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  • Other Sources  (1,484)
  • NASA Technical Reports  (1,484)
  • EARTH RESOURCES AND REMOTE SENSING  (643)
  • ASTROPHYSICS  (566)
  • METEOROLOGY AND CLIMATOLOGY  (275)
  • 1980-1984  (1,484)
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  • Other Sources  (1,484)
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  • NASA Technical Reports  (1,484)
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  • 1980-1984  (1,484)
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  • 1
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    In:  CASI
    Publication Date: 2006-04-26
    Description: The snowmelt-runoff model developed for two small central European watersheds simulate daily streamflow on the 228 sq km Dinwoody Creek basin in Wyoming, using snowcover extent for LANDSAT and conventionally measured temperature and precipitation. For the six-month snowmelt seasons of 1976 and 1974, the simulated seasonal runoff volumes were within 5 and 1%, respectively, of the measured runoff. Also the daily fluctuations of discharge were simulated to a high degree by the model. Thus far the limiting basin size for applying the model has not been reached, and improvements can be expected if the hydrometeorological data can be obtained from a station inside the basin. LANDSAT provides an efficient way to obtain the critical snowcover input parameter required by the model.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Goddard Lab. for Atmospheric Sci., Collected Reprints 1978 - 1979, Vol. 2; p 745-760
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  • 2
    Publication Date: 2006-04-26
    Description: Snow accumulation and depletion at specific locations can be monitored from space by observing related variations in microwave brightness temperatures. Using vertically and horizontally polarized brightness temperatures from the Nimbus 6 electrically scanning microwave radiometer, a discriminant function can be used to separate snow from no snow areas and map snowcovered area on a continental basis. For dry snow conditions on the Canadian high plains, significant relationships between snow depth or water equivalent and microwave brightness temperature were developed which could permit remote determination of these snow properties after acquisition of a wider range of data. The presence of melt water in the snowpack causes a marked increase in brightness temperature which can be used to predict snowpack priming and timing of runoff. As the resolutions of satellite microwave sensors improve the application of these results to snow hydrology problems should increase.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Goddard Lab. for Atmospheric Sci., Collected Reprints 1978 - 1979, Vol. 2; p 745-760
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  • 3
    Publication Date: 2006-04-26
    Description: Methods using snowcovered area to update seasonal forecasts as snowmelt progresses are also being used in quasi-operational situations. The input of snowcovered area to snowmelt models for short term perdictions was attempted in two ways; namely, the modification of existing hydrologic models and/or the use of models that were specifically designed to use snowcovered area. A daily snowmelt runoff model was used with LANDSAT data to simulate discharge on remote basins in the Wind River Mountains of Wyoming. Daily predicted and actual flows compare closely, and, summarized over the entire snowmelt season (April 1 - September 30), the average difference is only three percent. The model and snowcovered area data are currently being tested on additional watersheds to determine the method's transferability.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Goddard Lab. for Atmospheric Sci. Collected Reprints 1978 - 1979, Vol. 2; p 742
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  • 4
    Publication Date: 2006-01-16
    Description: Some operational and experimental products developed for aviation weather forecasting are briefly described. Experimental products include surface dew point, obstructions to vision, boundary layer model, computer-worded terminal forecasts, terminal alerting procedure, generalized equivalent Markov, and radar forecasts (0-2 hours).
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 209-212
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  • 5
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Doppler radar measurements of an intense wind shear occurance are discussed. The data suggest the presence of an incredibly strong low level jet outflow component of the microburst event, reaching 60 knots only 50 meters above the surface. Evidence also suggests that microbursts more typically occur in very weak thunderstorms that have hardly reached thunderstorm stage.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 201-202
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  • 6
    Publication Date: 2006-01-16
    Description: The phenomenology of one class of strong thunderstorm downdrafts, microbursts, is described. Several aircraft accidents are analyzed in which a microburst was involved and a concept for an early warning wind shear sensor is presented.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 186-200
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  • 7
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    In:  CASI
    Publication Date: 2006-01-16
    Description: A method to improve clear air turbulence (CAT) forecasting by more effectively using the currently operational rawinsonde (RW) system is discussed. The method is called the Diagnostic Richardson Number Tendency (DRT) technique. The technique does not attempt to use the RW as a direct detector of the turbulent motion or even of the CAT mechanism structure but rather senses the synoptic scale centers of action which provide the energy to the CAT mechanism at the mesoscale level. The DRT algorithm is deterministic rather than statistical in nature, using the hydrodynamic equations (equations of motion) relevant to the synoptic scale. However, interpretation, by necessity, is probabilistic. What is most important with respect to its operational implementation is that this method uses the same input data as currently used by the operational National Meteorological Center prognostic models.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 203-208
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  • 8
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    In:  CASI
    Publication Date: 2006-01-16
    Description: A clear air turbulence (CAT) flight test to evaluate and test four different sensors in the detection and measuring of CAT and other meteorological targets that relate to turbulence is discussed. The primary types of CAT investigated were mountain wave CAT, jetstream CAT, CAT in cirrus clouds, and CAT in frontal wind shears, troughs, and ridges. The sensors included the CO2 pulsed Doppler lidar and three radiometers. One of the radiometers, at a frequency of 55.5 GHz, looked at atmospheric temperature structure. Another, at a frequency of 180.1 GHz, looked at atmospheric water vapor and investigated the feasibility of measuring at the microwave frequency the turbulence features seen in the infrared (IR) frequencies. An IR radiometer at 27 to 33 microns was the fourth sensor. This last device and the temperature structure radiometer worked well at all flight levels.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 171-179
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  • 9
    Publication Date: 2006-01-16
    Description: The development of methods for the short range forecasting of visibility and ceiling conditions is discussed. Short range forecasts of one hour or less (5 or 30 minutes), immediately after a series of local observations can be expected to be more accurate and reliable than any forecast of more than one hour. These forecasts can be accomplished by the operational implementation of fully automated aviation observation systems and the utilization of statistical techniques such as the Generalized Equivalent Markov model.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 180-185
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  • 10
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Requirements for an improved aviation weather system are defined and specifically include the need for (1) weather observations at all airports with instrument approaches, (2) more accurate and timely radar detection of weather elements hazardous to aviation, and (3) better methods of timely distribution of both pilot reports and ground weather data. The development of the discrete address beacon system data link, Doppler weather radar network, and various information processing techniques are described.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 162-167
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  • 11
    Publication Date: 2006-01-16
    Description: The operational designs and performance capabilities of ground-based and airborne lightning detection systems are reviewed. The airborne Stormscope system is described and compared with onboard radar and the lightning detection and ranging system (LDAR). Two examples of difference-in-time-of-arrival systems for detecting spherics from discharges in electrified clouds are described: (1) The LDAR system and (2) Taylor's lightning mapping system. Next, an interferometric system adapted to lightning location is discussed. Finally, systems that are based upon crossed-loop magnetic direction finding principles but which have been refined and improved to accurately locate lightning discharges to ground are reviewed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 130-139
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  • 12
    Publication Date: 2006-01-16
    Description: The phenomenology of lightning and lightning measurement techniques are briefly examined with a particular reference to aeronautics. Developments made in airborne and satellite detection methods are reported. NASA research efforts are outlined which cover topics including in-situ measurements, design factors and protection, remote optical and radio frequency measurements, and space vehicle design.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Proc.: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 140-160
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  • 13
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The ability of various types of remote probes to measure wind is discussed. Two important advantages over in-situ sensors are reported: (1) their ability to measure atmospheric parameters without disturbing the air flow; (2) their ability to scan through large volumes of the atmosphere with relative ease. Direct measurement sensors such as anemometers and wind vanes are categorized into two groups; active and passive. Acoustic radar, microwave radar, and lidar are included in the first group and the latter group is typified by the infrared radiometers.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 109-124
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  • 14
