GEORGETA Maris Muntean - Academia.edu (original) (raw)

Uploads

Papers by GEORGETA Maris Muntean

Research paper thumbnail of An Empirical Model for Geoeffectiveness of High Speed Streams in Solar Wind

Zenodo (CERN European Organization for Nuclear Research), Feb 18, 2021

We present an empirical model to estimate the probability that a high speed stream produced by a ... more We present an empirical model to estimate the probability that a high speed stream produced by a coronal hole will be associated with a geomagnetic storm or not. The model is applied to a database build using the HSS catalogue available on the Institute of Geodynamics webpage at http://www.geodin.ro/hss-sc23/. We present the structure of the catalogue as well as a statistical analysis of these currents. We estimate that the model proposed may correctly predict the association or disassociation of a HSS that is generated by a coronal hole with a geomagnetic storm with a 80% efficiency.

Research paper thumbnail of Magnetospheric Energy Input during Intense Geomagnetic Storms in SC23

EGU General Assembly Conference Abstracts, Apr 1, 2015

Research paper thumbnail of Fast Solar Wind and Geomagnetic Variability during the 24th Solar Cycle (2009 - 2013)

EGU General Assembly Conference Abstracts, May 1, 2014

Research paper thumbnail of Complex Catalogue of High Speed Streams Associated with Geomagnetic Storms During Solar Cycle 24

Solar Physics, May 1, 2022

Research paper thumbnail of Detailed Analysis of a GE Oeffective ICME Triggered by the March 15, 2013 CME

Research paper thumbnail of A study of solar and interplanetary parameters of CMEs causing major geomagnetic storms during SC 23

Annales Geophysicae, 2013

In this paper we analyse 25 Earth-directed and strongly geoeffective interplanetary coronal mass ... more In this paper we analyse 25 Earth-directed and strongly geoeffective interplanetary coronal mass ejections (ICMEs) which occurred during solar cycle 23, using data provided by instruments on SOHO (Solar and Heliospheric Observatory), ACE (Advanced Composition Explorer) and geomagnetic stations. We also examine the in situ parameters, the energy transfer into magnetosphere, and the geomagnetic indexes. We compare observed travel times with those calculated by observed speeds projected into the plane of the sky and de-projected by a simple model. The best fit was found with the projected speeds. No correlation was found between the importance of a flare and the geomagnetic Dst (disturbance storm time) index. By comparing the in situ parameters with the Dst index we find a strong connection between some of these parameters (such as Bz, Bs • V and the energy transfer into the magnetosphere) with the strength of the geomagnetic storm. No correlation was found with proton density and plasma temperature. A superposed epoch analysis revealed a strong dependence of the Dst index on the southward component of interplanetary magnetic field, Bz, and to the Akasofu coupling function, which evaluates the energy transfer between the ICME and the magnetosphere. The analysis also showed that the geomagnetic field at higher latitudes is disturbed before the field around the Earth's equator.

Research paper thumbnail of On the prediction of geoeffectiveness of CMEs during the ascending phase of SC24 using a logistic regression method

Journal of Atmospheric and Solar-Terrestrial Physics, 2019

Coronal mass ejections (CMEs) are pieces of the puzzle that drive space weather. Numerous methods... more Coronal mass ejections (CMEs) are pieces of the puzzle that drive space weather. Numerous methods (theoretical, numerical and empirical) are being used to predict whether the CME will be geoeffective or not. We present here an attempt to predict the geoeffectiveness of a given CME using a modified version of logistic regression model proposed by Srivastava (2005), using only initial CME parameters. Our model attempts to forecast if the CME will be associated with geomagnetic storm defined by a minimum Dst value <-30 nT. We applied this modified logistic regression model for CMEs detected by LASCO during the ascending phase of solar cycle 24 (April 1, 2010 to June 30, 2011). Although the hit rate and proportion correctness were not promising for the training CME set, we obtained good hit rates and proportion correctness for the validation set. We expect to improve the model upon applying it to a dataset comprising

