Mesoscale convergence proceding thunderstorm development determined from cloud motions
Convergence was determined from wind vectors derived from cloudtracking on 5 minute interval SMS-2 data using the AOIPS.
Pelsen, C. A.↗
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High resolution tropical cyclone wind fields determined from cloud motions
Full resolution rapid scan infrared and visible images from the VISSR sensor on board SMS-2/GEOS-1 satellite have made it possible to maximize the number of tropical cyclone upper and lower tropospheric wind vectors by a factor of 6(2) over that of the images taken at 30 minute (15 minute) intervals. These full resolution rapid scan visible images have also made it possible to derive low level winds near the center of tropical cyclones.
Rodgers, E. B.↗
Stereographic cloud heights from the imagery of two scan-synchronized geostationary satellites
Scan synchronization of the sensors of two SMS-GOES satellites yields imagery from which cloud heights can be derived stereographically with a theoretical two-sigma random uncertainty of + or - 0.25 km for pairs of satellites separated by 60 degrees of longitude. Systematic height errors due to cloud motion can be kept below 100 m for all clouds with east-west components of speed below hurricane speed, provided the scan synchronization is within 40 seconds at the mid-point latitude, and the spin axis of each satellite is parallel to that of the earth.
Minzner, R. A.↗
Thunderstorm intensity as determined from satellite data
Digital infrared data from SMS 2 obtained on May 6, 1975 are used to study thunderstorm vertical growth rates and cloud top structure in relation to the occurrence of severe weather (tornadoes, hail, and high wind) on the ground. All thunderstorms from South Dakota to Texas along a N-S oriented cold front were monitored for a 4 h period with 5 min interval data. Thunderstorm growth rate, as determined by the rate of blackbody temperature isotherm expansion and minimum cloud top temperature, are shown to be correlated with reports of severe weather on the ground.
Adler, R. F.↗
Orbit/attitude estimation for the GOES spacecraft using VAS landmark data
A software system is described which provides for batch least squares estimation of spacecraft orbit, attitude, and camera bias parameters using image data from the Geostationary Operational Environmental Satellites (GOES). The image data are obtained by the Visible and Infrared Spin Scan Radiometer (VISSR) Atmospheric Sounder (VAS). The resulting estimated parameters are used for absolute image registration. Operating in the Digital Equipment Corporation (DEC) PDP-11/70 computer, the FORTRAN system also includes the capabilities of image display and manipulations. An overview of the system is presented as well as some numerical results obtained from observations taken by the SMS-2 satellite over a 3 day interval in August 1975.
Sielski, H.↗
Mark 3 VLBI system: Tropospheric calibration subsystems
Tropospheric delay calibrations are implemented in the Mark 3 system with two subsystems. Estimates of the dry component of tropospheric delay are provided by accurate barometric data from a subsystem of surface meteorological sensors (SMS). An estimate of the wet component of tropospheric delay is provided by a water vapor radiometer (WVR). Both subsystems interface directly to the ASCII Transceiver bus of the Mark 3 system and are operated by the control computer. Seven WVR's under construction are designed to operate in proximity to a radio telescope and can be commanded to point along the line-of-sight to a radio source. They should provide a delay estimate that is accurate to the + or - 2 cm level.
Resch, G. M.↗
Moisture convergence using satellite-derived wind fields - A severe local storm case study
Five-minute interval 1-km resolution SMS visible channel data were used to derive low-level wind fields by tracking small cumulus clouds on NASA's Atmospheric and Oceanographic Information Processing System. The satellite-derived wind fields were combined with surface mixing ratios to derive horizontal moisture convergence in the prestorm environment of April 24, 1975. Storms began developing in an area extending from southwest Oklahoma to eastern Tennessee 2 h subsequent to the time of the derived fields. The maximum moisture convergence was computed to be 0.0022 g/kg per sec and areas of low-level convergence of moisture were in general indicative of regions of severe storm genesis. The resultant moisture convergence fields derived from two wind sets 20 min apart were spatially consistent and reflected the mesoscale forcing of ensuing storm development. Results are discussed with regard to possible limitations in quantifying the relationship between low-level flow and between low-level flow and satellite-derived cumulus motion in an antecedent storm environment.
