- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Complex Systems and Time Series Analysis
- Statistical Mechanics and Entropy
- Solar Radiation and Photovoltaics
- Astrophysics and Cosmic Phenomena
- Spacecraft and Cryogenic Technologies
- Astrophysics and Star Formation Studies
- Planetary Science and Exploration
- Magnetic confinement fusion research
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Astronomical Observations and Instrumentation
- History and Developments in Astronomy
- Climate variability and models
- Fluid Dynamics and Turbulent Flows
- Financial Risk and Volatility Modeling
- Wind and Air Flow Studies
- GNSS positioning and interference
- Advanced Thermodynamics and Statistical Mechanics
- Spacecraft Design and Technology
Davidson College
2020-2024
Goddard Space Flight Center
2014-2023
University of New Hampshire
2023
Ben-Gurion University of the Negev
2023
Predictive Science (United States)
2023
University of Alabama in Huntsville
2023
Southwest Research Institute
2023
University of Waikato
2023
Space Science Institute
2023
University of Maryland, Baltimore County
2019
Magnetic field and plasma data from five spacecraft (Voyager 1 2, Helios IMP 8) were used to analyze the flow behind an interplanetary shock. The shock was followed by a turbulent sheath in which there large fluctuations both strength direction of magnetic field. This turn region (magnetic cloud) vectors observed change rotating nearly parallel plane, consistent with passage loop. loop extended at least 30° longitude between 2 AU, its radial dimension approximately 0.5 AU. In cloud high,...
Magnetic clouds are defined as regions with a radial dimension ≈ 0.25 AU (at 1 AU) in which the magnetic field strength is high and direction changes appreciably by means of rotation one component nearly parallel to plane. The geometry such cloud consistent that loop, but it cannot be determined uniquely. Forty‐five were identified interplanetary data obtained near earth between 1967 1978; at least passed every 3 months. Three classes identified, corresponding association shock, stream...
Interplanetary magnetic clouds, although not dominant, are a relatively common feature of the solar wind at 1 AU. Their diameters AU fall in range 0.2–0.4 AU, and they have enhanced field strength (B ≃ 15–30 nT AU), lower plasma temperature density than surrounding plasma. The internal is force‐free configuration, therefore current ( J ) proportional to B everywhere: = α , giving ▽× . If constant throughout cloud (Burlaga, 1988), then ▽² −α² which has cylindrically symmetric solution that...
Magnetic clouds observed at 1 AU are modeled as cylindrically symmetric, constant alpha force‐free magnetic fields. The model satisfactorily explains the types of variations field direction that a cloud moves past spacecraft in terms possible orientations axis cloud. also why strength is to be higher inside than near its boundaries. However, predicts profile should symmetric with respect cloud, whereas observations show this not generally case.
The magnetic field experiment on the Voyager 2 spacecraft revealed a strong planetary of Uranus and an associated magnetosphere fully developed bipolar masnetic tail. detached bow shock wave in solar wind supersonic flow was observed upstream at 23.7 radii (1 R(U) = 25,600 km) magnetopause boundary 18.0 R(U), near planet-sun line. A miaximum 413 nanotesla 4.19 R(U ), just before closest approach. Initial analyses reveal that is well represented by dipole offset from center planet 0.3 R(U)....
Finally Out Last summer, it was not clear if the Voyager 1 spacecraft had finally crossed heliopause—the boundary between heliosphere and interstellar space. Gurnett et al. (p. 1489 , published online 12 September) present results from Plasma Wave instrument on that provide evidence in plasma during two periods, October to November 2012 April May 2013, very likely continuously since series of crossings occurred July August 2012.
Nineteen magnetic clouds are identified in the years from 1978 through 1982 and studied using superposed epoch analysis. The field intensity, proton density, temperature enhanced ahead of that preceded by a shock, while strong intensity low observed within clouds. A relatively large (∼2.5%) decrease cosmic ray is associated with perhaps caused turbulent sheath behind an interplanetary shock cloud, whereas only small (∼0.5%) cloud itself. Magnetic can produce geomagnetic activity Dst index...
