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NASA NTRS2000

Space Plasma Physics

Dr. James L. Horwitz and R. Hugh Comfort's studies with the high altitude TIDE data have been progressing well. We concluded a study on the relationship of polar cap ion properties observed by TIDE near apogee with solar wind and IMF conditions. We found that in general H+ did not correlate as well as O+ with solar wind and IMF parameters. O+ density correlated(sub IMF), and Kp. At lower solar wind speeds, O+ density decreased with increasing latitude, but this trend was not observed at higher solar wind speeds. By comparing these results with results from other studies of O+ in different parts of the magnetosphere, we concluded that O+ ions often leave the ionosphere near the foot point of the cusp/cleft region, pass through the high-altitude polar cap lobes, and eventually arrive in the plasma sheet. We found that H+ outflows are a persistent feature of the polar cap and are not as dependent on the geophysical conditions; even classical polar wind models show H+ ions readily escaping owing to their low mass. Minor correlations with solar wind drivers were found; specifically, H+ density correlated best with IMF By, V(sub sw)B(sub IMF), and ESW(sub sw).

Wu, S. T.↗

NASA NTRS1981

Meteorological impact on aviation fuel efficiency

The connection between fuel consumption and weather data is discussed. Fuel efficient flights creating adequate near real time weather information are examined. The lack of highly resolved real time and near real time wind and temperature data at flight altitudes is investigated. The existing systems, which is based on twice a day balloon observations, supplemented by pilot reports or other occasional data, is not adequate for optimum flight planning. The impacts of upper winds and temperatures on fuel efficiency and flight planning are not widely appreciated and developing new weather products are considered.

Winer, D. E.↗

NASA NTRS1983

Stationary waves in the winter stratosphere - Seasonal and interannual variability

The zonal mean wind and stationary waves 1 and 2 in the January 1973 - February 1977 northern winter stratosphere are determined, on the basis of monthly average conventional and satellite data, by diagnosing wave propagation with the aid of the Eliassen-Palm (1961) flux and the refractive index-squared. Both the seasonal trend and the interannual variability of the amplitude of wave 1 reflect variations in zonal mean wind and the corresponding refractive index. During each year studied, a midwinter minimum in wave 1 amplitude occurs at and above 1 mb as a consequence of a midwinter curvature maximum. In three of the four sudden warmings of wave 1 type which occurred during the study period, the month prior to the warming was characterized by abnormally weak winds near the climatological mean jet, a detached secondary jet at low and high altitude, and abnormally large wave 1 amplitude throughout the upper and middle stratosphere.

Smith, A. K.↗

NASA NTRS1987

Yosemite Conference on Ionospheric Plasma in the Magnetosphere: Sources, Mechanisms and Consequences, meeting report

The sixth biennial Yosemite topical conference and the first as a Chapman Conference was held on February 3 to 6, 1986. Due to the recent changes in our perception of the dynamics of the ionospheric/magnetospheric system, it was deemed timely to bring researchers together to discuss and contrast the relative importance of solar versus terrestrial sources of magnetospheric plasma. Although the solar wind was once thought to dominate the supply of plasma in the Earth's magnetosphere, it is now thought that the Earth's ionosphere is a significant contributor. Polar wind and other large volume outflows of plasma have been seen at relatively high altitudes over the polar cap and are now being correlated with outflows found in the magnetotail. The auroral ion fountain and cleft ion fountain are examples of ionospheric sources of plasma in the magnetosphere, observed by the Dynamics Explorer 1 (DE 1) spacecraft. The conference was organized into six sessions: four consisting of prepared oral presentations, one poster session, and one session for open forum discussion. The first three oral sessions dealt separately with the three major topics of the conference, i.e., the sources, mechanisms, and consequences of ionospheric plasma in the magnetosphere. A special session of invited oral presentations was held to discuss extraterrestrial ionospheric/magnetospheric plasma processes. The poster session was extended over two evenings during which presenters discussed their papers on a one-on-one basis. The last session of the conferences was reserved for open discussions of those topics or ideas considered most interesting or controversial.

Gallagher, D. L.↗

NASA NTRS1991

Computational analysis of plume induced separation

Full Navier-Stokes simulations around axisymmetric boattailed and flared rockets are numerically investigated for plume induced separation phenomenon. At lower altitudes, the plume interaction with the external flow does not cause any flow separation on the body, but at conditions corresponding to higher altitudes large plume induced separation is observed. Addition of a flare to the afterbody limits the extent of separation at high altitudes. Computational solutions for the boattailed axisymmetric geometry are compared with available wind-tunnel and flight data. The effect of forebody ablation is studied by modifying the inflow boundary layer profile. Numerical solutions with thicker boundary layers show significantly greater plume-induced separation compared with nonablating cases. Heat transfer to the wall was computed for the flared afterbody geometry and is presented.

