Articles | Volume 32, issue 6
https://doi.org/10.5194/angeo-32-609-2014
© Author(s) 2014. 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-32-609-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Regular paper
| 
04 Jun 2014
Regular paper |
| 04 Jun 2014
Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1
Department of Space Physics, College of Electronic Information, Wuhan University, 430079 Wuhan, China
Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
Department of Space Physics, College of Electronic Information, Wuhan University, 430079 Wuhan, China
M. G. Johnsen
Tromsø Geophysical Observatory, Faculty of Science and Technology, University of Tromsø, Tromsø, Norway
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The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE are investigated. The absolute amplitudes of DE3 at low latitudes as well as DE1, D0 and DW2 at middle latitudes are highly related to the solar activity, while their relative amplitudes show little dependence on the solar activity. A clear modulation by the QBO is found in the relative amplitudes of DE3 at low latitudes.
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The complete time series of the geomagnetic disturbance index (K) from Norwegian magnetic observatories have been digitized. We compare and discuss the tree methods used to derive the index, finding that each method both have strengths and weaknesses. In total, we present all K-indices derived from Norwegian observatories since the 1930s until today, the used derivation methods and the long, historic time-series as a whole, enabling a critical use for future scientific work.
Chengkun Gan, Jiayu Hu, Xiaomin Luo, Chao Xiong, and Shengfeng Gu
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During magnetic storms the magnetic disturbance at low latitudes becomes asymmetric, enhanced in the evening sector and reduced around morning. This has been attributed to the asymmetric ring current. Here a new 3D current system is proposed for explaining the asymmetric signal. Anti-sunward net currents at high latitude are connected at their noon and night ends to field-aligned currents that lead the currents to the magnetopause on the dawn and dusk flanks where the current closure occurs.
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This paper presents a statistical study of the equatorward boundary of small-scale field-aligned currents (SSFACs) as observed by ESA's Swarm satellites and investigates the relation between this boundary and NASA’s Van Allen probe observed plasmapause (PP). It is found that the two boundaries are closely coincident in the midnight LT sector, where the new PP is formed. Our results point to the role of SSFACs in the creation of the PP and offer a unique tool to monitor PP dynamics.
Hui Wang, Kedeng Zhang, Zhichao Zheng, and Aaron James Ridley
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For subauroral polarization streams (SAPS) commencing at different universal
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Tao Huang, Hermann Lühr, and Hui Wang
Ann. Geophys., 35, 1249–1268, https://doi.org/10.5194/angeo-35-1249-2017, https://doi.org/10.5194/angeo-35-1249-2017, 2017
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This is the first study considering ionospheric currents (both field-aligned current and Hall current) derived from high-resolution magnetic field data of the Swarm constellation in both hemispheres. The prominent auroral electrojets are found to be closely controlled by the solar wind input, but we find no dependence of their intensity on the IMF By orientation. An important finding is that all the IMF By dependences of FACs and Hall currents practically disappear in the dark winter hemisphere.
Nadezda Yagova, Natalia Nosikova, Lisa Baddeley, Olga Kozyreva, Dag A. Lorentzen, Vyacheslav Pilipenko, and Magnar G. Johnsen
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A substorm is a dramatic phenomenon in the near-Earth space that is visualized as an aurora. Mostly substorms are caused by changes in the solar wind, but some of them can develop without any evident trigger. Such substorms together with undisturbed days were investigated using magnetometer and photometer data from Svalbard. Substorm precursors, i.e., specific features in 1–4 mHz geomagnetic and auroral luminosity pulsations, have been found at high geomagnetic latitudes.
Hermann Lühr, Tao Huang, Simon Wing, Guram Kervalishvili, Jan Rauberg, and Haje Korth
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ESA's constellation mission Swarm makes it possible for the first time to determine field-aligned currents (FACs) reliably in the ionosphere. FACs are able to transport energy from the solar wind to the Earth and heat the upper atmosphere. Here we investigate FAC structures that have been missed by previous satellite missions. Most of them are found poleward of the northern light zone. The energy sources seem to be located on the nightside of Earth about 100 000 km away.
Yun-Liang Zhou, Li Wang, Chao Xiong, Hermann Lühr, and Shu-Ying Ma
Ann. Geophys., 34, 463–472, https://doi.org/10.5194/angeo-34-463-2016, https://doi.org/10.5194/angeo-34-463-2016, 2016
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The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE are investigated. The absolute amplitudes of DE3 at low latitudes as well as DE1, D0 and DW2 at middle latitudes are highly related to the solar activity, while their relative amplitudes show little dependence on the solar activity. A clear modulation by the QBO is found in the relative amplitudes of DE3 at low latitudes.