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The problem of development of instrumentation for providing wind speed and direction information directly or indirectly to a pilot in the cockpit is considered. The pilots need for horizontal wind information at various stages of flight (i.e., at liftoff, in approach and departure corridors, and even in flight outside the terminal area) are emphasized.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 82-108
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  • 15
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The basic reference material for gust design criteria are cited. The status of clear air turbulence meteorology (forecasting and detection) is discussed. The directions of further research technology is indicated.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc: Fourth Ann. Workshop on Meterol. and Environ. Inputs to Aviation Systems; p 71-81
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  • 16
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    In:  CASI
    Publication Date: 2006-01-16
    Description: A list of icing instrumentation requirements are presented. Because of the Army's helicopter orientation, many of the suggestions are specific to rotary wing aircraft; however, some of the instrumentation are also suitable for general aviation aircraft.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 61-65
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  • 17
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The types and usage categories of icing instrumentation are discussed. The state-of-the-art for the technology governing the use of icing instrumentation is reported with particular emphasis on ground based facilities for icing tests.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 49-60
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  • 18
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The measurement of atmospheric turbulence is discussed in terms of a pilots viewpoint. Two areas of measurement are considered: frequency and severity of turbulence. Suggestions are given for helping the pilot solve the turbulence problem.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 66-70
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  • 19
    Publication Date: 2006-01-16
    Description: An overview is given of the developmental status of aviation weather services. Particular attention is given to justifying the need for better, more reliable service. The accomplishments of several automatic weather stations are discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 45-48
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  • 20
    Publication Date: 2006-01-16
    Description: The dynamic and rapid growth of technology in the area of aviation meteorology research and development are described with emphasis on the measurement of hazardous weather phenomena. Aspects of both onboard instrumentation and ground based facilities are evaluated in terms of their effectiveness of in avoiding hazards due to atmospheric electricity and lightning. Methods of alleviating terminal are hazards such as fog, low visibility and ceilings are also described.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 40-44
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  • 21
    Publication Date: 2006-01-16
    Description: Various aspects of aviation meteorology are discussed with respect to their relative effects on aircraft terminal operations. Existing data on turbulence and wind shear from aircraft and towers are summarized. The significance of obtaining more real time wind and temperature information is emphasized. The application and testing of various radiometer devices are also described. Airborne methods to indicate wind differences at flight altitude and at touchdown are reported.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Proc: Fourth Ann. Workshop on Meteorol. and Environ. Inputs to Aviation Systems; p 23-39
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  • 22
    Publication Date: 2006-01-16
    Description: Three projects are suggested which could be done using the Doppler lidar. The first is a cooperative effort at BAO, the purpose of which is to check out instrumentation and contribute to boundary layer investigations at BAO. The second concerns unintended weather modification. Its purpose is to detect mechanisms by which regions of industry and urbanization modify weather. The cirrus cloud study proposes to characterize cirrus clouds by their lidar signal and to compare lidar and visually observed characteristics.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center First Sci. Working Group Meeting of Airborne Doppler Lidar Wind Velocity Meas. Program; 5 p
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  • 23
    Publication Date: 2006-01-16
    Description: General criteria for a flight test option are that: (1) there be a good opportunity for comparison with other measurement techniques; (2) the flow to be measured is of considerable scientific or practical interest; and (3) the airborne laser Doppler system is well suited to measure the required quantities. The requirement for comparison, i.e., ground truth, is particularly important because this is the first year of operation for the system. It is necessary to demonstrate that the system does actually measure the winds and compare the results with other methods to provide a check on the system error analysis. The uniqueness of the laser Doppler system precludes any direct comparison, but point measurements from tower mounted wind sensors and two dimensional fields obtained from radars with substantially different sampling volumes are quite useful.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: First Sci. Working Group Meeting of Airborne Doppler Lidar Wind Velocity Meas. Program; 8 p
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  • 24
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    In:  CASI
    Publication Date: 2006-01-16
    Description: The experiment strives to improve understanding of the physics of convective precipitation. Major emphasis is placed on obtaining a good description of the whole convective precipitation system. A framework is presented within which single, significant, tractable problems are investigated.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center First Sci. Working Group Meeting of Airborne Doppler Lidar Wind Velocity Meas. Program; 25 p
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  • 25
    Publication Date: 2006-01-16
    Description: The objectives of the system are to provide the system operator with real time system performance check and to provide data recording of all SSMS data. Meteorologists are provided with real time indication of meteorological data measurements including aid for directing flight profiles in real time and aid for directing SSMS operations. A day-to-day feedback is provided to meteorologists, system operators, and flight crews for flight planning on subsequent flight tests days.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center First Sci. Working Group Meeting of Airborne Doppler Lidar Wind Velocity Meas. Program; 15 p
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  • 26
    Publication Date: 2006-01-16
    Description: The problem is to operate on two scalar fields to produce a vector field, to produce user products from the vector field, and to establish reliability of results. Data problems encountered include sparse measurements, irregular distribution, varying quality, imperfect orthogonality, aliasing due to sampling volume, and measurements not simultaneous. Desired algorithm characteristics, solution elements, and characteristics of the model are listed. The seven simulation elements, eight algorithm steps and the required user inputs are given.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center First Sci. Working Group Meeting of Airborne Doppler Lidar Wind Velocity Meas. Program; 8 p
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  • 27
    Publication Date: 2006-01-16
    Description: A group meeting was assembled to focus on the planning of specific experiments, to establish some priorities, identify interested scientists who would like to participate, establish any special requirements, make recommendations on data processing, and to prepare flight plan outlines. Since the number of convective storms in the CCOPE (Cooperative Convective Precipitation Experiment) field experiment area are limited to only a few days during the operational time period the flight plans must be designed with a hierarchy of abort experiments so that the easily identified and lowest probability events should take priority until their quota is filled.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: First Sci. Working Group Meeting of Airborne Doppler Lidar Wind Velocity Meas. Program; 10 p
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  • 28
    Publication Date: 2006-01-16
    Description: The development of pulsed and continuous wave Doppler lidars for atmospheric measurement is discussed. A description of how the lidar systems operate is presented. The scanning mode is also described.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 40-42
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  • 29
    Publication Date: 2006-01-16
    Description: An interpretation of the Doppler lidar return is presented. Possible applications of the system to severe storm research are discussed. The present project schedule of the Doppler lidar system is outlined.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 43-46
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  • 30
    Publication Date: 2006-01-16
    Description: Coherent Doppler lidar appears to hold great promise in contributing to the basic store of knowledge concerning flow field characteristics in the nonprecipitous regions surrounding severe storms. The Doppler lidar, through its ability to measure clear air returns, augments the conventional Doppler radar system, which is most useful in the precipitous regions of the storm. A brief description of the Doppler lidar severe storm measurement system is provided along with the technique to be used in performing the flow field measurements. The application of the lidar is addressed, and the planned measurement program is outlined.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 31-39
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  • 31
    Publication Date: 2006-01-16
    Description: The Doppler lidar system is potentially a very powerful measurement system. Three areas concerning the system are discussed: (1) error analysis of the system to verify the results; (2) application of the system to agricultural burning in California central valley; and (3) oceanographic possibilities of the system.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 25
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  • 32
    Publication Date: 2006-01-16
