ALBERT

Description: Satellite scatterometers are active microwave radars designed to yield measurements of near surface horizontal wind velocity over the ocean. Scatterometers are unique in that they are the only existing microwave remote sensing instruments that allow measurements of both wind speed and wind direction. NASA will fly a scatterometer, NSCAT, aboard the Navy Ocean Remote Sensing System (N-ROSS) mission starting in late 1990. N-ROSS is a spaceborne ocean remote sensing system with a planned mission life of three years. In addition to the NSCAT, N-ROSS will have three other microwave instruments mounted on a single satellite flying in a near polar orbit: an altimeter; a special sensor microwave/imager (SSM/I); and a low frequency microwave radiometer. The NSCAT to be flown on N-ROSS is described.

Description: The following topics are addressed: (1) motivation for the National Meteorological Center (NMC) simulation project; (2) history of the NMC simulation project; (3) experimental design of the WINDSAT observing system simulation experiment; (4) preparation of the simulated observations; and (5) strengths and weaknesses of the experimental design.

Description: High-resolution cloud motion wind (CMW) data sets obtained from geostationary satellites for approximately the past decade have been used for the purpose of estimating mesoscale wind fields in various research studies. Yet there remains much controversy surrounding the proper interpretation and use of the resultant wind vector and kinematic fields. This paper is concerned with: (1) how representative are cloud draft winds of actual ambient air motions; and (2) what is the degree of practical usefulness of CMW fields for both mesoscale analysis and as input to numerical weather prediction models.

Description: A potential improvement on measuring atmospheric winds by using a coherent Doppler system has led to a need for detailed knowledge concerning the aerosol backscattering characteristics, especially at CO2 wavelengths. In order to meet this requirement, a plan of study has been developed to establish a global data base of atmospheric aerosol backscattering coefficients.

Description: Photographs of cloud scenes taken from the orbiting space shuttle are being used to assess the overestimation in the amount of cloud cover sensed by satellites at angles other than nadir. Also these photographs and Landsat images indicate that the frequency distributions of clear and of cloudy intervals, at least in simple tropical cloud scenes, may be approximated by common distribution functions.

Description: It has been proposed that a Doppler lidar be placed in a polar orbit and scanned to provide estimates of lower tropospheric winds twice per day and with a spatial resolution of 300 km. Initial feasibility studies conducted primarily by NOAA and NASA presented an optimistic outlook for a space based lidar. The technology appeared within reach and initial computer simulations suggested that acceptable accuracies could be obtained. Those early studies exposed, however, several potential problem areas which included: (1) the algorithms for computing the wind vectors did not perform well when there were coherent gradients in the wind fields; and (2) the lifetime and power requirements of the lidar put severe restrictions on the pulse repetition frequency (PRF). These two basic problems are currently being addressed by a Doppler lidar simulation study focussed upon three primary objectives: (1) to develop optimum scan parameters and shot patterns for a satellite-based Doppler lidar; (2) to develop robust algorithms for computing wind vectors from lidar returns; and (3) to evaluate the impact of coherent mesoscale structures (wind gradients, clouds, aerosols) on up-scale wind estimates. An overview is provided of the simulation efforts with particular emphasis upon rationale and methodology. Since this research is currently underway, any results shown are meant only as evidence of progress.

Description: The Wave Propagation Laboratory of the National Oceanic and Atmospheric Administration's (NOAA) Environmental Research Laboratories has investigated the feasibility of measuring the global wind field by using an infrared coherent laser radar under a joint program with the U.S. Air Force Space Division Defense Meteorological Satellite Program (DMSP). These studies considered both the analytical and hardware feasibility of a spaceborne global wind measuring coherent laser radar (WINDSAT). Objectives and requirements of the Air Force Defense Meteorological Satellite Program were used in the study. The vertical distributions of the horizontal wind field were required throughout the troposphere with 300 km square horizontal and 1 km vertical resolution with a measurements accuracy of 1 m/s. Complete global coverage was required. The lidar system performance should also be scalable to operational satellite conditions. The analytical studies were performed for both a 300 km altitude Space Shuttle orbit and an operational polar orbit of 800 km altitude (Huffaker, 1978; Huffaker et al., 1980). A hardware definition study was performed for a Space Shuttle demonstration test flight (Lockheed Missiles and Space Co., 1981). Studies have also been conducted to determine the feasibility of mounting a WINDSAT payload on an Advanced TIROS-N spacecraft (RCA Corporation, 1983).

Description: A study has been completed to define a Shuttle experiment that solves the most crucial scientific and engineering problems involved in building a satellite Doppler wind profiler for making global wind measurements. The study includes: (1) a laser study to determine the feasibility of using the existing NOAA Windvan laser in the Space Shuttle spacecraft; (2) a preliminary optics and telescope design; (3) an accommodations study including power, weight, thermal, and control system requirements; and (4) a flight trajectory and operations plan designed to accomplish the required scientific and engineering goals. The experiment will provide much-needed data on the global distribution of atmospheric aerosols and demonstrate the technique of making wind measurements from space, including scanning the laser beam and interpreting the data. Engineering accomplishments will include space qualification of the laser, development of signal processing and lag angle compensation hardware and software, and telescope and optics design. All of the results of this limited Spacelab experiment will be directly applicable to a complete satellite wind profiler for the Earth Observation System/Space Station or other free-flying satellite.

Description: WINDSAT is a proposed space based global wind measuring system. A Shuttleborne experiment is proposed as a proof of principle demonstration before development of a full operational system. WINDSAT goals are to measure wind speed and direction to + or - 1 m/s and 10 deg accuracy over the entire earth from 0 to 20 km altitude with 1 km altitude resolution. The wind measuring instrument is a coherent lidar incorporating a pulsed CO2 TEA laser transmitter and a continuously scanning 1.25 m diameter optical system. The wind speed is measured by heterodyne detecting the backscattered return laser radiation and measuring this frequency shift.

Description: Hitherto, long-range wind-sensing coherent (heterodyne) lidars have utilized CO2 lasers (operating at a 10-micrometer wavelength) since these were the only high-power single-mode (spatial and axial) pulsed sources available. This property ensures temporal coherence over the required spatial resolution, e.g., the pulse length. Recent developments in Nd:YAG lasers makes possible the consideration of a 1.06-micrometer source (Kane et al., 1984). The relative merit of operation at various wavelengths is a function of system parameter, backscattering cross section, signal processing, beam propagation, and practical and eye safety considerations. These factors are discussed in the context of a global wind-sensing coherent lidar.

Description: The rapid development of laser diodes offers the opportunity to design an all solid state transmitter for coherent Doppler lidar by using Nd:YAG as the gain medium. We have demonstrated that the components of such a system operate as expected. We believe that LD-pumped solid state laser oscillators and amplifiers offer an approach to space qualified transmitters with coherence, power, efficiency, and operating lifetime necessary to meet satellite platform requirements.

Description: Coherent laser radar systems at 10 micrometers have been studied in Europe for well over a decade. In the past few years, the level of activity has increased rapidly and work is now in progress on systems and components at a large number of research institutions and industrial firms. Some of the organizations have had specific involvement with wind and aerosol measuring lidars, while others are largely concerned with components. Some of the particular European strong points are reviewed in device physics and technology. In addition to wind measurement systems, much work has been done on other applications of coherent laser radar including ranging, imaging, and coherent DIAL studies. Some of these other applications are also outlined.

