Articles | Volume 43, issue 1
https://doi.org/10.5194/angeo-43-331-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-43-331-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
27 Jun 2025
Regular paper |
| 27 Jun 2025
| 27 Jun 2025
Indications for particle precipitation impact on the ion-neutral collision frequency analyzed with EISCAT measurements
Florian Günzkofer
CORRESPONDING AUTHOR
Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), Neustrelitz, Germany
Gunter Stober
Institute of Applied Physics, Microwave Physics, University of Bern, Bern, Switzerland
Oeschger Center for Climate Change Research, Microwave Physics, University of Bern, Bern, Switzerland
Johan Kero
Swedish Institute of Space Physics (IRF), Kiruna, Sweden
David R. Themens
Space Environment and Radio Engineering Group (SERENE), School of Engineering, University of Birmingham, B15 2TT Birmingham, UK
Department of Physics, University of New Brunswick, 8 Bailey Drive, PO Box 4440, Fredericton, NB E3B 5A3, Canada
Anders Tjulin
EISCAT AB, Kiruna, Sweden
Njål Gulbrandsen
Tromsø Geophysical Observatory, UiT – The Arctic University of Norway, Tromsø, Norway
Masaki Tsutsumi
National Institute of Polar Research, Tachikawa, Japan
The Graduate University for Advanced Studies (SOKENDAI), Tokyo, Japan
Claudia Borries
Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), Neustrelitz, Germany
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Atmos. Meas. Tech., 16, 5897–5907, https://doi.org/10.5194/amt-16-5897-2023, https://doi.org/10.5194/amt-16-5897-2023, 2023
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Electric currents in the ionosphere can impact both satellite and ground-based infrastructure. These currents depend strongly on the collisions of ions and neutral particles. Measuring ion–neutral collisions is often only possible via certain assumptions. The direct measurement of ion–neutral collision frequencies is possible with multifrequency incoherent scatter radar measurements. This paper presents one analysis method of such measurements and discusses its advantages and disadvantages.
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Gravity waves (GWs) are waves in Earth's atmosphere and can be observed as cloud ripples. Under certain conditions, these waves can propagate up into the ionosphere. Here, they can cause ripples in the ionosphere plasma, observable as oscillations of the plasma density. Therefore, GWs contribute to the ionospheric variability, making them relevant for space weather prediction. Additionally, the behavior of these waves allows us to draw conclusions about the atmosphere at these altitudes.
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EGUsphere, https://doi.org/10.5194/egusphere-2025-1996, https://doi.org/10.5194/egusphere-2025-1996, 2025
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Analysis of 10 years of continuous measurements provided MMARIA/SIMONe Norway and MMARIA/SIMONe Germany reveals that the divergent and vortical motions in the mesosphere and lower thermosphere exchange the dominant role depending on the height and the time of the year. At summer mesopause altitudes over middle latitudes, the horizontal divergence and the relative vorticity contribute approximately the same, indicating an energetic balance between mesoscale divergent and vortical motions.
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EGUsphere, https://doi.org/10.5194/egusphere-2025-1396, https://doi.org/10.5194/egusphere-2025-1396, 2025
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Increases in middle atmospheric water vapour from the 2022 Hunga eruption have been measured worldwide. This study uses remote sensing measurements at two latitudes and accurate radiative transfer modeling to show significant long-wave heating effects. Though minimal at the surface, the water vapour enhancement can alter middle-atmospheric dynamics, potentially affecting ozone chemistry and weather patterns.
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Atmos. Meas. Tech., 18, 1091–1104, https://doi.org/10.5194/amt-18-1091-2025, https://doi.org/10.5194/amt-18-1091-2025, 2025
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Atmos. Meas. Tech., 18, 555–567, https://doi.org/10.5194/amt-18-555-2025, https://doi.org/10.5194/amt-18-555-2025, 2025
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Hardware and software developments have been made on a 22 GHz microwave radiometer for the measurement of middle-atmospheric water vapour near Bern, Switzerland. Previous measurements dating back to 2010 have been re-calibrated and an improved optimal estimation retrieval performed on these measurements, giving a 13-year dataset. Measurements made with new and improved instrumental hardware are used to correct previous measurements, which show better agreement than the non-corrected dataset.
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On 15 January 2022, the Hunga Tonga-Hunga Ha‘apai volcano exploded in a vigorous eruption, causing many atmospheric phenomena reaching from the surface up to space. In this study, we investigate how the mesospheric winds were affected by the volcanogenic gravity waves and estimated their propagation direction and speed. The interplay between model and observations permits us to gain new insights into the vertical coupling through atmospheric gravity waves.
