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3. Concurrent observations at the magnetic equator of small-scale irregularities and large-scale depletions associated with equatorial spread F

Author

Hickey, D. A., Martinis, C. R., Rodrigues, F. S., Varney, R. H., Milla, M. A., Nicolls, M. J., Strømme, Anja, and Arratia, J. F.

Subjects
Physics - Space Physics
Abstract

In 2014 an all-sky imager (ASI) and an Advanced Modular Incoherent Scatter Radar consisting of 14 panels (AMISR-14) system were installed at the Jicamarca Radio Observatory. The ASI measures airglow depletions associated with large-scale equatorial spread F irregularities (10s-100s km), while AMISR-14 detects small-scale irregularities (0.34 m). This study presents simultaneous observations of equatorial spread F (ESF) irregularities at 10-100 km scales using the all sky-imager, at 3 m scales using the JULIA (Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere) radar, and at 0.34 m scales using the AMISR-14 radar. We compare data from the three instruments on the night of 20-21 August, 2014 by locating the radar scattering volume in the optical images. During this night no topside plumes were observed, and we only compare with bottomside ESF. AMISR-14 had five beams perpendicular to the magnetic field covering ~200 km in the east-west direction at 250 km altitude. Comparing the radar data with zenith ASI measurements, we found that most of the echoes occur on the western wall of the depletions with fewer echoes observed the eastern wall and center, contrary to previous comparisons of topside plumes that showed most of the echoes in the center of depleted regions. We attribute these differences to the occurrence of irregularities produced at sub-meter scales by the lower-hybrid-drift instability. Comparisons of the ASI observations with JULIA images show similar results to those found in the AMISR-14 and ASI comparison., Comment: 35 pages (unformatted manuscript), 8 figures, 2 tables, accepted for publication in JGR Space Physics

Published
2015
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4. Characterization of N+ Abundances in the Terrestrial Polar Wind Using the Multiscale Atmosphere‐Geospace Environment.

Author

Albarran, R. M., Varney, R. H., Pham, K., and Lin, D.

Subjects
GEOPHYSICAL observatories, PRODUCTION losses, SOLAR activity, CHEMICAL reactions, IONOSPHERE
Abstract

The High‐latitude Ionosphere Dynamics for Research Applications (HIDRA) model is part of the Multiscale Atmosphere‐Geospace Environment model under development by the Center for Geospace Storms NASA DRIVE Science Center. This study employs HIDRA to simulate upflows of H+, He+, O+, and N+ ions, with a particular focus on the relative N+ concentrations, production and loss mechanisms, and thermal upflow drivers as functions of season, solar activity, and magnetospheric convection. The simulation results demonstrate that N+ densities typically exceed He+ densities, N+ densities are typically ∼10% O+ densities, and N+ concentrations at quiet‐time are approximately 50%–100% of N+ concentrations during storm‐time. Furthermore, the N+ and O+ upflow fluxes show similar trends with variations in magnetospheric driving. The inclusion of ion‐neutral chemical reactions involving metastable atoms is shown to have significant effects on N+ production rates. With this metastable chemistry included, the simulated ion density profiles compare favorably with satellite measurements from Atmosphere Explorer C and Orbiting Geophysical Observatory 6. Key Points: Simulated N+ and O+ densities increase while N+ to O+ density ratios decrease with solar activityN+ concentrations typically exceed He+ densities and N+ fluence rates versus solar activity qualitatively resemble those for O+The inclusion of metastable chemical production of N+ is critical to numerically reproduce observations [ABSTRACT FROM AUTHOR]

Published
2024
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8. Data‐Driven Empirical Conductance Relations During Auroral Precipitation Using Incoherent Scatter Radar and All Sky Imagers.

Author

Kaeppler, S. R., Markowski, D. G., Pepper, A. M., Troyer, R., Jaynes, A. N., Varney, R. H., and Hampton, D.

