Articles | Volume 21, issue 5
https://doi.org/10.5194/npg-21-1051-2014
© 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/npg-21-1051-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Complexity signatures in the geomagnetic H component recorded by the Tromsø magnetometer (70° N, 19° E) over the last quarter of a century
C. M. Hall
Tromsø Geophysical Observatory, University of Tromsø, Tromsø, Norway
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Gunter Stober, Alexander Kozlovsky, Alan Liu, Zishun Qiao, Masaki Tsutsumi, Chris Hall, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Patrick J. Espy, Robert E. Hibbins, and Nicholas Mitchell
Atmos. Meas. Tech., 14, 6509–6532, https://doi.org/10.5194/amt-14-6509-2021, https://doi.org/10.5194/amt-14-6509-2021, 2021
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Wind observations at the edge to space, 70–110 km altitude, are challenging. Meteor radars have become a widely used instrument to obtain mean wind profiles above an instrument for these heights. We describe an advanced mathematical concept and present a tomographic analysis using several meteor radars located in Finland, Sweden and Norway, as well as Chile, to derive the three-dimensional flow field. We show an example of a gravity wave decelerating the mean flow.
Joel P. Younger, Iain M. Reid, Chris L. Adami, Chris M. Hall, and Masaki Tsutsumi
Atmos. Meas. Tech., 14, 5015–5027, https://doi.org/10.5194/amt-14-5015-2021, https://doi.org/10.5194/amt-14-5015-2021, 2021
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A radar in Svalbard usually used to study meteor trails was used to observe a thin icy layer in the upper atmosphere. New methods used the layer to measure wind speed over short periods of time and found that the layer is most reflective within 6.8 ± 3.3° of vertical. Analysis of meteor trail radar echo durations found that the layer may shorten meteor trail echoes, but more data are needed. This study shows new uses for data collected by meteor radars for other purposes.
Wen Yi, Xianghui Xue, Iain M. Reid, Damian J. Murphy, Chris M. Hall, Masaki Tsutsumi, Baiqi Ning, Guozhu Li, Robert A. Vincent, Jinsong Chen, Jianfei Wu, Tingdi Chen, and Xiankang Dou
Atmos. Chem. Phys., 19, 7567–7581, https://doi.org/10.5194/acp-19-7567-2019, https://doi.org/10.5194/acp-19-7567-2019, 2019
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The seasonal variations in the mesopause densities, especially with regard to its global structure, are still unclear. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars from Arctic to Antarctic latitudes. The results reveal a significant AO and SAO in mesopause density, an asymmetry between the two polar regions and evidence of intraseasonal oscillations (ISOs), perhaps associated with the ISOs of the troposphere.
Chris M. Hall
Nonlin. Processes Geophys., 23, 215–222, https://doi.org/10.5194/npg-23-215-2016, https://doi.org/10.5194/npg-23-215-2016, 2016
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The relative ionospheric opacity meter ("riometer") is a traditional instrument for measuring the degree to which cosmic noise is absorbed by the ionosphere and therefore how energetic the particles – electrons, protons etc. – are that cause the ionisation. We identify the same signatures in the "hour-to-days" timescale variability as reported in solar and geomagnetic disturbances. The result demonstrates the relationship between riometer data and the underlying physics for different timescales.
Silje Eriksen Holmen, Chris M. Hall, and Masaki Tsutsumi
Atmos. Chem. Phys., 16, 7853–7866, https://doi.org/10.5194/acp-16-7853-2016, https://doi.org/10.5194/acp-16-7853-2016, 2016
Short summary
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Atmospheric temperatures at 90 km height above Tromsø, Norway, from 2003 to 2014 have been determined using meteor radar. Periodic oscillations ranging from ~ 9 days to a year were found in the dataset, which were related to the large-scale circulation in the middle atmosphere and with wave activity. A trend analysis was performed, revealing an overall weak cooling trend from 2003 to 2014, which is in line with other recent studies on mesopause region (~ 90 km) temperature trends.
Chris M. Hall, Silje E. Holmen, Chris E. Meek, Alan H. Manson, and Satonori Nozawa
Atmos. Chem. Phys., 16, 2299–2308, https://doi.org/10.5194/acp-16-2299-2016, https://doi.org/10.5194/acp-16-2299-2016, 2016
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Turbulent energy dissipation rates are calculated using MF-radar signals from 70 and 52° N for the period 2001–2014 inclusive, and they are used to estimate turbopause altitudes. A positive trend in turbopause altitude is identified for 70° N in summer, but not in winter and not at 52° N. The turbopause altitude change between 2001 and 2014 can be used to hypothesize a corresponding change in atomic oxygen concentration.
