C. C. Goodrich (Boston U), W. J. Hughes (Boston U), J. A. Linker (SAIC), J. G. Luhmann (UC Berkeley), J. G. Lyon (Dartmouth), Z. Mikic (SAIC), D. Odstrcil (CIRES and NOAA-SEC), S. C. Solomon (HAO), W. Wang (HAO), and M. Wiltberger (HAO)
This paper describes the 3D simulation of a space weather event using the coupled model approach adopted by the Center for Integrated Space Weather Modeling (CISM). The simulation employs coronal, solar wind, and magnetosphere MHD models, and a thermosphere/ionosphere fluid dynamic model, with interfaces that exchange parameters specifying each component of the connected solar terrestrial system. A coronal mass ejection is launched from the Sun by a process emulating photospheric field evolution, and an ejected magnetic flux rope propagates into the solar wind, producing an interplanetary shock and magnetic cloud. These reach 1 AU where the solar wind and interplanetary magnetic field parameters are used to drive the magnetosphere-ionosphere-thermosphere coupled model. The simulated magnetosphere responds with a magnetic storm, producing auroral ionization and enhanced convection in the ionosphere. These results demonstrate the potential for future studies using a modular, systemic numerical modeling approach to space weather research and forecasting.
Jon A. Linker, Zoran Mikic, Roberto Lionello and Pete Riley (Science Applications International Corporation, San Diego, CA, USA)
Coronal mass ejections (CMEs) are spectacular manifestations of solar activity. These immense eruptions of plasma and magnetic field are propelled outward from the sun with velocities as high as 2000 km/s. The fastest CMEs typically originate from active regions on the Sun. We describe MHD computations of the eruptive behavior of a localized active region field (modeled as a localized bipole) within a large-scale dipolar configuration. We discuss the differences between this more realistic configuration and some of the idealized configurations that have been considered previously. (Work supported by NASA and the Center for Integrated Space Weather Modeling, an NSF Science and Technology Center).
J.G. Luhmann, D.W. Curtis, R.P. Lin, D. Larson, P. Schroeder (SSL, UC Berkeley) ,A. Cummings, R.A. Mewaldt, E.C. Stone (Caltech) ,T. von Rosenvinge, M.H. Acuna (GSFC) ,R. Mueller-Mellin, H. Kunow (U. of Kiel) ,G.M. Mason (U. of Maryland) ,M. Wiedenbeck (JPL) ,A. Sauvaud, C. Aoustin (CESR/CNRS) ,A. Korth (MPAe) ,T. Sanderson (ESTEC) ,C.T. Russell (UCLA) ,P. Riley and J.A. Linker (SAIC) ,D. Odstrcil and V.J. Pizzo (CIRES and NOAA-SEC) ,C.N. Arge (AFRL)
The STEREO Solar Terrestrial Probe mission will make measurements important to the LWS community for both science and applications. Similarly, the BU-directed NSF sponsored Center for Integrated Space Weather Modeling (CISM) will produce knowledge and tools highly relevant to LWS goals. IMPACT is one of the STEREO in-situ investigations set to provide multipoint measurements ahead of and trailing the Earth in its orbit. IMPACT measures the interplanetary magnetic field, solar wind and suprathermal electrons, and solar energetic particles at these Earth-bracketing points at increasing separations. CISM solar and heliosphere models now in development can provide complementary 3D ambient solar wind and interplanetary field descriptions, and will ultimately describe coronal transient activity disturbances, for data comparisons and interpretation. In combination with STEREO PLASTIC solar wind ion, SWAVES radio, and SECCHI imaging, as well as SOHO upstream imaging and ACE and WIND L1 data, IMPACT measurements and CISM heliospheric models stand to make a substantial contribution to LWS resources. This poster summarizes their capabilities and illustrates their promise.
W.P. Abbett (University of California Berkeley Space Sciences Lab)
How can we understand the connection between the ``isolated'' flux systems that form and evolve within the high-beta turbulent convection zone with the magnetic fields of the low-beta solar corona? It remains computationally intractable to simulate the evolution of active-region magnetic fields throughout the entirety of the solar interior and atmosphere. Thus, we are faced with a choice. We can severely restrict the size of the computational domain, include a small portion of the sub-surface convective envelope along with the visible surface layers, and simulate the evolution of magnetic fields in a plasma that transitions from a high-beta to low-beta regime over the many pressure scale heights of the photosphere, chromosphere, transition region, and low corona; or we can drive large-scale models of the solar atmosphere with pre-existing sub-surface calculations or observations of the vector magnetic field at the solar photosphere. Since the photosphere necessarily represents the visible lower boundary of data-driven models of the solar corona (and large-scale Sun-to-Earth models being developed by collaborative projects such as CISM and MURI for use as space weather forecasting tools), we have focused on the latter method. We have made progress developing techniques necessary to initiate data-driven calculations, and to update the electric field in the boundary layers of an MHD model atmosphere when a true sub-surface code coupling is not possible. I will summarize our group's modeling efforts in these areas.
Pete Riley, J. A. Linker, R. Lionello, and Z. Mikic (Science Applications International Corporation, San Diego. CA 92121, USA ) ,D. Odstrcil (Space Environment Center, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA ) ,M. A. Hidalgo (Departamento de Fisica, Universidad de Alcal\'a, Alcal\'a de Henares, Madrid, Spain ) ,Q. Hu (Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA ) ,R. P. Lepping (Laboratory for Extraterrestrial Physics, NASA-Goddard Space Flight Center, Greenbelt, MD 20771, USA ) ,B. J. Lynch (Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA ) ,A. Rees (The Blackett Laboratory, Imperial College London, London SW7 2BW, UK )
Flux rope fitting (FRF) techniques have been shown to be an invaluable tool for extracting information about the properties of a sub-class of CMEs in the solar wind. However, it has proven difficult to assess their accuracy since the underlying global structure of the CME cannot be independently determined. In contrast, large-scale MHD simulations of CME evolution can provide both a global view as well as localized timeseries at specific points in space. In this study we apply 5 different fitting techniques to 2 hypothetical timeseries derived from MHD simulation results. Independent teams performed the analysis of the events in ``blind tests'', for which no information, other than the timeseries, was provided. From the results, we infer the following: (1) Accuracy decreases markedly with increasingly glancing encounters; (2) Correct identification of the boundaries of the flux rope can be a significant limiter; and (3) Results from techniques that infer global morphology must be viewed with caution. In spite of these limitations, FRF techniques remain a useful tool for describing in situ observations of flux rope CMEs.
Stan Solomon, Liying Qian, Art Richmond, Ray Roble (NCAR), and Tom Woods (CU)
During October-November 2003, a series of large coronal mass ejections and solar flares caused significant changes in the terrestrial upper atmosphere and ionosphere. Using measurements from solar irradiance instruments on the TIMED and SORCE satellites to drive the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), we show preliminary results of the effects of these events on the ionosphere, and quantify the relative importance of photon and auroral forcing of thermospheric density and temperature.