Global and local expansion of magnetic clouds in the inner heliosphere

Observations of magnetic clouds (MCs) are consistent with the presence of flux ropes detected in the solar wind (SW) a few days after their expulsion from the Sun as coronal mass ejections (CMEs). Both the \textit{in situ} observations of plasma velocity profiles and the increase of their size with solar distance show that MCs are typically expanding structures. The aim of this work is to derive the expansion properties of MCs in the inner heliosphere from 0.3 to 1 AU.We analyze MCs observed by the two Helios spacecraft using \textit{in situ} magnetic field and velocity measurements. We split the sample in two subsets: those MCs with a velocity profile that is significantly perturbed from the expected linear profile and those that are not. From the slope of the \textit{in situ} measured bulk velocity along the Sun-Earth direction, we compute an expansion speed with respect to the cloud center for each of the analyzed MCs. We analyze how the expansion speed depends on the MC size, the translation velocity, and the heliocentric distance, finding that all MCs in the subset of non-perturbed MCs expand with almost the same non-dimensional expansion rate ($\zeta$). We find departures from this general rule for $\zeta$ only for perturbed MCs, and we interpret the departures as the consequence of a local and strong SW perturbation by SW fast streams, affecting the MC even inside its interior, in addition to the direct interaction region between the SW and the MC. We also compute the dependence of the mean total SW pressure on the solar distance and we confirm that the decrease of the total SW pressure with distance is the main origin of the observed MC expansion rate. We found that $\zeta$ was $0.91\pm 0.23$ for non-perturbed MCs while $\zeta$ was $0.48\pm 0.79$ for perturbed MCs, the larger spread in the last ones being due to the influence of the environment conditions on the expansion

Quasi real-time electromagnetic and greenhouse gases monitoring station at Seymour - Marambio Island, Antarctica

A new permanent geophysical station was installed in the Seymour-Marambio Island, Antarctica, for monitoring electromagnetic, CO2, and CH4 gas signals. Those signals require specialized low noise instruments and the survey shall be carried out in places far away from cultural noise, such as populated human settlements. The most suitable place would be near the Earth's poles, where noise is the lowest possible. To measure these variables, the Geophysical Instrumentation Laboratory (Laboratorio de Instrumentación Geofísica - LIG) of the Universidad Nacional de Colombia, in a partnership with the Instituto Antártico Argentino (IAA) under the Argentinean National Antarctic Direction (Dirección Nacional del Antártico - DNA), deployed the COCOAonMEAT project, oriented to design, built and install a low-cost station with time synchronization via GPS and data transmission in almost real-time. Since January 2020, the project monitors continuously (24/7) seven variables: three magnetic components, two electric dipoles, methane (CH4), and carbon dioxide (CO2) gas. Due to operative facilities and its low electromagnetic noise, the place chosen for its installation was the Argentinean Marambio Scientific Base in the Antarctic Peninsula, with the Multidisciplinary Antarctic Laboratory's collaboration (Laboratorio Multidisciplinario Antártico en la Base Marambio - LAMBI). This station provides valuable information on electromagnetic signals and greenhouse gases related to regional tectonic activity and local perturbations associated with global climate change.

Characterization of upper mantle structures in the northern region of the Antarctic Peninsula, through an analysis of seismic velocity anomalies