Subjects
INCOHERENT scattering, AURORAS, MAXIMUM entropy method, RADAR, SPACE environment
Abstract

We present empirical conductance relations that are derived from incoherent scatter radar observations and correlated with all sky imager observations to identify the morphology of the aurora. We use 75,461 events collected using the Poker Flat Incoherent Scatter Radar (PFISR) with associated all sky imagers observations spanning the years 2012–2016. In addition to classifying these events based on auroral morphology, we estimated the Hall and Pedersen conductance and the differential number flux from which the energy flux and the average energy can be calculated. The differential number flux was estimated using the maximum entropy inversion method described in Semeter and Kamalabadi (2005, https://doi.org/10.1029/2004RS003042), but now incorporating the Fang et al. (2010, https://doi.org/10.1029/2010GL045406) ionization model. The main results of this investigation are the power law equations that describe the median, 90th, and 10th percentile Hall and Pedersen conductance as a function of energy flux and average energy. These power law fits are performed for different auroral morphology including all events, discrete, diffuse, and pulsating auroral events. The median Pedersen conductance is found to be in good agreement with past empirical conductance specifications by Robinson et al. (1987, https://doi.org/10.1029/JA092iA03p02565); however, the median Hall conductance from the PFISR observations is found to be larger than the empirical Hall conductance formulas by Robinson et al. (1987, https://doi.org/10.1029/JA092iA03p02565). Pulsating aurora is found to be the most frequently occurring auroral morphology. Furthermore, pulsating aurora has an important contribution to Hall conductance since it has higher average energies than discrete aurora. The results from this investigation are applicable to space weather models and may enable better agreement between model‐data comparisons. Key Points: Empirical conductance formulas are derived using 75,461 incoherent scatter radar observations with corresponding auroral morphologyPower law fits are presented for Hall and Pedersen conductances as function of average energy and energy fluxPulsating aurora found to be an important contribution for the Hall conductance at higher average energies [ABSTRACT FROM AUTHOR]

Published
2023
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9. Analysis of Electron Precipitation and Ionospheric Density Enhancements Due To Hiss Using Incoherent Scatter Radar and Arase Observations

Author

Ma, Q., primary, Xu, W., additional, Sanchez, E. R., additional, Marshall, R. A., additional, Bortnik, J., additional, Reyes, P. M., additional, Varney, R. H., additional, Kaeppler, S. R., additional, Miyoshi, Y., additional, Matsuoka, A., additional, Kasahara, Y., additional, Matsuda, S., additional, Tsuchiya, F., additional, Kumamoto, A., additional, Kasahara, S., additional, Yokota, S., additional, Keika, K., additional, Hori, T., additional, Mitani, T., additional, Nakamura, S., additional, Kazama, Y., additional, Wang, S.‐Y., additional, Jun, C.‐W., additional, Shinohara, I., additional, and Tam, S. W.‐Y., additional

Published
2022
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13. Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

Author

Bernhardt, P. A, Ballenthin, J. O, Baumgardner, J. L, Bhatt, A, Boyd, I. D, Burt, J. M, Caton, R. G, Coster, A, Erickson, P. J, Huba, J. D, Earle, G. D, Kaplan, C. R, Foster, J. C, Groves, K. M, Haaser, R. A, Heelis, R. A, Hunton, D. E, Hysell, D. L, Klenzing, J. H, Larsen, M. F, Lind, F. D, Pedersen, T. R, Pfaff, R. F, Stoneback, R. A, Roddy, P. A, Rodriguez, S. P, San Antonio, G. S, Schuck, P. W, Siefring, C. L, Selcher, C. A, Smith, S. M, Talaat, E. R, Thomason, J. F, Tsunoda, R. T, and Varney, R. H

Subjects
Space Sciences (General)
Abstract

On-orbit firings of both liquid and solid rocket motors provide localized disturbances to the plasma in the upper atmosphere. Large amounts of energy are deposited to ionosphere in the form of expanding exhaust vapors which change the composition and flow velocity. Charge exchange between the neutral exhaust molecules and the background ions (mainly O+) yields energetic ion beams. The rapidly moving pickup ions excite plasma instabilities and yield optical emissions after dissociative recombination with ambient electrons. Line-of-sight techniques for remote measurements rocket burn effects include direct observation of plume optical emissions with ground and satellite cameras, and plume scatter with UHF and higher frequency radars. Long range detection with HF radars is possible if the burns occur in the dense part of the ionosphere. The exhaust vapors initiate plasma turbulence in the ionosphere that can scatter HF radar waves launched from ground transmitters. Solid rocket motors provide particulates that become charged in the ionosphere and may excite dusty plasma instabilities. Hypersonic exhaust flow impacting the ionospheric plasma launches a low-frequency, electromagnetic pulse that is detectable using satellites with electric field booms. If the exhaust cloud itself passes over a satellite, in situ detectors measure increased ion-acoustic wave turbulence, enhanced neutral and plasma densities, elevated ion temperatures, and magnetic field perturbations. All of these techniques can be used for long range observations of plumes in the ionosphere. To demonstrate such long range measurements, several experiments were conducted by the Naval Research Laboratory including the Charged Aerosol Release Experiment, the Shuttle Ionospheric Modification with Pulsed Localized Exhaust experiments, and the Shuttle Exhaust Ionospheric Turbulence Experiments.