T. Takahashi, S. Nozawa, T. T. Tsuda, Y. Ogawa, N. Saito, T. Hidemori, T. D. Kawahara, C. Hall, H. Fujiwara, N. Matuura, A. Brekke, M. Tsutsumi, S. Wada, T. Kawabata, S. Oyama, and R. Fujii
Ann. Geophys., 33, 941–953, https://doi.org/10.5194/angeo-33-941-2015, https://doi.org/10.5194/angeo-33-941-2015, 2015
T. Takahashi, S. Nozawa, M. Tsutsumi, C. Hall, S. Suzuki, T. T. Tsuda, T. D. Kawahara, N. Saito, S. Oyama, S. Wada, T. Kawabata, H. Fujiwara, A. Brekke, A. Manson, C. Meek, and R. Fujii
Ann. Geophys., 32, 1195–1205, https://doi.org/10.5194/angeo-32-1195-2014, https://doi.org/10.5194/angeo-32-1195-2014, 2014
Gunter Stober, Alexander Kozlovsky, Alan Liu, Zishun Qiao, Masaki Tsutsumi, Chris Hall, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Patrick J. Espy, Robert E. Hibbins, and Nicholas Mitchell
Atmos. Meas. Tech., 14, 6509–6532, https://doi.org/10.5194/amt-14-6509-2021, https://doi.org/10.5194/amt-14-6509-2021, 2021
Short summary
Short summary
Wind observations at the edge to space, 70–110 km altitude, are challenging. Meteor radars have become a widely used instrument to obtain mean wind profiles above an instrument for these heights. We describe an advanced mathematical concept and present a tomographic analysis using several meteor radars located in Finland, Sweden and Norway, as well as Chile, to derive the three-dimensional flow field. We show an example of a gravity wave decelerating the mean flow.
Joel P. Younger, Iain M. Reid, Chris L. Adami, Chris M. Hall, and Masaki Tsutsumi
Atmos. Meas. Tech., 14, 5015–5027, https://doi.org/10.5194/amt-14-5015-2021, https://doi.org/10.5194/amt-14-5015-2021, 2021
Short summary
Short summary
A radar in Svalbard usually used to study meteor trails was used to observe a thin icy layer in the upper atmosphere. New methods used the layer to measure wind speed over short periods of time and found that the layer is most reflective within 6.8 ± 3.3° of vertical. Analysis of meteor trail radar echo durations found that the layer may shorten meteor trail echoes, but more data are needed. This study shows new uses for data collected by meteor radars for other purposes.
Wen Yi, Xianghui Xue, Iain M. Reid, Damian J. Murphy, Chris M. Hall, Masaki Tsutsumi, Baiqi Ning, Guozhu Li, Robert A. Vincent, Jinsong Chen, Jianfei Wu, Tingdi Chen, and Xiankang Dou
Atmos. Chem. Phys., 19, 7567–7581, https://doi.org/10.5194/acp-19-7567-2019, https://doi.org/10.5194/acp-19-7567-2019, 2019
Short summary
Short summary
The seasonal variations in the mesopause densities, especially with regard to its global structure, are still unclear. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars from Arctic to Antarctic latitudes. The results reveal a significant AO and SAO in mesopause density, an asymmetry between the two polar regions and evidence of intraseasonal oscillations (ISOs), perhaps associated with the ISOs of the troposphere.
Chris M. Hall
Nonlin. Processes Geophys., 23, 215–222, https://doi.org/10.5194/npg-23-215-2016, https://doi.org/10.5194/npg-23-215-2016, 2016
Short summary
Short summary
The relative ionospheric opacity meter ("riometer") is a traditional instrument for measuring the degree to which cosmic noise is absorbed by the ionosphere and therefore how energetic the particles – electrons, protons etc. – are that cause the ionisation. We identify the same signatures in the "hour-to-days" timescale variability as reported in solar and geomagnetic disturbances. The result demonstrates the relationship between riometer data and the underlying physics for different timescales.
Silje Eriksen Holmen, Chris M. Hall, and Masaki Tsutsumi
Atmos. Chem. Phys., 16, 7853–7866, https://doi.org/10.5194/acp-16-7853-2016, https://doi.org/10.5194/acp-16-7853-2016, 2016
Short summary
Short summary
Atmospheric temperatures at 90 km height above Tromsø, Norway, from 2003 to 2014 have been determined using meteor radar. Periodic oscillations ranging from ~ 9 days to a year were found in the dataset, which were related to the large-scale circulation in the middle atmosphere and with wave activity. A trend analysis was performed, revealing an overall weak cooling trend from 2003 to 2014, which is in line with other recent studies on mesopause region (~ 90 km) temperature trends.
