOAA special sites. The VAS, operating as a part of the GOES satellite system, was employed to provide two-dimensional cloud mapping capability during each of the AVE/VAS experiment periods. Among the goals of this AVE/VAS program, in addition to management of the acquisition and processing of the data, were to perform the research and development needed to produce data products from VAS radiances, to validate the data, and to assess the impact of the data on mesoscale meteorological forecasting and research requirements.

Hill, C. K.↗