Research paper thumbnail of An Empirical Model for Geoeffectiveness of High Speed Streams in Solar Wind

We present an empirical model to estimate the probability that a high speed stream produced by a ... more We present an empirical model to estimate the probability that a high speed stream produced by a coronal hole will be associated with a geomagnetic storm or not. The model is applied to a database build using the HSS catalogue available on the Institute of Geodynamics webpage at http://www.geodin.ro/hss-sc23/. We present the structure of the catalogue as well as a statistical analysis of these currents. We estimate that the model proposed may correctly predict the association or disassociation of a HSS that is generated by a coronal hole with a geomagnetic storm with a 80% efficiency.

Research paper thumbnail of North-South Asymmetry of the Sunspots

Romanian Astronomical Journal, 2006

Romanian Astronomical Journal Supplement, Vol. 16, Proceedings of the Scientific Session, Scienti... more Romanian Astronomical Journal Supplement, Vol. 16, Proceedings of the Scientific Session, Scientific Programs and Astronomy Education in See and Ukraine, Bucharest, Romania, 16--17 September 2005. Edited by Magda Stavinschi and Vasile Mioc., p. 229

Research paper thumbnail of Complex Catalogue of High Speed Streams Associated with Geomagnetic Storms During Solar Cycle 24

Research paper thumbnail of Detailed Analysis of a GE Oeffective ICME Triggered by the March 15, 2013 CME

Revue Roumaine de Geophysique, Mar 1, 2014

Research paper thumbnail of Magnetospheric Energy Input during Intense Geomagnetic Storms in SC23

EGU General Assembly Conference Abstracts, Apr 1, 2015

Research paper thumbnail of Fast Solar Wind and Geomagnetic Variability during the 24th Solar Cycle (2009 - 2013)

EGU General Assembly Conference Abstracts, May 1, 2014

Research paper thumbnail of Interplanetary coronal mass ejections and their geomagnetic consequences during solar cycle 24

Research paper thumbnail of Comparisons of Several Coupling Functions during Moderate Geomagnetic Storms of SC23

Research paper thumbnail of Interplanetary Magnetic Field Structure and Geomagnetic Storms during Solar Cycle 24

Interplanetary Magnetic Field (IMF) structure, determined by the solar magnetic field and its var... more Interplanetary Magnetic Field (IMF) structure, determined by the solar magnetic field and its variability, is responsible for an essential part of the geomagnetic perturbations. IMF in the terrestrial orbital plane is structured into two or four sectors with opposite direction of the magnetic field, “away” and “towards” the Sun so that the Earth is passing through the opposite magnetic structures during a solar rotation (27 days). The magnetic structure of IMF is significantly varying during the 11-yr solar cycle.

Research paper thumbnail of Magnetic Crochet Associated to the Seismically. Active Flare of March 29, 2014

On March 29, 2014 GOES detected a X1.0 solar flare in the central north-western part of the solar... more On March 29, 2014 GOES detected a X1.0 solar flare in the central north-western part of the solar disk. We present here its main characteristics and several interesting effects in the Earth's magnetosphere and ionosphere. We chose this flare because of its seismic emission (a recent discovery in solar physics which is not yet fully understood) and its many associations with different wavelength signatures. Seismic signatures share the same location (projected on the solar disk) as the hard X-ray emission suggesting that the energy released by the electrons is responsible for the excitation of the acoustic emission. Ground based instruments have detected a disturbance in the propagation of the terrestrial radio transmission. A flash in the extreme UV radiation influenced the ionization in the Earth's upper atmosphere and was seen as a sudden ionospheric disturbance (SID). Several ground based magnetometers have detected a magnetic crochet. We investigate the main emissions ch...