    Description: Doppler lidar measurements of phenomena associated with water clouds (such as aerosols) are discussed. The purpose of the measurements and details of executing the experiment are described.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 20-24
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  • 33
    Publication Date: 2006-01-16
    Description: Four aspects of the Doppler lidar are discussed: (1) error analysis of the system; (2) design of the first field program; (3) potential areas of application; and (4) verification of Doppler lidar data by independent measurements.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 16-17
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  • 34
    Publication Date: 2006-01-16
    Description: Areas of research which can be significantly aided by the Doppler lidar airborne system are described. The need for systematic development of the airborne Doppler lidar is discussed. The technology development associated with the systematic development of the system will have direct application to satellite systems for which the lidar also promises to be an effective instrument for atmospheric research.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 13-15
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  • 35
    Publication Date: 2006-01-16
    Description: The potential application of the Doppler lidar measurements to the determination of material (e.g., water vapor) and energy budgets, momentum transports, etc., in the environment at all stages and in the development of convective clouds are discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 18-19
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  • 36
    Publication Date: 2006-01-16
    Description: The ability to map velocities over a large area on one side of the aircraft flight path offers a number of opportunities to elucidate scientific questions related to atmospheric dynamics. Several types of experiments which are possible are described.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Marshall Space Flight Center Exploratory Meeting on Airborne Doppler Lidar Wind Velocity Meas.; p 11-12
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  • 37
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    In:  CASI
    Publication Date: 2006-02-14
    Description: Data of daily mean temperatures recorded at the Kennedy Center during the period of 1957-1977 were analyzed to forecast daily mean temperatures and their thirty-day moving averages for a period of ten to fifteen days in a given month. Since it is found that the standard deviation is linear in the mean, a logarithmic transformation of the data is used for finding an integrated moving average process IMA by the Box-Jenkins aproach. The first differences of the transformed data seem to fit a moving average model with parameter value 2, MA(2). The consideration of seasonality factor makes the fit worse.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: The 1981 NASA(ASEE Summer Fac. Fellowship Program; 13 p
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  • 38
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    Publication Date: 2011-08-19
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA, Washington Upper Atmosphere Res. Program; p 161-162
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  • 39
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
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  • 40
    Publication Date: 2011-08-18
    Description: The paper reports results of an extensive set of three-dimensional hydrodynamic calculations performed to investigate the susceptibility of rotating clouds to gravitational fragmentation; only isothermal collapse sequences were considered. It is found that rotating isothermal gas clouds are unstable to fragmentation under a wide range of conditions. The degree of instability and the mode (ring vs. blob) of fragmentation is sensitive to alpha, but insensitive to beta. The initial amplitude of a perturbation does not appear to be crucial; fragmentation should occur eventually even for low-amplitude initial NAPs.
    Keywords: ASTROPHYSICS
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  • 41
    Publication Date: 2011-08-18
    Description: Experiments using ground-based measurements of canopy temperatures have shown that plant temperatures are good indicators of plant water stress, and thus are useful for assessing water requirements and predicting yields. An intensive 23-day airborne- and ground-measurement program was conducted in Phoenix, Arizona in 1977 to compare airborne-acquired wheat canopy temperatures with simultaneous ground measurements. For canopies that covered at least 85 percent of the soil surface, airborne measurements differed from ground measurements of plant temperature by less than 2 C. Regardless of the amount of plant cover, the airborne measurements were virtually identical to ground-nadir measurements, and thus represent a combination of plant temperature and solid background temperature.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Feb. 198
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  • 42
    Publication Date: 2011-08-18
    Description: Spectroscopy and polarimetry of several very red stars, noted on Near Infrared Photographic Sky Survey photographs in the region of NGC 1333, have yielded a 'map' suggesting the extent of polarization arising from a two-cloud structure in the region. Spectral types and color indices of the stars make it possible to infer that grain radii in the clouds exceed typical interstellar medium values and, further, that they increase with optical depth into the cloud. The present observations indicate that the cloud structure is far more extensive than previously realized.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 85; Dec. 198
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  • 43
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    Publication Date: 2011-08-18
    Description: A numerical hydrodynamics computer code analysis of the collapse and establishment of equilibrium of adiabatic gas clouds restricted to axial symmetry found that the clouds are originally uniform in density and rotation. The method can compare the dynamic collapse and approach to equilibrium with the data on incompressible uniformly rotating equilibrium clouds and on equilibrium structures of differentially rotating polytropes. It is concluded that the stellar formation theory indicates that the low alpha fragments produced at the termination of the dynamic isothermal collapse phase of interstellar clouds may undergo significant dynamic collapse in an adiabatic regime leading to transitory ring formation and additional fragmentation on a smaller scale.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
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  • 44
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    Publication Date: 2011-08-18
    Description: Copernicus observations of H2 toward stars in the Pleiades and 23 Orionis have been obtained because of their importance in understanding the formation of interstellar CH(+). No model of CH(+) equilibrium seems to agree very well with these observations; in particular, the suggestions that CH(+) is formed either from collisions between vibrationally excited H2 and C(+) or from radiative association of C(+) and H2 can apparently be excluded. These data do suggest that there is a correlation between the amounts of rotationally excited H2 and CH(+) which are present. Observations of the Pleiades also help interpretations of the reflection nebulae near these stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
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  • 45
    Publication Date: 2011-08-18
    Description: A simple method of computing theoretical models of very massive stars endowed with fast axial rotation and tangled magnetic fields is described and used in the present paper. Both of the two perturbing (nongravitational) forces induce changes in the luminosity and radius that are studied as functions of zero-age chemical composition, opacity, and evolutionary state of the interior. The central condensation of the star is found to have a significant influence on shifts of the upper main-sequence band in the H-R diagram if the perturbing force is concentrated in the stellar envelope (but not if the perturbing force is distributed so as to be approximately proportional to gravity everywhere); the layers of the envelope that contribute most heavily to the central condensation lie approximately at a radius fraction of r/R = 0.5. It is shown that fast uniform rotation and intense envelope magnetic fields lead to probably the largest possible shifts of the main-sequence band in the H-R diagram that rotation and magnetic fields can induce. These displacements are, however, too small to account for the total width of the observed main-sequence band at luminosities brighter than log (L/solar luminosity) = 4.5.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
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  • 46
    Publication Date: 2011-08-18
    Description: It is shown that only a small fraction of the many supernovae in the Galaxy produces observable supernova remnants; this fraction, which is found to depend weakly on the lower mass limit of the SN progenitors, and more strongly on the specific characteristics of the associated interstellar medium, decreases from about 15% near the galactic center to 10% at R(gal) of about 10 kpc and drops nearly to zero for R(gal) greater than 15 kpc. Whether an SNR is detectable is determined by the density of the ambient interstellar medium in which it is embedded; it is found that SNRs are detectable only above some critical density (about 0.1 per cu cm). The presence of large low-density superbubble cavities around stellar associations due to the combined effects of stellar winds and supernova shells strongly suggests that a large portion of the detectable SNRs must have runaway stars as their progenitors.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
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  • 47
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    Publication Date: 2011-08-18
    Description: The transient gamma-ray burst observed on March 5, 1979 by the nine spacecraft forming the interplanetary gamma-ray burst network is discussed. Measurements reveal the event to be unlike any previously observed gamma-ray burst or X-ray burster, with a maximum intensity greater than several thousandths erg/sq cm per sec, a rise time of less than 200 microsec, a narrow and featureless initial spike and a regular 8-sec oscillation with a compound pulse shape. The source of the transient has been localized to a region including the supernova remnant N 49 in the Large Magellanic Cloud, at a distance of 55 pc, and a ratio of X-ray point-source steady state to transient emission of less than 10 to the -9th was obtained. The identification of the burst source with the supernova remnant at that distance would require an enormous source output if it was radiated isotropically, and substantially less if beaming is present. Alternatively, the event could be explained by a nearby, invisible neutron star.