Negri, A. J.↗
KU-Band rendezvous radar performance computer simulation model
The preparation of a real time computer simulation model of the KU band rendezvous radar to be integrated into the shuttle mission simulator (SMS), the shuttle engineering simulator (SES), and the shuttle avionics integration laboratory (SAIL) simulator is described. To meet crew training requirements a radar tracking performance model, and a target modeling method were developed. The parent simulation/radar simulation interface requirements, and the method selected to model target scattering properties, including an application of this method to the SPAS spacecraft are described. The radar search and acquisition mode performance model and the radar track mode signal processor model are examined and analyzed. The angle, angle rate, range, and range rate tracking loops are also discussed.
Griffin, J. W.↗
A computer system for geosynchronous satellite navigation
A computer system specifically designed to estimate and predict Geostationary Operational Environmental Satellite (GOES-4) navigation parameters using Earth imagery is described. The estimates are needed for spacecraft maneuvers while prediction provide the capability for near real-time image registration. System software is composed of four functional subsystems: (1) data base management; (2) image processing; (3) navigation; and (4) output. Hardware consists of a host minicomputer, a cathode ray tube terminal, a graphics/video display unit, and associated input/output peripherals. System validity is established through the processing of actual imagery obtained by sensors on board the Synchronous Meteorological Satellite (SMS-2). Results indicate the system is capable of operationally providing both accurate GOES-4 navigation estimates and images with a potential registration accuracy of several picture elements (pixels).
Koch, D. W.↗
Comparisons of some large scientific computers
In 1975, the National Aeronautics and Space Administration (NASA) began studies to assess the technical and economic feasibility of developing a computer having sustained computational speed of one billion floating point operations per second and a working memory of at least 240 million words. Such a powerful computer would allow computational aerodynamics to play a major role in aeronautical design and advanced fluid dynamics research. Based on favorable results from these studies, NASA proceeded with developmental plans. The computer was named the Numerical Aerodynamic Simulator (NAS). To help insure that the estimated cost, schedule, and technical scope were realistic, a brief study was made of past large scientific computers. Large discrepancies between inception and operation in scope, cost, or schedule were studied so that they could be minimized with NASA's proposed new compter. The main computers studied were the ILLIAC IV, STAR 100, Parallel Element Processor Ensemble (PEPE), and Shuttle Mission Simulator (SMS) computer. Comparison data on memory and speed were also obtained on the IBM 650, 704, 7090, 360-50, 360-67, 360-91, and 370-195; the CDC 6400, 6600, 7600, CYBER 203, and CYBER 205; CRAY 1; and the Advanced Scientific Computer (ASC). A few lessons learned conclude the report.
Credeur, K. R.↗
Monitoring tropical cyclone intensity using wind fields derived from short-interval satellite images
Rapid scan visible images from the Visible Infrared Spin Scan Radiometer sensor on board SMS-2 and GOES-1 were used to derive high resolution upper and lower tropospheric environmental wind fields around three western Atlantic tropical cyclones (1975-78). These wind fields were used to derive upper and lower tropospheric areal mean relative vorticity and their differences, the net relative angular momentum balance and upper tropospheric mass outflow. These kinematic parameters were shown by studies using composite rawinsonde data to be strongly related to tropical cyclone formation and intensity changes. Also, the role of forced synoptic scale subsidence in tropical cyclone formation was examined. The studies showed that satellite-derived lower and upper tropospheric wind fields can be used to monitor and possibly predict tropical cyclone formation and intensity changes. These kinematic analyses showed that future changes in tropical cyclone intensity are mainly related to the "spin-up" of the storms by the net horizontal transport of relative angular momentum caused by convergence of cyclonic vorticity in the lower troposphere and to a lesser extent the divergence of anticyclone vorticity in the upper troposphere.
