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18 results on '"Lumme, E."'

1. Probing the effect of cadence on the estimates of photospheric energy and helicity injections in eruptive active region NOAA AR 11158

Author

Lumme, E., Kazachenko, M. D., Fisher, G. H., Welsch, B. T., Pomoell, J., and Kilpua, E. K. J.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

In this work we study how the input data cadence affects the photospheric energy and helicity injection estimates in eruptive NOAA active region 11158. We sample the novel 2.25-minute vector magnetogram and Dopplergram data from the \emph{Helioseismic and Magnetic Imager} (HMI) instrument onboard the \emph{Solar Dynamics Observatory} (SDO) spacecraft to create input datasets of variable cadences ranging from 2.25 minutes to 24 hours. We employ state-of-the-art data processing, velocity and electric field inversion methods for deriving estimates of the energy and helicity injections from these datasets. We find that the electric field inversion methods that reproduce the observed magnetic field evolution through the use of Faraday's law are more stable against variable cadence: the PDFI (PTD-Doppler-FLCT-Ideal) electric field inversion method produces consistent injection estimates for cadences from 2.25 minutes up to 2 hours, implying that the photospheric processes acting on time scales below 2 hours contribute little to the injections, or that they are below the sensitivity of the input data and the PDFI method. On other hand, the electric field estimate derived from the output of DAVE4VM (Differential Affine Velocity Estimator for Vector Magnetograms), which does not fulfil Faraday's law exactly, produces significant variations in the energy and helicity injection estimates in the 2.25-minute to 2-hour cadence range. We present also a third, novel DAVE4VM-based electric field estimate, which corrects the poor inductivity of the raw DAVE4VM estimate. This method is less sensitive to the changes of cadence, but still faces significant issues for the lowest of considered cadences ($\geq$2 hours). We find several potential problems in both PDFI- and DAVE4VM-based injection estimates and conclude that the quality of both should be surveyed further in controlled environments.

Published
2019
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2. FORESAIL-1 cubesat mission to measure radiation belt losses and demonstrate de-orbiting

Author

FORESAIL collaboration, Palmroth, M., Praks, J., Vainio, R., Janhunen, P., Kilpua, E. K. J., Ganushkina, N. Yu., Afanasiev, A., Ala-Lahti, M., Alho, A., Asikainen, T., Asvestari, E., Battarbee, M., Binios, A., Bosser, A., Brito, T., Envall, J., Ganse, U., George, H., Gieseler, J., Good, S., Grandin, M., Haslam, S., Hedman, H. -P., Hietala, H., Jovanovic, N., Kakakhel, S., Kalliokoski, M., Kettunen, V. V., Koskela, T., Lumme, E., Meskanen, M., Morosan, D., Mughal, M. Rizwan, Niemelä, P., Nyman, S., Oleynik, P., Osmane, A., Palmerio, E., Pfau-Kempf, Y., Peltonen, J., Plosila, J., Polkko, J., Poluianov, S., Pomoell, J., Price, D., Punkkinen, A., Punkkinen, R., Riwanto, B., Salomaa, L., Slavinskis, A., Säntti, T., Tammi, J., Tenhunen, H., Toivanen, P., Tuominen, J., Turc, L., Valtonen, E., Virtanen, P., and Westerlund, T.

Subjects
Physics - Space Physics
Abstract

Today, the near-Earth space is facing a paradigm change as the number of new spacecraft is literally sky-rocketing. Increasing numbers of small satellites threaten the sustainable use of space, as without removal, space debris will eventually make certain critical orbits unusable. A central factor affecting small spacecraft health and leading to debris is the radiation environment, which is unpredictable due to an incomplete understanding of the near-Earth radiation environment itself and its variability driven by the solar wind and outer magnetosphere. This paper presents the FORESAIL-1 nanosatellite mission, having two scientific and one technological objectives. The first scientific objective is to measure the energy and flux of energetic particle loss to the atmosphere with a representative energy and pitch angle resolution over a wide range of magnetic local times. To pave the way to novel model - in situ data comparisons, we also show preliminary results on precipitating electron fluxes obtained with the new global hybrid-Vlasov simulation Vlasiator. The second scientific objective of the FORESAIL-1 mission is to measure energetic neutral atoms (ENAs) of solar origin. The solar ENA flux has the potential to contribute importantly to the knowledge of solar eruption energy budget estimations. The technological objective is to demonstrate a satellite de-orbiting technology, and for the first time, make an orbit manoeuvre with a propellantless nanosatellite. FORESAIL-1 will demonstrate the potential for nanosatellites to make important scientific contributions as well as promote the sustainable utilisation of space by using a cost-efficient de-orbiting technology., Comment: 26 pages, 7 figures, 5 tables Published online in JGR: Space Physics on 21 May 2019

