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- Publications
- Influence
Is the solar chromospheric magnetic field force-free?
- T. Metcalf, L. Jiao, A. N. 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… Expand
Nonlinear Force-Free Modeling of Coronal Magnetic Fields Part I: A Quantitative Comparison of Methods
- C. J. Schrijver, M. Derosa, +6 authors 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… Expand
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… Expand
An Overview of Existing Algorithms for Resolving the 180° Ambiguity in Vector Magnetic Fields: Quantitative Tests with Synthetic Data
- T. Metcalf, K. Leka, +12 authors Y. Moon
- Physics
- 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… Expand
Active-Region Magnetic Structure Observed in the Photosphere and Chromosphere
- K. Leka, T. Metcalf
- Physics
- 1 February 2003
The full magnetic vector has been measured in both the photosphere and chromosphere across sunspots and plage in NOAA Active Region 8299. We investigate the vertical magnetic structure above the… Expand
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… Expand
Patterns of Helicity in Solar Active Regions
- A. Pevtsov, R. Canfield, T. Metcalf
- Physics
- 20 April 1994
Using 46 vector magnetograms from the Stokes Polarimeter of Mees Solar Observatory (MSO), we studied patterns of local helicity in three diverse solar active regions. From these magnetograms we… Expand
Evidence for the Flare Trigger Site and Three-Dimensional Reconnection in Multiwavelength Observations of a Solar Flare
- L. Fletcher, T. Metcalf, D. Alexander, D. Brown, L. A. Ryder
- Physics
- 10 June 2001
Based on a multiwavelength data set and a topological model for the magnetic field, we argue that a M1.9 flare which occurred on 1993 May shows evidence of three-dimensional coronal reconnection in a… Expand
Magnetic Free Energy in NOAA Active Region 10486 on 2003 October 29
- T. Metcalf, K. Leka, D. Mickey
- Physics
- 17 March 2005
We calculate the total and the free magnetic energy for solar NOAA active region 10486 on 2003 October 29 using chromospheric vector magnetograms observed with the Imaging Vector Magnetograph at Mees… Expand