Peter Dalin, Urban Brändström, Johan Kero, Peter Voelger, Takanori Nishiyama, Trond Trondsen, Devin Wyatt, Craig Unick, Vladimir Perminov, Nikolay Pertsev, and Jonas Hedin
Atmos. Meas. Tech., 17, 1561–1576, https://doi.org/10.5194/amt-17-1561-2024, https://doi.org/10.5194/amt-17-1561-2024, 2024
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A novel infrared imaging instrument (OH imager) was put into operation in November 2022 at the Swedish Institute of Space Physics in Kiruna (Sweden). The OH imager is dedicated to the study of nightglow emissions coming from the hydroxyl (OH) and molecular oxygen (O2) layers in the mesopause (80–100 km). Based on a brightness ratio of two OH emission lines, the neutral temperature is estimated at around 87 km. The average daily winter temperature for the period January–April 2023 is 203±10 K.
Florian Günzkofer, Gunter Stober, Dimitry Pokhotelov, Yasunobu Miyoshi, and Claudia Borries
Atmos. Meas. Tech., 16, 5897–5907, https://doi.org/10.5194/amt-16-5897-2023, https://doi.org/10.5194/amt-16-5897-2023, 2023
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Electric currents in the ionosphere can impact both satellite and ground-based infrastructure. These currents depend strongly on the collisions of ions and neutral particles. Measuring ion–neutral collisions is often only possible via certain assumptions. The direct measurement of ion–neutral collision frequencies is possible with multifrequency incoherent scatter radar measurements. This paper presents one analysis method of such measurements and discusses its advantages and disadvantages.
Juliana Jaen, Toralf Renkwitz, Huixin Liu, Christoph Jacobi, Robin Wing, Aleš Kuchař, Masaki Tsutsumi, Njål Gulbrandsen, and Jorge L. Chau
Atmos. Chem. Phys., 23, 14871–14887, https://doi.org/10.5194/acp-23-14871-2023, https://doi.org/10.5194/acp-23-14871-2023, 2023
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Investigation of winds is important to understand atmospheric dynamics. In the summer mesosphere and lower thermosphere, there are three main wind flows: the mesospheric westward, the mesopause southward (equatorward), and the lower-thermospheric eastward wind. Combining almost 2 decades of measurements from different radars, we study the trend, their interannual oscillations, and the effects of the geomagnetic activity over these wind maxima.
Florian Günzkofer, Dimitry Pokhotelov, Gunter Stober, Ingrid Mann, Sharon L. Vadas, Erich Becker, Anders Tjulin, Alexander Kozlovsky, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Nicholas J. Mitchell, and Claudia Borries
Ann. Geophys., 41, 409–428, https://doi.org/10.5194/angeo-41-409-2023, https://doi.org/10.5194/angeo-41-409-2023, 2023
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Gravity waves (GWs) are waves in Earth's atmosphere and can be observed as cloud ripples. Under certain conditions, these waves can propagate up into the ionosphere. Here, they can cause ripples in the ionosphere plasma, observable as oscillations of the plasma density. Therefore, GWs contribute to the ionospheric variability, making them relevant for space weather prediction. Additionally, the behavior of these waves allows us to draw conclusions about the atmosphere at these altitudes.
Guochun Shi, Witali Krochin, Eric Sauvageat, and Gunter Stober
Atmos. Chem. Phys., 23, 9137–9159, https://doi.org/10.5194/acp-23-9137-2023, https://doi.org/10.5194/acp-23-9137-2023, 2023
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We present the interannual and climatological behavior of ozone and water vapor from microwave radiometers in the Arctic.
By defining a virtual conjugate latitude station in the Southern Hemisphere, we investigate altitude-dependent interhemispheric differences and estimate the ascent and descent rates of water vapor in both hemispheres. Ozone and water vapor measurements will create a deeper understanding of the evolution of middle atmospheric ozone and water vapor.
Gunter Stober, Alan Liu, Alexander Kozlovsky, Zishun Qiao, Witali Krochin, Guochun Shi, Johan Kero, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Kathrin Baumgarten, Evgenia Belova, and Nicholas Mitchell
Ann. Geophys., 41, 197–208, https://doi.org/10.5194/angeo-41-197-2023, https://doi.org/10.5194/angeo-41-197-2023, 2023
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The Hunga Tonga–Hunga Ha‘apai volcanic eruption was one of the most vigorous volcanic explosions in the last centuries. The eruption launched many atmospheric waves traveling around the Earth. In this study, we identify these volcanic waves at the edge of space in the mesosphere/lower-thermosphere, leveraging wind observations conducted with multi-static meteor radars in northern Europe and with the Chilean Observation Network De Meteor Radars (CONDOR).