Se realizó una tomografía sísmica de inversión conjunta basada en los residuales de tiempo de viaje de las ondas P y S, con el objeto de estudiar la estructura sísmica del manto superior infrayacente a la dorsal Sur del Scotia y extremo norte de la Península Antártica. La misma se basó en registros sismográficos adquiridos en forma continua en estaciones sismológicas situada en bases antárticas argentinas, procedentes del Proyecto Argentino Italiano para la gestión y mantenimiento de la red ASAIN: Antarctic Seismograph Argentinian Italian Network. Las señales analizadas corresponden a eventos sismotectónicos locales de moderada a elevada magnitud ocurridos entre los años 2009 y 2019. Para la inversión discreta de los datos se implementó el método de regularización. Los resultados fueron evaluados mediante pruebas de resolución sintéticas. Se caracterizaron e interpretaron las estructuras sísmicas resueltas en las tomografías. El estudio se complementó mediante la estimación del módulo de Poisson y de la anomalía de velocidad acústica φ, lo cual permitió incorporar condiciones de restricción y por tanto de valoración a la interpretación de las tomografías. Se destaca la presencia de una anomalía negativa de velocidad de onda S en el sector de la cuenca Bransfield, en correspondencia con lo reportado por otros autores. Se interpreta como una región de la corteza y manto sometida a modificaciones del estado reológico (disminución de la rigidez, incremento de la incompresibilidad y aumento de la anelasticidad) causada por un flujo térmico anómalo proveniente de una fuente localizada a mayor profundidad en el manto.In order to study the seismic structure of the upper mantle underlying the South ridge of Scotia and the northern end of the Antarctic Peninsula, a joint inversion seismic tomography, based on the travel time residuals of the P and S waves, was carried out. It was based on seismographic records acquired continuously at seismological stations located in Argentine Antarctic bases, from the Argentine-Italian Project for the management and maintenance of ASAIN: Antarctic Seismograph Argentinian Italian Network. The signals used correspond to local seismotectonic events of moderate to large magnitude that occurred between 2009 and 2019. The regularization method was implemented for the data discrete inversion. The results were evaluated by synthetic resolution tests. The seismic struc tures resolved with the tomographies were characterized and interpreted. The study was complemented by estimating the Poisson's modulus and the bulk sound velocity anomaly, which allowed the incorporation of restriction conditions and, therefore, assessment conditions in the interpretation of the tomographies. The presence of a negative S-wave velocity anomaly in the Bransfield basin sector is highlighted, in correspondence with that reported by other authors. It is interpreted as a region of the crust and mantle subjected to modifications of the rheological condition (decrease in rigidity, increase in incompressibility and increase in anelasticity) caused by an anomalous thermal flux from a source located deeper in the mantle.Fil: Zambrano, Oscar Marcos. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Laboratorio de Petrografia-petrologia; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; ArgentinaFil: Gulisano, Adriana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Poma, Stella Maris. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Laboratorio de Petrografia-petrologia; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Ruocco, María Inés. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

Characterization of upper mantle structures in the northern region of the Antarctic Peninsula, through an analysis of seismic velocity anomalies

Se realizó una tomografía sísmica de inversión conjunta basada en los residuales de tiempo de viaje de las ondas P y S, con el objeto de estudiar la estructura sísmica del manto superior infrayacente a la dorsal Sur del Scotia y extremo norte de la Península Antártica. La misma se basó en registros sismográficos adquiridos en forma continua en estaciones sismológicas situada en bases antárticas argentinas, procedentes del Proyecto Argentino Italiano para la gestión y mantenimiento de la red ASAIN: Antarctic Seismograph Argentinian Italian Network. Las señales analizadas corresponden a eventos sismotectónicos locales de moderada a elevada magnitud ocurridos entre los años 2009 y 2019. Para la inversión discreta de los datos se implementó el método de regularización. Los resultados fueron evaluados mediante pruebas de resolución sintéticas. Se caracterizaron e interpretaron las estructuras sísmicas resueltas en las tomografías. El estudio se complementó mediante la estimación del módulo de Poisson y de la anomalía de velocidad acústica φ, lo cual permitió incorporar condiciones de restricción y por tanto de valoración a la interpretación de las tomografías. Se destaca la presencia de una anomalía negativa de velocidad de onda S en el sector de la cuenca Bransfield, en correspondencia con lo reportado por otros autores. Se interpreta como una región de la corteza y manto sometida a modificaciones del estado reológico (disminución de la rigidez, incremento de la incompresibilidad y aumento de la anelasticidad) causada por un flujo térmico anómalo proveniente de una fuente localizada a mayor profundidad en el manto.In order to study the seismic structure of the upper mantle underlying the South ridge of Scotia and the northern end of the Antarctic Peninsula, a joint inversion seismic tomography, based on the travel time residuals of the P and S waves, was carried out. It was based on seismographic records acquired continuously at seismological stations located in Argentine Antarctic bases, from the Argentine-Italian Project for the management and maintenance of ASAIN: Antarctic Seismograph Argentinian Italian Network. The signals used correspond to local seismotectonic events of moderate to large magnitude that occurred between 2009 and 2019. The regularization method was implemented for the data discrete inversion. The results were evaluated by synthetic resolution tests. The seismic struc tures resolved with the tomographies were characterized and interpreted. The study was complemented by estimating the Poisson's modulus and the bulk sound velocity anomaly, which allowed the incorporation of restriction conditions and, therefore, assessment conditions in the interpretation of the tomographies. The presence of a negative S-wave velocity anomaly in the Bransfield basin sector is highlighted, in correspondence with that reported by other authors. It is interpreted as a region of the crust and mantle subjected to modifications of the rheological condition (decrease in rigidity, increase in incompressibility and increase in anelasticity) caused by an anomalous thermal flux from a source located deeper in the mantle.Fil: Zambrano, Oscar Marcos. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Laboratorio de Petrografia-petrologia; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; ArgentinaFil: Gulisano, Adriana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Poma, Stella Maris. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Geología. Laboratorio de Petrografia-petrologia; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Ruocco, María Inés. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