    Keywords: ASTROPHYSICS
    Type: Comments on Modern Physics; vol. 9
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  • 48
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    Publication Date: 2011-08-18
    Description: The paper presents data on the accumulated V-band orbital phase curves of polarization in Cygnus X-1 which disagree with the analysis of Simmons, Aspin, and Brown (1980). No curves which conform to the canonical model were observed, and a noncanonical structure is indicated by F tests on third, fourth, and fifth harmonics, which have a probability of 0.85 as a group. The fifth harmonic has a probability of 0.99; in contrast, the fundamental harmonic has a probability of only 0.6, which is below the detection threshold. Therefore, major conclusions of Simmons et al based on a nonsymmetrical canonical model assuming that fundamental harmonics are present, but harmonics with n greater than 2 are absent, are unacceptable. Analysis of the author's data by Simmons et al is criticized on the grounds that he did not take into account the cumulative aspects of the data and did not recognize the need to average out the random noise generated by Cygnus X-1 over many orbital cycles.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 91; 1-2,; Nov. 198
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  • 49
    Publication Date: 2011-08-18
    Description: The X-ray observations of the galaxy clusters Abell 2319 and 576 show a reduced temperature of the microwave background due to the Suniaev-Zeldovich effect. The X-ray maps indicate smooth emission in these clusters concentrated toward the optical center; the surface brightness in the 1-3 keV band falls with the inverse square of radius outside a small core, and fits the Hubble's law of optical surface brightness of elliptical galaxies. The low temperature indicates that in A576 (1) the core radius of the gravitational potential is two to three times larger than inferred from galaxy counts, (2) the temperature rises with radius over most of the cluster and falls to zero at large radii, and (3) the gas does not obey the equation of state.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
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  • 50
    Publication Date: 2011-08-18
    Description: Leith has suggested that climatic response to change in external forcing parameters of the climate system may be estimated via the fluctuation-dissipation theorem (FDT). The method, which uses the natural fluctuations of the atmosphere to probe its dynamics, is tested here using a twenty-variable truncation model of the barotropic vorticity equation. Dissipative terms are added to the equations, so that the model is pushed away from the region where it is expected to satisfy the FDT. It is found that, even though the FDT is no longer satisfied in every detail, the FDT continues to provide an excellent estimate of the climatic sensitivity of the model.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences; 37; Aug. 198
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  • 51
    Publication Date: 2011-08-18
    Description: Potential industrial sites were assessed using high and medium altitude aircraft photographs and supporting information on the 4,730 sq. km. (1,825 sq. mile) county. Factors evaluated include land availability, slope, site accessibility, soil drainage, other subsurface characteristics, and the expected physical as well as visual impacts on existing land use. Areas unavailable or unsuitable for development were eliminated first, and the remaining areas evaluated and the best sites identified.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Cornell Univ. Remote Sensing Program; 138 p
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  • 52
    Publication Date: 2011-08-18
    Description: A zoom stereoscope was used to interpret aerial color photographs of the Finger Lakes region near Bath, New York, and areas of conifers were delineated on acetate sheets. Scale was determined for each photograph and units were converted to acres. Photographically enlarged positive transparencies of imagery from LANDSAT bands 5,6, and 7 for the southern portion of the study area were placed in a cold additive viewer and registered with each other to provide a composite image. A green filter was used on band 5, blue on band 6, and red on band 7. Conifers appeared at dark, reddish purple. Average was determined using a grid. Results show that the total confer stands within 50 miles of Bath is approximately 176,000 acres of which 60,000 acres are in Pennsylvania. The study was conducted to determine the feasibility of locating a particleboard manufacturing firm in the Southern Tier.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Cornell Univ. Remote Sensing Program; 3 p
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  • 53
    Publication Date: 2011-08-18
    Description: Manual photointerpretation techniques were used to analyze images acquired by high altitude aircraft, the Skylab multispectral and Earth terrain camera (ETC), the LANDSAT multispectral scanner, and the LANDSAT-3 return beam vidicon camera. A color-additive viewer, and digital image analysis were also used on the LANDSAT MSS imagery. The value of each type of remotely sensed data was judged by the ease and accuracy of clearcut identification, and by the amount of detail discernible, especially regarding revegetation. Results of a site study in the Allegheny National Forest, Pennsylvania indicate that high altitude aerial photography, especially color infrared photography acquired during the growing season, is well suited for identifying clearcuts and assessing revegetation. Although photographs acquired with Skylab's ETC also yielded good results, only incomplete inventories of clearcuts could be made using LANDSAT imagery. Results for the Adirondack region of New York State were similar for the aircraft and satellite photography, but even less satisfactory for the LANDSAT imagery.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Cornell Univ. Remote Sensing Program; 157 p
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  • 54
    Publication Date: 2011-08-18
    Description: Operational weather satellites are built as a series of nearly identical instruments which are flown for 5 to 7 years. Minor improvements are made during the life of the series. However, major improvements and changes in design are made with the initiation of a new series of instruments. Similarly, procedures used to process the data are characterized by frequent changes early in the life of a satellite series as user experience is gained with the new instrument. Later the changes become less frequent, both because the processing system becomes well tuned to that particular set of instruments and because, at the end of a series, resources are devoted to generating the processing system for the next set of instruments. Past and present systems are considered with emphasis on the vertical temperature profile radiometer and a procedure for deriving clear radiances in partly cloudy areas.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Goddard Space Flight Center VAS Demonstration Sounding Workshop; p 11-18
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  • 55
    Publication Date: 2011-08-17
    Description: The nova outburst is modeled by spherically accreting H-rich material onto a 1 solar mass He white dwarf at a rate of 10 to the -8th solar mass/yr. The star accretes for 5848 years, when the nuclear reactions run away near the base of the accreted envelope. The nuclear-energy generation rate rises to 4.6(8) solar luminosities, and the envelope expands in response to it. However, nova-like mass ejection does not occur because the envelope is of insufficient mass, the base of the envelope is only mildly electron degenerate, and there is no enrichment of the CNO abundance. To overcome these limiting conditions, it is suggested that the H-rich material be accreted either more slowly than 10 to the -10th solar mass/yr or with angular momentum. Outbursts resulting in the former case should be similar to the nova models computed by Starrfield, Truran, and Sparks. Outbursts in the latter case should be strengthened, and novae might result because the H-rich material will be mixed into the surface layers of the white dwarf, as first suggested by Kippenhahn and Thomas (1978).