Description: Now, there are four Doppler lidar configurations which are being promoted for the measurement of tropospheric winds: (1) the coherent CO2 Lidar, operating in the 9 micrometer region using a pulsed, atmospheric pressure CO2 gas discharge laser transmitter, and heterodyne detection; (2) the coherent Neodymium doped YAG or Glass Lidar, operating at 1.06 micrometers, using flashlamp or diode laser optical pumping of the solid state laser medium, and heterodyne detection; (3) the Neodymium doped YAG/Glass Lidar, operating at the doubled frequency (at 530 nm wavelength), again using flashlamp or diode laser pumping of the laser transmitter, and using a high resolution tandem Fabry-Perot filter and direct detection; and (4) the Raman shifted Xenon Chloride Lidar, operating at 350 nm wavelength, using a pulsed, atmospheric pressure XeCl gas discharge laser transmitter at 308 nm, Raman shifted in a high pressure hydrogen cell to 350 nm in order to avoid strong stratospheric ozone absorption, also using a high resolution tandem Fabry-Perot filter and direct detection. Comparisons of these four systems can include many factors and tradeoffs. The major portion of this comparison is devoted to efficiency. Efficiency comparisons are made by estimating the number of transmitted photons required for a single pulse wind velocity estimate of + or - 1 m/s accuracy in the middle troposphere, from an altitude of 800 km, which is assured to be reasonable for a polar orbiting platform.

Description: To gain a proper perspective of the potential of coherent Doppler lidars for global wind sensing sometime in the future, we need to examine where we are, how we got here, and the expectations for future lidar system development. First we give a brief review of lidar developments leading to our present technology. Next we survey present U.S. infrared systems with particular attention to the pulsed systems since they are the ones that will have sufficient range to operate from satellites. Finally we comment on trends and probable future developments. Only unclassified lidars are considered. The considerable DoD support for classified applications certainly enhances future developments in components and subsystems.

Description: This paper describes the current status of a prototype 0.53 micrometer Doppler lidar system under development at RCA. This system consists of a frequency doubled Nd:YAG laser constrained to yield a narrow bandwidth, single frequency pulse, a Fabry-Perot Inteferometer (FPI) using an Image Plane Detector (IPD) to measure the backscatter spectrum for each pulse and a Data Acquisition System (DAS) to sample, store, and analyze the backscattered signal. These individual subsystem components have been assembled and preliminary atmospheric testing has recently begun. Atmospheric backscatter spectra are presented which demonstrate the capabilities of this system to distinguish between return signals from aerosols, molecules, and clouds.

Description: The topics covered include the following: principles of Doppler measurements, laser backscatter, eye safety, demonstration concepts, the wavelength-meter, the interferometer detector, return signal model, and comparison of incoherent and coherent lidars.

Description: Nature has provided us with a natural and easily visible method of tracing atmospheric motion through the measurement of cloud velocities. This source of wind information has been available from geosynchronous satellites since the launch of the ATS-1 Spin Scan camera. This sensor provided adequate spatial and temporal resolution views of individual cloud systems that could represent the wind with useful accuracy. During the last decade, cloud motion derived winds have become part of the operational system as they are routinely provided to the National Meteorological Center as input to the global numerical models. The principal limitations of cloud motion winds are that they (1) can be measured within the limits that cloud motions can represent the wind only where trackable clouds exist, (2) require knowledge of the cloud height, (3) require high spatial and temporal resolution geosynchronous satellite systems with high attitude determination accuracy, and (4) need sophisticated interactive computer systems for the calculation of high resolution fields. These limitations are examined and suggestions are made for how this product could be improved. Also, uses of the data for mesoscale purposes are discussed.

Description: The story of the Aircraft to Satellite Data Relay (ASDAR) program began when airline meteorologists realized that B-747's and other commercial jets provided cockpit displays of digital values for outside air temperature and winds. Later, when a few B-747's were used to carry portable air quality monitoring equipment for the Global Air Sampling Program (GASP), scientists at NASA-Lewis explored ways in which these digital values could be used to label data collected during the GASP flights. Digital values of GASP analyses were recorded along with digital values of location and altitude, time, winds, and temperature, obtained by microprocessors from within the host aircraft's avionics. These data suggested a way in which manually recorded in-flight meteorological reports could be replaced by an automatic system, which could record winds and air temperatures as often as desired. NASA's prototype ASDAR showed that automated data relay by meteorological geostationary satellites could be accomplished from an aircraft. Testing of the instruments and analyses of its data are examined.

Description: A balloon-borne triple-etalon Fabry-Perot Interferometer, observing the Doppler shifts of absorption lines caused by molecular oxygen and water vapor in the far red/near infrared spectrum of backscattered sunlight, has been used to evaluate a passive spaceborne remote sensing technique for measuring winds in the troposphere and stratosphere. There have been two successful high altitude balloon flights of the prototype UCL instrument from the National Scientific Balloon Facility at Palestine, TE (May 80, Oct. 83). The results from these flights have demonstrated that an interferometer with adequate resolution, stability and sensitivity can be built. The wind data are of comparable quality to those obtained from operational techniques (balloon and rocket sonde, cloud-top drift analysis, and from the gradient wind analysis of satellite radiance measurements). However, the interferometric data can provide a regular global grid, over a height range from 5 to 50 km in regions of clear air. Between the middle troposphere (5 km) and the upper stratosphere (40 to 50 km), an optimized instrument can make wind measurements over the daylit hemisphere with an accuracy of about 3 to 5 m/sec (2 sigma). It is possible to obtain full height profiles between altitudes of 5 and 50 km, with 4 km height resolution, and a spatial resolution of about 200 km, along the orbit track. Below an altitude of about 10 km, Fraunhofer lines of solar origin are possible targets of the Doppler wind analysis. Above an altitude of 50 km, the weakness of the backscattered solar spectrum (decreasing air density) is coupled with the low absorption crosssection of all atmospheric species in the spectral region up to 800 nm (where imaging photon detectors can be used), causing the along-the-track resolution (or error) to increase beyond values useful for operational purposes. Within the region of optimum performance (5 to 50 km), however, the technique is a valuable potential complement to existing wind measuring systems and can provide a low cost addition to powerful active (LIDAR) wind measuring systems now under development.

Description: A survey is presented of instrumentation suitable for measurement of wind near the surface of the earth by using in-situ techniques and further restricted to sensors that are operational. In this case, a sensor is deemed to be operational if it is commercially available. There is no discussion here of the systems that might be used to acquire, process, display, and store the sensor data. It is assumed that some sort of automatic data logging equipment would be used. Without special requirements such as need for high frequency response, low power consumption, etc., this treatment must be quite general and provides little detail. Also, without special restrictions, emphasis must be placed on conventional sensors that provide the bulk of wind data today.

Description: The superpressure balloon was developed to provide a method of obtaining global winds at all altitudes from 5 to 30 km. If a balloon could be made to fly for several weeks at a constant altitude, and if it could be tracked accurately on its global circuits, the balloon would provide a tag for the air parcel in which it was embedded. The Lagrangian data on the atmospheric circulation would provide a superior data input to the numerical model. The Global Atmospheric Research Program (GARP) was initiated in large part based on the promise of this technique coupled with free-floating ocean buoys and satellite radiometers. The initial name proposed by Charney for GARP was SABABURA 'SAtellite BAlloon BUoy RAdiometric system' (Charney, 1966). However, although the superpressure balloon exceeded its designers' expectations for flight duration in the stratosphere (longest flight duration of 744 days), flight duration below 10 km was limited by icing in super-cooled clouds to a few days. The balloon was relegated to a secondary role during the GARP Special Observing Periods. The several major superpressure balloon programs for global wind measurement are described as well as those new developments which make the balloon once again an attractive vehicle for measurement of global winds as a reference and bench-mark system for future satellite systems.

Description: The accuracy is studied of temperature estimates derived from the divergence equation when wind observations of various spatial and temporal resolutions and accuracies are available. The basic data set used is the high resolution model data set used by Kuo and Anthes (1984a) in observing systems simulation experiments (OSSE) designed to estimate the errors in heat and moisture budgets (Kuo and Anthes, 1984b) calculated from the AVE-SESAME-1979 spatial observational network. This model data set is modified in ways to simulate wind observations that appear feasible from an operational regional network of wind profilers.

Description: Continuous, automated measurement of tropospheric wind profiles with UHF and VHF Doppler radars has been demonstrated. Ground-based networks of these radars will be available as part of a global wind measurement system, and remote single stations could be built to further complement a spaceborne measurement device. A number of ground-based wind profilers will be in place by the time a space system is tested so the global wind measurement system should be designed with these ground-based profilers providing part of the picture.

