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Poster contributions

Automated detection of filaments and their eruptions from SDO data
E. Buchlin C. Mercier S. Parenti S. Engin J.-C. Vial
(Institut d'astrophysique spatiale)
It is clearly important for space weather applications to understand the evolution of filaments, and especially their eruptions, associated with CMEs. In the view of the cadence and continuity of SDO observations, AIA and HMI offer a unique tool for such a program. Because of the data volume and requirement of short latency, only an automated detection can be used. We report here on results obtained with the Bernasconi et al. (2005) code from images in Halpha, and on preliminary results from a new code that we are developing for images in He II 30.4 nm (SOHO/EIT, STEREO/SECCHI and SDO/AIA). We compare the efficiency of these codes and we discuss the selectivity obtained with the addition of magnetic information, e.g. on the polarity inversion lines from SDO/HMI.


A universal law for solar wind turbulence at electron scales
Galtier & Meyrand
(IAS, Université Paris-Sud)
Solar wind turbulence is characterized by a Kolmogorovian magnetic fluctuations spectrum at large scales followed by a second inertial range with steeper spectra associated to nonlinear dispersive processes. Recent observations reveal the presence of a third region - called dissipation range - at scales smaller than the electron inertial length and characterized by even more steeper spectra. We investigate this regime in the electron magnetohydrodynamics approximation and derive an exact and universal law for third-order structure functions. This law corresponds to a magnetic fluctuations isotropic spectrum in $k^\{-11/3\}$ compatible with the observations. We conclude on the possible existence of a third turbulence regime in the solar wind instead of a dissipation range as recently postulated.


Exact nonlinear diffusion equations for anisotropic MHD turbulence with cross-helicity
Galtier & Buchlin
(IAS, Université Paris-Sud)
Exact nonlinear diffusion equations of spectral transfer are derived for anisotropic magnetohydrodynamics in the regime of wave turbulence. The background of the analysis is the asymptotic Alfvén wave turbulence equations from which a differential limit is taken. The result is a universal diffusion-type equation in $\{\bf k\}$-space which describes in a simple way and without free parameter the energy transport perpendicular to the external magnetic field $\{\bf B\_0\}$ for transverse and parallel fluctuations. These exact equations are compatible with both the thermodynamic equilibrium and the finite flux spectra derived by Galtier et al. (2000); it improves therefore the approximate model proposed by Litwick & Goldreich (2003) for which only the second solution is recovered. This new system offers a powerful description of a wide class of astrophysical plasmas with non-zero cross-helicity.


CDPP activities in the international Virtual Observatories context
Jacquey, C.; Gangloff, M.; André, N.; Génot, V.; Cecconi, B.; Lavraud, B.; Pallier, E.; Budnik, E.; Bouchemit, M.; Bourrel, N.; Harvey, C.; Penou, E.; Hitier, R.; Francoise, D.; Heulet, D.; Besson, B.
(CESR)
The CDPP (Centre de Données de la Physique des Plasmas) has been archiving space plasma data for more than ten years. Beside its archiving activities, the CDPP was early involved in space physics data model standardization through its collaboration to the SPASE group and CAA. More recently it took an active part in the development of Virtual Observatories in the fields of heliophysics (within HELIO (FP7) in collaboration with MEDOC and BASS2000 data centres), planetology (within EUROPLANET RI (FP7)) and space weather within (VISPANET (ESA)). A review of the CDPP involvement in these projects will be presented.


Science outputs of the CDPP on-line analysis tool AMDA
Génot, V.; Jacquey, C.; Budnik, E.; Bouchemit, M.; Gangloff, M.; Fedorov, A.; Lavraud, B.; André, N.; Fruit, G.; Louarn, P.; Harvey, C. C.; Pallier, E.; Penou, E.; Hitier, R.; Cecconi, B.; Francoise, D.; Heulet, D.; Pinçon, J.L.; Besson, B.
(CESR)
According to the Virtual Observatory paradigm the CDPP developed an on-line data mining / event searching tool, AMDA (Automated Multi-Dataset Analysis) : it is a web-based facilities for analyzing on-line space physics data coming from its own local database as well as remote ones (CDAWeb, CAA, MAPSKP, THEMIS database). This tool allows the user to perform on-line classical manipulations such as data visualization, parameter computation or data extraction. AMDA also offers innovative functionalities such as event searching using the data from multiple sources in either a visual or an automated way, the generation, exploitation and management of time-tables, or event lists. This presentation will focus on scientific analyses performed by AMDA users in recent years. This will illustrate how the use of analysis tool accessing large distributed data sets may reveal new scientific results, and generate new ideas for analysis tools.



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suivant: Session PNST-PCHE monter: Session PNST précédent: Session PNST
Samuel Boissier 2010-06-16