Chris M. Hall, Silje E. Holmen, Chris E. Meek, Alan H. Manson, and Satonori Nozawa
Atmos. Chem. Phys., 16, 2299–2308, https://doi.org/10.5194/acp-16-2299-2016, https://doi.org/10.5194/acp-16-2299-2016, 2016
Short summary
Short summary
Turbulent energy dissipation rates are calculated using MF-radar signals from 70 and 52° N for the period 2001–2014 inclusive, and they are used to estimate turbopause altitudes. A positive trend in turbopause altitude is identified for 70° N in summer, but not in winter and not at 52° N. The turbopause altitude change between 2001 and 2014 can be used to hypothesize a corresponding change in atomic oxygen concentration.
T. Takahashi, S. Nozawa, T. T. Tsuda, Y. Ogawa, N. Saito, T. Hidemori, T. D. Kawahara, C. Hall, H. Fujiwara, N. Matuura, A. Brekke, M. Tsutsumi, S. Wada, T. Kawabata, S. Oyama, and R. Fujii
Ann. Geophys., 33, 941–953, https://doi.org/10.5194/angeo-33-941-2015, https://doi.org/10.5194/angeo-33-941-2015, 2015
T. Takahashi, S. Nozawa, M. Tsutsumi, C. Hall, S. Suzuki, T. T. Tsuda, T. D. Kawahara, N. Saito, S. Oyama, S. Wada, T. Kawabata, H. Fujiwara, A. Brekke, A. Manson, C. Meek, and R. Fujii
Ann. Geophys., 32, 1195–1205, https://doi.org/10.5194/angeo-32-1195-2014, https://doi.org/10.5194/angeo-32-1195-2014, 2014
Related subject area
Subject: Time series, machine learning, networks, stochastic processes, extreme events | Topic: Ionosphere, magnetosphere, planetary science, solar science
Quantification of magnetosphere–ionosphere coupling timescales using mutual information: response of terrestrial radio emissions and ionospheric–magnetospheric currents
Nonlinear vortex solution for perturbations in the Earth's ionosphere
The physics of space weather/solar-terrestrial physics (STP): what we know now and what the current and future challenges are
Complex network description of the ionosphere
Evolution of fractality in space plasmas of interest to geomagnetic activity
Satellite drag effects due to uplifted oxygen neutrals during super magnetic storms
Characterization of high-intensity, long-duration continuous auroral activity (HILDCAA) events using recurrence quantification analysis
Spectral characteristics of high-latitude raw 40 MHz cosmic noise signals
Long-term changes in the north–south asymmetry of solar activity: a nonlinear dynamics characterization using visibility graphs
Nonlinear fluctuation analysis for a set of 41 magnetic clouds measured by the Advanced Composition Explorer (ACE) spacecraft
Can irregularities of solar proxies help understand quasi-biennial solar variations?
Alexandra Ruth Fogg, Caitríona M. Jackman, Sandra C. Chapman, James E. Waters, Aisling Bergin, Laurent Lamy, Karine Issautier, Baptiste Cecconi, and Xavier Bonnin
Nonlin. Processes Geophys., 31, 195–206, https://doi.org/10.5194/npg-31-195-2024, https://doi.org/10.5194/npg-31-195-2024, 2024
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Auroral kilometric radiation (AKR) is a radio emission emitted by Earth. Due to the complex mixture of phenomena in the magnetosphere, it is tricky to estimate the time difference between the excitation of two systems. In this study, AKR is compared with indices describing Earth's system. Time differences between the excitation of AKR and the indices are estimated using mutual information. AKR feels an enhancement before the aurora but after more polar latitude features.
Miroslava Vukcevic and Luka Č. Popović
Nonlin. Processes Geophys., 27, 295–306, https://doi.org/10.5194/npg-27-295-2020, https://doi.org/10.5194/npg-27-295-2020, 2020
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The soliton vortex two-dimensional solution has been derived for the ionosphere. Why are solitons so important? The advantage of an analytical soliton solution is its localization in space and time as a consequence of balance between nonlinearity and dispersion. One very good example of the balance between nonlinear and dispersive effects is tsunami, a surface gravity one-dimensional wave that can propagate with constant velocity and constant amplitude when it is assured by a parameter regime.
