Articles | Volume 35, issue 6
https://doi.org/10.5194/angeo-35-1341-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/angeo-35-1341-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Relative outflow enhancements during major geomagnetic storms – Cluster observations
Audrey Schillings
CORRESPONDING AUTHOR
Swedish Institute of Space Physics, Kiruna, Sweden
Division of Space Technology, Luleå University of Technology, Kiruna, Sweden
Hans Nilsson
Swedish Institute of Space Physics, Kiruna, Sweden
Division of Space Technology, Luleå University of Technology, Kiruna, Sweden
Rikard Slapak
Division of Space Technology, Luleå University of Technology, Kiruna, Sweden
Masatoshi Yamauchi
Swedish Institute of Space Physics, Kiruna, Sweden
Lars-Göran Westerberg
Division of Fluid and Experimental Mechanics, Luleå University of Technology, Luleå, Sweden
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The Earth's atmosphere is constantly losing molecules and charged particles, amongst them oxygen ions or O+. Quantifying this loss provides information about the evolution of the atmosphere on geological timescales. In this study, we investigate the final destination of O+ observed with Cluster satellites in a high-altitude magnetospheric region (plasma mantle) by tracing the particles forward in time using simulations. We find that approximately 98 % of O+ escapes the Earth's magnetosphere.
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The Earth's atmosphere is constantly losing molecules and charged particles, amongst them oxygen ions or O+. Quantifying this loss provides information about the evolution of the atmosphere on geological timescales. In this study, we investigate the final destination of O+ observed with Cluster satellites in a high-altitude magnetospheric region (plasma mantle) by tracing the particles forward in time using simulations. We find that approximately 98 % of O+ escapes the Earth's magnetosphere.
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Terrestrial ion transport and total escape are synthesized, with stress on the high-latitude polar region and the inner magnetosphere where Custer significantly improved knowledge. After estimating the outflow flux and destinations, complicated ion dynamics in the inner magnetosphere was classified and summarized, through which more than half the O+ is finally lost to space. Together with direct escapes, total O+ escape is high enough to influence the evolution of the biosphere.
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Extraction of the solar wind kinetic energy (∆K) by mass loading of escaping O+ is modelled in the exterior cusp and plasma mantle of the Earth. We found ∆K proportional to mass flux of escaping ions and square of solar wind velocity, but independent to the other parameters. The amount is sufficient to power the cusp field-aligned currents, further enhancing ion escape through Joule heating of the ionospheric ions, completing positive feedback to enhance escape with geomagnetic activities.
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Ann. Geophys., 35, 869–877, https://doi.org/10.5194/angeo-35-869-2017, https://doi.org/10.5194/angeo-35-869-2017, 2017
Short summary
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The ion total transports in the near-Earth plasma sheet have been investigated and quantified. Specifically, the net O+ transport is about 1024 s−1 in the earthward direction, which is 1 order of magnitude smaller than the typical O+ ionospheric outflows, strongly indicating that most outflow will eventually escape, leading to significant atmospheric loss. The study also shows that low-velocity flows (< 100 km s−1) dominate the mass transport in the near-Earth plasma sheet.
Rikard Slapak, Audrey Schillings, Hans Nilsson, Masatoshi Yamauchi, Lars-Göran Westerberg, and Iannis Dandouras
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Short summary
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In this study, we have used Cluster satellite data to quantify the ionospheric oxygen ion (O+) escape into the solar wind and its dependence on geomagnetic activity. During times of high activity, the escape may be 2 orders of magnitude higher than under quiet conditions, strongly suggesting that the escape rate was much higher when the Sun was young. The results are important for future studies regarding atmospheric loss over geological timescales.
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The solar wind magnetic field drapes around the active nucleus of comet 67P/CG, creating a magnetosphere. The solar wind density increases and with that the pressure, which compresses the magnetosphere, increasing the magnetic field strength near Rosetta. The higher solar wind density also creates more ionization through collisions with the gas from the comet. The new ions are picked-up by the magnetic field and generate mirror-mode waves, creating low-field high-density "bottles" near 67P/CG.
I. Richter, C. Koenders, H.-U. Auster, D. Frühauff, C. Götz, P. Heinisch, C. Perschke, U. Motschmann, B. Stoll, K. Altwegg, J. Burch, C. Carr, E. Cupido, A. Eriksson, P. Henri, R. Goldstein, J.-P. Lebreton, P. Mokashi, Z. Nemeth, H. Nilsson, M. Rubin, K. Szegö, B. T. Tsurutani, C. Vallat, M. Volwerk, and K.-H. Glassmeier
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R. Slapak, H. Nilsson, L. G. Westerberg, and R. Larsson
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T. Pitkänen, M. Hamrin, P. Norqvist, T. Karlsson, H. Nilsson, A. Kullen, S. M. Imber, and S. E. Milan
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An azimuthal velocity shear with a reversal within an earthward magnetotail fast flow is studied using Cluster observations. In addition, ionospheric SuperDARN data and different magnetospheric models (T96 and TF04) are utilized when interpreting the Cluster observations. Untwisting of twisted tail B field lines is a good candidate to explain the observations.
I. A. Barghouthi, H. Nilsson, and S. H. Ghithan
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K. Axelsson, T. Sergienko, H. Nilsson, U. Brändström, K. Asamura, and T. Sakanoi
Ann. Geophys., 32, 499–506, https://doi.org/10.5194/angeo-32-499-2014, https://doi.org/10.5194/angeo-32-499-2014, 2014
M. Yamauchi, Y. Ebihara, H. Nilsson, and I. Dandouras
Ann. Geophys., 32, 83–90, https://doi.org/10.5194/angeo-32-83-2014, https://doi.org/10.5194/angeo-32-83-2014, 2014
M. Yamauchi, I. Dandouras, H. Rème, R. Lundin, and L. M. Kistler
Ann. Geophys., 31, 1569–1578, https://doi.org/10.5194/angeo-31-1569-2013, https://doi.org/10.5194/angeo-31-1569-2013, 2013
R. Slapak, H. Nilsson, and L. G. Westerberg
Ann. Geophys., 31, 1005–1010, https://doi.org/10.5194/angeo-31-1005-2013, https://doi.org/10.5194/angeo-31-1005-2013, 2013
S. Kirkwood, E. Belova, P. Dalin, M. Mihalikova, D. Mikhaylova, D. Murtagh, H. Nilsson, K. Satheesan, J. Urban, and I. Wolf
Ann. Geophys., 31, 333–347, https://doi.org/10.5194/angeo-31-333-2013, https://doi.org/10.5194/angeo-31-333-2013, 2013
K. Axelsson, T. Sergienko, H. Nilsson, U. Brändström, Y. Ebihara, K. Asamura, and M. Hirahara
Ann. Geophys., 30, 1693–1701, https://doi.org/10.5194/angeo-30-1693-2012, https://doi.org/10.5194/angeo-30-1693-2012, 2012
Short summary
The Earth's atmosphere is constantly losing ions and in particular oxygen ions. This phenomenon is important to understand the atmospheric evolution on a large timescale. In this study, the O+ outflow is estimated during six extreme geomagnetic storms using the European Cluster mission data. These estimations are compared with average magnetospheric conditions and show that during those six extreme storms, the O+ outflow is approximately 2 orders of magnitude higher.
The Earth's atmosphere is constantly losing ions and in particular oxygen ions. This phenomenon...