Published
2013
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17. Characterization of N+Abundances in the Terrestrial Polar Wind Using the Multiscale Atmosphere‐Geospace Environment

Author

Albarran, R. M., Varney, R. H., Pham, K., and Lin, D.

Abstract

The High‐latitude Ionosphere Dynamics for Research Applications (HIDRA) model is part of the Multiscale Atmosphere‐Geospace Environment model under development by the Center for Geospace Storms NASA DRIVE Science Center. This study employs HIDRA to simulate upflows of H+, He+, O+, and N+ions, with a particular focus on the relative N+concentrations, production and loss mechanisms, and thermal upflow drivers as functions of season, solar activity, and magnetospheric convection. The simulation results demonstrate that N+densities typically exceed He+densities, N+densities are typically ∼10% O+densities, and N+concentrations at quiet‐time are approximately 50%–100% of N+concentrations during storm‐time. Furthermore, the N+and O+upflow fluxes show similar trends with variations in magnetospheric driving. The inclusion of ion‐neutral chemical reactions involving metastable atoms is shown to have significant effects on N+production rates. With this metastable chemistry included, the simulated ion density profiles compare favorably with satellite measurements from Atmosphere Explorer C and Orbiting Geophysical Observatory 6. Simulated N+and O+densities increase while N+to O+density ratios decrease with solar activityN+concentrations typically exceed He+densities and N+fluence rates versus solar activity qualitatively resemble those for O+The inclusion of metastable chemical production of N+is critical to numerically reproduce observations Simulated N+and O+densities increase while N+to O+density ratios decrease with solar activity N+concentrations typically exceed He+densities and N+fluence rates versus solar activity qualitatively resemble those for O+ The inclusion of metastable chemical production of N+is critical to numerically reproduce observations

Published
2024
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18. Electrets and Electrostatic Measurement

Author

Varney, R. N. and Hahn, H. T.

Abstract

Electrets, the electrical counterparts of magnets, are polarized dielectrics that are permanent on a scale of months. Describes procedures for making electrets out of plastic sheets like Mylar, for testing them and measuring their pole strengths, and for establishing necessary and sufficient demonstrations that they are not simply surface charged. (Author/MLH)

Published
1975

29. AMISR-14: Observations of equatorial spread F

Author

Rodrigues, F. S., primary, Nicolls, M. J., additional, Milla, M. A., additional, Smith, J. M., additional, Varney, R. H., additional, Strømme, A., additional, Martinis, C., additional, and Arratia, J. F., additional

Published
2015
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34. Heater-induced ionization inferred from spectrometric airglow measurements

Author

Hysell, D. L., Miceli, R. J., Kendall, E. A., Schlatter, Nicola Manuel, Varney, R. H., Watkins, B. J., Pedersen, T. R., Bernhardt, P. A., Huba, J. D., Hysell, D. L., Miceli, R. J., Kendall, E. A., Schlatter, Nicola Manuel, Varney, R. H., Watkins, B. J., Pedersen, T. R., Bernhardt, P. A., and Huba, J. D.

Abstract

Spectrographic airglow measurements were made during an ionospheric modification experiment at High Frequency Active Auroral Research Program on 12 March 2013. Artificial airglow enhancements at 427.8, 557.7, 630.0, 777.4, and 844.6 nm were observed. On the basis of these emissions and using a methodology based on the method of Backus and Gilbert (1968, 1970), we estimate the suprathermal electron population and the subsequent equilibrium electron density profile, including contributions from electron impact ionization. We find that the airglow is consistent with heater-induced ionization in view of the spatial intermittency of the airglow., QC 20140625

Published
2014
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38. 1600 actuator tweeter mirror upgrade for the Palomar Adaptive Optics system (PALAO)

Author

Dekany, R., Mitchell Troy, Brack, G., Bleau, C., Du Varney, R., Ealey, M., and Wizinowich, Peter L.