BRIEF REPORT Proteasome Inhibitors Synergize with Tumor Necrosis Factor-Related Apoptosis-Induced Ligand to Induce Anaplastic Thyroid Carcinoma Cell Death

Context: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive types of cancer characterized by complete refractoriness to multimodal treatment approaches. Therapeutic strategies based on the simultaneous use of proteasome inhibitors and death receptor ligands have been shown to induce apoptosis in several tumor types but have not yet been explored in ATC. Objective and Methods: The aim of this study was to investigate the ability of the proteasome inhibitor Bortezomib to induce apoptosis in ATC cell lines. Bortezomib was used as a single agent or in combination with TNF-related apoptosis-induced ligand (TRAIL), a member of the TNF family that selectively induces tumor cell apoptosis. The molecular effects of Bortezomib were investigated by analyzing the expression of key regulators of cell cycle and apoptosis and the activation of different apoptotic pathways. Results: Bortezomib induced apoptosis in ATC cells at doses achieved in the clinical setting, differently from conventional chemotherapeutic agents. Simultaneous treatment with low doses of Bortezomib and TRAIL had a synergistic effect in inducing massive ATC cell apoptosis. Bortezomib increased the expression of cytotoxic TRAIL receptors, p21 (WAF/CIP1) and proapoptotic second mitochondria-derived activator of caspases/direct inhibitor of apoptosis binding protein with low pI, and reduced the expression of antiapoptotic mediators such as cellular Fas-associated death domain-like IL-1␤ converting enzyme inhibitory protein, Bcl-2, Bcl-X L , and inhibitor of apoptosis-1, thus resulting in cell death induction through the mitochondrial apoptotic pathway. Conclusions: The combination of proteasome inhibitors and TRAIL synergizes to induce the destruction of chemoresistant neoplastic thyrocytes and could represent a promising therapeutic strategy for the treatment of anaplastic thyroid carcinoma. (J Clin Endocrinol Metab 92: 1938 -1942, 2007

BRIEF REPORT Proteasome Inhibitors Synergize with Tumor Necrosis Factor-Related Apoptosis-Induced Ligand to Induce Anaplastic Thyroid Carcinoma Cell Death