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 56
    Publication Date: 2011-08-17
    Description: A model is proposed in which regions of enhanced synchrotron emission are formed via radiative thermal instabilities in relativistic flows. A perturbed volume in which the magnetic field is enhanced by a few tens of a percent relative to the steady value collapses due to the increased cooling rate and consequent loss in pressure. The collapse further increases the magnetic field, leading to even shorter radiative lifetimes. The instability progresses in this way until either the external electron pressure is balanced by the perturbed magnetic pressure or the overall expansion of the flow becomes important. A fluid-dynamical treatment of the instability is performed, and the results are shown to apply to flux variations and formation of knots in the relativistic flows which are thought to occur in quasars and active galactic nuclei. The knots possess the same kinematic properties as the collimated flow and can thus be responsible for the apparent superluminal motions observed in compact radio sources.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 57
    Publication Date: 2011-08-17
    Description: The various stages in carrying out a monocluster block unsupervised classification using Landsat MSS data are described. Procedures for carrying out these various stages were found to be far from well-established for the type of terrain being investigated, which is rugged and contains many small land cover units. Two particular difficulties were encountered: first, that of precise ground location of pixels; and, secondly, that of objectively evaluating the results. Ways in which these can be surmounted are suggested.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
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  • 58
    Publication Date: 2011-08-17
    Description: A binary star model is used to account for the 16.59-d flaring behavior of the X-ray emission from Circinus X-1. The orbital eccentricity of 0.8 + or - 0.1 is derived from the X-ray light curve by assuming that the sharp X-ray cut-off every 16.59-d is a result of bound-free absorption in the primary star's stellar wind. The shape of the light curve has changed over the last eight years, and this is interpreted as due to orbital precession of the binary system. Simultaneous radio and X-ray observations of the flare from Circinus X-1 on February 1-5, 1978 are reported. These are accounted for within the framework of the model. The radio observations at 5 GHz are used independently to derive a high value of the orbital eccentricity (e = 0.7).
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 86; 3, Ju; July 198
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  • 59
    Publication Date: 2011-08-17
    Description: IUE observations of the eclipsing binary system Zeta Aurigae made prior to and during the eclipse of the relatively small B8 V star by the cool supergiant star (spectral type K2 II) are reported. Spectral lines produced by the absorption of B star radiation in the atmosphere of the K star during eclipse can be used as a probe of the extended K star atmosphere, due to the negligible cool star continuum in the 1200-3200 A region. Spectra taken prior to eclipse are found to be similar to those of the single B8 V star 64 Ori, with the exception of very strong multi-component absorption lines of Si II, Si IV, C IV and the Mg resonance doublet with strong P Cygni profiles, indicating a double shell. Absorption lines including those corresponding to Al II, Al III, Cr II, Mn II, Fe II, Ni II and Ca II are observed to increase in strength and number as the eclipse progresses, with high-ionization-potential lines formed far from the K star, possibly in a shock wave, and low-ionization potential lines, formed in cool plasma, probably a cool wind, nearer to the K star. Finally, an emission-line spectra with lines corresponding to those previously observed in absorption is noted at the time the B-star continuum had disappeared.
    Keywords: ASTROPHYSICS
    Type: Nature; 286; Aug. 7
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  • 60
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
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  • 61
    Publication Date: 2011-08-17
    Description: Current estimates of QSO luminosity, number density, evolution, and spectral index are used to study whether the diffuse cosmic ray background is (1) entirely due to thermal bremmstrahlung of the intergalactic medium (IGM), (2) completely supplied by QSO X-rays, or (3) a combination of both. The upper limits on an IGM fractional density with respect to closure are Omega = 0.26, 0.24, and 0.21 for pure collisional, photo/collisional, and pure photoionization, respectively. These calculations give emission spectra, Compton distortion of the microwave background, and optical depths to distant QSOs for comparison with relevant data.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
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  • 62
    Publication Date: 2011-08-17
    Description: Three algorithms for calculating polychromatic atmospheric transmittance functions have been tested using a set of eleven distinct temperature profiles in order to compare transmittance accuracies achievable by the three methods. The comparison of rms errors demonstrates that the iterative method of McMillin and Fleming (1976) is the most accurate of the efficient algorithms currently available for gases with constant mixing ratios; its accuracy approaches that of the spectroscopic parameters and the computational approximations used in the ground-truth line-by-line calculations. The method of Arking et al. (1974), while less accurate, has the advantage of being perfectly general and easily adapted to cases where spectral bandwidths are varied
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Applied Optics; 19; July 15
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  • 63
    Publication Date: 2011-08-17
    Description: Improvements to a computer model of coma photochemistry are described. These include an expansion of the chemical reactions network and new rate constants that have been measured only recently. Photolytic reactions of additional molecules are incorporated, and photolytic branching ratios are treated in far greater detail than previously. A total of 25 photodissociative ionization (PDI) reactions are now considered (as compared to only 3 PDI reactions previously). Solar PDI of the mother molecule CO2 is shown to compete effectively with photoionization of CO in the production of observed CO(+). The CO(+) density peak predicted by the improved model, for CO2 or CO mother molecules, is deep in the inner coma, in better agreement with observation than the old CO2 model. However, neither CO2 nor CO mother molecule calculations reproduce the CO(+)/H2O(+) ratio observed in comet Kohoutek. PDI products of CO2, CO, CH4, and NH3 mother molecules fuel a complex chemistry scheme, producing inner coma abundances of CN, C2, and C3 much greater than previously calculated.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
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  • 64
    Publication Date: 2011-08-17
    Description: The formation of CN radicals by flash photolysis of a number of parent molecules was monitored by laser induced fluorescence in the B2Sigma(plus)-X2Sigma(plus) transition of CN. The rotational and vibrational energy of the newly formed radicals in the X state was measured directly. Formation of CN(A2Pi) in the lower vibrational levels was determined by an indirect method based on resonant energy transfer to higher vibrational levels of the ground state. These laboratory studies have shown that high initial internal excitation of CN with rotational levels of maximum N equals 50-70 is the rule. In general, the formation of simple molecules in excited states is commonly the case. There appear to be astrophysical systems where radiation from these excited levels may be detectable. Such observations would serve as a probe of molecular formation.
