Search Publications
VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager
Schou, J.; Kubo, M.; Borrero, J. M. +4 more
In this paper we describe in detail the implementation and main properties of a new inversion code for the polarized radiative transfer equation (VFISV: Very Fast Inversion of the Stokes Vector). VFISV will routinely analyze pipeline data from the Helioseismic and Magnetic Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It will prov…
Global MHD Modeling of the Solar Corona and Inner Heliosphere for the Whole Heliosphere Interval
Riley, P.; Luhmann, J.; Linker, J. A. +3 more
In an effort to understand the three-dimensional structure of the solar corona and inner heliosphere during the Whole Heliosphere Interval (WHI), we have developed a global magnetohydrodynamics (MHD) solution for Carrington rotation (CR) 2068. Our model, which includes energy-transport processes, such as coronal heating, conduction of heat paralle…
Galactic Cosmic Ray Intensity Response to Interplanetary Coronal Mass Ejections/Magnetic Clouds in 1995 - 2009
Cane, H. V.; Richardson, I. G.
We summarize the response of the galactic cosmic ray (CGR) intensity to the passage of the more than 300 interplanetary coronal mass ejections (ICMEs) and their associated shocks that passed the Earth during 1995 - 2009, a period that encompasses the whole of Solar Cycle 23. In ∼ 80% of cases, the GCR intensity decreased during the passage of thes…
Quantitative Analysis of CME Deflections in the Corona
Wang, Yuming; Wang, Shui; Shen, Chenglong +4 more
In this paper, ten CME events viewed by the STEREO twin spacecraft are analyzed to study the deflections of CMEs during their propagation in the corona. Based on the three-dimensional information of the CMEs derived by the graduated cylindrical shell (GCS) model (Thernisien, Howard, and Vourlidas in Astrophys. J.652, 1305, 2006), it is found that …
Evolution of Coronal Holes and Implications for High-Speed Solar Wind During the Minimum Between Cycles 23 and 24
de Toma, G.
We analyze coronal holes present on the Sun during the extended minimum between Cycles 23 and 24, study their evolution, examine the consequences for the solar wind speed near the Earth, and compare it with the previous minimum in 1996. We identify coronal holes and determine their size and location using a combination of EUV observations from SOH…
Twisted Flux Tube Emergence Evidenced in Longitudinal Magnetograms: Magnetic Tongues
Mandrini, C. H.; van Driel-Gesztelyi, L.; Démoulin, P. +1 more
Bipolar active regions (ARs) are thought to be formed by twisted flux tubes, as the presence of such twist is theoretically required for a cohesive rise through the whole convective zone. We use longitudinal magnetograms to demonstrate that a clear signature of a global magnetic twist is present, particularly, during the emergence phase when the A…
Solar Flares and Coronal Mass Ejections: A Statistically Determined Flare Flux - CME Mass Correlation
Hughes, W. J.; Stassun, K. G.; McGregor, S. L. +1 more
In an effort to examine the relationship between flare flux and corresponding CME mass, we temporally and spatially correlate all X-ray flares and CMEs in the LASCO and GOES archives from 1996 to 2006. We cross-reference 6733 CMEs having well-measured masses against 12 050 X-ray flares having position information as determined from their optical c…
Coronal Field Opens at Lower Height During the Solar Cycles 22 and 23 Minimum Periods: IMF Comparison Suggests the Source Surface Should Be Lowered
Sun, X.; Luhmann, J. G.; Arge, C. N. +3 more
The solar cycle 23 minimum period has been characterized by a weaker solar and interplanetary magnetic field. This provides an ideal time to study how the strength of the photospheric field affects the interplanetary magnetic flux and, in particular, how much the observed interplanetary fields of different cycle minima can be understood simply fro…
A New Method for Polar Field Interpolation
Liu, Y.; Sun, X.; Hoeksema, J. T. +2 more
The photospheric magnetic field in the Sun's polar region is not well observed compared to the low-latitude regions. Data are periodically missing due to the Sun's tilt angle, and the noise level is high due to the projection effect on the line-of-sight (LOS) measurement. However, the large-scale characteristics of the polar magnetic field data ar…
On the Formation Height of the SDO/HMI Fe 6173 Å Doppler Signal
Straus, T.; Couvidat, S.; Fleck, B.
The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) is designed to study oscillations and the magnetic field in the solar photosphere. It observes the full solar disk in the Fe I absorption line at 6173 Å. We use the output of a high-resolution, 3D, time-dependent, radiation-hydrodynamic simulation based on the …