Flux rope axis geometry of magnetic clouds deduced from in situ data

AbstractMagnetic clouds (MCs) consist of flux ropes that are ejected from the low solar corona during eruptive flares. Following their ejection, they propagate in the interplanetary medium where they can be detected by in situ instruments and heliospheric imagers onboard spacecraft. Although in situ measurements give a wide range of data, these only depict the nature of the MC along the unidirectional trajectory crossing of a spacecraft. As such, direct 3D measurements of MC characteristics are impossible. From a statistical analysis of a wide range of MCs detected at 1 AU by the Wind spacecraft, we propose different methods to deduce the most probable magnetic cloud axis shape. These methods include the comparison of synthetic distributions with observed distributions of the axis orientation, as well as the direct integration of observed probability distribution to deduce the global MC axis shape. The overall shape given by those two methods is then compared with 2D heliospheric images of a propagating MC and we find similar geometrical features.

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The link between CME-associated dimmings and interplanetary magnetic clouds

Proceedings of the International Astronomical Union ◽

10.1017/s174392130902938x ◽

2008 ◽

Vol 4 (S257) ◽

pp. 265-270 ◽

Cited By ~ 2

Author(s):

Cristina H. Mandrini ◽

María S. Nakwacki ◽

Gemma Attrill ◽

Lidia van Driel-Gesztelyi ◽

Sergio Dasso ◽

...

Keyword(s):

Magnetic Flux ◽

Large Scale ◽

Extreme Ultraviolet ◽

Magnetic Cloud ◽

Flux Rope ◽

Magnetic Clouds ◽

Magnetic Structures ◽

Doppler Imager ◽

Imaging Telescope

AbstractCoronal dimmings often develop in the vicinity of erupting magnetic configurations. It has been suggested that they mark the location of the footpoints of ejected flux ropes and, thus, their magnetic flux can be used as a proxy for the ejected flux. If so, this quantity can be compared to the flux in the associated interplanetary magnetic cloud (MC) to find clues about the origin of the ejected flux rope. In the context of this interpretation, we present several events for which we have done a comparative solar-interplanetary analysis. We combine SOHO/Extreme Ultraviolet Imaging Telescope (EIT) data and Michelson Doppler Imager (MDI) magnetic maps to identify and measure the flux in the dimmed regions. We model the associated MCs and compute their magnetic flux using in situ observations. We find that the magnetic fluxes in the dimmings and MCs are compatible in some events; though this is not the case for large-scale and intense eruptions that occur in regions that are not isolated from others. We conclude that, in these particular cases, a fraction of the dimmed regions can be formed by reconnection between the erupting field and the surrounding magnetic structures, via a stepping process that can also explain other CME associated events.

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On the Radial and Longitudinal Variation of a Magnetic Cloud: ACE, Wind, ARTEMIS and Juno Observations

Solar Physics ◽

10.1007/s11207-020-01714-z ◽

2020 ◽

Vol 295 (11) ◽

Author(s):

Emma E. Davies ◽

Robert J. Forsyth ◽

Simon W. Good ◽

Emilia K. J. Kilpua

Keyword(s):

Axial Magnetic Field ◽

Magnetic Cloud ◽

Flux Rope ◽

Time History ◽

Minimum Variance ◽

Magnetic Clouds ◽

Analysis Method ◽

History Of

AbstractWe present observations of the same magnetic cloud made near Earth by the Advance Composition Explorer (ACE), Wind, and the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) mission comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and THEMIS C spacecraft, and later by Juno at a distance of 1.2 AU. The spacecraft were close to radial alignment throughout the event, with a longitudinal separation of $3.6^{\circ}$ 3.6 ∘ between Juno and the spacecraft near Earth. The magnetic cloud likely originated from a filament eruption on 22 October 2011 at 00:05 UT, and caused a strong geomagnetic storm at Earth commencing on 24 October. Observations of the magnetic cloud at each spacecraft have been analysed using minimum variance analysis and two flux rope fitting models, Lundquist and Gold–Hoyle, to give the orientation of the flux rope axis. We explore the effect different trailing edge boundaries have on the results of each analysis method, and find a clear difference between the orientations of the flux rope axis at the near-Earth spacecraft and Juno, independent of the analysis method. The axial magnetic field strength and the radial width of the flux rope are calculated using both observations and fitting parameters and their relationship with heliocentric distance is investigated. Differences in results between the near-Earth spacecraft and Juno are attributed not only to the radial separation, but to the small longitudinal separation which resulted in a surprisingly large difference in the in situ observations between the spacecraft. This case study demonstrates the utility of Juno cruise data as a new opportunity to study magnetic clouds beyond 1 AU, and the need for caution in future radial alignment studies.

