Magnetohydrodynamic Shock Heating and Solar Wind Acceleration at Coronal Holes - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Magnetohydrodynamic Shock Heating and Solar Wind Acceleration at Coronal Holes write by José Alejandro Orta Ortiz de Zárate. This book was released on 2002. Magnetohydrodynamic Shock Heating and Solar Wind Acceleration at Coronal Holes available in PDF, EPUB and Kindle.
Coronal Holes and Solar Wind Acceleration
Coronal Holes and Solar Wind Acceleration - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Coronal Holes and Solar Wind Acceleration write by John L. Kohl. This book was released on 2013-11-09. Coronal Holes and Solar Wind Acceleration available in PDF, EPUB and Kindle. The SOHO-7 Workshop was held from 28 September through 1 October 1998 at the Asticou Inn in Northeast Harbor, Maine. The primary topic of this Workshop was the impact of SOHO observations on our understanding of the nature and evolution of coronal holes and the acceleration and composition of the solar wind. The presentations and discussions occasionally went beyond this topic to include the impact of the reported research on other solar structures and the heliosphere. SOHO (the Solar and Heliospheric Observatory), a project of international cooperation between ESA and NASA, was launched in December 1995 and began its science operations during the first few months of 1996. To many solar and space physicists, it was a great advantage that SOHO began itscomprehensive look at the Sun during the 1996 solar minimum. The qualitatively simple two-phase corona, with polar coronal holes expanding into the high-speed solar wind, and a steady equatorial streamer belt related somehow to the stochastic slow-speed solar wind, allowed various SOHO diagnostics to be initiated with a reasonably well understoodcircumsolar geometry. The analysis of subsequentSOHO measurements made during the rising phase of solar cycle 23 will continue to benefit from what has been learned from the first two years of data.
Magnetohydrodynamic Modeling of the Solar Corona and Heliosphere
Magnetohydrodynamic Modeling of the Solar Corona and Heliosphere - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Magnetohydrodynamic Modeling of the Solar Corona and Heliosphere write by Xueshang Feng. This book was released on 2019-08-01. Magnetohydrodynamic Modeling of the Solar Corona and Heliosphere available in PDF, EPUB and Kindle. The book covers intimately all the topics necessary for the development of a robust magnetohydrodynamic (MHD) code within the framework of the cell-centered finite volume method (FVM) and its applications in space weather study. First, it presents a brief review of existing MHD models in studying solar corona and the heliosphere. Then it introduces the cell-centered FVM in three-dimensional computational domain. Finally, the book presents some applications of FVM to the MHD codes on spherical coordinates in various research fields of space weather, focusing on the development of the 3D Solar-InterPlanetary space-time Conservation Element and Solution Element (SIP-CESE) MHD model and its applications to space weather studies in various aspects. The book is written for senior undergraduates, graduate students, lecturers, engineers and researchers in solar-terrestrial physics, space weather theory, modeling, and prediction, computational fluid dynamics, and MHD simulations. It helps readers to fully understand and implement a robust and versatile MHD code based on the cell-centered FVM.
Physics of the Solar Corona
Physics of the Solar Corona - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Physics of the Solar Corona write by Markus Aschwanden. This book was released on 2006-01-30. Physics of the Solar Corona available in PDF, EPUB and Kindle. A thorough introduction to solar physics based on recent spacecraft observations. The author introduces the solar corona and sets it in the context of basic plasma physics before moving on to discuss plasma instabilities and plasma heating processes. The latest results on coronal heating and radiation are presented. Spectacular phenomena such as solar flares and coronal mass ejections are described in detail, together with their potential effects on the Earth.
