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An engineering model of microbursts was developed as an aid to possible future flight simulation in wind shear. Planetary boundary layer and high altitude turbulence were also modeled.
The development of a ground based direct detection Doppler lidar based on the recently described aerosol double edge technique is reported. A pulsed, injection seeded Nd:YAG laser operating at 1064 nm is used to make range resolved measurements of atmospheric winds in the free troposphere. The wind measurements are determined by measuring the Doppler shift of the laser signal backscattered from atmospheric aerosols. The lidar instrument and double edge method are described and initial tropospheric wind profile measurements are presented. Wind profiles are reported for both day and night operation. The measurements extend to altitudes as high as 14 km and are compared to rawinsonde wind profile data from Dulles airport in Virginia. Vertical resolution of the lidar measurements is 330 m and the rms precision of the measurements is a low as 0.6 m/s.
Several new data products and applications for elastic backscatter lidar are achieved using simple conical scanning. Atmospheric boundary layer spatial and temporal structure is revealed with resolution not possible with static pointing lidars. Cloud fractional coverage as a function of altitude is possible with high temporal resolution. Wind profiles are retrieved from the cloud and aerosol structure motions revealed by scanning. New holographic technology will soon allow quasi-conical scanning and push-broom lidar imaging without mechanical scanning, high resolution, on the order of seconds.
Supersonic inflatable aerodynamic decelerators (IADs) are drag devices intended to be deployed at high Mach numbers. In the application considered here they assist in the descent and landing of spacecraft on Mars. Although promising, present IAD technology is not yet sufficiently mature for use in the near future. This paper describes a technology maturation plan for tension cone IADs using subscale test articles to reduce development costs. As envisioned, the proposed test plan includes three phases: wind tunnel tests (subsonic), unpowered high-altitude flight tests (transonic), and powered high-altitude tests (supersonic). This test plan is based on a building block approach in which successful completion of each phase adds to the understanding of the behavior of IADs and reduces the risk of the subsequent, more expensive phases. By properly scaling the IADs, test articles of the same size and nearly the same construction can be used for all three phases. The final phase is a dynamically scaled flight test with IAD deployment at the same Mach number as the full-scale vehicle on Mars. Two full-scale example cases are presented: one for a single-stage system (15 m dia. IAD to subsonic retropropulsion), and another for a two-stage system (10.5 m dia. IAD to subsonic parachute). Using scale factors of 0.333 and 0.476 yield subscale test IADs of 5 m dia. The dynamically scaled powered flight test starts at Mach 4 and an altitude of 33.5 km. Existing balloons and rocket motors are shown to be adequate to meet the required test conditions.
We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.
Exchange between the upper tropical troposphere and the lower troposphere is considered by examining high altitude aircraft observations of water, ozone, methane, wind and temperature for scale invariance.
A Meteorological Measurement System (MMS) was designed for the high-altitude ER-2 aircraft (NASA 706). Through dedicated instrumentation installed on the aircraft and repeated calibrations, the MMS provides accurate in situ measurements of free-stream pressure, temperature, and the wind vector. The MMS has participated in two major high-altitude scientific expeditions, the Stratosphere-Troposphere Exchange Project (STEP) based in northern Australia and the Airborne Antarctic Ozone Experiment (AAOE) based in southern Chile. Key MMS subsystems are described. The MMS consists of a dedicated inertial navigation system (INS), a randome differential pressure system, a data acquisition system, and air data instrumentation. The MMS incorporates a high-resolution INS (Litton LIN-72RH model), which is specially configured and is updated at 25 Hz. The differential pressure system, consisting of two sets of pressure ports and transducers, is installed in the ER-2 radome to provide sensitive measurements of the airflow angles (angle of attack and angle of sideslip). The data acquisition system was designed to meet aircraft requirements of compactness and light weight (2 cu ft 50 lb) and for MMS requirements to sample, control, process, and store 45 parameters (some redundant) at a sampling rate up to 10 Hz. The MMS data are stored both in a tape recorder (20 MB) and a hermatically-sealed winchester hard disc (10 MB). Special and redundant instrumentation for temperature and pressure measurements were also installed on the aircraft.
Observational evidence of rather large period waves (23-60 d) in the troposphere/stratosphere, particularly during the winter months, is presented. Wind data collected on a regular basis employing high-altitude balloons and meteorological rockets over the past few years are used. Maximum entropy methods applied to the time series of zonal wind data indicate the presence of 23-60-waves more prominently than shorter-period waves. The waves have substantial amplitudes in the stratosphere and lower mesosphere, often larger than those noted in the troposphere. The mean zonal wind in the troposphere (5-15 km altitude) during December, January, and February exhibits the presence of strong westerlies at latitudes between 8 and 21 deg N.