Context: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive types of cancer characterized by complete refractoriness to multimodal treatment approaches. Therapeutic strategies based on the simultaneous use of proteasome inhibitors and death receptor ligands have been shown to induce apoptosis in several tumor types but have not yet been explored in ATC. Objective and Methods: The aim of this study was to investigate the ability of the proteasome inhibitor Bortezomib to induce apoptosis in ATC cell lines. Bortezomib was used as a single agent or in combination with TNF-related apoptosis-induced ligand (TRAIL), a member of the TNF family that selectively induces tumor cell apoptosis. The molecular effects of Bortezomib were investigated by analyzing the expression of key regulators of cell cycle and apoptosis and the activation of different apoptotic pathways. Results: Bortezomib induced apoptosis in ATC cells at doses achieved in the clinical setting, differently from conventional chemotherapeutic agents. Simultaneous treatment with low doses of Bortezomib and TRAIL had a synergistic effect in inducing massive ATC cell apoptosis. Bortezomib increased the expression of cytotoxic TRAIL receptors, p21 (WAF/CIP1) and proapoptotic second mitochondria-derived activator of caspases/direct inhibitor of apoptosis binding protein with low pI, and reduced the expression of antiapoptotic mediators such as cellular Fas-associated death domain-like IL-1␤ converting enzyme inhibitory protein, Bcl-2, Bcl-X L , and inhibitor of apoptosis-1, thus resulting in cell death induction through the mitochondrial apoptotic pathway. Conclusions: The combination of proteasome inhibitors and TRAIL synergizes to induce the destruction of chemoresistant neoplastic thyrocytes and could represent a promising therapeutic strategy for the treatment of anaplastic thyroid carcinoma. (J Clin Endocrinol Metab 92: 1938 -1942, 2007

Use of water-Cherenkov detectors to detect Gamma-Ray-Bursts at the Large Aperture GRB Observatory (LAGO)

The Large Aperture GRB Observatory (LAGO) project aims at the detection of high energy photons from Gamma Ray Bursts (GRB) using the single particle technique in ground-based water-Cherenkov detectors (WCD). To reach a reasonable sensitivity, high altitude mountain sites have been selected in Mexico (Sierra Negra, 4550 m a.s.l.), Bolivia (Chacaltaya, 5300 m a.s.l.) and Venezuela (Me´ rida, 4765 m a.s.l.). We report on detector calibration and operation at high altitude, search for bursts in 4 months of preliminary data, as well as search for signal at ground level when satellites report a burst.Fil: Allard, D.. Université Paris Diderot - Paris 7; FranciaFil: Allekotte, Ingomar. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Alvarez, C.. Facultad de Ciencias Fısico-Matematicas; MéxicoFil: Asorey, Hernán Gonzalo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Barros, H.. Universidad Simon Bolivar; VenezuelaFil: Bertou, Xavier Pierre Louis. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Burgoa, O.. Instituto de Investigaciones Fisicas; BoliviaFil: Gomez Berisso, Mariano. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Martinez, O.. Facultad de Ciencias Fısico-Matematicas; MéxicoFil: Miranda Loza, P.. Instituto de Investigaciones Fısicas; BoliviaFil: Murrieta, T.. Facultad de Ciencias Fısico-Matematicas; MéxicoFil: Perez, G.. Facultad de Ciencias Fısico-Matematicas; MéxicoFil: Rivera, H.. Instituto de Investigaciones Fısicas; BoliviaFil: Rovero, Adrian Carlos. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Saavedra, O.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Salazar, H.. Facultad de Ciencias Fısico-Matematicas ; MéxicoFil: Tello, J. C.. Universidad Simon Bolıvar; VenezuelaFil: Ticona Peralda, R.. Instituto de Investigaciones Fısicas; BoliviaFil: Velarde, A.. Instituto de Investigaciones Fısicas; BoliviaFil: Villaseñor, L.. Universidad de Michoacan; MéxicoFil: Areso, Omar Antonio. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Arnaldi, Luis Horacio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Dasso, Sergio Ricardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Gonzalez, M.. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Gulisano, Adriana Maria. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Martin, R.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Masías Meza, Jimmy Joel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Sidelnik, Iván Pedro. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Alvarez, W.. Universidad de San Carlos; GuatemalaFil: The LAGO Collaboration

