Slow and fast solar wind acceleration near solar maximum

Breen, A. R.; Thomasson, P.; Jordan, C.; Tappin, S. J.; Fallows, R. A.; Canals, A.; Moran, Patrick

doi:10.1016/s0273-1177(02)00339-3

Cited by 15 publications

(19 citation statements)

References 10 publications

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“…Also, the values of the number density and radial speed at 2.5 R S and 20 R S , respectively, are of the same magnitude as those shown in Figures 7 and 8 of Feng et al (2007), Figure 5 of Hu et al (2008), and Figures 1 and 2 of Wei et al (2003). Additionally, the speeds at 2.5 R S and 20 R S are supported by the results derived from the observations by LASCO C2 and C3 Porfir'eva et al 2009), by interplanetary scintillation (Breen et al 2002), and by the Ulysses solar corona experiment (Pätzold et al 1997).…”

Section: Numerical Results For Steady-state Solar Wind Structure Of Csupporting

confidence: 79%

THREE-DIMENSIONAL SOLARWINDMODELING FROM THE SUN TO EARTH BY A SIP-CESE MHD MODEL WITH A SIX-COMPONENT GRID

Feng

Yang

Cui

et al. 2010

ApJ

174

144

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The objective of this paper is to explore the application of a six-component overset grid to solar wind simulation with a three-dimensional (3D) Solar-InterPlanetary Conservation Element/Solution Element MHD model. The essential focus of our numerical model is devoted to dealing with: (1) the singularity and mesh convergence near the poles via the use of the six-component grid system, (2) the ∇ · B constraint error via an easy-to-use cleaning procedure by a fast multigrid Poisson solver, (3) the Courant-Friedrichs-Levy number disparity via the Courant-number insensitive method, (4) the time integration by multiple time stepping, and (5) the time-dependent boundary condition at the subsonic region by limiting the mass flux escaping through the solar surface. In order to produce fast and slow plasma streams of the solar wind, we include the volumetric heating source terms and momentum addition by involving the topological effect of the magnetic field expansion factor f S and the minimum angular distance θ b (at the photosphere) between an open field foot point and its nearest coronal hole boundary. These considerations can help us easily code the existing program, conveniently carry out the parallel implementation, efficiently shorten the computation time, greatly enhance the accuracy of the numerical solution, and reasonably produce the structured solar wind. The numerical study for the 3D steady-state background solar wind during Carrington rotation 1911 from the Sun to Earth is chosen to show the above-mentioned merits. Our numerical results have demonstrated overall good agreements in the solar corona with the Large Angle and Spectrometric Coronagraph on board the Solar and Heliospheric Observatory satellite and at 1 AU with WIND observations.

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Section: Numerical Results For Steady-state Solar Wind Structure Of Csupporting

confidence: 79%

THREE-DIMENSIONAL SOLARWINDMODELING FROM THE SUN TO EARTH BY A SIP-CESE MHD MODEL WITH A SIX-COMPONENT GRID

Feng

Yang

Cui

et al. 2010

ApJ

174

144

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“…Interplanetary scintillation (IPS) observations by Grall et al [1996] have revealed that the fast solar wind emanating from a polar coronal hole is rapidly accelerated to its final flow velocity within 20 R s . This rapid acceleration was confirmed by IPS observations made using the EISCAT (932 MHz) and MERLIN (5 GHz) facilities by Breen et al [2000, 2002]. Closer to the Sun, the Solar and Heliospheric Observatory (SOHO) spacecraft observed the acceleration of the fast solar wind taking place within several solar radii [ Kohl et al , 1998; Axford et al , 1999; Cranmer et al , 1999; Breen et al , 2000; Giordano et al , 2000; Patsourakos and Vial , 2000; Miralles et al , 2001; Breen et al , 2002; Teriaca et al , 2003].…”