Description: The Upper Atmosphere Research Satellite (UARS), to be launched in 1989, is to provide a global data set required to understand the mechanisms controlling upper atmosphere structure and processes, as well as the response of the upper atmosphere to natural and human perturbations. The High Resolution Doppler Imager (HRDI) is the primary instrument for measuring the dynamics of the stratosphere and mesosphere. The goal of HRDI is to measure wind velocities in the stratosphere and mesosphere during the day and the mesosphere and thermosphere at night with an accuracy of 5 m/sec. HRDI will determine winds by measuring Doppler shifts of atmosphere absorption and emission features. Line of sight winds will be taken in two directions, thus allowing the wind vector to be formed. The HRDI instrument is overviewed. The basis of the measurement is explained, as is an outline of the instrument. Since neither instrument nor observational techniques is fully mature, only a brief sketch is presented.

Description: It has been recognized for some time that water vapor structure visible in infrared imagery offers a potential for obtaining motion vectors when several images are considered in sequence (Fischer et al., 1981). A study evaluating water vapor winds obtained from the VISSR atmospheric sounder (Stewart et al., 1985) has confirmed the viability of the approach. More recently, 20 data sets have been produced from METEOSAT water vapor imagery for the FGGE period of 10-25 November 1979. Where possible, two data sets were prepared for each day at 0000 and 1200 GMT and compared with rawinsondes over Europe, Africa, and aircraft observations over the oceans. Procedures for obtaining winds were, in general, similar to the earlier study. Motions were detected both by a single pixel tracking and a cross correlation method by using three images individually separated by one hour. A height assignment was determined by matching the measured brightness temperature to the temperature structure represented by the FGGE-IIIB analyses. Results show that the METEOSAT water vapor winds provide uniform horizontal coverage of mid-level flow over the globe with good accuracy.

Description: The European Centre for Medium Range Weather Forecasts (ECMWF) is producing operational global analyses every 6 hours and operational global forecasts every day from the 12Z analysis. How the wind data are used in the ECMWF golbal analysis is described. For each current wind observing system, its ability to provide initial conditions for the forecast model is discussed as well as its weaknesses. An assessment of the impact of each individual system on the quality of the analysis and the forecast is given each time it is possible. Sometimes the deficiencies which are pointed out are related not only to the observing system itself but also to the optimum interpolation (OI) analysis scheme; then some improvements are generally possible through ad hoc modifications of the analysis scheme and especially tunings of the structure functions. Examples are given. The future observing network over the North Atlantic is examined. Several countries, coordinated by WMO, are working to set up an 'Operational WWW System Evaluation' (OWSE), in order to evaluate the operational aspects of the deployment of new systems (ASDAR, ASAP). Most of the new systems are expected to be deployed before January 1987, and in order to make the best use of the available resources during the deployment phase, some network studies are carried out at the present time, by using simulated data for ASDAR and ASAP systems. They are summarized.

Description: Two fraternal twin experiments were conducted as part of this study. A data impact experiment using real data (runs 1 and 2) was conducted to assess the impact that rawin wind observations have on both a 5-day assimilation and a single 5-day forecast generated at the end of each assimilation. An observing system simulation experiment (OSSE) using simulated observations (runs 3, 4, and 5) was conducted in order to first calibrate the OSSE results and second to use this calibration to estimate the 'real world' impact from the contribution of global 3-dimensional wind profiles generated from a space-based lidar system known as Windsat. Each of the three runs in the seond experiment were also 5-day assimilation runs with a 5-day forecast initialized from the last 6-hour update cycle of the assimilation. The data impact study revealed a consistent positive impact when rawin winds were added back into an otherwise complete FGGE data set. Both the 6-hour and 5-day forecasts were improved at all levels, in both hemispheres, and for both the wind and the geopotential height fields. Similar results were obtained from the two parallel simulation runs, 3 and 4. Together with the results from runs 1 and 2, calibration coefficients were generated so as to 'correct' the results determined from the addition of Windsat winds (run 5). The Windsat simulation showed a positive improvement in all cases studied. Even though only the tropics were enhanced with these wind observations, hemispheric rms errors were decreased in both the assimilation and 5-day forecast. The 6-hour forecasts of zonal wind from the assimilation run were improved by as much as 50 pct. on the average, and the single forecast showed an average improvement of near 30 pct. Even though these calibrated values are considered too optimistic, the skill of the forecast generated from this run extended the useful forecast period by 18-24 hours.

Description: A series of realistic simulation studies is being conducted as a cooperative effort between the European Centre for Medium Range Weather Forecasts (ECMWF), the National Meteorological Center (NMC), and the Goddard Laboratory for Atmospheres (GLA), to provide a quantitative assessment of the potential impact of future observing systems on large scale numerical weather prediction. A special objective is to avoid the unrealistic character of earlier simulation studies. Following a brief review of previous simulation studies and real data impact tests, the methodology for the current simulation system will be described. Results from an assessment of the realism of the simulation system and of the potential impact of advanced observing systems on numerical weather prediction and preliminary results utilizing this system will be presented at the conference.

Description: A brief review is presented of recent uses of ground-based wind profile data in mesoscale forecasting. Some of the applications are in real time, and some are after the fact. Not all of the work mentioned here has been published yet, but references are given wherever possible. As Gage and Balsley (1978) point out, sensitive Doppler radars have been used to examine tropospheric wind profiles since the 1970's. It was not until the early 1980's, however, that the potential contribution of these instruments to operational forecasting and numerical weather prediction became apparent. Profiler winds and radiosonde winds compare favorably, usually within a few m/s in speed and 10 degrees in direction (see Hogg et al., 1983), but the obvious advantage of the profiler is its frequent (hourly or more often) sampling of the same volume. The rawinsonde balloon is launched only twice a day and drifts with the wind. In this paper, I will: (1) mention two operational uses of data from a wind profiling system developed jointly by the Wave Propagation and Aeronomy Laboratories of NOAA; (2) describe a number of displays of these same data on a workstation for mesoscale forecasting developed by the Program for Regional Observing and Forecasting Services (PROFS); and (3) explain some interesting diagnostic calculations performed by meteorologists of the Wave Propagation Laboratory.

Description: Observational requirements are provided for the 'regional scale' (10(exp 2) to 10(exp 3) km space scale; 3 to 24 h time scale). Given this range, the regional scale represents a spatial and temporal domain in which important scale-interactive processes occur that act to concentrate large vertical wind shears, significant horizontal thermal gradients, and vertical motion patterns into narrow regions. A short review of the mass and momentum adjustments associated with jet streak-induced circulations is discussed. Evidence for the need to specify the wind field in the upper troposphere to accurately simulate forcing for the transverse circulations is also presented. The importance of specifying temperature tendency to resolve the lower tropospheric portion of the transverse circulations is highlighted. The observational requirements are then discussed, along with possible approaches for meeting the requirements on the regional scale.

Description: A passive infrared sensor is described for remote sounding of the wind field in the stratosphere and mesosphere from near Earth orbital spacecraft. The instrument uses gas correlation spectroscopy together with electro-optic phase modulation techniques to measure winds in the 20- to 120-km altitude range globally, both in the day and at night, and with a vertical resolution of better than the atmospheric scale height. Measurement of temperature and the amounts of key atmospheric species may also be made simultaneously and in coincident fields of view with the wind observations. The sensor is currently being developed at the Jet Propulsion Laboratory as a candidate for the upcoming NASA Earth Observation System.