Abstract

We discuss conceptual design issues for a 1600 actuator tweeter mirror/multiconjugate AO upgrade to the 349 actuator Palomar Adaptive Optics System (PALAO). Based upon a 42 X 42 actuator Photonex deformable mirror technology, developed by Xinetics, Inc., this upgrade would enable unique science at visible wavelengths and deliver unprecedented near-infrared Strehl ratios for modestly bright (mV equals 9) guide stars. When used in conjunction with the existing 349 actuator Xinetics, Inc. deformable mirror, a series of pressing issues regarding the practical utility of multiconjugate adaptive correction for extremely large telescopes could be addressed. By utilizing a low noise (EEV39) wavefront sensor camera developed by SciMeasure Analytical Systems, Inc., this system would provide on-axis K-band Strehl ratio of > 95%, improving scientific throughput and enabling the detection and spectroscopy of unresolved companions in an unprecedented contrast space around nearby stars.

Published
2000

41. Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

Author

Bernhardt, P. A., primary, Ballenthin, J. O., additional, Baumgardner, J. L., additional, Bhatt, A., additional, Boyd, I. D., additional, Burt, J. M., additional, Caton, R. G., additional, Coster, A., additional, Erickson, P. J., additional, Huba, J. D., additional, Earle, G. D., additional, Kaplan, C. R., additional, Foster, J. C., additional, Groves, K. M., additional, Haaser, R. A., additional, Heelis, R. A., additional, Hunton, D. E., additional, Hysell, D. L., additional, Klenzing, J. H., additional, Larsen, M. F., additional, Lind, F. D., additional, Pedersen, T. R., additional, Pfaff, R. F., additional, Stoneback, R. A., additional, Roddy, P. A., additional, Rodriquez, S. P., additional, San Antonio, G. S., additional, Schuck, P. W., additional, Siefring, C. L., additional, Selcher, C. A., additional, Smith, S. M., additional, Talaat, E. R., additional, Thomason, J. F., additional, Tsunoda, R. T., additional, and Varney, R. H., additional

Published
2012
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47. 975 A phase I/II single arm trial to determine the safety, tolerability, and biological activity of intrahepatic delivery of doxorubicin hydrochloride adsorbed to magnetic targeted carriers (MTC-DOX) in patients with metastatic tumors in the liver

Author

Just, R., primary, Hoh, C., additional, Vogl, T., additional, Neese, P., additional, Doemeny, J., additional, Schechter, M., additional, Varney, R., additional, Stanton, W., additional, Schiemann, M., additional, and Goldfarb, P., additional

Published
2003
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49. Pathways of Fregion thermospheric mass density enhancement via soft electron precipitation

Author

Zhang, B., Varney, R. H., Lotko, W., Brambles, O. J., Wang, W., Lei, J., Wiltberger, M., and Lyon, J. G.

Abstract

The efficiencies of pathways of thermospheric heating via soft electron precipitation in the dayside cusp region are investigated using the coupled magnetosphere‐ionosphere‐thermosphere model (CMIT). Event‐based data‐model comparisons show that the CMIT model is capable of reproducing the thermospheric mass density variations measured by the CHAMP satellite during both quite and active periods. During the 24 August 2005 storm event (Kp= 6−) while intense Joule heating rate occurs in the polar cusp region, including soft electron precipitation is important for accurately modeling the Fregion thermospheric mass density distribution near the cusp region. During the 27 July 2007 event (Kp= 2−) while little Joule heating rate occurs in the polar cusp region, the controlled CMIT simulations suggest that the direct pathway through the energy exchange between soft electrons and thermospheric neutrals is the dominant process during this event, which only has a small effect on the neutral temperature and mass density at 400 km altitude. Comparisons between the two case studies show that the indirect pathway via increasing the Fregion Joule heating rate is a dominant process during the 24 August 2005 storm event, which is much more efficient than the direct heating process. Soft electrons affect Fregion thermospheric mass densityThe indirect heating pathway is efficient during active periodsThe direct heating pathway is relatively inefficient

Published
2015
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