Venkatapathy, Ethiraj↗

NASA NTRS1989

A one-dimensional multispecies magnetohydrodynamic model of the dayside ionosphere of Mars

A one-dimensional multispecies magnetohydrodynamic model of the Martian ionosphere is developed using methods similar to those used by Shinagawa and Cravens (1988) for Venus, and is used to examine the nature of the solar wind interaction with the Martian ionosphere. The four ion species included in the model are CO2(+), O2(+), O(+), and H(+). Scenarios with and without a small intrinsic field are modeled for the Viking conditions (solar minimum). It was found that the inclusion of an intrinsic magnetic field does not improve the agreement between the calculated ion density profiles and the measured ones. The results also indicate that large horizontal plasma motions must be present at high altitudes, indicating that the dynamics of the upper ionosphere of Mars is controlled by the solar wind.

Shinagawa, H.↗

NASA NTRS2013

Observations of C-Band Brightness Temperatures and Ocean Surface Wind Speed and Rain Rate from the Hurricane Imaging Radiometer (HIRAD) during GRIP and HS3

HIRAD flew on high-altitude aircraft over Earl and Karl during NASA s GRIP (Genesis and Rapid Intensification Processes) campaign in August - September of 2010, and at the time of this writing plans to fly over Atlantic tropical cyclones in September of 2012 as part of the Hurricane and Severe Storm Sentinel (HS3) mission. HIRAD is a new C-band radiometer using a synthetic thinned array radiometer (STAR) technology to obtain cross-track resolution of approximately 3 degrees, out to approximately 60 degrees to each side of nadir. By obtaining measurements of emissions at 4, 5, 6, and 6.6 GHz, observations of ocean surface wind speed and rain rate can be retrieved. This technique has been used for many years by precursor instruments, including the Stepped Frequency Microwave Radiometer (SFMR), which has been flying on the NOAA and USAF hurricane reconnaissance aircraft for several years to obtain observations within a single footprint at nadir angle. Results from the flights during the GRIP and HS3 campaigns will be shown, including images of brightness temperatures, wind speed, and rain rate. Comparisons will be made with observations from other instruments on the campaigns, for which HIRAD observations are either directly comparable or are complementary. Features such as storm eye and eye-wall, location of storm wind and rain maxima, and indications of dynamical features such as the merging of a weaker outer wind/rain maximum with the main vortex may be seen in the data. Potential impacts on operational ocean surface wind analyses and on numerical weather forecasts will also be discussed.

Miller, Timothy L.↗

NASA NTRS1983

High-latitude stratospheric winds near summer solstice - The diurnal and semidiurnal solar tides

A technique for studying winds and tides at altitudes of approximately 30 km is the continuous and precise tracking of zero-pressure, stratospheric balloons. The CONSOL navigation system allows tracking of a balloon over the North Atlantic for two days or longer. Tidal wind data from 14 balloon trajectories (approximately 670 balloon hours) are presented and compared with theoretical predictions.

Neubert, T.↗

NASA NTRS1987

Stability of the polar wind

The classical polar wind is an ambipolar outflow of thermal plasma from the terrestrial ionosphere at high latitudes. At altitudes above about 3000 km, the H(+) flow becomes supersonic and collisionless, and the H(+) velocity distribution becomes non-Maxwellian. The non-Maxwellian features include a temperature anisotropy, with the parallel H(+) temperature greater than the perpendicular temperature, and an asymmetry, with an elongated tail in the upward direction. These distortions from a Maxwellian increase as the H(+) gas escapes in the diverging geomagnetic field, and at 10 earth radii, the parallel-to-perpendicular temperature ratio is about 50 and the elongated tail is sufficiently long to move the drift velocity point off the peak of the distribution function. The stability of these highly non-Maxwellian H(+) velocity distributions was studied with regard to the excitation of electrostatic waves, and the plasma was found to be remarkably stable for a wide range of electron temperatures. This indicates that the various macroscopic formulations of the classical polar wind are valid. The stability of a perpendicularly heated polar wind was also studied, assuming bulk perpendicular heating of H(+) in the cusp, followed by the subsequent convection of the heated plasma into the polar cap. Two regions of instability were found.

