A5076121673- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Stellar, planetary, and galactic studies
- Solar Radiation and Photovoltaics
- Geophysics and Gravity Measurements
- Oil, Gas, and Environmental Issues
- Earthquake Detection and Analysis
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Spacecraft and Cryogenic Technologies
- Magnetic confinement fusion research
- Astronomy and Astrophysical Research
- Calibration and Measurement Techniques
- Computational Physics and Python Applications
- Inertial Sensor and Navigation
- Cosmology and Gravitation Theories
- Scientific Research and Discoveries
- Characterization and Applications of Magnetic Nanoparticles
- Laser-induced spectroscopy and plasma
- Astronomical Observations and Instrumentation
- Advanced X-ray Imaging Techniques
- Planetary Science and Exploration
- Historical Astronomy and Related Studies
Montana State University
2003-2016
University of Hawaii System
1989-2011
Honolulu University
1987-1996
University of Hawaiʻi at Mānoa
1992-1996
National Institute of Standards and Technology
1992
Marshall Space Flight Center
1992
University of California, San Diego
1978-1989
University of California, Berkeley
1980
Kitt Peak National Observatory
1971-1976
High Altitude Observatory
1970
view Abstract Citations (514) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Latitudinal Variation of Helicity Photospheric Magnetic Fields Pevtsov, Alexei A. ; Canfield, Richard C. Metcalf, Thomas R. Using a 1988-1994 data set original photospheric vector magnetograms as well published data, we have studied the average magnetic helicity 69 diverse active regions, adopting linear force-free field parameter alpha measure. This value was...
Soft X‐ray images of solar active regions frequently show S‐ or inverse‐S (sigmoidal) morphology. We have studied the Yohkoh X‐Ray Telescope video movie for 1993 and 1997. classified according to morphology (sigmoidal non‐sigmoidal) nature activity (eruptive non‐eruptive). As well, we used NOAA sunspot areas each region as a measure size. find that are significantly more likely be eruptive if they either sigmoidal large.
view Abstract Citations (379) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Flare loop radiative hydrodynamics. V - Response to thick-target heating. VI Chromospheric evaporation due heating by nonthermal electrons. VII Dynamics of the heated chromosphere Fisher, G. H. ; Canfield, R. C. McClymont, A. N. The results model simulations hydrodynamic and response solar-loop atmosphere short bursts energetic electrons are presented in extensive...
view Abstract Citations (274) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS H alpha Surges and X-Ray Jets in AR 7260 Canfield, Richard C. ; Reardon, Kevin P. Leka, K. D. Shibata, Yokoyama, T. Shimojo, M. We discuss nine events, observed simultaneously as jets X-rays surges Hα, which are associated with moving magnetic bipoles. The X-ray share many features those discovered by Yohkoh active regions, emerging flux bright points (see paper...
view Abstract Citations (254) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Is the Solar Chromospheric Magnetic Field Force-free? Metcalf, Thomas R. ; Jiao, Litao McClymont, Alexander N. Canfield, Richard C. Uitenbroek, Han We use observations of Na I lambda 5896 spectral line, made with Stokes Polarimeter at Mees Observatory, to measure chromospheric vector magnetic field in NOAA active region 7216. compute from parameters six wavelengths...
view Abstract Citations (301) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Flare Loop Radiative Hydrodynamics - Part Six Chromospheric Evaporation due to Heating by Nonthermal Electrons Fisher, G. H. ; Canfield, R. C. McClymont, A. N. The response of the solar chromosphere flare heating nonthermal electrons is examined. A number interesting phenomena appear in our numerical solutions equations hydrodynamics and radiative transfer. Here we...
view Abstract Citations (233) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Flare Loop Radiative Hydrodynamics - Part Seven Dynamics of the Thick Target Heated Chromosphere Fisher, G. H. ; Canfield, R. C. McClymont, A. N. It is shown that hydrodynamic phenomena in chromospheric portion flaring solar atmosphere depend dramatically on whether evaporation by thick-target fast-electron heating "gentle" or "explosive." In case gentle evaporation,...
view Abstract Citations (171) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Patterns of Helicity in Solar Active Regions Pevtsov, Alexei A. ; Canfield, Richard C. Metcalf, Thomas R. Using 46 vector magnetograms from the Stokes Polarimeter Mees Observatory (MSO), we studied patterns local helicity three diverse solar active regions. From these computed maps parameter alpha = Jz/Bz. Although such are noisy, found at level approximately 2 to 3...
The Japanese Yohkoh satellite is now in orbit observing the sun with a set of x-ray imagers and gamma-ray spectrometers. data from this successful mission provide new information on solar flares sun's corona. This paper discusses observations presents sample first scientific results mission.
view Abstract Citations (157) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Morphology of Flare Phenomena, Magnetic Fields, and Electric Currents in Active Regions. I. Introduction Methods Canfield, Richard C. ; de La Beaujardiere, J. -F. Fan, Yuhong Leka, K. D. McClymont, A. N. Metcalf, Thomas R. Mickey, Donald L. Wuelser, Jean-Pierre Lites, Bruce W. current systems solar active regions their spatial relationship to sites electron...