Rodgers, E. B.↗
Absolute image registration for geosynchronous satellites
A procedure for the absolute registration of earth images acquired by cameras on geosynchronous satellites is described. A conventional least squares process is used to estimate navigational parameters and camera pointing biases from observed minus computed landmark line and element numbers. These estimated parameters along with orbit and attitude dynamic models are used to register images, employing an automated grey-level correlation technique, inside the span represented by the landmark data. Experimental results obtained from processing the SMS-2 observation data base covering May 2, 1979 through May 20, 1979 show registration accuracies with a standard deviation of less than two pixels if the registration is within the landmark data span. It is also found that accurate registration can be expected for images obtained up to 48 hours outside of the landmark data span.
Nankervis, R.↗
Simulation for STS flight crew training
Training activities for flights of the Space Shuttle Orbiter are performed in the most complicated flight simulation facility yet assembled. The Shuttle Mission Simulator (SMS) provides training for the entire mission from prelaunch to postlanding. An extensive pilot-cues environment is provided in which visual, aural, and motion cues are presented. The planning and execution of training on the simulator must take into account the complexity of the Shuttle systems, the complexity of the procedures and crew interface on the Shuttle, and the complexity of the mission, itself. The major points of this training program are highlighted.
Hughes, F. E.↗
An operational software system for geosynchronous satellite navigation
A software system has been designed to provide navigation parameters during the VAS experiment of the GOES-4 mission along with annotation data for near real time image registration. The four functional subsystems of the software system, Data Base Management, Image Processing, Navigation, and Output, and the principal hardware components are characterized. The ability of the system to fulfil its two principal objectives is verified by results obtained from processing actual SMS-2 satellite imagery.
Koch, D. W.↗
Comparison of measured and calculated mode redistribution associated with spinning mode transmission through circumferentially segmented lined ducts
An experiment was conducted to investigate mode redistribution in lined circular ducts with circumferential impedance nonuniformities. Mode insertion losses were measured for six-segment, two-segment, and uniform liners in a spinning mode synthesizer (SMS) in the quiet flow facility in the Langley Aircraft Noise Reduction Laboratory and correlated with predicted transmission losses. Both experiment and theory show that circumferentially segmented duct liners do scatter energy into circumferential modes of different orders. Good agreement measured and calculated attenuations was obtained for circumferential mode numbers paired with zero order radial mode numbers. For the higher order radials, the agreement was not as good.
Parrott, T. L.↗
Utilization of satellite and surface observations in a gravity wave study
The possibility of detecting gravity waves in the upper troposphere by means of satellite imagery is examined. Attention is focused on the gravity wave event of March 27, 1975, for which the surface wave is analyzed by a pressure perturbation analysis based on barograph traces and a surface wind divergence analysis. IR observations were also made of the event with instrumentation on board the synchronous meteorological satellite (SMS-1). Strong wind gusts were reported at surface stations immediately following severe drops in the surface pressures, events which were found not to be connected with convective activity. The wave was concluded to extend throughout the troposphere with an axis tilted with height, indicating the wave was generated from an upper level energy source. It is suggested that the gravity wave was an adjustment to ageostrophic motions within the jet stream entering the Midwest. The finding is in concert with previous observations of jet streaks upstream from surface gravity waves.
Pecnick, M. J.↗
Monitoring tropical-cyclone intensity using environmental wind fields derived from short-interval satellite images
The feasibility of predicting changes in tropical storm intensity based on satellite observations of the dynamical relationships between the large-scale upper and lower tropospheric circulations surrounding the cyclone and the characteristics of the storm's inner core is studied. Rapid-scan visible images from the SMS-1 and GOES-1 satellites were used to examine the local change in relative angular momentum (RAM), the lower and upper tropospheric environmental areal mean relative vorticity and transverse circulation on three consecutive days for tropical storms Caroline (August, 1975), Anita (August and September, 1977) and Ella (September, 1978). The three case studies suggest that storm intensification may be predicted from the storm's local change of net RAM, with this quantity best correlated with storm intensification after a time lag of 6 hours. Intensification is also found to be related to the environmental lower and upper tropospheric areal-mean relative vorticity, and to the upper tropospheric environmental circulation, which acts either to hinder or to enhance the storm's anticyclonic outflow channels.
Rodgers, E.↗
Solid modelling in the Department of Energy
Three solid modellers (SMs) are evaluated in this study. The findings and opinions about their merits and deficiencies are discussed.
Peterson, D. R.↗