Gunter Stober, Alan Liu, Alexander Kozlovsky, Zishun Qiao, Ales Kuchar, Christoph Jacobi, Chris Meek, Diego Janches, Guiping Liu, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, and Nicholas Mitchell
Atmos. Meas. Tech., 15, 5769–5792, https://doi.org/10.5194/amt-15-5769-2022, https://doi.org/10.5194/amt-15-5769-2022, 2022
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Precise and accurate measurements of vertical winds at the mesosphere and lower thermosphere are rare. Although meteor radars have been used for decades to observe horizontal winds, their ability to derive reliable vertical wind measurements was always questioned. In this article, we provide mathematical concepts to retrieve mathematically and physically consistent solutions, which are compared to the state-of-the-art non-hydrostatic model UA-ICON.
Witali Krochin, Francisco Navas-Guzmán, David Kuhl, Axel Murk, and Gunter Stober
Atmos. Meas. Tech., 15, 2231–2249, https://doi.org/10.5194/amt-15-2231-2022, https://doi.org/10.5194/amt-15-2231-2022, 2022
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This study leverages atmospheric temperature measurements performed with a ground-based radiometer making use of data that was collected during a 4-year observational campaign applying a new retrieval algorithm that improves the maximal altitude range from 45 to 55 km. The measurements are validated against two independent data sets, MERRA2 reanalysis data and the meteorological analysis of NAVGEM-HA.
Sumanta Sarkhel, Gunter Stober, Jorge L. Chau, Steven M. Smith, Christoph Jacobi, Subarna Mondal, Martin G. Mlynczak, and James M. Russell III
Ann. Geophys., 40, 179–190, https://doi.org/10.5194/angeo-40-179-2022, https://doi.org/10.5194/angeo-40-179-2022, 2022
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A rare gravity wave event was observed on the night of 25 April 2017 over northern Germany. An all-sky airglow imager recorded an upward-propagating wave at different altitudes in mesosphere with a prominent wave front above 91 km and faintly observed below. Based on wind and satellite-borne temperature profiles close to the event location, we have found the presence of a leaky thermal duct layer in 85–91 km. The appearance of this duct layer caused the wave amplitudes to diminish below 91 km.
Juliana Jaen, Toralf Renkwitz, Jorge L. Chau, Maosheng He, Peter Hoffmann, Yosuke Yamazaki, Christoph Jacobi, Masaki Tsutsumi, Vivien Matthias, and Chris Hall
Ann. Geophys., 40, 23–35, https://doi.org/10.5194/angeo-40-23-2022, https://doi.org/10.5194/angeo-40-23-2022, 2022
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To study long-term trends in the mesosphere and lower thermosphere (70–100 km), we established two summer length definitions and analyzed the variability over the years (2004–2020). After the analysis, we found significant trends in the summer beginning of one definition. Furthermore, we were able to extend one of the time series up to 31 years and obtained evidence of non-uniform trends and periodicities similar to those known for the quasi-biennial oscillation and El Niño–Southern Oscillation.
Christoph Jacobi, Friederike Lilienthal, Dmitry Korotyshkin, Evgeny Merzlyakov, and Gunter Stober
Adv. Radio Sci., 19, 185–193, https://doi.org/10.5194/ars-19-185-2021, https://doi.org/10.5194/ars-19-185-2021, 2021
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We compare winds and tidal amplitudes in the upper mesosphere/lower thermosphere region for cases with disturbed and undisturbed geomagnetic conditions. The zonal winds in both the mesosphere and lower thermosphere tend to be weaker during disturbed conditions. The summer equatorward meridional wind jet is weaker for disturbed geomagnetic conditions. The effect of geomagnetic variability on tidal amplitudes, except for the semidiurnal tide, is relatively small.
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.
Dimitry Pokhotelov, Isabel Fernandez-Gomez, and Claudia Borries
Ann. Geophys., 39, 833–847, https://doi.org/10.5194/angeo-39-833-2021, https://doi.org/10.5194/angeo-39-833-2021, 2021
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During geomagnetic storms, enhanced solar wind and changes in the interplanetary magnetic field lead to ionisation anomalies across the polar regions. The superstorm of 20 November 2003 was one of the largest events in recent history. Numerical simulations of ionospheric dynamics during the storm are compared with plasma observations to understand the mechanisms forming the polar plasma anomalies. The results are important for understanding and forecasting space weather in polar regions.
Gunter Stober, Ales Kuchar, Dimitry Pokhotelov, Huixin Liu, Han-Li Liu, Hauke Schmidt, Christoph Jacobi, Kathrin Baumgarten, Peter Brown, Diego Janches, Damian Murphy, Alexander Kozlovsky, Mark Lester, Evgenia Belova, Johan Kero, and Nicholas Mitchell
Atmos. Chem. Phys., 21, 13855–13902, https://doi.org/10.5194/acp-21-13855-2021, https://doi.org/10.5194/acp-21-13855-2021, 2021
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Little is known about the climate change of wind systems in the mesosphere and lower thermosphere at the edge of space at altitudes from 70–110 km. Meteor radars represent a well-accepted remote sensing technique to measure winds at these altitudes. Here we present a state-of-the-art climatological interhemispheric comparison using continuous and long-lasting observations from worldwide distributed meteor radars from the Arctic to the Antarctic and sophisticated general circulation models.