Published
2019
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3. Optimization of Photospheric Electric Field Estimates for Accurate Retrieval of Total Magnetic Energy Injection

Author

Lumme, E., Pomoell, J., and Kilpua, E. K. J.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

Estimates of the photospheric magnetic, electric and plasma velocity fields are essential for studying the dynamics of the solar atmosphere, for example through the derivative quantities of Poynting and relative helicity flux and by using of the fields to obtain the lower boundary condition for data-driven coronal simulations. In this paper we study the performance of a data processing and electric field inversion approach that requires only high-resolution and high-cadence line-of-sight or vector magnetograms -- which we obtain from Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO). The approach does not require any photospheric velocity estimates, and the lacking velocity information is compensated using ad hoc assumptions. We show that the free parameters of these assumptions can be optimized to reproduce the time evolution of the total magnetic energy injection through the photosphere in NOAA AR 11158, when compared to the recent estimates for this active region. However, we find that the relative magnetic helicity injection is reproduced poorly reaching at best a modest underestimation. We discuss also the effect of some of the data processing details on the results, including the masking of the noise-dominated pixels and the tracking method of the active region, both of which have not received much attention in the literature so far. In most cases the effect of these details is small, but when the optimization of the free parameters of the ad hoc assumptions is considered a consistent use of the noise mask is required. The results found in this paper imply that the data processing and electric field inversion approach that uses only the photospheric magnetic field information offers a flexible and straightforward way to obtain photospheric magnetic and electric field estimates suitable for practical applications such as coronal modeling studies.

Published
2017
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5. Solar Wind Properties and Geospace Impact of Coronal Mass Ejection‐Driven Sheath Regions: Variation and Driver Dependence

Author

Kilpua, E. K. J., Fontaine, Dominique, Moissard, C., Ala‐Lahti, M., Palmerio, E., Yordanova, E., Good, S. W., Kalliokoski, M. M. H., Lumme, E., Osmane, A., Palmroth, M., Turc, Lucile, Laboratoire de Physique des Plasmas (LPP), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; We present a statistical study of interplanetary conditions and geospace response to 89 coronal mass ejection‐driven sheaths observed during Solar Cycles 23 and 24. We investigate in particular the dependencies on the driver properties and variations across the sheath. We find that the ejecta speed principally controls the sheath geoeffectiveness and shows the highest correlations with sheath parameters, in particular in the region closest to the shock. Sheaths of fast ejecta have on average high solar wind speeds, magnetic (B) field magnitudes, and fluctuations, and they generate efficiently strong out‐of‐ecliptic fields. Slow‐ejecta sheaths are considerably slower and have weaker fields and field fluctuations, and therefore they cause primarily moderate geospace activity. Sheaths of weak and strong B field ejecta have distinct properties, but differences in their geoeffectiveness are less drastic. Sheaths of fast and strong ejecta push the subsolar magnetopause significantly earthward, often even beyond geostationary orbit. Slow‐ejecta sheaths also compress the magnetopause significantly due to their large densities that are likely a result of their relatively long propagation times and source near the streamer belt. We find the regions near the shock and ejecta leading edge to be the most geoeffective parts of the sheath. These regions are also associated with the largest B field magnitudes, out‐of‐ecliptic fields, and field fluctuations as well as largest speeds and densities. The variations, however, depend on driver properties. Forecasting sheath properties is challenging due to their variable nature, but the dependence on ejecta properties determined in this work could help to estimate sheath geoeffectiveness through remote‐sensing coronal mass ejection observations.