The Evolution of Modeled Coronal Mass Ejection in the Lower Corona
The Evolution of Modeled Coronal Mass Ejection in the Lower Corona - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook The Evolution of Modeled Coronal Mass Ejection in the Lower Corona write by Rebekah Minnel Evans Frolov. This book was released on 2011. The Evolution of Modeled Coronal Mass Ejection in the Lower Corona available in PDF, EPUB and Kindle. Coronal mass ejections (CMEs) and their associated shocks are major sources of space weather. In order to forecast their impact at Earth, it is crucial to accurately model their propagation in interplanetary space. The only tool capable of treating the large scales of CME evolution is global magnetohydrodynamics (MHD) modeling. However, this approach cannot resolve the small scales on which important processes occur (such as the acceleration of the solar wind and coronal heating). The solar wind solution depends on which method is utilized to mimic these processes. And because the evolution of a CME depends crucially on its interaction with the solar wind, the CME evolution will also be connected to the heating mechanisms and drivers utilized in an MHD model. In the first part of the thesis, we show that the ad hoc approaches to coronal heating used in global MHD models leads to unphysical conditions for CME-driven shock formation in the lower corona (1-10 solar radii). We present this argument in two steps. First, we present a CME simulation in which the solar wind was accelerated and heated by reducing the value of the polytropic index (to less than the adiabatic value) in the lower corona. As it is not well understood, we do not model the CME initiation process - we utilize an out-of-equilibrium Titov-Demoulin flux rope to begin the eruption. We analyze several aspects of the CME, such as its kinematics and energy evolution, the shock formation and evolution, the plasma flows in the CME-sheath and their connection to the CME magnetic field vector, and the plasma pile-up at the front of the CME. We find that some characteristics are inconsistent with the observed properties of CMEs, and we connect these to the ad hoc treatment of the solar wind heating. Second, we use data of CME shock-accelerated solar energetic particle events to constrain the profile of the Alfven speed in the lower corona. We show that the Alfven speed profile from global MHD models with ad hoc heating is not aligned with these observations, but that local (one dimensional) models with physically-motivated Alfven wave dissipation as a heating mechanism were in agreement. In the second part of the thesis, we study the resonant absorption of surface Alfven waves (SAW), a process which heats the solar wind. It is driven by a transverse gradient in the local Alfven speed (in relation to the magnetic field direction). In the solar corona, we expect this mechanism to occur at the boundaries of open and closed magnetic fields. We make the first estimation of SAW energy dissipation in the solar corona and find that it is comparable to the ad hoc heating a polytropic model at the boundary of open and closed magnetic fields and in subpolar open field regions. Next, we implemented the SAW damping mechanism into the new solar corona component of the Space Weather Modeling Framework, in which Alfven wave energy transport is self-consistently coupled to the MHD equations. The model already included wave dissipation along open magnetic field lines, mimicking turbulence. We demonstrate that including SAW dissipation in the model improved agreement with observations of coronal temperature both near the Sun and in the inner heliosphere by comparing with data from Ulysses and the Solar Terrestrial Relations Observatory (STEREO). Also, the inclusion of SAW dissipation steepened the Alfven speed profile in the lower corona, aligning the Alfven profile better with observational constraints of shock formation. In the final part of the thesis, we modeled a CME in this newly developed solar wind background, and studied the interaction between the CME and the wind. We generate the eruption with a flux rope. We constrain the parameters of the flux rope with data from the 13 May 2005 eruption, including H-alpha images of the pre-eruption magnetic field, coronagraph images of the CME's shape and velocity. Because the flux rope traveled faster than the local magnetosonic speed, it acted as a piston and drove a shock wave ahead of it. The CME-driven shock had a strong impact on the solar wind environment through which it propagates: it altered the wave energy by concentrating it in the sheath through advection, and also increasing its value through momentum transfer. This simulation demonstrated how Alfven waves are focused into the sheaths of ICMEs. The wave energy is then dissipated at the shock due to SAW damping. The shock heating accounted for 10% of the total change in thermal energy of the CME. The resulting temperature distribution of the CME is more aligned with observations than from a CME modeled in a polytropic solar wind. This thesis has improved our understanding of the interaction between a CME and the solar wind through which it propagates. Our picture of CME-evolution in the lower corona will be tested by future missions Solar Probe (which will sample this region directly) and the Solar Orbiter.
