A5057118067- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Solar Radiation and Photovoltaics
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Earthquake Detection and Analysis
- Web and Library Services
- Geophysics and Gravity Measurements
- Astrophysics and Cosmic Phenomena
- Nursing Education, Practice, and Leadership
- Radiation Therapy and Dosimetry
- Online and Blended Learning
- Library Science and Information Literacy
- Open Education and E-Learning
- Planetary Science and Exploration
- Health Sciences Research and Education
- Photovoltaic System Optimization Techniques
- Global Energy and Sustainability Research
- Nursing Diagnosis and Documentation
- Magnetic confinement fusion research
- Isotope Analysis in Ecology
- Dark Matter and Cosmic Phenomena
Goddard Space Flight Center
2015-2024
University of Maryland, College Park
2015-2024
Heliophysics
2017-2024
Heliophysics Science Division
2020-2024
University of California, Berkeley
2023
Iowa State University
2019-2022
University of New Hampshire
2019
Imperial College London
1984-2011
United States Air Force Research Laboratory
2011
Atmospheric and Environmental Research
2011
We summarize the occurrence of interplanetary coronal mass ejections (ICMEs) in near‐Earth solar wind during 1996–2002, corresponding to increasing and maximum phases cycle 23. In particular, we give a detailed list such events. This list, based on situ observations, is not confined subsets ICMEs, as “magnetic clouds” or those preceded by “halo” injections (CMEs) observed Solar Heliospheric Observatory/Large Angle Spectrometric Coronagraph, provides an overview 214 ICMEs this period. The...
We present the results of an investigation sequence events from Sun to Earth that ultimately led 88 major geomagnetic storms (defined by minimum Dst ≤ −100 nT) occurred during 1996–2005. The are achieved through cooperative efforts originated at Living with a Star (LWS) Coordinated Data‐Analysis Workshop (CDAW) held George Mason University in March 2005. On basis careful examination complete array solar and situ wind observations, we have identified characterized, for each storm, overall...
This paper focuses on the interactions between fast solar wind from coronal holes and intervening slower wind, leading to creation of stream interaction regions that corotate with Sun may persist for many rotations. Stream have been observed near 1 AU, in inner heliosphere (at ∼0.3 -1 AU) by Helios spacecraft, outer distant Pioneer 10 11 Voyager 2 out ecliptic Ulysses, these observations are reviewed. accelerate energetic particles, modulate intensity Galactic cosmic rays generate enhanced...
Occurrences of solar wind plasma with abnormally low proton temperatures ( T p ) have long been associated the interplanetary manifestations (which we term “ejecta”) coronal mass ejections (CMEs). We survey National Space Science Data Center Omni database for 1965–1991, and data from Helios 1 2 spacecraft more limited periods, to identify in which is less than temperature expected ex well‐established correlation between speed normal expansion. The occurrence rate low‐temperature...
We determine the solar wind structures (coronal mass ejection (CME)‐related, corotating high‐speed streams, and slow wind) driving geomagnetic storms of various strength over nearly three cycles (1972–2000). The most intense (defined by Kp ) at both minimum maximum are almost all (∼97%) generated transient associated with CMEs. Weaker preferentially streams CMEs maximum, reflecting change in structure between these phases cycle. Slow generates a small fraction weaker maximum. also size...
We assess the contribution of various types solar wind structures (coronal mass ejections (CMEs), high‐speed streams, and slow wind) to averages aa geomagnetic activity index ( ) during cycle. used plasma, magnetic field, energetic particle data identify flow present in near‐Earth 1972–1986 (encompassing decline cycle 20 all 21). Corotating streams contribute ∼ 70% outside maximum 30% at (1978–1982). CME‐related (shocks/postshock flows/ejecta) account for 50% <10% maximum. Slow...
In a series of three interlinked papers we present study an interplanetary magnetic cloud and its interaction with the Earth's magnetosphere on January 14/15, 1988. This first paper is divided into parts describing principal results concerning cloud. First, by applying cylindrically symmetric, flux rope model to high time resolution field plasma data obtained IMP‐8 spacecraft, show that axis in question approximately ecliptic orthogonal Earth‐Sun line. We note presence pulsations ∼5‐hour...
We examine the contributions of principal solar wind components (corotating high‐speed streams, slow wind, and transient structures, i.e., interplanetary coronal mass ejections (CMEs), shocks, postshock flows) to averages aa geomagnetic index magnetic field (IMF) strength in 1972–2000 during nearly three cycles. A prime motivation is understand influence cycle variations structure on long‐term (e.g., approximately annual) these parameters. show that streams account for two‐thirds at minimum,...