Published
2019
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8. FORESAIL‐1 CubeSat Mission to Measure Radiation Belt Losses and Demonstrate Deorbiting

Author

Palmroth, M., primary, Praks, J., additional, Vainio, R., additional, Janhunen, P., additional, Kilpua, E. K. J., additional, Afanasiev, A., additional, Ala‐Lahti, M., additional, Alho, A., additional, Asikainen, T., additional, Asvestari, E., additional, Battarbee, M., additional, Binios, A., additional, Bosser, A., additional, Brito, T., additional, Dubart, M., additional, Envall, J., additional, Ganse, U., additional, Ganushkina, N. Yu., additional, George, H., additional, Gieseler, J., additional, Good, S., additional, Grandin, M., additional, Haslam, S., additional, Hedman, H.‐P., additional, Hietala, H., additional, Jovanovic, N., additional, Kakakhel, S., additional, Kalliokoski, M., additional, Kettunen, V. V., additional, Koskela, T., additional, Lumme, E., additional, Meskanen, M., additional, Morosan, D., additional, Mughal, M. Rizwan, additional, Niemelä, P., additional, Nyman, S., additional, Oleynik, P., additional, Osmane, A., additional, Palmerio, E., additional, Peltonen, J., additional, Pfau‐Kempf, Y., additional, Plosila, J., additional, Polkko, J., additional, Poluianov, S., additional, Pomoell, J., additional, Price, D., additional, Punkkinen, A., additional, Punkkinen, R., additional, Riwanto, B., additional, Salomaa, L., additional, Slavinskis, A., additional, Säntti, T., additional, Tammi, J., additional, Tenhunen, H., additional, Toivanen, P., additional, Tuominen, J., additional, Turc, L., additional, Valtonen, E., additional, Virtanen, P., additional, and Westerlund, T., additional

Published
2019
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11. FORESAIL‐1 CubeSat mission to measure radiation belt losses and demonstrate deorbiting

Author

Palmroth, M. (M.), Praks, J. (J.), Vainio, R. (R.), Janhunen, P. (P.), Kilpua, E. K. (E. K. J.), Afanasiev, A. (A.), Ala-Lahti, M. (M.), Alho, A. (A.), Asikainen, T. (T.), Asvestari, E. (E.), Battarbee, M. (M.), Binios, A. (A.), Bosser, A. (A.), Brito, T. (T.), Dubart, M. (M.), Envall, J. (J.), Ganse, U. (U.), Ganushkina, N. Y. (N. Yu.), George, H. (H.), Gieseler, J. (J.), Good, S. (S.), Grandin, M. (M.), Haslam, S. (S.), Hedman, H.-P. (H.-P.), Hietala, H. (H.), Jovanovic, N. (N.), Kakakhel, S. (S.), Kalliokoski, M. (M.), Kettunen, V. V. (V. V.), Koskela, T. (T.), Lumme, E. (E.), Meskanen, M. (M.), Morosan, D. (D.), Rizwan Mughal, M. (M.), Niemelä, P. (P.), Nyman, S. (S.), Oleynik, P. (P.), Osmane, A. (A.), Palmerio, E. (E.), Peltonen, J. (J.), Pfau-Kempf, Y. (Y.), Plosila, J. (J.), Polkko, J. (J.), Poluianov, S. (S.), Pomoell, J. (J.), Price, D. (D.), Punkkinen, A. (A.), Punkkinen, R. (R.), Riwanto, B. (B.), Salomaa, L. (L.), Slavinskis, A. (A.), Säntti, T. (T.), Tammi, J. (J.), Tenhunen, H. (H.), Toivanen, P. (P.), Tuominen, J. (J.), Turc, L. (L.), Valtonen, E. (E.), Virtanen, P. (P.), Westerlund, T. (T.), Palmroth, M. (M.), Praks, J. (J.), Vainio, R. (R.), Janhunen, P. (P.), Kilpua, E. K. (E. K. J.), Afanasiev, A. (A.), Ala-Lahti, M. (M.), Alho, A. (A.), Asikainen, T. (T.), Asvestari, E. (E.), Battarbee, M. (M.), Binios, A. (A.), Bosser, A. (A.), Brito, T. (T.), Dubart, M. (M.), Envall, J. (J.), Ganse, U. (U.), Ganushkina, N. Y. (N. Yu.), George, H. (H.), Gieseler, J. (J.), Good, S. (S.), Grandin, M. (M.), Haslam, S. (S.), Hedman, H.-P. (H.-P.), Hietala, H. (H.), Jovanovic, N. (N.), Kakakhel, S. (S.), Kalliokoski, M. (M.), Kettunen, V. V. (V. V.), Koskela, T. (T.), Lumme, E. (E.), Meskanen, M. (M.), Morosan, D. (D.), Rizwan Mughal, M. (M.), Niemelä, P. (P.), Nyman, S. (S.), Oleynik, P. (P.), Osmane, A. (A.), Palmerio, E. (E.), Peltonen, J. (J.), Pfau-Kempf, Y. (Y.), Plosila, J. (J.), Polkko, J. (J.), Poluianov, S. (S.), Pomoell, J. (J.), Price, D. (D.), Punkkinen, A. (A.), Punkkinen, R. (R.), Riwanto, B. (B.), Salomaa, L. (L.), Slavinskis, A. (A.), Säntti, T. (T.), Tammi, J. (J.), Tenhunen, H. (H.), Toivanen, P. (P.), Tuominen, J. (J.), Turc, L. (L.), Valtonen, E. (E.), Virtanen, P. (P.), and Westerlund, T. (T.)