Observations made by the Polar satellite have shown that plasma of solar wind magnetosheath origin is rammed into the high altitude polar cusp creating a diamagnetic cavity of large dimensions. The Earth's dipole field can be excluded from this region in it turbulent manner with the magnitude of the field strength reaching close to zero nT at times. At such times energetic particles are produced in this region in intensities which exceed those measured in the trapping regions of the magnetosphere beyond L = 6.5. These particles can then flow back out of the cusp along field lines that form the magnetopause. A fraction of these particles can enter the magnetosphere along the magnetopause on the dusk and dawn flanks. Due to existing gradients in the geomagnetic field, cusp accelerated ions can enter the magnetosphere along the dawn flank and electrons along the dusk flank. For those particles entering near the geomagnetic equatorial plane with pitch angles close to ninety degrees they will drift along contours of constant magnetic field strength reaching deep into the nightside inner magnetosphere. From observations made by the Polar ATS-6, and ISEE satellites it is argued that this cusp source appears to be capable of providing energetic ions to the magnetosphere and possibly energetic electrons which form the source population of the Subsequent radial diffusion and formation of the radiation belts.
Using polarized brightness (pB) measurements made by the High Altitude Observatory (HAO) Mauna Loa Mk III K-coronameter, we investigate the daily changes of path-integrated density at1.15 R-circle dot.
A full-scale ejector cooling investigation was made on a turbojet engine - afterburner installation in the NACA Lewis altitude wind tunnel. Ejector performance was studied at primary exhaust-gas temperatures from 2700 degrees to 3400 degrees R (corresponding to ejector temperature ratios from 2.0 to 5.0), primary pressure ratios from 1.79 to 3.4, secondary air flows up to 29 percent of the primary gas flow, and for diameter ratios from 1.08 to 1.42 and spacing ratios from 0.04 to 1.16. In addition, variations were made in the primary exhaust-nozzle area. Ejectors with large diameter ratios permit the attainment of high gas flow ratios, but the jet-thrust losses become prohibitive as the spacing ratio is increased from 0 to 0.16. As the ejector diameter is reduced, the obtainable gas-flow ratio and the thrust loss are reduced. Previous results showing that data obtained at a temperature ratio of 1.0 could not be extrapolated to determine ejector performance at high temperature ratios by the application of the temperature ratio factor to the gas-flow ratios are substantiated by the present investigation.
Microwave remote sensing observations of hurricanes, from NOAA and USAF hurricane surveillance aircraft, provide vital data for hurricane research and operations, for forecasting the intensity and track of tropical storms. The current operational standard for hurricane wind speed and rain rate measurements is the Stepped Frequency Microwave Radiometer (SFMR), which is a nadir viewing passive microwave airborne remote sensor. The Hurricane Imaging Radiometer, HIRAD, will extend the nadir viewing SFMR capability to provide wide swath images of wind speed and rain rate, while flying on a high altitude aircraft. HIRAD was first flown in the Genesis and Rapid Intensification Processes, GRIP, NASA hurricane field experiment in 2010. This paper reports on geophysical retrieval results and provides hurricane images from GRIP flights. An overview of the HIRAD instrument and the radiative transfer theory based, wind speed/rain rate retrieval algorithm is included. Results are presented for hurricane wind speed and rain rate for Earl and Karl, with comparison to collocated SFMR retrievals and WP3D Fuselage Radar images for validation purposes.
