The Relationship Between X-Ray Radiance and Magnetic Flux
- A. Pevtsov, G. Fisher, T. Metcalf
- Physics
- 1 December 2003
We use soft X-ray and magnetic field observations of the Sun (quiet Sun, X-ray bright points, active regions, and integrated solar disk) and active stars (dwarf and pre-main-sequence) to study the…
Nonlinear Force-free Field Modeling of a Solar Active Region around the Time of a Major Flare and Coronal Mass Ejection
- C. Schrijver, M. Derosa, J. Thalmann
- Physics
- 30 November 2007
Solar flares and coronal mass ejections are associated with rapid changes in field connectivity and are powered by the partial dissipation of electrical currents in the solar atmosphere. A critical…
Is the solar chromospheric magnetic field force-free?
- T. Metcalf, L. Jiao, A. Mcclymont, R. Canfield, H. Uitenbroek
- Physics
- 1995
Latitudinal variation of helicity of photospheric magnetic fields
- A. Pevtsov, R. Canfield, T. Metcalf
- Physics
- 20 February 1995
Using a 1988-1994 data set of original photospheric vector magnetograms as well as published data, we have studied the average magnetic helicity of 69 diverse active regions, adopting the linear…
Coronal Heating in Active Regions as a Function of Global Magnetic Variables
- G. Fisher, D. Longcope, T. Metcalf, A. Pevtsov
- Physics
- 1 December 1998
A comparison of X-ray images of the Sun and full disk magnetograms shows a correlation between the locations of the brightest X-ray emission and the locations of bipolar magnetic active regions. This…
Nonlinear Force-Free Modeling of Coronal Magnetic Fields Part I: A Quantitative Comparison of Methods
- C. Schrijver, M. Derosa, T. Wiegelmann
- Physics
- 1 May 2006
We compare six algorithms for the computation of nonlinear force-free (NLFF) magnetic fields (including optimization, magnetofrictional, Grad–Rubin based, and Green's function-based methods) by…
Resolving the 180-degree ambiguity in vector magnetic field measurements: The ‘minimum’ energy solution
- T. Metcalf
- Physics
- 1 December 1994
I present a robust algorithm that resolves the 180-deg ambiguity in measurements of the solar vector magnetic field. The technique simultaneously minimizes both the divergence of the magnetic field…
Resolving the 180° Ambiguity in Solar Vector Magnetic Field Data: Evaluating the Effects of Noise, Spatial Resolution, and Method Assumptions
The objective testing of algorithms for performing ambiguity resolution in vector magnetic field data is continued, with an examination of the effects of noise in the data. Through the use of…
An Overview of Existing Algorithms for Resolving the 180° Ambiguity in Vector Magnetic Fields: Quantitative Tests with Synthetic Data
- T. Metcalf, K. Leka, Y. Moon
- Geology
- 23 July 2006
We report here on the present state-of-the-art in algorithms used for resolving the 180° ambiguity in solar vector magnetic field measurements. With present observations and techniques, some…
A Concise History of Modern India
- B. Metcalf, T. Metcalf
- History, Economics
- 26 November 2001
List of illustrations Preface to the second edition Preface to the first edition Glossary Chronology 1. Sultans, Mughals and pre-colonial Indian society 2. Mughal twilight: the emergence of regional…
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