Description: This paper reviews the current status of lidar image correlation techniques of remote wind measurement. It also examines the potential use of satellite borne lidar global wind measurements using this approach. Lidar systems can easily detect spatial variations in the volume scattering cross section of naturally occurring aerosols. Lidar derived RHI, PPI and range-time displays of aerosol backscatter have been extensively employed in the study of atmospheric structure. Descriptions of this type of data can be obtained in many references including Kunkel et al. (1977), Kunkel et al. (1980), Boers et al. (1984), Uthe et al. (1980), Melfi et al. (1985) and Browell et al. (1983). It is likely that the first space-borne lidars for atmospheric studies will observe aerosol backscatter to measure parameters such as boundary layer depth and cloud height. This paper examines the potential application of these relatively simple aerosol backscatter lidars to global wind measurements.

Description: A stated objective for this symposium is to identify requirements for global wind measurements. This paper will draw from recent reports which considered the impact of over 100 environmental factors known to affect military operations. A conclusion that can be drawn from those analyses is that one environmental factor, atmospheric wind, has an operational impact on each of the 48 mission areas examined. This paper will characterize the impact of wind on the various mission areas and will define and summarize both 'technical' and 'operational' requirements for wind intelligence.

Description: There are two theoretical arguments that have been used to discuss the relative importance of mass and wind data in numerical weather prediction (NWP). We will analyze these arguments in this section as clearly as possible in order to draw conclusions which may help to interpret experimental results on four-dimensional data assimilation, simulations of future observing systems, as well as give guidance on how to improve the efficiency with which we use the present observing system.

Description: The Capillary Pumped Loop (CPL) experiment, G-471 is a thermal control system with high density heat acquisition and transport capability. The CPL consists of two capillary pumped evaporators with integral heaters, a fluid loop charged with ammonia (NH3), a condenser plate (heat sink), and various control electronics. The purpose of the experiment is to demonstrate the capability of a capillary pumped system under zero gravity conditions for use in the thermal control of large scientific instruments, advanced orbiting spacecraft, and space station components.

Description: The low-g fluids management group with the Center for Space Construction is engaged in active research on the following topics: gauging; venting; controlling contamination; sloshing; transfer; acquisition; and two-phase flow. Our basic understanding of each of these topics at present is inadequate to design space structures optimally. A brief report is presented on each topic showing the present status, recent accomplishings by our group and our plans for future research. Reports are presented in graphic and outline form.

Description: A list of requirements for computational fluid dynamics verification is analyzed and evaluated. Requirements include: clearly defined physics and modeling, sensitivity studies, range, validation to real conditions, duplication of key experiments and computations, and combining experiments and computations. All results are presented in viewgraph format.

Description: Information is given in viewgraph form on computational fluid dynamics (CFD) validation experiments at the Lockheed-Georgia Company. Topics covered include validation experiments on a generic fighter configuration, a transport configuration, and a generic hypersonic vehicle configuration; computational procedures; surface and pressure measurements on wings; laser velocimeter measurements of a multi-element airfoil system; the flowfield around a stiffened airfoil; laser velocimeter surveys of a circulation control wing; circulation control for high lift; and high angle of attack aerodynamic evaluations.

Description: Computational fluid dynamics objectives are presented for Marshall Space Flight Center. Topics covered include: codes in use, applications to hardware development, and the Center's benchmark plan for the future. All results are presented in viewgraph format.

Description: Requirements and meaning of validation of computational fluid dynamics codes are discussed. Topics covered include: validating a code, validating a user, and calibrating a code. All results are presented in viewgraph format.

Description: Development of a pressure-strain model, an algebraic stress model, and wall functions appropriate for flows with spanwise variations in the local wall shear stress are accomplished. Furthermore, a hot-wire measurement technique was also developed for determining the local mean velocity and Reynolds stresses in a complex flow. Experiments were performed on supersonic and subsonic turbulent flow in a square duct, flow about a strut-endwall, flow within a transition duct, and on co-flowing annular jets with swirl. All results are presented in a viewgraph format.

Description: Information is given in viewgraph form on computational fluid dynamics (CFD) for aircraft design. Topics covered include CFD validation for advanced systems, cavity flow, transonic flow, separated flow, boundary layer interaction, hypersonic flow, heat transfer, zonal modeling, the mathematical foundation for Navier-Stokes simulation, hypersonic inlets, and the role of wind tunnel tests.

Description: The objective is to establish a detailed experimental data base for evaluation of Navier-Stokes codes for confined separated flows in diffusing s-ducts. The computational thrusts include the following: (1) extension and validation of the LeRC parabolized Navier-Stokes solver, PEPSIG, into the separated flow regime using 'flare' type approximations; (2) evaluation and extensions of state-of-the-art turbulence models for confined separated flow with and without swirl; and (3) evaluation and validation of LeRC time marching 3-D Navier-Stokes code, PROTEUS, into confined separate flow regime. Various aspects of the study are presented in viewgraph form.

Description: The topics are presented in viewgraph form and include the following: codes for computational aeroelasticity validation; the benchmark transonic flutter (BTF) model; BTF testing; the BTF model program; features of transonic flutter; characteristics of attached and separated flow for complete aircraft; and the benchmark aeroelastic model program.

Description: Current multi-stage turbomachinery design/analysis methods are based on a time-averaged, axisymmetric representation of the flow field. The actual flow field is asymmetric and unsteady due to blade row interactions. The Reynolds averaged Navier-Stokes solvers are limited to single-stage machines for existing computers. Therefore, advanced multi-stage compressors will operate far off-design for portions of the flight regime. The objectives are to provide an experimentally validated average-passage calculation of multistage compressor blade row interactions and an experimentally validated time-accurate calculation of multi-stage compressor blade row interactions. Various aspects of this investigation are presented in viewgraph form.

Description: The objective of the research project is to develop and validate analytical methods for low-speed aerodynamics. The experimental needs for computational methods are presented. All data and results are presented in viewgraph format.

Description: A discussion is presented on the coupling of computational analysis and experiment. It is believed that this coupling is critical in developing new aerodynamic insights. Additionally, new methods for analyzing and interpreting data are discussed. These methods need to be developed in small-scale research studies and then applied to large-scale technology programs. The specific objectives of this program are threefold: (1) provide definitive data sets for the assessment of numerical simulations to the Navier-Stokes equations; (2) incorporate advanced instrumentation to measure the spatial and temporal structure of fluid flows; and (3) develop true parallelism between computational and experimental research using the 'scientific workstation' concept. The discussion is presented in viewgraph form.

Description: A computational fluid dynamics code is validated using data obtained through a nonintrusive laser Doppler velocimeter. A space marching technique and a parabolic marching technique are use to calculate the flow in a compressor using compressible and incompressible flow assumptions. In a viewgraph format, both computational fluid dynamics techniques and experimental data are compared to each other.

Description: Wind tunnel tests are performed in order to validate a computational fluid dynamics code. A large scale, two dimensional separation bubble is created on a flat plate, and low speed, turbulent flow is used. Extensive data sets are obtained with a nonintrusive laser velocimeter in addition to wall static pressure, total pressure, and hot-film measurements. All data and results are presented in a viewgraph format.

Description: Information is given in viewgraph form on General Dynamics' perspective on computational fluid dynamics (CFD) code calibration and validation. Topics covered include a hypersonic blunted cone, a hypersonic wedge/cylinder, a wing vortex defined by Mach contours, pressure distributions, and 3D turbulent flow behind a 2D flat plate as measured in a water tunnel with a laser Doppler velocimeter.

Description: The dynamic characteristics of an oscillating airfoil are presented through graphical data derived from wind tunnel tests. The parameters examined include: transition position, boundary layer effects, lift coefficient, moment coefficient, free stream velocity, and Reynolds number.

Description: Information is given in viewgraph form on computational fluid dynamics (CFD) validation experiments at McDonnell Aircraft Company. Topics covered include a high speed research model, a supersonic persistence fighter model, a generic fighter wing model, surface grids, force and moment predictions, surface pressure predictions, forebody models with 65 degree clipped delta wings, and the low aspect ratio wing/body experiment.

Description: Information is given in viewgraph form on current computational fluid dynamics (CFD) efforts in projectile aerodynamics. Topics covered include spinning projectiles, fin stabilized projectiles, model geometry, the variation of base drag with base bleed, the variation of normal force with Mach number, and chordwise pressure distribution.