Barakat, A. R.↗

NASA NTRS1972

Neutral winds above 200Km at high latitudes

Motion from multiple chemical releases between 200 and 300 km from 15 rockets launched from 4 high latitude locations are analyzed. The observations in the evening and midnight hours at magnetic altitudes or = 65 deg suggest that in these regions ion drag is the dominant force in driving neutral winds between 200 and 300 km. This conclusion is based on both the agreement between ion and neutral drift directions, and the fact that there are distinct changes in the wind associated with (a) the reversal in east-west ion drift at the Harang discontinuity, and (b) the transition from auroral belt, sunward ion drift and polar cap, anti-solar ion drift.

Meriwether, J. W.↗

NASA NTRS1977

Saturn - Long-term variation of H2 and CH4 absorptions

Results are presented for observations of various H2 quadrupole lines and CH4 absorption bands in spectra of Saturn obtained with a coude scanner at each apparition since 1969. The data are found to indicate a long-term variation in Saturn's H2 equivalent widths, a seasonal dependence of H2 line strength, and a fairly steady increase in CH4 absorption during the period from 1973 to 1976. A possible correlation between planetary shading and the strength of H2 absorption features is discussed along with seasonal variations in Saturn's NH3 cloud deck and atmospheric models that correspond to the observed H2 equivalent widths. It is suggested that: (1) significant shadowing by the rings may cause dynamical atmospheric activity due to the occurrence of a temperature gradient in the penumbral boundaries of the ring shadow in the planet's upper atmosphere; (2) cooling in the shadow may be a source of a high-altitude CH4 mist; and (3) spreading of this mist over the globe by advective winds would reduce the H2 and CH4 absorptions, as observed.

Trafton, L.↗

NASA NTRS2018

Remote Sensing of the Ocean Surface Refractive Index via Short-Wave Infrared Polarimetry

The linear polarization of sunlight reflected by ocean surfaces in the shortwave infrared (SWIR), at geometries where specular reflection dominates the signal, is a direct function of the refractive index of the surface microlayer(SML). This simple physical concept is at the base of a novel technique presented in this study. We invert observations obtained by the airborne Research Scanning Polarimeter (RSP) in the sun glint region, where each pixel's radiance is dominated by the signal originating from the wave slopes oriented precisely to cause specular reflection. The SWIR wavelength ensures minimization of aerosol interference when radiance travels through the atmosphere; strong absorption by the water body then limits the penetration depth to the first micrometer or so, effectively probing the SML. The resulting Degree of Linear Polarization (DoLP) is then governed by the refractive index via the Fresnel law for the specfic pixel geometry, independently of the wind speed. The selected dataset concerns several field deployments from both low- and high-altitude aircraft, including total reflectance measurements with the sole purpose of accounting for the residual aerosol effect.Stable retrievals from transects above pure seawater yielded values of refractive index that match the values published in the literature within an accuracy of 5 x 10 [superscript 4]. Flying over the oil spill caused by the explosion of the Deepwater Horizon platform, detected variations were found compatible with the presence of an oil slick. The robustness of the results, guaranteedby the high RSP polarimetric accuracy (less than or equal to 0:2%), opens the possibility for remote-sensing detection of other entities that similarly affect the refractive index including whitecaps, microplastics, biological gels, seaweed and grass mats.

Surface Microlayer↗

NASA NTRS1993

An Algorithm for Forecasting Mountain Wave Related Turbulence in the Stratosphere

A global mountain wave parameterization for prediction of wave related displacements and turbulence is described. The parameterization is used with input from NMC analyses of wind and temperature to examine small-scale disturbances encountered by the NASA high-altitude ER-2 during the Second Airborne Arctic Stratosphere Experiment (AASE-II). The magnitude and location of observed large wave events are well reproduced. A strong correlation is suggested between patches of moderate turbulence encountered by the ER-2 and locations where breaking mountain waves are predicted by the parameterization. These facts suggest that useful forecasts of global mountain wave activity, including wave related CAT, can be made quickly and inexpensively using our mountain wave parameterization with input from current numerical forecast models.