Multiple rocket exhaust plume interactions at high altitudes can produce base flow recirculation with attendant alteration of the base pressure coefficient and increased base heating. A search for a good wind tunnel benchmark problem to check grid clustering technique and turbulence modeling turned up the experiment done at AEDC in 1961 by Goethert and Matz on a 4.25-in. diameter domed missile base model with four rocket nozzles. This wind tunnel model with varied external bleed air flow for the base flow wake produced measured p/p(sub ref) at the center of the base as high as 3.3 due to plume flow recirculation back onto the base. At that time in 1961, relatively inexpensive experimentation with air at gamma = 1.4 and nozzle A(sub e)/A of 10.6 and theta(sub n) = 7.55 deg with P(sub c) = 155 psia simulated a LO2/LH2 rocket exhaust plume with gamma = 1.20, A(sub e)/A of 78 and P(sub c) about 1,000 psia. An array of base pressure taps on the aft dome gave a clear measurement of the plume recirculation effects at p(infinity) = 4.76 psfa corresponding to 145,000 ft altitude. Our CFD computations of the flow field with direct comparison of computed-versus-measured base pressure distribution (across the dome) provide detailed information on velocities and particle traces as well eddy viscosity in the base and nozzle region. The solution was obtained using a six-zone mesh with 284,000 grid points for one quadrant taking advantage of symmetry. Results are compared using a zero-equation algebraic and a one-equation pointwise R(sub t) turbulence model (work in progress). Good agreement with the experimental pressure data was obtained with both; and this benchmark showed the importance of: (1) proper grid clustering and (2) proper choice of turbulence modeling for rocket plume problems/recirculation at high altitude.
Since about 1974, Doppler radars operating in UHF and VHF ranges have been used increasingly to study atmospheric winds. Historically, large systems capable of obtaining data from high altitudes have focused attention on the mesosphere and stratosphere, rather than on the troposphere wherein abides most of the weather considered by most meteorologists. Research address some questions the meteorologist must logically ask first, viz., what is the actual performance capability of these systems, how accurate is the wind data of interest to meteorologists, and from what altitudes in the troposphere are the data reliably obtained.
The prevalent attributes of near-Mars space are described: the ambient interplanetary environment, the ionosphere, the upper atmosphere, and more remote regions that are affected by the presence of Mars. The descriptions are based on existing Martian data and/or models constructed from measurements made near Venus. Specific attention is given to the features of solar wind interaction with magnetospheric and ionospheric obstacles. The high-altitude plasma and field environment, the energetic particle environment, the ionosphere environment, and the neutral upper atmosphere environment are described with extensive graphic information, based on existing measurements collected from nine Martian missions. The ionospheric obstacle is assumed to prevail as a mechanism for describing the scenario. Martian perturbation of solar wind is theorized to be of a relatively small order. A distinctive local energetic particle population of planetary origin is shown to result from the direct interaction of solar wind plasma. This phenomenon is considered evidence of the important scavenging of planetary elements from Mars. The absence of a planetary dipole field around Mars, like its low gravity and distance from the sun, is considered important in determining the environment of this earthlike laboratory.
A simple analytical microburst model was developed for use in estimating vertical winds from horizontal wind measurements. It is an axisymmetric, steady state model that uses shaping functions to satisfy the mass continuity equation and simulate boundary layer effects. The model is defined through four model variables: the radius and altitude of the maximum horizontal wind, a shaping function variable, and a scale factor. The model closely agrees with a high fidelity analytical model and measured data, particularily in the radial direction and at lower altitudes. At higher altitudes, the model tends to overestimate the wind magnitude relative to the measured data.
We present for the first time detailed maps of charged temperatures and winds in Jupiter's stratosphere, from infrared spectra acquired during the Cassini swingby of Jupiter. The maps reveal a high-altitude equatorial jet 1140 m s-', as strong as the cloud-top winds. It may result from wave forcing and be analogous to the quasi-biennial oscillation in the earth's stratosphere. The maps give the best characterization of the motions of stratospheric waves, and they better define the vertical penetration of the auroral hot spots into the stratosphere.
Ideally, a statistically representative sample of measured high-resolution wind profiles with wavelengths as small as tens of meters is required in design studies to establish aerodynamic load indicator dispersions and vehicle control system capability. At most potential launch sites, high- resolution wind profiles may not exist. Representative samples of Rawinsonde wind profiles to altitudes of 30 km are more likely to be available from the extensive network of measurement sites established for routine sampling in support of weather observing and forecasting activity. Such a sample, large enough to be statistically representative of relatively large wavelength perturbations, would be inadequate for launch vehicle design assessments because the Rawinsonde system accurately measures wind perturbations with wavelengths no smaller than 2000 m (1000 m altitude increment). The Kennedy Space Center (KSC) Jimsphere wind profiles (150/month and seasonal 2 and 3.5-hr pairs) are the only adequate samples of high resolution profiles approx. 150 to 300 m effective resolution, but over-sampled at 25 m intervals) that have been used extensively for launch vehicle design assessments. Therefore, a simulation process has been developed for enhancement of measured low-resolution Rawinsonde profiles that would be applicable in preliminary launch vehicle design studies at launch sites other than KSC.