Description: The objective is to validate code capabilities to model and predict the critical physics associated with heat transfer in highly 3-D flows. Various aspects of this study are presented in viewgraph form and include the following: LeRC 3-D viscous codes; the 3-D compressible flow tunnel; RVC3D laminar horseshoe vortex calculation; the 3-D heat transfer code validation experiment; and measurements in 3-D compressible flow tunnel.

Description: The topics are presented in viewgraph form and include the following: NFL body experiment; high-speed validation problems; 3-D Euler/Navier-Stokes inlet code; two-strut inlet configuration; pressure contours in two longitudinal planes; sidewall pressure distribution; pressure distribution on strut inner surface; inlet/forebody tests in 60 inch helium tunnel; pressure distributions on elliptical missile; code validations; small scale test apparatus; CARS nonintrusive measurements; optimized cone-derived waverider study; etc.

Description: Validation activities and facility types are discussed for six different flow codes: (1) perfect gas; (2) real gas; (3) nozzle/plume; (4) combustion; (5) thermochemical nonequilibrium; and (6) boundary layer and transition. All data and results are presented in viewgraph format.

Description: It is established that Computational Fluid Dynamics (CFD) code validation is an integral part of all flow testing. Specific attention is given to the development of new methods/instruments to obtain time varying 3-D data. Additionally, a discussion concerning wind tunnels and small test facilities is presented. All results and data are presented in viewgraph form.

Description: The role of experiment in Computational Fluid Dynamics (CFD) is discussed. Flow modeling of complex physics and determination of accuracy limits (confidence) are two ways in which experimentation can be used to develop CFD. The results of this discussion are presented in viewgraph form.

Description: Thermocapillary flow and gaseous convection in microgravity were investigated in GAS payload G-0518 during Space Shuttle Mission 41-D. A cylinder of paraffin was supported and heated differentially from its ends to induce a melt from solid to liquid and drive thermocapillary flow in the resulting liquid phase. Laminar thermocapillary flow was observed in the liquid paraffin and found to show a transition to time-dependent oscillatory motion at a Marangoni number of about Ma = 34000 with a period of approximately T = 8 seconds. In addition, free convection in a gas in microgravity was observed for the first time. The gaseous convection was caused by the thermal and/or velocity boundary layers present at the heater-liquid interface. Oscillation occurred in the gaseous convection simultaneously with those in the liquid, implying the two are strongly coupled. The gaseous convection may be driven by coupled thermocapillary flow/thermal expansion convection or microgravity bouyancy convection.

Description: The Get Away Special (GAS) G-025, which flew on shuttle Mission 51-G, examined the behavior of a liquid in a tank under microgravity conditions. The experiment is representative of phenomena occurring in satellite tanks with liquid propellants. A reference fluid in a hemispherical model tank will be subjected to linear acceleration inputs of known levels and frequencies, and the dynamic response of the tank liquid system was recorded. Preliminary analysis of the flight data indicates that the experiment functioned perfectly. The results will validate and refine mathematical models describing the dynamic characteristics of tank-fluid systems. This will in turn support the development of future spacecraft tanks, in particular the design of propellant management devices for surface tension tanks.

Description: What happens if a stainless steel ball hits a water ball in the weightless space ot the Universe? In other words, it was the objective of our experiments in the Space to observe the surface tension of liquid by means of making a solid collide with a liquid. Place a small volume of water between 2 glass sheets to make a thin water membrane: the 2 glass sheets cannot be separated unless an enormous force is applied. It is obvious from this phenomenom that the surface tension of water is far greater than presumed. On Earth, however, it is impossible in most cases to observe only the surface tension of liquid, because gravity always acts on the surface tension. Water and stainless steel balls were chosen the liquid and solids for the experiments. Because water is the liquid most familiar to us, its properties are well known. And it is also of great interest to compare its properties on the Earth with those in the weightless space.

Description: Information is given in viewgraph form on the validation of computational fluid dynamics codes. Topics covered include the types of validation required, aerodynamic heating to a slender 5 degree cone, heat transfer on cones with isentropic compression surfaces, the validation of turbulence data, modeling of thermodynamic and transport properties, real gas code validation, the Flight Dynamics Laboratory validation efforts, and reacting gas experimental data in low density flow.

Description: Information on the planar compressible reacting shear layer is given in viewgraph form. topics covered include heat transfer in 3D flow regions, chemical reacting flows, an unsteady 2D compressible reacting code (MRVC2D), a plane mixing layer, and critical needs in shear layer physics.

Description: The topics are presented in viewgraph form and include the following: fundamental physics validation experiments; applied physics validation experiments; physical flow phenomena; boundary layer tunnel; boundary layer research; centrifugal compressors; centrifugal compressor flow phenomena; turbomachinery computational fluid dynamics (CFD) validation; inlet, duct, and nozzle CFD validation; and chemical reacting flows CFD validation.

Description: The topics are presented in viewgraph form and include the following: motivation, approach, planned experimental activities, shock-on-lip studies, and mass addition cooling studies.

Description: The topics are presented in viewgraph form and include the following: definitions of computational fluid dynamics (CFD) code validation; climate in hypersonics and LaRC when first 'designed' CFD code calibration studied was initiated; methodology from the experimentalist's perspective; hypersonic facilities; measurement techniques; and CFD code calibration studies.

Description: The objective of this research project is to determine the ability of Euler and Navier-Stokes codes to predict vortex/shock-dominated flow that is representative of modern fighter aircraft. The motivation for this project is fourfold: (1) current fighter aircraft are capable of operating beyond C(sub L(sub MAX)); (2) high angle-of-attack vortex/shock-dominated flows are not well understood; (3) current design methods are of the trial-and-error type; and (4) current data bases are inadequate for Computational Fluid Dynamics (CFD) validation. All data and results are presented in viewgraph format.

Description: The two types of Computational Fluid Dynamics code validations, solution-to-solution comparison and solution-to-experiment comparison, are discussed. It is suggested that to develop more detailed experiments the following things are necessary: (1) further development of turbulence models; (2) better methods for numerical validation of CFD codes; (3) evaluation of disagreements; and (4) continued determination of experimental scatter. All data and results are presented in viewgraph form.

Description: The aerodynamic and heat transfer coefficients are studied within the range of thermo-fluid-dynamic conditions experienced by a satellite during Tethered Satellite System (TSS) atmospheric flights. The gasdynamic processes occuring downstream of the bow wave standing in front of the satellite are also studied. The knowledge of the chemistry and physics of the upper atmosphere related to satellite aerothermodynamics is furthered. The existence of an overshooting of the air drag coefficient of the sphere in the transition regime is validated. A complete set of measurements is performed in order to provide the data base to develop and validate theoretical models of free molecule transition flow fields.

Description: An objective parameterization technique is developed for general nonlinear hydrodynamical systems. The typical structure of hydrodynamical systems, regardless of their complexity, is one in which the rates of change of the dependent variables depend on homogeneous quadratic and linear forms, as well as on inhomogeneous forcing terms. As a prototype of the generic problem containing this typical structure, the parameterization technique is applied to various three component subsets of a five component nonlinear spectral model of forced, dissipative quasi-geostrophic flow in a channel. The results obtained lead to specification of the necessary data coverage requirements for applying the technique in general.

Description: A steady, axisymmetric model of the general circulation is developed as a basis for climate stability studies. The model includes the effects of heating, rotation, and internal friction, but neglects topography. It is assumed that the axisymmetric flow may be modeled by making the Boussinesq and deep convection approximations. The hydrostatic assumption is not made, thus permitting the advective terms to be included in the vertical equation of motion. The initial set of five primitive equations is reduced to three equations in terms of the zonal velocity, meridional streamfunction, and the potential temperature perturbation. The application of the Boussinesq, deep convection, and quasi-geostrophic assumptions limits the ranges of the heating and rotation rates. For values not too far from typical atmospheric values, the model produces a stability boundary separating Hadley from Rossby flow. The boundary is characterized by a particular value of vertical wind shear, which suggests that baroclinic instability is the primary mechanism for the loss of stability. The initial growth rates are largest for longitudinal waves 4-7, also in agreement with studies of baroclinic instability.