Chan, Roland↗

NASA NTRS1990

The Meteorological Measurement System on the NASA ER-2 aircraft

A Meteorological Measurement System (MMS) was designed and installed on one of the NASA high-altitude ER-2 aircraft (NASA 706). The MMS provides in situ measurements of free-stream pressure (+ or - 0.3 mb), temperature (+ or - 0.3 C), and wind vector (+ or - 1 m/s). It incorporates a high-resolution inertial navigation system specially configured for scientific applications, a radome differential pressure system for measurements of the airflow angles, and a compact, computer-controlled data acquisition system to sample, process and store 45 variables on tape and on disk. The MMS hardware and software development is described, and resolution and accuracy of the instrumentation discussed. Custom software facilitates preflight system checkout, inflight data acquisition, and fast postflight data download. It accommodates various modes of MMS data: analog and digital, serial and parallel, and synchronous and asynchronous. Flight results are presented to demonstrate the capability of the system.

Scott, Stan G.↗

NASA NTRS2001

In Situ Measurements of Meteoric Ions

Metal ions found in the atmosphere above 60 km are the result of incoming meteoroid atmospheric ablation. Layers of metal ions are detected by sounding rocket in situ mass spectrometric sampling in the 80 to 130 km region, which coincides with the altitude region where meteors are observed. Enhancements of metal ion concentrations occur during meteor showers. Even outside of shower periods, the metal ion altitude profiles vary from measurement to measurement. Double layers are frequent at middle latitudes. More than 40 different meteoric atomic and molecular ions, including isotopes, have been detected. Atmospheric metal ions on average have an abundance that matches chrondritic material, the same composition as the early solar system. However there are frequently local departures from this composition due to differential ablation, species dependent chemistry and mass dependent ion transport. Metal ions react with atmospheric O2, O, O3, H2O and H2O2 to form oxygenated and hydrogenated ionic compounds. Metal atomic ions at high altitudes have long lifetimes. As a result, these ions, in the presence of Earth's magnetic field, are transported over long distances by upper atmospheric winds and ionospheric electric fields. Satellite measurements have detected metal ions as high as, approximately 1000 km and have revealed circulation of the ions on a global scale.

Grebowsky, Joseph M.↗

NASA NTRS1993

Vertical velocity in cirrus case obtained from wind profiler

Cirrus clouds play an important role in the climate and general circulation because they significantly modulate the radiation properties of the atmosphere. However understanding the processes that govern their presence is made difficult by their high altitude, variable thickness, complex microphysical structure, and relatively little knowledge of the vertical motion field. In the FIRE 2 (First International Satellite Cloud Climatology Regional Experiment) experiment, a 404 MHz wind profiler was set up to provide continuous measurements of clear air wind field at Parsons, Kansas. Simultaneously, the NOAA wind profiler network supplied a wider spacial scale observation. On 26 Nov. 1991, the most significant cirrus cloud phenomena during the experiment with a jet streak at 250 Mb occurred. Analyses of the vertical wind velocity are made by utilizing different methods based on wind profiler data, among them the direct measurements from CSU wind profiler and NOAA network wind profilers, VAD (Velocity Azimuth Display) technique and the kinematic method.

Song, Ran↗

NASA NTRS1980

High-altitude resolution stratospheric measurements with the Arecibo 430-MHz radar

Instrumental modification at the Arecibo Observatory are described, which make possible a resolution of 150 m, the maximum allowed by the transmitter bandwidth. Attention is given to digital decoding, the radar controller, and the fact that a complementary coded pulse scheme generating no pulse side lobes has been used for the first time. It is noted that power spectra of the signals corresponding to 256 altitudes are evaluated on line by means of an array processor. A profile of the E-W component of the wind as a function of altitude has been observed, as well as the discrete layered structure of turbulence, especially at higher altitudes; in addition, the maximum range at which an echo has been detected is about 31 km. The results obtained show the importance for stratospheric studies of high resolution when using radar to obtain wind information from the Doppler shift of turbulence echoes.

Woodman, R. F.↗

NASA NTRS1985

Lyman alpha coronagraph research sounding rocket program

The ultraviolet light coronagraph was developed and successfully flown on three rocket flights on 13 April 1979, 16 February 1980 and 20 July 1982. During each of these flights, the Ultraviolet Light Coronagraph was flown jointly with the White Light Coronagraph provided by the High Altitude Observatory. Ultraviolet diagnostic techniques and instrumentation for determining the basic plasma parameters of solar wind acceleration regions in the extended corona were developed and verified and the understanding of the physics of the corona through the performance, analysis and interpretation of solar observations advanced. Valuable UV diagnostics can be performed in the absence of a natural solar eclipse.

Parkinson, W. H.↗