    Keywords: ASTROPHYSICS
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  • 65
    Publication Date: 2011-08-17
    Description: Low-resolution spectra of IRC + 10216 have been obtained from 2 to 8.5 microns from NASA's Kuiper Airborne Observatory at an altitude of 12.5 km (41,000 feet). Observations were made during 1976 January and 1977 February. In both sets of data, the spectral flux reaches its maximum between 6.0 and 6.6 microns and the previously reported 3.1-micron feature is observed; no obvious new absorption features have been found. The new data together with other spectral data and measurements of the spatial extent of IRC + 10216 impose conditions that must be met by models of the continuum. Several simple models for 2-8.5 micron radiation are examined. The new continuum data impose a constraint on the size of the grains in the cooler, optically thin part of the object. Earlier photometry has been combined with the present data to yield an improved value of the average period: 644 + or - 17 days. It appears that the variability is irregular and that the minima have been deeper in recent years than they were in 1965-1969.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
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  • 66
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    Publication Date: 2011-08-17
    Description: A series of two-dimensional numerical experiments is performed in order to test the response of an isothermal, self-gravitating gas disk to a uniformly rotating, barlike gravitational potential. The barlike potential is an equilibrium stellar model from the n-body calculations of Miller and Smith (1979). In the bar-dominated, central regions of the disk, a gas bar whose phase depends primarily on the location of principal resonances in the disk is formed. This response can be understood in terms of orbit-crowding effects. In the gas-dominated outer regions of the disk, two-armed trailing spiral waves are formed. The local pitch angle of these waves increases with increasing fractional gas mass. These self-gravitating gas waves are not self-sustaining. They are driven from the ends of equilibrium stellar bars, and their phase does not depend on the location of resonances in the disk. The relevance of these self-gravitating waves to observations and models of barred spiral galaxies is discussed. It is concluded that these waves and their associated ringlike structures may be consistent with the morphological distribution of gas features in barred spiral galaxies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
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  • 67
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    Publication Date: 2011-08-17
    Description: It is suggested that Freeman's (1970) result that the disk portions of spiral galaxies have a preferred central surface brightness might be the consequence of observing optically thick ensembles of a standard mix of stars and dust. Regardless of whether this hypothesis is correct, the observation that elliptical galaxies usually have central surface brightnesses considerably greater than the disk portions of spirals can be understood if there is much less dust within the elliptical systems. In particular, ellipticals probably have dust-to-total-mass ratios at least a factor of 100 smaller than in the disk portions of spirals, although there is no evidence that the dust-to-interstellar-gas ratios are different. When stars were forming within ellipticals, these galaxies were probably dustier than they are now, and their visible light output could have been substantially affected. It will probably be necessary to establish the dust content of galaxies as a function of redshift to use these objects as cosmological probes.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
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  • 68
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
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  • 69
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 191
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  • 70
    Publication Date: 2011-08-17
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Environmental Quality; 9; Jan
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  • 71
    Publication Date: 2011-08-17
    Description: X-ray spectral observations of two nearby low-luminosity clusters of galaxies are presented. For the Centaurus cluster an emission feature at 7.9 keV is detected at about one-third of the strength of the 6.7 keV line. This higher energy line represents K-beta emission from highly ionized iron. In addition, it is demonstrated that for neither the Centaurus nor the A1060 cluster can an isothermal model with an Fe emission line adequately fit the data. Instead, the simplest models which provide acceptable fits include a second, harder component which may be either a second exponential or a power law. The implications of the two-component nature of the continuum on the Fe abundance and the X-ray surface-brightness distribution are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
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  • 72
    Publication Date: 2011-08-17
    Description: Observations and limiting values for the flux of 1-20 MeV gamma rays from the Crab, the Seyfert galaxy NGC 4151, the black hole candidate Cyg X-1, Cyg X-3 and the two nearest quasars CG 135+1 and 3C 273 are reported. Measurements of the energy and scatter angle of gamma rays at zenith angles between 10 and 30 deg were obtained by a balloon-borne double-scatter gamma-ray telescope. The flux from the Crab from 1.2 to 10 MeV is found to be 0.0039 + or - 0.0020 photons/sq cm per sec, and the energy distribution of the flux from 1.2 to 20 MeV is determined. Two-standard-deviation upper limits to the gamma-ray flux in the intervals 1.2-3, 3-5, 5-10 and 10-20 MeV of 0.0003, 0.0002, 0.00006 and 0.00004 photons/sq cm/sec are found for NGC 4151, Cyg X-1 and Cyg X-3, while those of 0.0005, 0.0003, 0.0001 and 0.00004 photons/sq cm per sec are determined for both quasars. These upper limits are interpreted as restricting confirmed gamma-ray sources to the Crab and NP 0532, and as evidence against Seyfert galaxies as the source of cosmic diffuse radiation.
    Keywords: ASTROPHYSICS
    Type: Nature; 284; Apr. 17
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  • 73
    Publication Date: 2011-08-17
    Description: Copernicus and SAS-3 observations of Sco X-1 during very active states show strong and rapid X-ray flickering with time scales as short as 20 sec. Simultaneous optical photometry reveals similar and remarkably well correlated flickering of lower amplitude. The level of correlation decreases when the X-ray source becomes fainter, but optical and X-ray fluxes, averaged over 1 min, are usually well correlated for B magnitudes less than 12.9. Cross-correlation analysis of the data during periods of high activity shows no really significant time delay between X-ray and optical features, although the cross-correlation function peaks systematically for positive lag values (optical following X-rays). The amplitude of the X-ray flickering exhibits a strong energy-dependence consistent with the well-known intensity versus spectral-hardness relation derived from previous observations. The highly correlated optical activity is interpreted as due to reprocessing of X-ray photons in the binary system.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 191
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  • 74
    Publication Date: 2011-08-17
    Description: The present analysis is an application of the theory described by Lucy (1971) for the calculation of P Cygni resonance line profiles formed by isotropic and coherent scattering in spherically symmetric expanding circumstellar envelopes. Copernicus satellite measurements of resonance features in the FUV spectrum of the O 7 supergiant UW Canis Majoris (= HD 57060) are compared with theoretical P Cygni profiles. Grids of line profiles are computed using four free parameters which contain information about the velocity law, ionization equilibrium, temperature, and envelope density. Thus, with the assumption of a spherically symmetric steady flow, and of solar element abundances, the stellar mass loss rate and the electron temperature of the expanding shell can be derived. The mass flow is treated in a fully transonic way, i.e., the Sobolev approximation is applied.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 83; 3, Ma; Mar. 198
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  • 75
    Publication Date: 2011-08-17
    Description: Recent IUE observations reveal striking differences in the UV spectra of two symbiotic stars, R Aqr and RW Hya. RW Hya is found to be an unexpectedly intense source of UV radiation. The measurements reported demonstrate the presence of a hot component in each star, supporting the view that each is a binary system with a luminous red primary and a hot, subluminous companion. In one case, the hot companion manifests itself by exciting a compact nebulosity; in the other case the continuous spectrum of the hot star is directly detected, while the continuum of nebulosity excited by the hot star is detected at longer wavelengths.