Research paper thumbnail of Observations solaires. Rotation 1703_- 1716

Research paper thumbnail of Observations solaires. Rotations 1744 - 1756, 9 janvier - 28 décembre 1984

Research paper thumbnail of Observations solaires. Rotations 1730 - 1743, 23 décembre 1982 - 8 janvier 1984

Research paper thumbnail of An Empirical Model for Geoeffectiveness of High Speed Streams in Solar Wind

Zenodo (CERN European Organization for Nuclear Research), Feb 18, 2021

We present an empirical model to estimate the probability that a high speed stream produced by a ... more We present an empirical model to estimate the probability that a high speed stream produced by a coronal hole will be associated with a geomagnetic storm or not. The model is applied to a database build using the HSS catalogue available on the Institute of Geodynamics webpage at http://www.geodin.ro/hss-sc23/. We present the structure of the catalogue as well as a statistical analysis of these currents. We estimate that the model proposed may correctly predict the association or disassociation of a HSS that is generated by a coronal hole with a geomagnetic storm with a 80% efficiency.

Research paper thumbnail of Magnetospheric Energy Input during Intense Geomagnetic Storms in SC23

EGU General Assembly Conference Abstracts, Apr 1, 2015

Research paper thumbnail of Fast Solar Wind and Geomagnetic Variability during the 24th Solar Cycle (2009 - 2013)

EGU General Assembly Conference Abstracts, May 1, 2014

Research paper thumbnail of Complex Catalogue of High Speed Streams Associated with Geomagnetic Storms During Solar Cycle 24

Solar Physics, May 1, 2022

Research paper thumbnail of Detailed Analysis of a GE Oeffective ICME Triggered by the March 15, 2013 CME

Research paper thumbnail of A study of solar and interplanetary parameters of CMEs causing major geomagnetic storms during SC 23

Annales Geophysicae, 2013

In this paper we analyse 25 Earth-directed and strongly geoeffective interplanetary coronal mass ... more In this paper we analyse 25 Earth-directed and strongly geoeffective interplanetary coronal mass ejections (ICMEs) which occurred during solar cycle 23, using data provided by instruments on SOHO (Solar and Heliospheric Observatory), ACE (Advanced Composition Explorer) and geomagnetic stations. We also examine the in situ parameters, the energy transfer into magnetosphere, and the geomagnetic indexes. We compare observed travel times with those calculated by observed speeds projected into the plane of the sky and de-projected by a simple model. The best fit was found with the projected speeds. No correlation was found between the importance of a flare and the geomagnetic Dst (disturbance storm time) index. By comparing the in situ parameters with the Dst index we find a strong connection between some of these parameters (such as Bz, Bs • V and the energy transfer into the magnetosphere) with the strength of the geomagnetic storm. No correlation was found with proton density and plasma temperature. A superposed epoch analysis revealed a strong dependence of the Dst index on the southward component of interplanetary magnetic field, Bz, and to the Akasofu coupling function, which evaluates the energy transfer between the ICME and the magnetosphere. The analysis also showed that the geomagnetic field at higher latitudes is disturbed before the field around the Earth's equator.

Research paper thumbnail of On the prediction of geoeffectiveness of CMEs during the ascending phase of SC24 using a logistic regression method

Journal of Atmospheric and Solar-Terrestrial Physics, 2019

Coronal mass ejections (CMEs) are pieces of the puzzle that drive space weather. Numerous methods... more Coronal mass ejections (CMEs) are pieces of the puzzle that drive space weather. Numerous methods (theoretical, numerical and empirical) are being used to predict whether the CME will be geoeffective or not. We present here an attempt to predict the geoeffectiveness of a given CME using a modified version of logistic regression model proposed by Srivastava (2005), using only initial CME parameters. Our model attempts to forecast if the CME will be associated with geomagnetic storm defined by a minimum Dst value <-30 nT. We applied this modified logistic regression model for CMEs detected by LASCO during the ascending phase of solar cycle 24 (April 1, 2010 to June 30, 2011). Although the hit rate and proportion correctness were not promising for the training CME set, we obtained good hit rates and proportion correctness for the validation set. We expect to improve the model upon applying it to a dataset comprising