Description: A two layer spectral quasi-geostrophic model is used to simulate the effects of topography on the equilibria, their stability, and the long term evolution of incipient unstable waves. The flow is forced by latitudinally dependent radiative heating. Dissipation is in the form of Rayleigh friction. An analytical solution is found for the propagating finite amplitude waves which result from baroclinic instability of the zonal winds when topography is absent. The appearance of this solution for wavelengths just longer than the Rossby radius of deformation and disappearance of ultra-long wavelengths is interpreted in terms of the Hopf bifurcation theory. Simple dynamic and thermodynamic criteria for the existence of periodic Rossby solutions are presented. A Floquet stability analysis shows that the waves are neutral. The nature of the form drag instability of high index equilibria is investigated. The proximity of the equilibrium shear to a resonant value is essential for the instability, provided the equilibrium occurs at a slightly stronger shear than resonance.

Description: Estimates of cloud street geometry produced by a model of the parallel/thermal instability modes of shallow convection are compared with observations obtained during the 1981 KonTur experiment. Good agreement between the modeled and observed orientation angles, wavelengths and Reynolds numbers are found when the streets are assumed to derive their energy from the average shear and the lowest order sine terms of a Fourier expansion of the mean wind profile (or equivalently from the lowest order cosine terms of the mean shear profile). The modes associated with the cosine terms of the wind profile (or the sine terms of the wind shear profile) do not agree well with the observations. These results suggest that the boundary layer rolls observed during KonTur might have developed owing to a combined parallel/thermal instability originating primarily from the cosine terms of the ambient roll parallel wind shear.

Description: Multipolarized airborne Synthetic Aperture Radar (SAR) data were acquired over a largely agricultural test site near Macomb, Illinois, in conjunction with the Shuttle Imaging Radar (SIR-B) experiment in October 1984. The NASA/JPL L-band SAR operating at 1.225 GHz made a series of daily overflights with azimuth view angles both parallel and orthogonal to those of SIR-B. The SAR data was digitally recorded in the quadpolarization configuration. An extensive set of ground measurements were obtained throughout the test site and include biophysical and soil measurements of approximately 400 agricultural fields. Preliminary evaluation of some of the airborne SAR imagery indicates a great potential for crop discrimination and assessment of canopy condition. False color composites constructed from the combination of three linear polarizations (HH, VV, and HV) were found to be clearly superior to any single polarization for purposes of crop classification. In addition, an image constructed using the HH return to modulate intensity and the phase difference between HH and VV returns to modulate chroma indicates a clear capability for assessment of canopy height and/or biomass. In particular, corn fields heavily damaged by infestations of corn borer are readily distinguished from noninfested fields.

Description: Multipolarization Synthetic Aperture Radar (SAR) data from the NASA/JPL aircraft SAR were used in conjunction with LANDSAT Thematic Mapper (TM), Thermal Infrared Multispectral Scanner (TIMS), and Airborne Imaging Spectrometer (AIS) data as part of a three-year research program to evaluate the utility of remote sensing measurements for analysis of sedimentary basins. The purpose of this research effort is to construct stratigraphic columns, map variations in the lithology, geometry, and structure of sedimentary rocks in the Wind River/Bighorn Basin area, Wyoming, and to integrate remote sensing data with conventional rain models of basin formation and evolution.

Description: Several digital data processing techniques were evaluated in an effort to identify and map active/abandoned, partially reclaimed, and fully revegetated surface mine areas in the central portion of Logan County. The TM data were first subjected to various enhancement procedures, including a linear contrast stretch, principal components and canonical analysis transformations. At the same time, four general procedures were followed to produce six classifications as a means of comparing the techniques involved. Preliminary results show that various feature extraction/data reduction techniques provide classification results equal or superior to the more straightforward unsupervised clustering technique. Analyst interaction time for labelling clusters is reduced using the canonical analysis and principal components procedures, though the canonical technique has clearly produced better results to date.

Description: An experiment designed to study some fundamental aspects of microgravity fluid dynamics has been built and is scheduled for flight. The purpose of the experiment is to investigate differences in behavior of wetting and nonwetting fluid systems at low Bond numbers. Methods were developed to determine liquid quantity, estimate vapor contact area and measure liquid layer thickness. Both the responses of the fluid systems to external perturbations and the transfer of liquid through a connection between two containers can be studied.

Description: Airborne Imaging Spectrometer data from Mono Lake, California, were studied in order to establish spectral radiance of test areas under solar illumination. The objective is to provide a method of atmospheric correction for major absorbers from the spectrometer data themselves. Crucial to the analysis is radiometric calibration of the instrument. Good agreement is found between calculated and measured radiances for uniform surface targets (beaches), but simulations of atmospheric properties with LOWTRAN lead to unreasonably low values of atmospheric precipitable water. Absorptions from carbon dioxide are not detected in the AIS data, but are strongly present in the LOWTRAN model. The apparent low contrast of all atmospheric absorption bands leads to a study of contamination from overlapping spectral orders in the AIS data. The suspected contamination is shown unambiguously to be present beyond approximately 1500 nm and consists of an extra radiance term including atmospheric bands from the delta/2 wavelength interval. A rigorous removal of the unwanted spectral contamination does not seem possible for any data taken in the rock mode. Rough estimates for tree-mode observations might be pieced together is a suitable after-the-fact radiometric claibration of the instrument can be formulated.

Description: The Space Shuttle Challenger was observed spectroscopically in two passes over Maui during the Spacelab 2 mission. Through most of one of the passes strong bands centered at 1.52 and 1.69 microns, tentatively identified as OH bands, were detected. The average luminosity of the Shuttle in the 1.45 to 1.75 micron range was roughly equal to that of a star of magnitude +5.5. The luminosity was much lower during part of the pass. Spectra from 0.65 to 2.4 microns were obtained during the second pass. These showed that most of the nonthermal emission is in the 1.2 to 2.2 micron range as would be expected for vibrationally excited OH.

Description: The working group agreed that the first (primary) objective should be the determination of methods for the accurate measurement of total rain water and total cloud water with passive microwave methods. There was no argument on the points concerning nonlinear relationships between T sub B and rain rate (R) over the range of important rain rates (half of oceanic rainfall occurs at rates greater than 15 mm h-1), such that variations in rain rate within a footprint lead to an incorrect measurement of the average rate for that footprint, and one cannot determine the characteristics of the sensed rain area. This is especially true near 18 GHz, where the dynamic range above 15 mm h-1 is very small because this frequency does not clearly fall in either a scattering regime or emissive regime at these wavelengths. It is also not clear whether very low frequency (emissive) techniques will be the best at measuring rain processes, or high frequency (scattering) techniques, where precipitation-size ice plays a major role in the signal attenuation. It is still not known what signal of rain is at certain rates on an observational basis because of the many different conditions that can exist within a single satellite observed footprint.

Description: The data collection phase of a Doppler wind measurement experiment supported by high-resolution Jimsphere/FPS-16 wind data and Windsonde data was carried out at the Kennedy Space Center in February, March and early April of 1985. The Doppler wind measurements were made using a hybrid doppler profiler put in place by the Johnson Space Center and a SOUSY profiler operated by Radian Corporation. Both systems operated at 50 Mhz. Although the doppler profiler systems were located 10 km apart to enable concurrent operation of the systems for data comparison, little concurrent data were obtained due to set-up delays with the SOUSY system, and system problems with the WPL system during the last month of the test. During the test period, special serial Jimsphere soundings were taken at two-hour intervals on six days in March and April in addition to balloon soundings taken in support of the Shuttle launch operations. In addition, there is temperature, moisture and wind information available from the daily morning Radiosonde sounding taken at the Kennedy site. The balloon release point was at the same location as the SOUSY profiler. Vertical resolution of the SOUSY profiler was 150 M to approximately 20 km. The vertical resolution of the WPL profiler was 290 M to 10 km and 870 M to 17 km. Winds determined form the Jimsphere balloon have a vertical resolution of 30 M.