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A numerical study of the interaction between two ejecta in the interplanetary medium: one- and two-dimensional hydrodynamic simulations

Annales Geophysicae ◽

10.5194/angeo-22-3741-2004 ◽

2004 ◽

Vol 22 (10) ◽

pp. 3741-3749 ◽

Cited By ~ 16

Author(s):

A. Gonzalez-Esparza ◽

A. Santillán ◽

J. Ferrer

Keyword(s):

Hydrodynamic Model ◽

Physical Mechanism ◽

Interplanetary Medium ◽

Numerical Study ◽

Two Dimensions ◽

Magnetic Clouds ◽

The Sun ◽

Two Dimensional ◽

Hydrodynamic Simulations

Abstract. We studied the heliospheric evolution in one and two dimensions of the interaction between two ejecta-like disturbances beyond the critical point: a faster ejecta 2 overtaking a previously launched slower ejecta 1. The study is based on a hydrodynamic model using the ZEUS-3-D code. This model can be applied to those cases where the interaction occurs far away from the Sun and there is no merging (magnetic reconnection) between the two ejecta. The simulation shows that when the faster ejecta 2 overtakes ejecta 1 there is an interchange of momentum between the two ejecta, where the leading ejecta 1 accelerates and the tracking ejecta 2 decelerates. Both ejecta tend to arrive at 1AU having similar speeds, but with the front of ejecta 1 propagating faster than the front of ejecta 2. The momentum is transferred from ejecta 2 to ejecta 1 when the shock initially driven by ejecta 2 passes through ejecta 1. Eventually the two shock waves driven by the two ejecta merge together into a single stronger shock. The 2-D simulation shows that the evolution of the interaction can be very complex and there are very different signatures of the same event at different viewing angles; however, the transferring of momentum between the two ejecta follows the same physical mechanism described above. These results are in qualitative agreement with in-situ plasma observations of "multiple magnetic clouds" detected at 1AU.

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Configuration of a Magnetic Cloud From Solar Orbiter and Wind Spacecraft In-situ Measurements

Frontiers in Physics ◽

10.3389/fphy.2021.706056 ◽

2021 ◽

Vol 9 ◽

Author(s):

Qiang Hu ◽

Wen He ◽

Lingling Zhao ◽

Edward Lu

Keyword(s):

Magnetic Field ◽

Three Dimensional ◽

Flux Rope ◽

3D Models ◽

Field Configuration ◽

Magnetic Clouds ◽

Physical Parameters ◽

The Sun ◽

Wind Spacecraft

Coronal mass ejections (CMEs) represent one type of the major eruption from the Sun. Their interplanetary counterparts, the interplanetary CMEs (ICMEs), are the direct manifestations of these structures when they propagate into the heliosphere and encounter one or more observing spacecraft. The ICMEs generally exhibit a set of distinctive signatures from the in-situ spacecraft measurements. A particular subset of ICMEs, the so-called Magnetic Clouds (MCs), is more uniquely defined and has been studied for decades, based on in-situ magnetic field and plasma measurements. By utilizing the latest multiple spacecraft measurements and analysis tools, we report a detailed study of the internal magnetic field configuration of an MC event observed by both the Solar Orbiter (SO) and Wind spacecraft in the solar wind near the Sun-Earth line. Both two-dimensional (2D) and three-dimensional (3D) models are applied to reveal the flux rope configurations of the MC. Various geometrical as well as physical parameters are derived and found to be similar within error estimates for the two methods. These results quantitatively characterize the coherent MC flux rope structure crossed by the two spacecraft along different paths. The implication for the radial evolution of this MC event is also discussed.

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Advances in altimetric snow depth estimates using bi-frequency SARAL/CryoSat-2 Ka/Ku measurements

10.5194/tc-2021-79 ◽

2021 ◽

Author(s):

Florent Garnier ◽

Sara Fleury ◽

Gilles Garric ◽

Jérôme Bouffard ◽

Michel Tsamados ◽

...