Studies using SOHO spacecraft data have demonstrated that frontside halo coronal mass ejections (CMEs) detected by the LASCO coronagraphs generally precede geomagnetic storms. Nonetheless, about three quarters of such CMEs do not result in even moderate activity. We study relationship all ejecta (interplanetary CMEs) which passed Earth during 1996–1999 to coronagraph and reach following conclusions: (1) Only half encounter Earth; (2) The geoeffectiveness depends strongly on southward...
Seventy‐nine major geomagnetic storms (minimum Dst ≤ −100 nT) observed in 1996 to 2004 were the focus of a “Living with Star” Coordinated Data Analysis Workshop (CDAW) March 2005. In nine cases, storm driver appears have been purely corotating interaction region (CIR) without any contribution from coronal mass ejection‐related material (interplanetary ejections (ICMEs)). These generated by structures within CIRs located both before and/or after stream interface that included persistently...
We investigate the use of multiple simultaneous solar wind plasma compositional anomalies, relative to composition ambient wind, for identifying interplanetary coronal mass ejection (ICME) plasma. first summarize characteristics several signatures ( O 7 / 6 , Mg/O, Ne/O, Fe charge states, He/p) observed by ACE and Wind spacecraft within ICMEs during 1996–2002 identified Cane Richardson [2003] hereafter CR03. then develop a set simple criteria that may be used identify such anomalies hence...
We examined the properties and associations of 280 solar proton events that extended above 25 MeV occurred in years 1997–2006. The include early peak intensities five species over several energy ranges intensity‐time profiles. Solar event were made for as many possible. parameters determined coronal mass ejection flare radio emissions from a wavelength range meters to kilometers. divided into representative types based on relative abundances particle profiles more easily illustrate how...
Using a classification of the near-Earth solar wind into three basic flow types: (1) High-speed streams associated with coronal holes at Sun; (2) Slow, interstream wind; and (3) Transient flows originating mass ejections (CMEs) Sun, including interplanetary CMEs upstream shocks post-shock regions, we determine drivers geomagnetic storms various size ranges based on Kp index NOAA “G” criteria since 1964, close to beginning space era, 2011, encompassing more than four cycles (20–23). We also...
In past studies, we classified the near-Earth solar wind into three basic flow types based on inspection of plasma and magnetic field parameters in OMNI database additional data (e.g., geomagnetic indices, energetic particle, cosmic ray observations). These are: (1) High-speed streams associated with coronal holes at Sun, (2) Slow, interstream wind, (3) Transient flows originating mass ejections including interplanetary upstream shocks post-shock regions. The classification these previous...
Abstract We discuss observations of the journey throughout Solar System a large interplanetary coronal mass ejection (ICME) that was ejected at Sun on 14 October 2014. The ICME hit Mars 17 October, as observed by Express, Atmosphere and Volatile EvolutioN Mission (MAVEN), Odyssey, Science Laboratory (MSL) missions, 44 h before encounter planet with Siding‐Spring comet, for which space weather context is provided. It reached comet 67P/Churyumov‐Gerasimenko, perfectly aligned 3.1 AU, Rosetta...
Abstract The Wind spacecraft, launched on November 1, 1994, is a critical element in NASA’s Heliophysics System Observatory (HSO)—a fleet of spacecraft created to understand the dynamics Sun‐Earth system. combination its longevity (>25 years service), diverse complement instrumentation, and high resolution accurate measurements has led it becoming “standard candle” solar wind measurements. over 55 selectable public data products with ∼1,100 total variables (including OMNI products)...
Solar Energetic Particle (SEP) events are interesting from a scientific perspective as they the product of broad set physical processes corona out through extent heliosphere, and provide insight into particle acceleration transport that widely applicable in astrophysics. From operations perspective, SEP pose radiation hazard for aviation, electronics space, human space exploration, particular missions outside Earth's protective magnetosphere including to Moon Mars. Thus, it is critical...
We present solar wind Fe charge state data measured on the Advanced Composition Explorer (ACE) from early 1998 to middle of 2000. Average states in are typically around 9+ 11+. However, deviations these average occur, including intervals with a large fraction ≥16+ which consistently associated interplanetary coronal mass ejections (ICMEs). By studying distribution we able extract electron temperatures often exceeding 2 × 10 6 kelvins. also discuss temporal trends events, indicating more...
We show that the variations of interplanetary magnetic field strength (B) over a 22‐year period are tracked by inverted profile cosmic ray density measured neutron monitors. suggest global changes in Sun's more important for long‐term modulation than enhancements resulting from merging high‐speed flows and coronal mass ejections outer heliosphere. The unexpectedly close relationship we find between “tilt angle” heliospheric current sheet away solar minimum both polarity states may be...