This work discusses the relations among (1) an interplanetary force‐free magnetic cloud containing a plug of cold high‐density material with unusual composition, (2) coronal mass ejection (CME), (3) eruptive prominence, and (4) model prominence supported by flux rope in streamer. The moved past Wind spacecraft located solar wind upstream Earth on January 10 11, 1997. field configuration was approximately constant‐α, rope. 4 He ++ /H + abundance most similar to that streamer belt material,...
An interplanetary magnetic cloud observed by the Helios 1 spacecraft was found to be associated with a coronal mass ejection NRL Solwind coronagraph on P78‐1. The June 20, 1980 when at 0.54 AU and nearly 90° west of earth‐sun line. This large loop‐like over limb 18, 1980, moving toward 1. speed front event (470 ± 10) km/s, which is close mean transit (∽ 500 km/s). similar others described in literature: field strength higher than average; density relatively low; pressure greatly exceeded ion...
An analysis of high resolution magnetic field measurements from the GSPC magnetometer on Explorer 113 showed that low intensities (< 1 y ) in solar wind at AU occur as distinct depressions or "holes," otherwise nearly average conditions.These holes are new kinetic-scale phenomena, having a characteristic dimension order 20,000 km.They rate 1.5/day 18-day interval (March 18 to April 6, 1971) was considered.Most characterized by both depression IBI and change direction, some these possibly...
The National Aeronautics and Space Administration Goddard Flight Center-University of Delaware Bartol Research Institute magnetic field experiment on the Voyager 2 spacecraft discovered a strong complex intrinsic Neptune an associated magnetosphere tail. detached bow shock wave in supersonic solar wind flow was detected upstream at 34.9 radii (R(N)), magnetopause boundary tentatively identified 26.5 R(N) near planet-sun line (1 = 24,765 kilometers). A maximum nearly 10,000 nanoteslas...
Data from ISEE 3, Helios A, and B were used to identify the components of two compound streams determine their configurations. (A stream is a which has formed as result interaction or more distinct fast flows.) In one case, ejecta containing magnetic cloud associated with disappearing quiescent filament interacting corotating stream. second 2B flare overtaking different source. Each these produced an unusually large geomagnetic storm, on April 1979, 25, respectively. The largest storm in...
This paper demonstrates the existence of intermittent turbulence in solar wind at 8.5 AU. The p th‐order velocity structure functions show scaling behavior range periods from 0.85 hour to 13.6 hours for ≤ 20. exponent law s ( ) is a quadratic function . Our observations compressible MHD on scale order ∼1 AU = 1.5×10 8 km are consistent with laboratory measurements gasdynamic 1 m, indicating universal character turbulence. not described by “constant β” model They marginally lognormal model....
Results obtained by the Goddard Space Flight Center magnetometers on Voyager 1 are described. These results concern large-scale configuration of Jovian bow shock and magnetopause, magnetic field in both inner outer magnetosphere. There is evidence that a tail extending away from planet nightside formed solar wind-Jovian interaction. This much like Earth's magnetosphere but new for Jupiter's not previously considered earlier Pioneer data. We report analysis interpretation perturbations...
Magnetic fields measured by Voyager 1 show that the spacecraft crossed or was termination shock on about 16 December 2004 at 94.0 astronomical units. An estimate of compression ratio magnetic field strength B (+/- standard error mean) across is B2/B1 = 3.05 +/- 0.04, but ratios in range from 2 to 4 are admissible. The average heliosheath day through 110 2005 0.136 0.035 nanoteslas, approximately 4.2 times predicted Parker's model for B. 361 pointing away Sun along Parker spiral. probability...
At 1 AU there is a distinct boundary (the stream interface) in the interaction region of solar wind, characterized by an abrupt (approximately factor 2 change <106 km) drop density, similar increase temperature, and small speed. In some cases this tangential discontinuity, others it probably evolving into discontinuity. It suggested that interfaces form interplanetary medium as consequence nonlinear evolution streams generated temperature envelope. This eventually leads to formation reverse...
The changes in the cosmic ray intensity >70 MeV/nucleon observed by Voyager 1 (hereinafter called V1) near 30° heliographic latitude and 2 V2) 0° from 1986 to 1990 were closely related large‐scale fluctuations magnetic field strength at V1 V2, respectively. decreases V2 generally merged interaction regions (MIRs). An exception this relation was about day 45 110, 1987 V1. MIRs are of three general types: “global MIRs” (GMIRs), which extend around Sun high latitudes, whose effects persist...