Section: Introductionmentioning

confidence: 79%

“…From this analysis, average velocities of 770–780 km s −1 were obtained at distances of 0.13–0.3 AU, which were 19 ± 17 km s −1 lower than those at 0.3–0.9 AU. The results from this work, taken together with measurements of SOHO/LASCO, EISCAT and MERLIN [ Breen et al , 2002], Helios [ Schwenn et al , 1978], and Ulysses [ McComas et al , 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 R s and a small but not negligible acceleration exists beyond 30 R s which tends to become smaller at farther heliocentric distances.…”

mentioning

confidence: 75%

Fast solar wind after the rapid acceleration

et al. 2004

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[1] We have studied the radial dependence of the velocity of high-latitude fast solar wind in the heliocentric distance range of 0.13-0.9 AU. For this study a new tomographic analysis method which can evaluate uncertainties was developed to obtain velocity distribution maps on two reference spheres at 0.13 and 0.3 AU using interplanetary scintillation (IPS) observations. First of all, it is tested that this tomographic method has enough sensitivity and reliability to investigate the radial dependence of the wind velocity. The analysis was made for the IPS observations during 3 years, from 1995 to 1997, when solar activity was minimum. From this analysis, average velocities of 770-780 km s À1 were obtained at distances of 0.13-0.3 AU, which were 19 ± 17 km s À1 lower than those at 0.3-0.9 AU. The results from this work, taken together with measurements of SOHO/ LASCO, EISCAT and MERLIN [Breen et al., 2002], Helios [Schwenn et al., 1978], and Ulysses [McComas et al., 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 R s and a small but not negligible acceleration exists beyond 30 R s which tends to become smaller at farther heliocentric distances.

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“…Here, we should note that the scale sizes of optical features, which are used as a tracer of the solar wind motion for LASCO observations (∼ 10 000 km), are very different from those of density irregularities producing IPS at microwave frequencies (∼ 100 km). In spite of this fundamental difference, an acceleration profile of the low-speed solar wind was deduced by combining IPS measurements from the EISCAT facility and the Multiple Element Radio-Linked Interferometer (MERLIN) system with LASCO data (Breen et al 2000(Breen et al , 2002. The same technique used in the study of the fast wind acceleration was employed in their studies to derive solar wind speeds from EISCAT and MERLIN observations, so that the LOS integration effect was removed from IPS data.…”

Section: Discussionmentioning

confidence: 99%

Two-Station Interplanetary Scintillation Measurements of Solar Wind Speed near the Sun Using the X-band Radio Signal of the Nozomi Spacecraft

et al. 2011

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Interplanetary scintillation (IPS) measurements of the solar wind speed for the distance range between 13 and 37 R S were carried out during the solar conjunction of the Nozomi spacecraft in 2000 -2001 using the X-band radio signal. Two large-aperture antennas were employed in this study, and the baseline between the two antennas was several times longer than the Fresnel scale for the X-band. We successfully detected a positive correlation of IPS from the cross-correlation analysis of received signal data during ingress, and estimated the solar wind speed from the time lag corresponding to the maximum correlation by assuming that the solar wind flows radially. The speed estimates range between 200 and 540 km s −1 with the majority below 400 km s −1 . We examined the radial variation in the solar wind speed along the same streamline by comparing the Nozomi data with data obtained at larger distances. Here, we used solar wind speed data taken from 327 MHz IPS observations of the Solar-Terrestrial Environment Laboratory (STEL), Nagoya University, and in situ measurements by the Advanced Composition Explorer (ACE) for the comparison, and we considered the effect of the line-of-sight integration inherent to IPS observations for the comparison. As a result, Nozomi speed data were proven to belong to the slow component of the solar wind. Speed estimates within 30 R S were found to be systematically slower by 10 -15 % than the terminal speeds, suggesting that the slow solar wind is accelerated between 13 and 30 R S .

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Slow and fast solar wind acceleration near solar maximum

Cited by 15 publications

References 10 publications

THREE-DIMENSIONAL SOLARWINDMODELING FROM THE SUN TO EARTH BY A SIP-CESE MHD MODEL WITH A SIX-COMPONENT GRID

THREE-DIMENSIONAL SOLARWINDMODELING FROM THE SUN TO EARTH BY A SIP-CESE MHD MODEL WITH A SIX-COMPONENT GRID

Fast solar wind after the rapid acceleration

Two-Station Interplanetary Scintillation Measurements of Solar Wind Speed near the Sun Using the X-band Radio Signal of the Nozomi Spacecraft

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