Bruce T. Tsurutani, Gurbax S. Lakhina, and Rajkumar Hajra
Nonlin. Processes Geophys., 27, 75–119, https://doi.org/10.5194/npg-27-75-2020, https://doi.org/10.5194/npg-27-75-2020, 2020
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Current space weather problems are discussed for young researchers. We have discussed some of the major problems that need to be solved for space weather forecasting to become a reality.
Shikun Lu, Hao Zhang, Xihai Li, Yihong Li, Chao Niu, Xiaoyun Yang, and Daizhi Liu
Nonlin. Processes Geophys., 25, 233–240, https://doi.org/10.5194/npg-25-233-2018, https://doi.org/10.5194/npg-25-233-2018, 2018
Víctor Muñoz, Macarena Domínguez, Juan Alejandro Valdivia, Simon Good, Giuseppina Nigro, and Vincenzo Carbone
Nonlin. Processes Geophys., 25, 207–216, https://doi.org/10.5194/npg-25-207-2018, https://doi.org/10.5194/npg-25-207-2018, 2018
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Fractals are self-similar objects (which look the same at all scales), whose dimensions can be noninteger. They are mathematical concepts, useful to describe various physical systems, as the fractal dimension is a measure of their complexity. In this paper we study how these concepts can be applied to some problems in space plasmas, such as the activity of the Earth's magnetosphere, simulations of plasma turbulence, or identification of magnetic structures ejected from the Sun.
Gurbax S. Lakhina and Bruce T. Tsurutani
Nonlin. Processes Geophys., 24, 745–750, https://doi.org/10.5194/npg-24-745-2017, https://doi.org/10.5194/npg-24-745-2017, 2017
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A preliminary estimate of the drag force per unit mass on typical low-Earth-orbiting satellites moving through the ionosphere during Carrington-type super magnetic storms is calculated by a simple first-order model which takes into account the ion-neutral drag between the upward-moving oxygen ions and O neutral atoms. It is shown that oxygen ions and atoms can be uplifted to 850 km altitude, where they produce about 40 times more satellite drag per unit mass than normal.
Odim Mendes, Margarete Oliveira Domingues, Ezequiel Echer, Rajkumar Hajra, and Varlei Everton Menconi
Nonlin. Processes Geophys., 24, 407–417, https://doi.org/10.5194/npg-24-407-2017, https://doi.org/10.5194/npg-24-407-2017, 2017
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The effects of the Sun upon the Earth's atmosphere occur in several ways. Significant electrodynamic coupling processes transfer particles and energy from the solar wind into the Earth's environment. Applied to the dynamical characteristics of high-intensity, long-duration, continuous auroral activity (HILDCAA) and non-HILDCAA events, nonlinear analysis tools like RQA aid to unravel peculiarities related to two concurrent space mechanisms known as magnetic reconnection and viscous interaction.
Chris M. Hall
Nonlin. Processes Geophys., 23, 215–222, https://doi.org/10.5194/npg-23-215-2016, https://doi.org/10.5194/npg-23-215-2016, 2016
Short summary
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The relative ionospheric opacity meter ("riometer") is a traditional instrument for measuring the degree to which cosmic noise is absorbed by the ionosphere and therefore how energetic the particles – electrons, protons etc. – are that cause the ionisation. We identify the same signatures in the "hour-to-days" timescale variability as reported in solar and geomagnetic disturbances. The result demonstrates the relationship between riometer data and the underlying physics for different timescales.
Y. Zou, R. V. Donner, N. Marwan, M. Small, and J. Kurths
Nonlin. Processes Geophys., 21, 1113–1126, https://doi.org/10.5194/npg-21-1113-2014, https://doi.org/10.5194/npg-21-1113-2014, 2014
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We use visibility graphs to characterize asymmetries in the dynamics of sunspot areas in both solar hemispheres. Our analysis provides deep insights into the potential and limitations of this method, revealing a complex interplay between effects due to statistical versus dynamical properties of the observed data. Temporal changes in the hemispheric predominance of the graph connectivity are found to lag those directly associated with the total hemispheric sunspot areas themselves.
A. Ojeda González, W. D. Gonzalez, O. Mendes, M. O. Domingues, and R. R. Rosa
Nonlin. Processes Geophys., 21, 1059–1073, https://doi.org/10.5194/npg-21-1059-2014, https://doi.org/10.5194/npg-21-1059-2014, 2014
A. Shapoval, J. L. Le Mouël, M. Shnirman, and V. Courtillot
Nonlin. Processes Geophys., 21, 797–813, https://doi.org/10.5194/npg-21-797-2014, https://doi.org/10.5194/npg-21-797-2014, 2014
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