Description: The Atmospheric Sciences Division (ASD) of the Systems Dynamics Laboratory at NASA's Marshall Space Flight Center (MSFC) is currently involved in interactive information processing for the Mesoscale Analysis and Space Sensor (MASS) program. Specifically, the ASD is engaged in the development and implementation of new space-borne remote sensing technology to observe and measure mesoscale atmospheric processes. These space measurements and conventional observational data are being processed together to gain an improved understanding of the mesoscale structure and the dynamical evolution of the atmosphere relative to cloud development and precipitation processes. To satisfy its vast data processing requirements, the ASD has developed a Researcher Computer System consiting of three primary computer systems which provides over 20 scientists with a wide range of capabilities for processing and displaying a large volumes of remote sensing data. Each of the computers performs a specific function according to its unique capabilities.

Description: During FY-85 the data gathering process was completed. This gave researchers a reasonably complete picture of the Shuttle's operational weather support units and requirements. They expanded on the site visits of FY-84 with telephone follow-up. They finalized recommendations and wrote the final report. The final report was accepted by NASA and has been published as NASA Contractor Report CR-171418.

Description: The software developed on this project in FY-84 was put into final form and documented for McIDAS user access. The various users have been asked to utilize the techniques and to provide feedback to the developers. Researchers have received limited feedback to date, but nearly all has been helpful and generally favorable. The stereo display has been used by most of the operational users of McIDAS or its progenies. Specifically, the National Hurricane Center, the National Severe Storm Forecast Center, the National Meteorological Center, and the Cape Canaveral Forecast Facility have all made use of the 4-D display techniques to help evaluate meteorological situations on various occasions.

Description: A 4800 band synchronous communications link was established between the Perkin-Elmer (P-E) 3250 Atmospheric Modeling and Sensor Simulation (AMASS) system and the Cyber 205 located at the Goddard Space Flight Center. An extension study of off-the-shelf array processors offering standard interface to the Perkin-Elmer was conducted to determine which would meet computational requirements of the division. A Floating Point Systems AP-120B was borrowed from another Marshall Space Flight Center laboratory for evaluation. It was determined that available array processors did not offer significantly more capabilities than the borrowed unit, although at least three other vendors indicated that standard Perkin-Elmer interfaces would be marketed in the future. Therefore, the recommendation was made to continue to utilize the 120B ad to keep monitoring the AP market. Hardware necessary to support requirements of the ASD as well as to enhance system performance was specified and procured. Filters were implemented on the Harris/McIDAS system including two-dimensional lowpass, gradient, Laplacian, and bicubic interpolation routines.

Description: A concept for a solar radiometer network to provide supporting data during the Satellite Preciptiation and Cloud Experiment (SPACE) was developed. Each of the 9 prime and 10 supplementary SPACE ground sites will be equipped with an upward pointing global solar pyranometer. About half of the sites will also be equipped with upward pointing diffuse (shade ring) solar pyranometers, and a downward pointing global albedo pyranometer. These radiometers will be used to monitor the spatial and temporal variability of solar insolation and haze optical depth. The insolation data will ultimately be input to numerical models of the pre-storm and near-storm boundary layer. The optical depth data will be compared with simultaneous measurements from airborne and satellite-based passive visible radiometers and airborne lidars.

Description: The investigations over the past year have led to the finalization of results from the study of mesoscale atmospheric parameters derived from the visible infrared spin scan radiometer (VISSR) atmospheric sounder (VAS). Soundings from several retrieval techniques for the 6 to 7 March 1982 special observation period were evaluated for mesoscale accuracy. Specific results and comparisons between data from a regression and two physical retrieval schemes are forthcoming in the Journal of Atmospheric and Oceanic Technology (JTech) this year. A generalization of these results is outlined. Large temperature and moisture biases existed in the VAS derived profiles, particularly in layers near inversions. Standard errors ranged from 1 to 3 C and 3 to 6 C for temperature and dewpoint, respectively. Parameters derived from VAS soundings (geopotential height, thickness, and precipitable water) often reflected the temperature and moisture profile biases. VAS derived mesoscale gradients were often weaker than those from corresponding rawinsonde data. Little improvement was made in defining the vertical structure of the atmosphere over the first guess information. VAS soundings were able to improve in the horizontal structure due to the high spatial resolution of the radiance data.

Description: Preliminary planning has been performed to support NASA/Marshall Space Flight Center (MSFC) in the coordination of the field experiment to be conducted in Central Tennessee, Northern Alabama, and Mississippi during the Spring/Summer of 1986. The goal of Satellite Precipitation and Cloud Experiments (SPACE) is to investigate mesoscale cloud/precipitation systems and development of associated satellite remote sensing technology. The field program will incorporate remote sensing observations from aircraft, satellite imagery, radar observations, ground based lightning measurements, rawinsonde observations, and various surface meteorological observations. The coordination of existing and special observation networks will provide a data base for analysis of precipitation events and provide ground truth comparisons for remote sensing capabilities. Existing surface-based observational networks include National Weather Service Meso/Alpha Scale Rawinsonde, radar, and surface measurements; the Tennessee Valley Authority automated and manual precpitation recording stations; and NASA/MSFC lightning measurement stations. Special observational features to be implemented include a meso/beta scale rawinsonde network, a special surface observational network within the rawinsonde network, and the installation of a RADAP II/ICRAD data processing unit on the National Weather Service radar at Nashville, TN. Initial coordination of these observational requirements to accomplish the goals of SPACE have been performed.

Description: Researchers goals are to describe the information content of Vertical Atmospheric Sounder (VAS) radiance data, especially the 6.7 micrometers water vapor channel, to better interpret the atmosphere's water vapor structure from 6.7 micrometers imagery, and to investigate new analysis and forecasting techniques utilizing retrieved VAS soundings. Researchers made major progress toward these goals during FY-85. They are investigating 6.7 micrometer imagery on 6 to 7 March 1982, a day when special mesoscale ground truth data were collected during the 1982 atmospheric variability experiment/vertical amospheric sounder (AVE/VAS) field experiment. A dark (dry) image streak having mesoscale details was located over the special data region, and it provides the major focus of the case study. Mesoscale radiosonde-derived humidity data are found to verify fine scale features of the image that are not evident from the standard National Weather Service network. Thus, VAS imagery is a reliable detector of mesoscale moisture structure during this case. To investigate causes for the image streak, researchers are calculating water vapor budgets. Subsidence is found to be a factor in the current case as well; however, patterns of descent are not related to the jet streak according to traditional conceptual models. Thus, it appears that more research into jet stream dynamics is needed in order to better interpret 6.7 micrometer imagery.

Description: Development of cloud relative tracking for severe thunderstorm identification and the beginning of the development of mesoscale airmass characteristics based on vertical atmospheric sounding data were accomplished.

Description: In the case of the Carolina tornadoes, researchers prepared visible and IR GOES imagery covering the period 2000 Z when the storm entered South Carolina from Georgia until it exited North Carolina at 0200 Z into Virginia. The GOES IR imagery clearly demonstrated that this storm was imbedded in a continuously propagating mesolow with a well defined cold dome. The ground damage track paralleled exactly with the cold dome throughout the storm's life across the Carolinas. There were no advanced very high resolution radiometer (AVHRR) data during the period to allow researchers to inspect the cloud top for warm temperature anomalies. The Carolina storm did exhibit rightward deviating outflow which was oriented about 60 degrees to the 300 mb streamlines. The tornadoes of April 27, 1984 were part of a tornado producing cold front which stretched from Oklahoma to Minnesota. As the front moved eastward it touched off numerous tornadoes in eastern Wisconsin. GOES imagery for this data was prepared and it was strikingly clear that all along the North-South oriented squall line, the individual tunderstorms had cirrus plumes which had remarkable right deviation to the upper air flow. Unlike the Carolina long track supercell cell-mesolow system, these storms were isolated individual thunderstorms which touched off at least 16 tornadoes in eastern Wisconsin stretching from the Milwaukee area on the south to Vilas County in the north. The monster tornado of June 8, 1984 which leveled 90 percent of the village of Barneveld, Wisconsin and killed 9 persons is also discussed.