Abstract

Today, the near‐Earth space is facing a paradigm change as the number of new spacecraft is literally skyrocketing. Increasing numbers of small satellites threaten the sustainable use of space, as without removal, space debris will eventually make certain critical orbits unusable. A central factor affecting small spacecraft health and leading to debris is the radiation environment, which is unpredictable due to an incomplete understanding of the near‐Earth radiation environment itself and its variability driven by the solar wind and outer magnetosphere. This paper presents the FORESAIL‐1 nanosatellite mission, having two scientific and one technological objectives. The first scientific objective is to measure the energy and flux of energetic particle loss to the atmosphere with a representative energy and pitch angle resolution over a wide range of magnetic local times. To pave the way to novel model‐in situ data comparisons, we also show preliminary results on precipitating electron fluxes obtained with the new global hybrid‐Vlasov simulation Vlasiator. The second scientific objective of the FORESAIL‐1 mission is to measure energetic neutral atoms of solar origin. The solar energetic neutral atom flux has the potential to contribute importantly to the knowledge of solar eruption energy budget estimations. The technological objective is to demonstrate a satellite deorbiting technology, and for the first time, make an orbit maneuver with a propellantless nanosatellite. FORESAIL‐1 will demonstrate the potential for nanosatellites to make important scientific contributions as well as promote the sustainable utilization of space by using a cost‐efficient deorbiting technology.

Published
2019

12. Photospheric magnetic and electric field maps for NOAA AR 11158

Author

Lumme, E.