J. Park, H. Lühr, C. Stolle, G. Malhotra, J. B. H. Baker, S. Buchert, and R. Gill
Ann. Geophys., 33, 829–835, https://doi.org/10.5194/angeo-33-829-2015, https://doi.org/10.5194/angeo-33-829-2015, 2015
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Though high-latitude plasma convection has been monitored with a number of methods, more independent measurements are still warranted. In this study we introduce an automatic method to estimate along-track plasma drift velocity in the high-latitude ionosphere using the Swarm constellation. The obtained velocity is in qualitative agreement with Super Dual Auroral Radar Network (SuperDARN) data. The method can be generalized to any satellite constellations in pearls-on-a-string configurations.
T. Huang, H. Wang, J.-H. Shue, L. Cai, and G. Pi
Ann. Geophys., 33, 437–448, https://doi.org/10.5194/angeo-33-437-2015, https://doi.org/10.5194/angeo-33-437-2015, 2015
T. A. Siddiqui, H. Lühr, C. Stolle, and J. Park
Ann. Geophys., 33, 235–243, https://doi.org/10.5194/angeo-33-235-2015, https://doi.org/10.5194/angeo-33-235-2015, 2015
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This paper presents the long-term observations of lunar tidal signatures in the equatorial electrojet (EEJ) and their relation to stratospheric sudden warming (SSW) events. We propose an approach to estimate the occurrence of SSW events before their direct observations (before 1952) from the magnetic field observations at Huancayo.
C. Xiong, Y.-L. Zhou, H. Lühr, and S.-Y. Ma
Ann. Geophys., 33, 185–196, https://doi.org/10.5194/angeo-33-185-2015, https://doi.org/10.5194/angeo-33-185-2015, 2015
J. Park, H. Lühr, and M. Noja
Ann. Geophys., 33, 129–135, https://doi.org/10.5194/angeo-33-129-2015, https://doi.org/10.5194/angeo-33-129-2015, 2015
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Total electron content (TEC) between low-Earth-orbit (LEO) satellites and the Global Navigation Satellite System (GNSS) satellites can be used to constrain three-dimensional morphology of equatorial plasma bubbles (EPBs). TEC gradient observed along the LEO track is strongest when the corresponding GNSS satellite is located equatorward and westward of the LEO satellite. This anisotropy supports the idea that EPBs have three-dimensional shell structures.
K. Schlegel and H. Lühr
Hist. Geo Space. Sci., 5, 149–154, https://doi.org/10.5194/hgss-5-149-2014, https://doi.org/10.5194/hgss-5-149-2014, 2014
C. Xiong and H. Lühr
Ann. Geophys., 32, 623–631, https://doi.org/10.5194/angeo-32-623-2014, https://doi.org/10.5194/angeo-32-623-2014, 2014
H. Wang, H. Lühr, A. Ridley, and T. Huang
Ann. Geophys., 32, 533–542, https://doi.org/10.5194/angeo-32-533-2014, https://doi.org/10.5194/angeo-32-533-2014, 2014
G. N. Kervalishvili and H. Lühr
Ann. Geophys., 32, 249–261, https://doi.org/10.5194/angeo-32-249-2014, https://doi.org/10.5194/angeo-32-249-2014, 2014
H. Wang and H. Lühr
Ann. Geophys., 31, 1521–1534, https://doi.org/10.5194/angeo-31-1521-2013, https://doi.org/10.5194/angeo-31-1521-2013, 2013
J. Park, H. Lühr, and J. Rauberg
Ann. Geophys., 31, 1507–1520, https://doi.org/10.5194/angeo-31-1507-2013, https://doi.org/10.5194/angeo-31-1507-2013, 2013
H. Lühr and C. Manoj
Ann. Geophys., 31, 1315–1331, https://doi.org/10.5194/angeo-31-1315-2013, https://doi.org/10.5194/angeo-31-1315-2013, 2013
C. Xiong and H. Lühr
Ann. Geophys., 31, 1115–1130, https://doi.org/10.5194/angeo-31-1115-2013, https://doi.org/10.5194/angeo-31-1115-2013, 2013
J. Park and H. Lühr
Ann. Geophys., 31, 1035–1044, https://doi.org/10.5194/angeo-31-1035-2013, https://doi.org/10.5194/angeo-31-1035-2013, 2013
G. N. Kervalishvili and H. Lühr
Ann. Geophys., 31, 541–554, https://doi.org/10.5194/angeo-31-541-2013, https://doi.org/10.5194/angeo-31-541-2013, 2013
B. Heilig and H. Lühr
Ann. Geophys., 31, 529–539, https://doi.org/10.5194/angeo-31-529-2013, https://doi.org/10.5194/angeo-31-529-2013, 2013
H. Lühr, F. Yin, and R. Bock
J. Sens. Sens. Syst., 2, 9–17, https://doi.org/10.5194/jsss-2-9-2013, https://doi.org/10.5194/jsss-2-9-2013, 2013
Y. L. Zhou, S. Y. Ma, R. S. Liu, H. Luehr, and E. Doornbos
Ann. Geophys., 31, 15–30, https://doi.org/10.5194/angeo-31-15-2013, https://doi.org/10.5194/angeo-31-15-2013, 2013