Keyword(s):

Sea Ice ◽

Snow Depth ◽

Ocean Modeling ◽

The Arctic ◽

Validation Data ◽

Band Frequency ◽

In Situ Data ◽

Wide Range ◽

Assimilation System

Abstract. Although snow depth on sea ice is a key parameter for Sea Ice Thickness (SIT), there currently does not exist reliable estimations. In Arctic, nearly all SIT products use a snow depth climatology (the Warren-99 modified climatology, W99m) constructed from in-situ data obtained prior to the first significant impacts of climate change. In Antarctica, the lack of information on snow depth remains a major obstacle in the development of reliable SIT products. In this study, we present the latest version of the Altimetric Snow Depth (ASD) product computed over both hemispheres from the difference of the radar penetration into the snow pack between the CryoSat-2 Ku-band and the SARAL Ka-band frequency radars. The ASD solution is compared against a wide range of snow depth products including model data (Pan-Arctic Ice-Ocean Modeling and Assimilation System (PIOMAS) or its equivalent in Antarctica the Global Ice-Ocean Modeling and Assimilation System (GIOMAS), the MERCATOR model and NASA's Eulerian Snow On Sea Ice Model (NESOSIM, only in Arctic)), the Advanced Microwave Scanning Radiometer 2 (AMSR-2) passive radiometer data, and the Dual-altimeter Snow Thickness (DuST) Ka-Ku product (only in Arctic). It is validated in the Arctic against in-situ and airborne validation data. These comparisons demonstrate that ASD provide a consistent snow depth solution, with space and time patterns comparable with those of the alternative Ka-Ku DuST product, but with a mean bias of about 6.5 cm. We also demonstrate that ASD is consistent with the validation data. Comparisons with Operation Ice Bridge's (OIB) airborne snow radar in Arctic during the period of 2014–2018 show a correlation of 0.66 and a RMSE of about 6 cm. Furthermore, a first-guess monthly climatology has been constructed in Arctic from the ASD product, which shows a good agreement with OIB during 2009–2012. This climatology is shown to provide a better solution than the W99m climatology when compared with validation data. Finally, we have characterised the SIT uncertainty due to the snow depth from an ensemble of SIT solutions computed for the Arctic by using the different snow depth products previously used in the comparison with the ASD product. During the period of 2013–2019, we found a spatially averaged SIT mean standard deviation of 20 cm. Deviations between SIT estimations due to different snow depths can reach up to 77 cm. Using the ASD data instead of W99m to estimate SIT over this time period leads to a reduction of the average SIT of about 30 cm.

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Coronal transients during two solar minima: their source regions and interplanetary counterparts

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312004760 ◽

2011 ◽

Vol 7 (S286) ◽

pp. 149-153

Author(s):

Hebe Cremades ◽

Cristina H. Mandrini ◽

Sergio Dasso

Keyword(s):

Solar Corona ◽

Coronal Mass Ejections ◽

Magnetic Clouds ◽

Time Intervals ◽

Solar Source ◽

In Situ Data ◽

Source Regions ◽

Multi Wavelength ◽

First Time

AbstractWe have investigated two full solar rotations belonging to two distinct solar minima, in the frame of two coordinated observational and research campaigns. The nearly uninterrupted gathering of solar coronal data since the beginning of the SOHO era offers the exceptional possibility of comparing two solar minima for the first time, with regard to coronal transients. This study characterizes the variety of outward-travelling transients observed in the solar corona during both time intervals, from very narrow jet-like events to coronal mass ejections (CMEs). Their solar source regions and ensuing interplanetary structures were identified and characterized. Multi-wavelength images from the space missions SOHO, Yohkoh and STEREO, and ground-based observatories were studied for coronal ejecta and their solar sources, while in situ data registered by the ACE spacecraft were inspected for interplanetary CMEs and magnetic clouds. Instrumental aspects such as dissimilar resolution, cadence, and fields of view are considered in order to discern instrumentally-driven disparities from inherent differences between solar minima.