Quasi real-time electromagnetic and greenhouse gases monitoring station at seymour - marambio island, antarctica

A new permanent geophysical station was installed in the Seymour-Marambio Island, Antarctica, for monitoring electromagnetic, CO2, and CH4 gas signals. Those signals require specialized low noise instruments and the survey shall be carried out in places far away from cultural noise, such as populated human settlements. The most suitable place would be near the Earth's poles, where noise is the lowest possible. To measure these variables, the Geophysical Instrumentation Laboratory (Laboratorio de Instrumentación Geofísica - LIG) of the Universidad Nacional de Colombia, in a partnership with the Instituto Antártico Argentino (IAA) under the Argentinean National Antarctic Direction (Dirección Nacional del Antártico - DNA), deployed the COCOAonMEAT project, oriented to design, built and install a low-cost station with time synchronization via GPS and data transmission in almost real-time. Since January 2020, the project monitors continuously (24/7) seven variables: Three magnetic components, two electric dipoles, methane (CH4), and carbon dioxide (CO2) gas. Due to operative facilities and its low electromagnetic noise, the place chosen for its installation was the Argentinean Marambio Scientific Base in the Antarctic Peninsula, with the Multidisciplinary Antarctic Laboratory's collaboration (Laboratorio Multidisciplinario Antártico en la Base Marambio - LAMBI). This station provides valuable information on electromagnetic signals and greenhouse gases related to regional tectonic activity and local perturbations associated with global climate change.Fil: Solano, Juan Manuel. Universidad Nacional de Colombia; ColombiaFil: Vargas, Carlos Alberto. Universidad Nacional de Colombia; ColombiaFil: Gulisano, Adriana Maria. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin

Estimation of the bias of the Minimum Variance technique in the determination of magnetic clouds global quantities and orientation

Magnetic clouds (MCs) are highly magnetized plasma structures that have a low proton temperature and a magnetic field vector that rotates when seen by a heliospheric observer. More than 25 years of observations of magnetic and plasma properties of MCs at 1 AU have provided significant knowledge of their magnetic structure. However, because in situ observations only give information along the trajectory of the spacecraft, their real 3D magnetic configuration remains still partially unknown. We generate a set of synthetic clouds, exploring the space of parameters that represents the possible orientations and minimum distances of the satellite trajectory to the cloud axis, p. The synthetic clouds have a local cylindrical symmetry and a linear force-free magnetic configuration. From the analysis of synthetic clouds, we quantify the errors introduced in the determination of the orientation/size (and, consequently, of the global magnetohydrodynamic quantities) by the Minimum Variance method when p is not zero.Fil: Gulisano, Adriana Maria. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Dasso, Sergio Ricardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Démoulin, Pascal. Centre National de la Recherche Scientifique. Observatoire de Paris; Franci

Model-independent large-scale magnetohydrodynamic quantities in magnetic clouds

Magnetic clouds are the interplanetary manifestation of coronal mass ejections, which are transient expulsions of major quantities of magnetized plasma, from the Sun toward the heliosphere. The magnetic flux and helicity are two key physical magnitudes to track solar structures from the photosphere-corona to the interplanetary medium. To determine the content of flux and helicity in magnetic clouds, we have to know their 3D structure. However, since spacecrafts register data along a unique direction, several aspects of their global configuration cannot be observed. We present a method to estimate the magnetic flux and the magnetic helicity per unit length in magnetic clouds, directly from in situ magnetic observations, assuming only a cylindrical symmetry for the magnetic field configuration in the observed cross-section of the cloud. We select a set of 20 magnetic clouds observed by the spacecraft Wind and estimate their magnetic flux and their helicity per unit length. We compare the results obtained from our direct method with those obtained under the assumption of a helical linear force-free field. This direct method improves previous estimations of helicity in clouds.Fil: Dasso, Sergio Ricardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Gulisano, Adriana Maria. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Démoulin, Pascal. Centre National de la Recherche Scientifique. Observatoire de Paris; Franci