Abstract

This dataset contains the main time series of photospheric magnetic and electric field maps in NOAA AR 11158 created for the publication Lumme et al. (2017). The time series of photospheric magnetic field maps (i.e. vector magnetograms), ELECTRICIT_vector_magnetogram_series_AR11158.zip, was created from SDO/HMI disambiguated full-disk vector magnetograms using the ELECTRICIT software toolkit. The dataset contains the three components of the photospheric magnetic field (Bx,By,Bz) in local Cartesian coordinate system. The system is formed so that the photosphere is projected to a flat surface using Mercator projection centered at the location of the active region at each time (for further details see Lumme et al., 2017). Magnetograms are determined in a 744 x 610 grid with constant grid spacing of 0.03 deg (ca. 364 km) in the Mercator-projected heliographic coordinates. The time series spans from 2011 Feb 10 12:00 TAI to 2011 Feb 18 03:00 TAI (TAI is 37 seconds ahead of UT) with cadence of 12 minutes. The filename format is "{TIME}_{field_component}.fits". We have also published the maps of bad pixels that we removed from full-disk SDO/HMI vector magnetograms when creating the magnetogram time series above (see the publication for further details about the bad pixels). The file bad_pixel_maps_11158.zip contains time series of full-disk vector magnetogram cutouts, each of which span over the pixels that are required in interpolating each final magnetic field map in the time series described above. For each time the cutouts include a bitmap, where value 1 signifies a bad pixel, and a map of the Line-Of-Sight (LOS) component of the magnetic field in the same grid. Four time series of horizontal electric field maps (i.e. electrograms) and one time series of maps of the horizontal components of the magnetic vector potential were created. The following three series were created using the ELECTRICIT toolkit: ELECTRICIT_electrograms_AR11158_div_E0_and_vector_potential.zip, ELECTRICIT_electrograms_AR11158_div_E_omega_21_256.zip, ELECTRICIT_electrograms_AR11158_div_E_U_42.zip, where the titles refer to the use of the respective assumption for the non-inductive component - and thus also on the divergence - of the electric field (see the publication for details). The electric field components (Ex, Ey) are given in the same local Cartesian coordinate system as the magnetic field components described above. The first time series contains also the horizontal components of the vector potential (Ax, Ay) consistent with the Bz component of each magnetogram. Both the electric field and the vector potential are given in a staggered grid (Yee mesh, Yee, 1966) with respect to the magnetogram grid. Moreover, the electric field inversion is done in a way that crops one pixel from each side of the input magnetogram grid. Thus Ex (and Ax) component is given in 742 x 609 grid and Ey (and Ay) component in 743 x 608 grid. The time series spans from 2011 Feb 10 13:12 TAI to 2011 Feb 18 00:48 TAI. The fourth electric field time series, DAVE4VM_electrograms_AR11158.zip, was created using DAVE4VM velocity inversion code from which output the electric field was calculated using the ideal Ohm's law. The horizontal components of the electric field (Ex,Ey) are given in the same coordinate system and grid as the magnetic field series above. The time series spans from 2011 Feb 10 12:00 TAI to 2011 Feb 18 03:00 TAI. October 22, 2017 Erkka Lumme Space Physics Research Team University of Helsinki References: Lumme, E., Pomoell, J., and Kilpua. E. K. J., Optimization of photospheric electric field estimates for accurate retrieval of total magnetic energy injection. Solar Physics. 2017, submitted. Yee, K. Numerical solution of initial boundary value problems involving Maxwell's equations in isotropic media. IEEE Transactions on antennas and propagation. 1966.

Published
2017
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15. Dam sinking at Lyndhurst, New South Wales

Author

Lumme, E. A. (Evan Antoni Johann), 1865-1935. and Lumme, E. A. (Evan Antoni Johann), 1865-1935.

Abstract

Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an8526486-3473.

16. Mandurama photograph collection [914]

Author

Lumme, E. A. (Evan Antoni Johann), 1865-1935. and Lumme, E. A. (Evan Antoni Johann), 1865-1935.

Abstract

Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an8526486-914.

17. Mandurama photograph collection [3257]

Author

Lumme, E. A. (Evan Antoni Johann), 1865-1935. and Lumme, E. A. (Evan Antoni Johann), 1865-1935.

Abstract

Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an8526486-3257.

18. Time-dependent Data-driven Modeling of Active Region Evolution Using Energy-optimized Photospheric Electric Fields.

Author

Pomoell J, Lumme E, and Kilpua E

Abstract

In this work, we present results of a time-dependent data-driven numerical simulation developed to study the dynamics of coronal active region magnetic fields. The evolving boundary condition driving the model, the photospheric electric field, is inverted using a time sequence of vector magnetograms as input. We invert three distinct electric field datasets for a single active region. All three electric fields reproduce the observed evolution of the normal component of the magnetic field. Two of the datasets are constructed so as to match the energy input into the corona to that provided by a reference estimate. Using the three inversions as input to a time-dependent magnetofrictional model, we study the response of the coronal magnetic field to the driving electric fields. The simulations reveal the magnetic field evolution to be sensitive to the input electric field despite the normal component of the magnetic field evolving identically and the total energy injection being largely similar. Thus, we demonstrate that the total energy injection is not sufficient to characterize the evolution of the coronal magnetic field: coronal evolution can be very different despite similar energy injections. We find the relative helicity to be an important additional metric that allows one to distinguish the simulations. In particular, the simulation with the highest relative helicity content produces a coronal flux rope that subsequently erupts, largely in agreement with extreme-ultraviolet imaging observations of the corresponding event. Our results suggest that time-dependent data-driven simulations that employ carefully constructed driving boundary conditions offer a valuable tool for modeling and characterizing the evolution of coronal magnetic fields., Electronic Supplementary Material: The online version of this article (10.1007/s11207-019-1430-x) contains supplementary material, which is available to authorized users., Competing Interests: The authors declare that they have no conflicts of interest.

Published
2019
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