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New Force-Free Models of Magnetic Clouds

Highlights of Astronomy ◽

10.1017/s1539299600015331 ◽

2005 ◽

Vol 13 ◽

pp. 133-133

Author(s):

M. Vandas ◽

E. P. Romashets ◽

S. Watari

Keyword(s):

Magnetic Field ◽

Magnetic Cloud ◽

Free Field ◽

Flux Rope ◽

Field Vector ◽

Magnetic Clouds ◽

Field Magnitude ◽

Flux Ropes ◽

Magnetic Field Magnitude ◽

The Magnetic Field

AbstractMagnetic clouds are thought to be large flux ropes propagating through the heliosphere. Their twisted magnetic fields are mostly modeled by a constant-alpha force-free field in a circular cylindrical flux rope (the Lundquist solution). However, the interplanetary flux ropes are three dimensional objects. In reality they possibly have a curved shape and an oblate cross section. Recently we have found two force-free models of flux ropes which takes into account the mentioned features. These are (i) a constant-alpha force-free configuration in an elliptic flux rope (Vandas & Romashets 2003, A&A, 398, 801), and (ii) a non-constant-alpha force-free field in a toroid with arbitrary aspect ratio (Romashets & Vandas 2003, AIP Conf Ser. 679, 180). Two magnetic cloud observations were analyzed. The magnetic cloud of October 18-19, 1995 has been fitted by Lepping et al. (1997, JGR, 102, 14049) with use of the Lundquist solution. The cloud has a very flat magnetic field magnitude profile. We fitted it by the elliptic solution (i). The magnetic cloud of November 17-18, 1975 has been fitted by Marubashi (1997) with use of a toroidally adjusted Lundquist solution. The cloud has a large magnetic field vector rotation and a large magnetic field magnitude increase over the background level. We fitted it by the toroidal solution (ii). The both fits match the rotation of the magnetic field vector in a comparable quality to the former fits, but the description of the magnetic field magnitude profiles is remarkable better. It is possible to incorporate temporal effects (expansion) of magnetic clouds into the new solutions through a time-dependent alpha parameter as in Shimazu & Vandas (2002, EP&S, 54, 783).

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Combining MODIS, AVHRR and in situ data for evapotranspiration estimation over heterogeneous landscape of the Tibetan Plateau

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-1507-2014 ◽

2014 ◽

Vol 14 (3) ◽

pp. 1507-1515 ◽

Cited By ~ 28

Author(s):

Y. Ma ◽

Z. Zhu ◽

L. Zhong ◽

B. Wang ◽

C. Han ◽

...

Keyword(s):

Tibetan Plateau ◽

Ground Truth ◽

The Tibetan Plateau ◽

Evaporative Fraction ◽

Modis Data ◽

In Situ Data ◽

Heterogeneous Landscape ◽

Wide Range ◽

Avhrr Data

Abstract. In this study, a parameterization method based on MODIS (Moderate Resolution Imaging Spectroradiometer) data, AVHRR (Advanced Very High-Resolution Radiometer) data and in situ data is introduced and tested for estimating the regional evaporative fraction Λ over a heterogeneous landscape. As a case study, the algorithm was applied to the Tibetan Plateau (TP) area. Eight MODIS data images (17 January, 14 April, 23 July and 16 October in 2003; 30 January, 15 April, 1 August and 25 October in 2007) and four AVHRR data images (17 January, 14 April, 23 July and 16 October in 2003) were used in this study to compare winter, spring, summer and autumn values and for annual variation analysis. The results were validated using the "ground truth" measured at Tibetan Observation and Research Platform (TORP) and the CAMP/Tibet (CEOP (Coordinated Enhanced Observing Period) Asia-Australia Monsoon Project (CAMP) on the Tibetan Plateau) meteorological stations. The results show that the estimated evaporative fraction Λ in the four different seasons over the TP is in clear accordance with the land surface status. The Λ fractions show a wide range due to the strongly contrasting surface features found on the TP. Also, the estimated Λ values are in good agreement with "ground truth" measurements, and their absolute percentage difference (APD) is less than 10.0% at the validation sites. The AVHRR data were also in agreement with the MODIS data, with the latter usually displaying a higher level of accuracy. It was therefore concluded that the proposed algorithm was successful in retrieving the evaporative fraction Λ using MODIS, AVHRR and in situ data over the TP. MODIS data are the most accurate and should be used widely in evapotranspiration (ET) research in this region.

