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pro vyhledávání: '"Ulrich, Roger K."'
The methods for reducing the observations from the 150-foot Tower Telescope on Mt.~Wilson are reviewed and a new method for determining the North/South (sectoral) and the East/West (zonal) velocity components is described and applied. Due to a calibr
Externí odkaz:
http://arxiv.org/abs/2307.06387
Publikováno v:
Space Weather, 16, published on line November 4, 2018
This study identifies the solar origins of magnetic clouds that are observed at 1 AU and predicts the helical handedness of these clouds from the solar surface magnetic fields. We started with the magnetic clouds listed by the Magnetic Field Investig
Externí odkaz:
http://arxiv.org/abs/1811.03560
Autor:
Ulrich, Roger K.1 (AUTHOR) ulrich@astro.ucla.edu, Tran, Tham1 (AUTHOR), Boyden, John E.1 (AUTHOR)
Publikováno v:
Solar Physics. Oct2023, Vol. 298 Issue 10, p1-17. 17p.
Akademický článek
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Autor:
Ulrich, Roger K., Tran, Tham
We address the problem of calculating the transverse magnetic field in the solar wind outside of the hypothetical sphere called the source surface where the solar wind originates. This calculation must overcome a widely used fundamental assumption ab
Externí odkaz:
http://arxiv.org/abs/1603.02697
Autor:
Ulrich, Roger K., Tran, Tham
Publikováno v:
Astrophysical Journal, 2013
We have examined the global structure of the solar magnetic field using data from the FeI spectral line at {\lambda}5250.2{\AA} obtained at the 150-foot tower telescope at the Mt. Wilson Observatory (MWO). For each point on the solar surface, we find
Externí odkaz:
http://arxiv.org/abs/1304.1249
Autor:
Li, Jing, Ulrich, Roger K.
Tilt angles of close to 30,600 sunspots are determined using Mount Wilson daily averaged magnetograms taken from 1974 to 2012, and MDI/SoHO magnetograms taken from 1996 to 2010. Within a cycle, more than 90% of sunspots have a normal polarity alignme
Externí odkaz:
http://arxiv.org/abs/1209.1642
We present the initial results of an observational study into the variation of the dominant length-scale of quiet solar emission: supergranulation. This length-scale reflects the radiative energy in the plasma of the upper solar chromosphere and tran
Externí odkaz:
http://arxiv.org/abs/1102.0303
Autor:
Ulrich, Roger K.
Publikováno v:
ApJ, 725, 658-669 (2010)
Doppler shifts of the Fe I spectral line at lambda5250 Angstroms from the full solar disk obtained over the period 1986 to 2009 are analyzed to determine the circulation velocity of the solar surface along meridional planes. Simultaneous measurements
Externí odkaz:
http://arxiv.org/abs/1010.0487
We show that systematic differences between surface Doppler and magnetic element tracking measures of solar meridional flow can be explained by the effects of surface turbulent magnetic diffusion. Feature-tracking speeds are lower than plasma speeds
Externí odkaz:
http://arxiv.org/abs/1008.2772