Description: In the time composite sounding mode, the Vertical Atmospheric Sounder (VAS) data is collected in a series of images of one spin each rather than in the dwell sound mode where single lines are repeatedly scanned. A drawback of the time composite method is temporal smearing of the data, but to compensate this there is also the chance that shifting cloud patterns will permit better spatial coverage. Time composite sounding was performed for a single case study, June 14, 1984. Four, ten minute single spin swaths were processed. The principal conclusion was that the time composite results were at least equivalent to the conventional dwell sounding results, despite the fact that compositing was done in a less than optimum way because of software limitations.

Description: The goals of this research were to better understand interactions between areas of intense convection and their surrounding mesoscale environments by using diagnostic budgets of kinetic (KE) and available potential energy (APE). Three cases of intense convection were examined in detail. 1) Atmospheric Variability Experiments (AVE) carried out on 24 to 25 April 1975 were studied. Synoptic scale data at 3 to 6 hour intervals, contained two mesoscale convective complexes (MCCs). Analyses included total KE budgets and budgets of divergent and rotational components of KE. 2) AVE-Severe Environmental Storms and Mesoscale Experiments (SESAME)-4 carried out on 10 to 11 April 1979 were studied. Synotpic and meso alpha-scale data (250 km spacing, 3 hour intervals), contained the Red River Valley tornado outbreak. Analyses included total KE budgets (separate synoptic and mesoscale version), budgets for the divergent and rotational components, and the generation of APE by diabatic processes. 3) AVE-SESAME 5 studies were carried out on 20 to 31 May 1979. Synoptic and meso beta-scale data (75 km spacing, 1 1/2 to 3 hour intervals), contained a small MCC. Analyses include separate KE budgets for the synotic and meso beta-scales and a water vapor budget. Major findings of these investigations are: (1) The synoptic scale storm environment contains energy conversions and transports that are comparable to those of mature midlatitude cyclones. (2) Energetic in the mesoscale storm environment are often an order of magnitude larger than those in an undisturbed region. (3) Mesoscale wind maxima form in the upper troposphere on the poleward sides of convective areas, whereas speeds decrease south of storm regions.

Description: A two-dimensional mesoscale model was used to initialize a two-dimensional cloud model with both mesoscale thermodynamic and dynamic information utilized in the initialization. The Mesoscale-cloud mdoel linkage was used to examine differential convective response due to mesoscale variations for the April 24, 1982 Atmospheric Variability Experiment-Vertical Atmospheric Sounder (AVE-VAS), Case 4. On this day both data analyses and mesoscale model simulations indicated strong variations in thermodynamic and dynamic structure across the panhandle of Texas where a moderately strong convective line formed. Using the cloud model, the current research has shown a preferred area for strong convection to occur due to concomitant mesoscale convergence and mesoscale destabilization of the atmosphere.

Description: The importance of mesoscale moisture information in the forecasting of weather events is discussed. A test is being prepared with the March 6, 1982 Vertical Atmospheric Sounder/Atmospheric Variability Experiment (VAS/AVE) case study to be run on the sub-synoptic scale model (SSM). Model intracomparison of three carefully designed simulations should isolate the role of mesoscale information in the initial conditions for both mositure and vertical motion. Three simulations will be made for the period 1200Z 6 March to 0000Z 7 March starting with the regular synoptic time data of 1200Z. The distinction between the three cases arises from data manipulation at 1800Z midway through the forecast period: (1) Control Case: no alterations at 1800Z. (2) Moisture Information Suppression: at 1800Z the model simulation field for water vapor, which by this time contains considerable mesoscale structure, is replaced by a smoothed version from which the mesoscale structure has been eliminated. No other variables are structure altered. (3) Vertical Motion Information Suppression: at 1800Z the model is subjected to a dead start procedure which primarily imposes a nondivergent constraint of the horizontal motion field field suppressing vertical motion. The main effect is to eliminate the mesoscale component. Comparison of results for the 1800Z to 0000Z time period will give the information desired.

Description: Investigations in FY-85 were centered on three case study days in 1982. Two of these, March 6 and April 24, were Atmospheric Variability Experiment/Verical Atmospheric Sounder (AVE/VAS) days for which high spatial and temporal resolution RAOB and Vertical Atmospheric Sounder (VAS) data sets were available. The third investigation day, April 26, was a day of interesting severe weather. In the last part of FY-84 and early FY-85 we were able to demonstrate most importantly the complimentary nature of satellite soundings and winds in a forecast/analysis system. In our variational analysis scheme, cloud drift and water vapor winds enter into the height field as gradient information. The cloud drift winds especially, have the character of supplying information in cloudy areas where satellite soundings are not possible. In the April 26 experiments, analyses and forecasts using the combination satellite winds and soundings were superior to those using only soundings. Good consistency was shown between independent satellite forecasts from different initialization times run to the same verification time. A significant accomplishment in FY-85 was expanding experiments on April 26 to include quasi-continuous initialization inserting satellite soundings and winds from several different times into an analysis/forecast. Contrary to the first set of experiments on April 26, here forecast initialization fields were not independent, but contained satellite information from two data times.

Description: Researchers achieved full implementation of the LAMPS mesoscale model on the Atmospheric Sciences Division computer and derived balanced and real wind initial states for three case studies: March 6, April 24, April 26, 1982. Numerical simulations were performed for three separate studies: (1) a satellite moisture data impact study using Vertical Atmospheric Sounder (VAS) precipitable water as a constraint on model initial state moisture analyses; (2) an evaluation of mesoscale model precipitation simulation accuracy with and without convective parameterization; and (3) the sensitivity of model precipitation to mesoscale detail of moisture and vertical motion in an initial state.

Description: The importance of mesoscale moisture information in the forecasting of weather events is being studied. A test is being prepared with the March 6, 1982 Vertical Atmospheric Sounder/Atmospheric Variability Experiment (VAS/AVE) case study to be run on the sub-synoptic scale model (SSM). Intracomparison of three carefully designed simulations should isolate the role of mesoscale information in the initial conditions for both moisture and vertical motion. Three simulations will be made for the period 1200Z 6 March to 0000Z 7 March starting with the regular synoptic time data of 1200Z. The distinction between the three cases arises from data manipulation at 1800Z midway through the forecast period. Comparison of results for the 1800Z to 0000Z time period will give the information desired.

Description: The full-physics version of the LAMPS model has been implemented on the Perkin-Elmer computer. In Addition, LAMPS graphics processors have been rewritten to the run on the Perkin-Elmer and they are currently undergoing final testing. Numerical experiments investigating the impact of convective parameterized latent heat release on the evolution of a precipitating storm have been performed and the results are currently being evaluated. Curent efforts include the continued evaluation of the impact of initial conditions on LAMPS model results. This work will help define measurement requirements for future research field projects as well as for observations in support of operational forecasts. Also, the impact of parameterized latent heat on the evolution of precipitating systems is continuing. This research is in support of NASA's proposed Earth Observation Mission (EOM).

Description: An automated technique for extracting mesoscale winds from sequences of GOES visible infrared spin scan radiatiometer (VISSR) image pairs has been developed, tested extensively, and configured for quasi-real time research applications on the Atmospheric Sciences Division's research computing sytem. The entire system of computer codes was successfully vectorized for execution on an array processor resulting in job turnaround in less than 1 hour. An objective quality control system provides much greater than 99 percent accuracy in eliminating questionable wind estimates. Dynamical analysis of cloud wind divergence has revealed temporally consistent convergence centers on the meso-beta scale that are highly correlated with ongoing and future developing convective storms.