Research paper thumbnail of An Empirical Model for Geoeffectiveness of High Speed Streams in Solar Wind

We present an empirical model to estimate the probability that a high speed stream produced by a ... more We present an empirical model to estimate the probability that a high speed stream produced by a coronal hole will be associated with a geomagnetic storm or not. The model is applied to a database build using the HSS catalogue available on the Institute of Geodynamics webpage at http://www.geodin.ro/hss-sc23/. We present the structure of the catalogue as well as a statistical analysis of these currents. We estimate that the model proposed may correctly predict the association or disassociation of a HSS that is generated by a coronal hole with a geomagnetic storm with a 80% efficiency.

Research paper thumbnail of North-South Asymmetry of the Sunspots

Romanian Astronomical Journal, 2006

Romanian Astronomical Journal Supplement, Vol. 16, Proceedings of the Scientific Session, Scienti... more Romanian Astronomical Journal Supplement, Vol. 16, Proceedings of the Scientific Session, Scientific Programs and Astronomy Education in See and Ukraine, Bucharest, Romania, 16--17 September 2005. Edited by Magda Stavinschi and Vasile Mioc., p. 229

Research paper thumbnail of Complex Catalogue of High Speed Streams Associated with Geomagnetic Storms During Solar Cycle 24

Research paper thumbnail of Detailed Analysis of a GE Oeffective ICME Triggered by the March 15, 2013 CME

Revue Roumaine de Geophysique, Mar 1, 2014

Research paper thumbnail of Magnetospheric Energy Input during Intense Geomagnetic Storms in SC23

EGU General Assembly Conference Abstracts, Apr 1, 2015

Research paper thumbnail of Fast Solar Wind and Geomagnetic Variability during the 24th Solar Cycle (2009 - 2013)

EGU General Assembly Conference Abstracts, May 1, 2014

Research paper thumbnail of Interplanetary coronal mass ejections and their geomagnetic consequences during solar cycle 24

Research paper thumbnail of Comparisons of Several Coupling Functions during Moderate Geomagnetic Storms of SC23

Research paper thumbnail of Interplanetary Magnetic Field Structure and Geomagnetic Storms during Solar Cycle 24

Interplanetary Magnetic Field (IMF) structure, determined by the solar magnetic field and its var... more Interplanetary Magnetic Field (IMF) structure, determined by the solar magnetic field and its variability, is responsible for an essential part of the geomagnetic perturbations. IMF in the terrestrial orbital plane is structured into two or four sectors with opposite direction of the magnetic field, “away” and “towards” the Sun so that the Earth is passing through the opposite magnetic structures during a solar rotation (27 days). The magnetic structure of IMF is significantly varying during the 11-yr solar cycle.

Research paper thumbnail of Magnetic Crochet Associated to the Seismically. Active Flare of March 29, 2014

On March 29, 2014 GOES detected a X1.0 solar flare in the central north-western part of the solar... more On March 29, 2014 GOES detected a X1.0 solar flare in the central north-western part of the solar disk. We present here its main characteristics and several interesting effects in the Earth's magnetosphere and ionosphere. We chose this flare because of its seismic emission (a recent discovery in solar physics which is not yet fully understood) and its many associations with different wavelength signatures. Seismic signatures share the same location (projected on the solar disk) as the hard X-ray emission suggesting that the energy released by the electrons is responsible for the excitation of the acoustic emission. Ground based instruments have detected a disturbance in the propagation of the terrestrial radio transmission. A flash in the extreme UV radiation influenced the ionization in the Earth's upper atmosphere and was seen as a sudden ionospheric disturbance (SID). Several ground based magnetometers have detected a magnetic crochet. We investigate the main emissions ch...

Research paper thumbnail of Observations solaires. Rotation 1703_- 1716

Research paper thumbnail of Observations solaires. Rotations 1744 - 1756, 9 janvier - 28 décembre 1984

Research paper thumbnail of Observations solaires. Rotations 1730 - 1743, 23 décembre 1982 - 8 janvier 1984