    Keywords: ASTROPHYSICS
    Type: Nature; 284; Mar. 13
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  • 76
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    Publication Date: 2011-08-17
    Description: The dynamic collapse of rotating gas clouds is calculated for a wide range of initial conditions. Properties of cloud models are compared with observed radio and optical properties of Bok globules, to test the hypothesis that globules undergo collapse and to determine parameters which are not easily observed. Five of the six globules studied are consistent with collapse models. It is inferred that these objects have masses of about 100 solar masses and ages smaller than their free-fall times. Inferred initial densities are much larger than minimum densities for gravitational collapse, suggesting that collapse is initiated by strong external compression or that globules are fragments of larger condensed clouds. Values inferred for the (C-13)O/H2 ratio are smaller than previous estimates and depend strongly on cloud density.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
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  • 77
    Publication Date: 2011-08-17
    Description: For the first time the Hoyle-Narlikar theory with creation of matter and a variable gravitational constant G, is subjected to the following cosmological tests: (1) the magnitude versus z relation, (2) the N(m) versus m relation for quasars, (3) the metric angular diameters versus z relation, (4) the isophotal angles versus z relation, (5) the log N-log S radio source count, and finally (6) the 3 K radiation. It is shown that the theory passes all these tests just as well as the standard cosmology, with the additional advantage that the geometry of the universe is uniquely determined, with a curvature parameter equal to zero. It is also interesting to note that the variability of G affects the log N-log S curve in a way similar to the density evolution introduced in standard cosmologies. The agreement with the data is therefore achieved without recourse to an ad hoc density evolution.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 236
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  • 78
    Publication Date: 2011-08-17
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
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  • 79
    Publication Date: 2011-08-17
    Description: The identification of the 114,221-MHz line in the spectrum of the evolved carbon star IRC +10216 with a blend of the rotational transition of C4H and the first rotational transition of vibrationally excited CO is investigated. A spectrum of the source was obtained using an 11-m telescope in the range covering the N = 12 to 11 and 11 to 10 spin-doublet rotational transitions of C4H. Two peaks of equal intensity and width are found in each band, suggesting a spin rotation constant of 1.06 for the 12 to 11 doublet and 1.09 for the 11 to 10 doublet, and excluding the possibility that vibrationally excited CO made any contribution to the 12 to 11 doublet. An additional survey of the regions from 103.8 to 107.5 and 113.3 to 117.0 GHz has revealed no new lines stronger than 0.1 K in the spectrum of IRC +10216.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
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  • 80
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    Publication Date: 2011-08-17
    Description: The determination of the geometrical structure of the universe through the magnitude-vs-redshift relation in standard cosmology has not been very successful, mainly because of the intrinsic insensitivity of the m-vs-z relation to a deceleration parameter, which determines the spatial curvature and therefore the geometry. By relaxing the assumption usually made, i.e., the identity of gravitational and atomic clocks, sufficient sensitivity is achieved. Existing observational evidence then leads one to conclude that the universe is open.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters; 44; Mar. 17
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  • 81
    Publication Date: 2011-08-17
    Description: This paper describes the overall Large Area Crop Inventory Experiment technical approach utilizing the global weather-reporting network and the Landsat satellite to make a quasi-operational application of existing research results, and the accomplishments of this cooperative experiment in utilizing the weather information. Global weather data were utilized in preparing timely yield estimates for selected areas of the U.S. Great Plains, the U.S.S.R. and Canada. Additionally, wheat yield models were developed and pilot tested for Brazil, Australia, India and Argentina. The results of the work show that heading dates for wheat in North America can be predicted with an average absolute error of about 5 days for winter wheat and 4 days for spring wheat. Independent tests of wheat yield models over a 10-year period for the U.S. Great Plains produced a root-mean-square error of 1.12 quintals per hectare (q/ha) while similar tests in the U.S.S.R. produced an error of 1.31 q/ha. Research designed to improve the initial capability is described as is the rationale for further evolution of a capability to monitor global climate and assess its impact on world food supplies.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Applied Meteorology; 19; Jan. 198
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  • 82
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N80-19588)
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Dec. 198
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  • 83
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N79-33530)
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Nov. 198
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  • 84
    Publication Date: 2011-08-18
    Description: The development of agricultural remote sensing systems requires knowledge of agricultural field size distributions so that the sensors, sampling frames, image interpretation schemes, registration systems, and classification systems can be properly designed. Malila et al. (1976) studied the field size distribution for wheat and all other crops in two Kansas LACIE (Large Area Crop Inventory Experiment) intensive test sites using ground observations of the crops and measurements of their field areas based on current year rectified aerial photomaps. The field area and size distributions reported in the present investigation are derived from a representative subset of a stratified random sample of LACIE sample segments. In contrast to previous work, the obtained results indicate that most field-size distributions are not log-normally distributed. The most common field size observed in this study was 10 acres for most crops studied.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Remote Sensing of Environment; 10; Nov. 198
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  • 85
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    Publication Date: 2011-08-18
    Description: Topics of astronomy are discussed in terms of black holes, galaxies, quasars, and models of the universe. Black holes are approached through consideration of stellar evolution, white dwarfs, supernovae, neutron stars, pulsars, the event horizon, Cygnus X-1, white holes, and worm holes. Attention is also given to radio waves from high speed electrons, the radiation emitted by quasars, active galaxies, galactic energy sources, and interpretations of the redshift. Finally, the life cycle of the universe is deliberated, along with the cosmic time scale, evidence for the Big Bang, and the future of the universe.
    Keywords: ASTROPHYSICS
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  • 86
    Publication Date: 2011-08-18
    Description: Using stepwise discriminant analysis on spectral reflectance and spectral emissivity data collected by a Multispectral Scanner and Data System, mounted in an NC-130B aircraft and flown at an altitude of approximately 3 km, spectral bands were ranked as to their usefulness in separating specific rock types and rock alteration products in seven geologically diverse Utah sites. The optimum band for rock discrimination included the 1.18 to 1.30 micron interval, and the optimum combination of bands comprised the 1.18 to 1.30, 4.50 to 4.75, 0.46 to 0.50, 1.52 to 1.73, and 2.10 to 2.36 micron intervals. It is concluded that the spectral interval combination was more successful in differentiating geologic materials than either simulated Multispectral Scanner bands or simulated Thematic Mapper bands.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Photogrammetric Engineering and Remote Sensing; 46; Sept
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  • 87
    Publication Date: 2011-08-18
    Description: The applicability of the piecewise linear function in place of a similar smoothly-varying current profile is examined in the baroclinic context. Within the framework of small-perturbation linearization, the behavior of the vertical velocity and the horizontal divergence is analyzed at the discontinuity of the current shear. In the conventional geostrophic-type instability regime, the discontinuity in the horizontal divergence at the shear discontinuity is suppressed, and, therefore, the piecewise linear profile leads to a useful approximation to the true solution. In the symmetric-type instability regime, however, due to the magnified discontinuity in the horizontal divergence at the shear discontinuity, the solution thus obtained will show a major distortion, rendering the piecewise linear profile inadequate for modeling the smoothly-varying current profile. Using exemplary current profiles, numerical results are presented to demonstrate the behavior of the horizontal divergence near the discontinuity of current shear.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Meteorological Society of Japan; vol. 58
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  • 88
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    Publication Date: 2011-08-18
    Description: Molecular clouds may be stabilized against gravitational collapse by the turbulent velocity field within them. It is suggested that the energy derived from differential galactic rotation can maintain the turbulent flow in the interstellar medium. The characteristic decay time for interstellar turbulence is found to be about 10-billion years. The rate and efficiency of star formation in giant molecular clouds reflect the stochastic nature of turbulence.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
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  • 89
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    Publication Date: 2011-08-18
    Description: The rapid coherent oscillation during a dwarf nova outburst is attributed to an accretion-driven wave going around the white dwarf component of the binary system. The increase and decrease in the period of this oscillation is due to the change in the velocity of the wave as it is first being driven and then damped. Qualitatively, a large number of observations can be explained with such a model. The beginnings of a mathematical representation of this model are developed.
    Keywords: ASTROPHYSICS
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  • 90
    Publication Date: 2011-08-18
    Description: Numerical calculations of the collapse of adiabatic clouds from uniform density and rotation initial conditions show that when restricted to axisymmetry, the clouds form either near-equilibrium spheroids or rings. Rings form in the collapse of low thermal energy clouds and have a ratio of rotational kinetic energy to the absolute value of gravitational potential energy greater than approximately 0.43. When the axisymmetric constraint is removed and an initial m = 2 density variation is introduced, clouds either collapse to form near-equilibrium ellipsoids or else fragment into binary systems through a bar phase. Ellipsoids form in the collapse of high thermal energy clouds and have a rotational kinetic energy/absolute value of gravitational potential energy ratio less than approximately 0.27. The results are consistent with the critical values of the rotational kinetic energy/absolute value of gravitational potential energy ratio for instabilities in Maclaurin spheroids, and suggest that protostellar clouds may undergo a dynamic fragmentation in the nonisothermal collapse regime.