Applying the same methods we used in solar cycle 22, study active region vector magnetograms, full-disk X-ray images, and line-of-sight magnetograms to derive helicity of magnetic fields first 4 years 23. We find that these three data sets all exhibit two key tendencies—significant scatter weak hemispheric asymmetry—as were observed 22. This supports interpretation tendencies as signatures writhing flux by turbulence convection zone.
Using X-ray images, Hα and vector magnetograms, we have studied the evolution of coronal structure magnetic field NOAA Active Region 7154 during 1992 May 5-12. A two-ribbon 4B/M7.4 flare associated with an filament eruption was observed on 8, 15:13-19:16 UT. An interesting feature region a long, twisted structure, which formed shortly before disappeared after it, being replaced by system unsheared postflare loops. Neither nor morphology photospheric shows any indication gradual buildup...
Using photospheric vector magnetograms from the Haleakala Stokes Polarimeter and coronal X-ray images Yohkoh Soft X-Ray Telescope (SXT), we infer values of force-free field parameter α at both levels within 140 active regions. We determine value for a linear that best fits each magnetogram in least-squares sense. average all available to obtain single mean α-value ⟨αp⟩ region. From SXT estimate corona by determining (π/L) sin γ individual loops, where is observed shear angle loops length L....
view Abstract Citations (92) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS H alpha Spectra of Dynamic Chromospheric Processes in Five Well-observed X-Ray Flares Canfield, Richard C. ; Penn, Matthew J. Wulser, Jean-Pierre Kiplinger, Alan L. Simultaneous H-alpha and hard X-ray (HXR) spectra were obtained for five solar flares to determine the relationship profiles nonthermal part flare represented by burst. All exhibited impulsive-phase...
view Abstract Citations (109) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Impulsive H alpha Diagnostics of Electron-Beam--heated Solar Flare Model Chromospheres Canfield, Richard C. ; Gayley, Kenneth G. Time-dependent H-alpha profiles were computed for the dynamic model atmospheres Fisher, and McClymont (1985) simulating effects an intense impulsively initiated power-law beam electrons incident on chromosphere. The temporal response arises...
view Abstract Citations (110) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The H-alpha spectral signatures of solar flare nonthermal electrons, conductive flux, and coronal pressure Canfield, R. C. ; Gunkler, T. A. Ricchiazzi, P. J. During a flare, number mechanisms heat the chromosphere above its preflare temperature. Ricchiazzi Canfield (1983) have modeled response to processes related energetic thermal conductivity, enhanced pressure....
To better understand eruptive events in the solar corona, we combine sequences of multi-wavelength observations and modelling coronal magnetic field NOAA AR 8210, a highly flare-productive active region. From photosphere to give us information about motion elements (photospheric magnetograms), location flares (e.g., Hα, EUV or soft X-ray brightenings), type (Hα blueshift events). Assuming that evolution above an region can be described by successive equilibria, follow time changes 3D...
view Abstract Citations (110) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Chromospheric evaporation in a well-observed compact flare Acton, L. W. ; Leibacher, J. Canfield, R. C. Gunkler, T. A. Hudson, H. S. Kiplinger, Hudson and Ohki (1972) pointed out that the increase of soft X-ray emission measure during flares might be accounted for two different ways, either by 'coronal condensation', or what they termed 'chromospheric rarefaction',...
Aims.Coronal sigmoids are important sources of eruptions into interplanetary space, and a handful models have been proposed to explain their characteristic S shape. However, the coronal X-ray images available date generally not had sufficient resolution distinguish between these models. The goal present investigation is determine whether new observations from Hinode can help us make such distinction.
view Abstract Citations (84) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Computed Profiles for Solar MG b- and NA D-Lines Athay, R. Grant ; Canfield, Richard C. are computed the Doppler cores of solar Mg Na D-lines multilevel model atoms selected ranges chromospheric parameters. Comparison observed profiles from center to limb on disk yields depth variation horizontal vertical components microturbulence. The two found be unequal amplitude...
view Abstract Citations (87) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Explosive Plasma Flows in a Solar Flare Zarro, Dominic M. ; Canfield, Richard C. Strong, Keith T. Metcalf, Thomas R. Maximum Mission soft X-ray data and Sacramento Peak Observatory H-alpha observations are combined study of the impulsive phase solar flare. A blue asymmetry, indicative upflows, was observed coronal Ca XIX line during rise phase. red downflows,...
In this work we relate the magnetic and topological parameters of twelve interplanetary clouds to associated solar active regions. We use a cylindrically symmetric constant‐α force‐free model derive field line twist, total current, flux from in situ observations clouds. compare these properties with those regions, which infer vector magnetograms. Our comparison fluxes currents reveals: (1) ratios Φ MC /Φ AR tend be order unity, (2) current I / are orders magnitude smaller, (3) there is...
view Abstract Citations (71) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A static model of chromospheric heating in solar flares Ricchiazzi, P. J. ; Canfield, R. C. The response the chromosphere to flare processes, namely nonthermal electrons, thermal conduction, and coronal pressure, is modeled. Finite difference methods employing linearization iteration are used obtaining simultaneous solutions equations steady-state energy balance,...