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Combination satellite and in-situ data for the determination of evapotranspiration over heterogeneous landscape of the Tibetan Plateau

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-8435-2013 ◽

2013 ◽

Vol 13 (3) ◽

pp. 8435-8453

Author(s):

Y. Ma ◽

Z. Zhu ◽

L. Zhong ◽

B. Wang ◽

C. Han ◽

...

Keyword(s):

Tibetan Plateau ◽

Land Surface ◽

The Tibetan Plateau ◽

Modis Data ◽

In Situ Data ◽

Heterogeneous Landscape ◽

Plateau Area ◽

Wide Range ◽

Avhrr Data

Abstract. In this study, a new parameterization method based on MODIS (Moderate Resolution Imaging Spectroradiometer) data, AVHRR (Advanced Very High-Resolution Radiometer) data and in-situ data is constructed and tested for deriving the regional evaporative fraction (EF) over heterogeneous landscape. As a case study, the methodology was applied to the Tibetan Plateau area. Eight images of MODIS data (17 January 2003, 14 April 2003, 23 July 2003 and 16 October 2003; 30 January 2007, 15 April 2007, 1 August 2007 and 25 October 2007) and four images of AVHRR data (17 January 2003, 14 April 2003, 23 July 2003 and 16 October 2003) were used in this study for the comparison among winter, spring, summer and autumn and the annual variation analysis. The derived results were also validated by using the "ground truth" measured in the stations of the Tibetan Observation and Research Platform (TORP) and the CAMP/Tibet (CEOP (Coordinated Enhanced Observing Period) Asia-Australia Monsoon Project (CAMP) on the Tibetan Plateau). The results show that the derived EF in four different seasons over the Tibetan Plateau area is in good accordance with the land surface status. The EF show a wide range due to the strong contrast of surface features over the Tibetan Plateau. Also, the estimated EF is in good agreement with the ground measurements, and their absolute percent difference (APD) is less than 10% in the validation sites. The results from AVHRR were also in agreement with MODIS, with the latter usually displaying a higher level of accuracy. It is therefore concluded that the proposed methodology is successful for the retrieval of EF using the MODIS data, AVHRR data and in-situ data over the Tibetan Plateau area, and the MODIS data is the better one and it should be used widely for the evapotranspiration (ET) research over this region.

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Reconstruction of the Parker spiral with the Reverse In situ data and MHD APproach - RIMAP

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2020072 ◽

2020 ◽

Author(s):

Ruggero Biondo ◽

Alessandro Bemporad ◽

Andrea Mignone ◽

Fabio Reale

Keyword(s):

Interplanetary Medium ◽

Small Scale ◽

Reconstruction Technique ◽

The Sun ◽

Plasma Parameters ◽

In Situ Data ◽

Mhd Simulations ◽

Solar Eruptions ◽

In Situ Observations

The reconstruction of plasma parameters in the interplanetary medium is very important to understand the interplanetary propagation of solar eruptions and for Space Weather application purposes. Because only a few spacecraft are measuring in situ these parameters, reconstructions are currently performed by running complex numerical Magneto-hydrodynamic (MHD) simulations starting from remote sensing observations of the Sun. Current models apply full 3D MHD simulations of the corona or extrapolations of photospheric magnetic fields combined with and semiempirical relationships to derive the plasma parameters on a sphere centered on the Sun (inner boundary). The plasma is then propagated in the interplanetary medium up to the Earth’s orbit and beyond. Nevertheless, this approach requires significant theoretical and computational efforts, and the results are only in partial agreement with the in situ observations. In this paper we describe a new approach to this problem called RIMAP - Reverse In situ data and MHD APproach. The plasma parameters in the inner boundary at 0.1 AU are derived directly from the in situ measurements acquired at 1 AU, by applying a back reconstruction technique to remap them into the inner heliosphere. This remapping is done by using the Weber and Davies solar wind theoretical model to reconstruct the wind flowlines. The plasma is then re-propagated outward from 0.1 AU by running a MHD numerical simulation based on the PLUTO code. The interplanetary spiral reconstructions obtained with RIMAP are not only in a much better agreement with the in situ observations, but are also including many more small-scale longitudinal features in the plasma parameters that are not reproduced with the approaches developed so far.

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