    Keywords: ASTROPHYSICS
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  • 91
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    Publication Date: 2011-08-18
    Description: Changes in solar radius and luminosity are discussed as a function of age. Surface and satellite observations showing departures from mean solar irradiance on a time scale of a few days are summarized. The most prominent depressions in these data appear to be correlated with sunspot number, indicating that the activity modulation of solar luminosity may be larger than expected. High activity is correlated with low luminosity, but during the Maunder minimum the mini ice age (presumably low luminosity) was accompanied by a near absence of solar activity. Pulsations driven by sources deep within the Sun are thought to be an unlikely cause of luminosity changes, but causes may be sought in the unstable convective zone. Experiments designed to measure the solar radius are mentioned, along with modelling efforts.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: CNES Sun and Climate; p 295-304
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  • 92
    Publication Date: 2011-08-18
    Description: The Goddard Laboratory for Atmospheric Sciences approach to temperature sounding from satellite observations is fundamentally different from that of NESS in that heavy reliance is placed on the ability to model accurately the instrumental response to atmospheric and surface conditions, while no use is made of statistical relationships between satellite observations and atmospheric temperature profiles. The method involves starting with a guess set of atmospheric and surface conditions from which expected brightness temperatures for the satellite observations are computed. Then, iterative relaxation of atmospheric and surface conditions is performed according to the difference between observed and computed brightness temperatures until sufficient agreement is reached. In the absence of sufficient agreement, no retrieval is produced for that location.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: VAS Demonstration Sounding Workshop; p 41-55
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  • 93
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    Publication Date: 2011-08-18
    Description: The analytical equations used to interpret TIROS-N sounding radiances for operational applications are presented. Both the National Environmental Satellite System (NESS) Global Operational Synoptic Scale and the NESS/University of Wisconsin (UW) North American Mesoscale Sounding Production Systems are considered.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA. Goddard Space Flight Center VAS Demonstration Sounding Workshop; p 1-10
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  • 94
    Publication Date: 2011-08-17
    Description: Visible and near-infrared field spectral reflectance measurements of plutonic rocks were acquired in the 0.45- to 2.45-micron region with a portable field reflectance spectrometer. These spectra were used to determine spectral signatures for the various rock types and to evaluate the separability of these rocks based on their spectral characteristics. A total of 135 samples were divided into 11 groups based on their mineralogy. These 11 groups approximately correspond to traditional rock classifications and include five granitic groups, three gabbroic groups, and three ultramafic groups. The positions, intensity, and presence of iron, CO3(-2), and Al-OH and Mg-OH absorption bands varied among the 11 groups. Each rock group also had a range of albedos characteristic of the group. Stepwise linear discriminant analysis was performed on the spectral data to determine the separability of the 11 groups. Classification accuracy for 30 equally spaced wavelength bands between 0.45 and 2.45 microns was 78% with 10% serious misclassifications. The same analysis was repeated, limiting the spectral data to the wavelength regions corresponding to the proposed Landsat D thematic mapper scanner.
    Keywords: EARTH RESOURCES AND REMOTE SENSING
    Type: Journal of Geophysical Research; 85; May 10
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  • 95
    Publication Date: 2011-08-17
    Description: The Solid State Spectrometer on the Einstein Observatory has detected line emission from Mg, Si and S in the thermal X-ray spectrum of the supernova remnant G292.0 + 1.8. An over-abundance of sulfur and a probable under-abundance of iron relative to their solar values is indicated by the data. The X-ray and optical data for this object support an interpretation of emission originating in ejecta from the comparatively recent explosion of a massive (about 20-solar-mass) progenitor star.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 193
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  • 96
    Publication Date: 2011-08-17
    Description: Fluxes in 1 A bands at the centers of the H and K lines are being measured in main-sequence F-G-K-M stars in the northern half of the Woolley et al. (1970) 'Catalog of stars within twenty-five parsecs of the sun', in a survey not yet completed. Results for 486 stars are presented in the form of flux-color diagrams and discussed in light of evidence that chromospheric activity declines with age in main-sequence stars. Support is noted for the reality of the Sirius moving group. The relative numbers of more-active (Hyades-like) and less-active (solar-like) F-G stars are tolerably in agreement with a nearly constant rate of formation, but there exists an apparent deficiency in the number of F-G stars exhibiting intermediate activity. The possibility that the gap is an accidental characteristic of the sample will be investigated by extending the survey to southern declinations and greater distances.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 92
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  • 97
    Publication Date: 2011-08-17
    Description: Short-interval SMS-2 visible digital image data are used to derive wind vectors from cloud tracking on time-lapsed sequences of geosynchronous satellite images. The cloud tracking areas are located in the Central Plains, where on May 6, 1975 hail-producing thunderstorms occurred ahead of a well defined dry line. Cloud tracking is performed on the Goddard Space Flight Center Atmospheric and Oceanographic Information Processing System. Lower tropospheric cumulus tracers are selected with the assistance of a cloud-top height algorithm. Divergence is derived from the cloud motions using a modified Cressman (1959) objective analysis technique which is designed to organize irregularly spaced wind vectors into uniformly gridded wind fields. The results demonstrate the feasibility of using satellite-derived wind vectors and their associated divergence fields in describing the conditions preceding severe local storm development. For this case, an area of convergence appeared ahead of the dry line and coincided with the developing area of severe weather. The magnitude of the maximum convergence varied between -10 to the -5th and -10 to the -14th per sec. The number of satellite-derived wind vectors which were required to describe conditions of the low-level atmosphere was adequate before numerous cumulonimbus cells formed. This technique is limited in areas of advanced convection.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Monthly Weather Review; 108; Sept
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  • 98
    Publication Date: 2011-08-17
    Description: Observations of the neighboring X-ray pulsars 4U 1145-61 and 1E 1145.1-6141 obtained by OSO 8, HEAO 1 and the Einstein Observatory between 1975 and 1979 are reported. A temporal analysis of Einstein Solid State Spectrometer and Monitor Proportional Counter data, OSO 8 A and C detector data and HEAO 1 A-2(3) experiment data confirms the presence of two periodicites at 291 and 297 sec in the region, with the shorter period located within 3 arcmin of 4U 1145-61. Observations indicate the spectrum of 4U 1145-61 to obey a power law with an index of 1.5 out to at least 60 keV, with little variation with pulse phase, and a 500-eV EW iron line at 6.7 keV. The spectrum of the other source is found to be more absorbed. Similarities between the pulsars are noted, and it is suggested that they may be the result of pulsar formation in a homogeneous cloud of progenitors.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 99
    Publication Date: 2011-08-17
    Description: Cygnus X-3 was observed by the Monitor Proportional Counter on the Einstein (HEAO 2) X-ray Observatory for 2.4 days in 1978 December. The analysis of the data from these observations is used in conjunction with a self-consistent re-examination of previous results from the Uhuru, ANS, COS B, and SAS 3 satellites to investigate earlier reports that the 4.8 hour period of Cygnus X-3 is increasing. It is found that there is indeed a period derivative, P = (1.78 plus or minus 0.40) x 10 to the -9th s/s, which confirms the principal conclusion of previous authors. The possibility that the X-ray source is in an elliptical orbit and that some, or all, of the observed period derivative may be due to apsidal motion is discussed. The elliptic orbit hypothesis explains the observed asymmetry in the average X-ray light curve and leads to the conclusion that the most likely companion to the X-ray source is a helium star, possibly with a light hydrogen envelope
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 100
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    Publication Date: 2011-08-17
    Description: An observational H-R diagram for the O and B stars is discussed and compared with the predicted positions of massive model stars for the case of no mass loss and the case of mass loss. It is shown that the flux effective temperatures of O and B supergiants and of early O stars are less than the effective temperatures which might be inferred from the relative intensities of lines from two stages of ionization of an element.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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