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.
Daniel Kastinen, Johan Kero, Alexander Kozlovsky, and Mark Lester
Atmos. Meas. Tech., 14, 3583–3596, https://doi.org/10.5194/amt-14-3583-2021, https://doi.org/10.5194/amt-14-3583-2021, 2021
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When a meteor enters the atmosphere, it causes a trail of diffusing plasma that moves with the neutral wind. An interferometric radar system can measure such trails and determine its location. However, there is a chance of determining the wrong position due to noise. We simulate this behaviour and use the simulations to successfully determine the true location of ambiguous events. We also successfully test two simple temporal integration methods for avoiding such erroneous determinations.
Gunter Stober, Diego Janches, Vivien Matthias, Dave Fritts, John Marino, Tracy Moffat-Griffin, Kathrin Baumgarten, Wonseok Lee, Damian Murphy, Yong Ha Kim, Nicholas Mitchell, and Scott Palo
Ann. Geophys., 39, 1–29, https://doi.org/10.5194/angeo-39-1-2021, https://doi.org/10.5194/angeo-39-1-2021, 2021
Daniel Kastinen and Johan Kero
Atmos. Meas. Tech., 13, 6813–6835, https://doi.org/10.5194/amt-13-6813-2020, https://doi.org/10.5194/amt-13-6813-2020, 2020
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The behaviour of position determination with interferometric radar systems and possible ambiguities therein depends on the spatial configuration of the radar-receiving antennas and their individual characteristics. We have simulated the position determination performance of five different radar systems. These simulations showed that ambiguities are dynamic and need to be examined on a case-by-case basis. However, the simulations can be used to analyse and understand previously ambiguous data.
Masatoshi Yamauchi, Magnar G. Johnsen, Carl-Fredrik Enell, Anders Tjulin, Anna Willer, and Dmitry A. Sormakov
Ann. Geophys., 38, 1159–1170, https://doi.org/10.5194/angeo-38-1159-2020, https://doi.org/10.5194/angeo-38-1159-2020, 2020
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The paper reports a new finding on space weather effects at around 70–75 ° geographic latitudes. We found that X flares cause an unexpectedly strong ionospheric current driven by solar flares. The effect is as large as a substorm that is known to cause strong auroras and may enhance ongoing substorms. However, it has been overlooked in the past due to the narrow latitudinal range at high latitudes. Since severe magnetic storms often occur with X flares, this may cause geomagnetic hazards.
Gunter Stober, Kathrin Baumgarten, John P. McCormack, Peter Brown, and Jerry Czarnecki
Atmos. Chem. Phys., 20, 11979–12010, https://doi.org/10.5194/acp-20-11979-2020, https://doi.org/10.5194/acp-20-11979-2020, 2020
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This paper presents a first cross-comparison of meteor ground-based observations and a meteorological analysis (NAVGEM-HA) to compare a seasonal climatology of winds and temperatures at the mesosphere/lower thermosphere. The validation is insofar unique as we not only compare the mean state but also provide a detailed comparison of the short time variability of atmospheric tidal waves. Our analysis questions previous results claiming the importance of lunar tides.
Leonie Bernet, Elmar Brockmann, Thomas von Clarmann, Niklaus Kämpfer, Emmanuel Mahieu, Christian Mätzler, Gunter Stober, and Klemens Hocke
Atmos. Chem. Phys., 20, 11223–11244, https://doi.org/10.5194/acp-20-11223-2020, https://doi.org/10.5194/acp-20-11223-2020, 2020
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With global warming, water vapour increases in the atmosphere. Water vapour is an important gas because it is a natural greenhouse gas and affects the formation of clouds, rain and snow. How much water vapour increases can vary in different regions of the world. To verify if it increases as expected on a regional scale, we analysed water vapour measurements in Switzerland. We found that water vapour generally increases as expected from temperature changes, except in winter.
Franziska Schranz, Jonas Hagen, Gunter Stober, Klemens Hocke, Axel Murk, and Niklaus Kämpfer
Atmos. Chem. Phys., 20, 10791–10806, https://doi.org/10.5194/acp-20-10791-2020, https://doi.org/10.5194/acp-20-10791-2020, 2020
Short summary
Short summary
We measured middle-atmospheric ozone, water vapour and zonal and meridional wind with two ground-based microwave radiometers which are located at Ny-Alesund, Svalbard, in the Arctic. In this article we present measurements of the small-scale horizontal ozone gradients during winter 2018/2019. We found a distinct seasonal variation of the ozone gradients which is linked to the planetary wave activity. We further present the signatures of the SSW in the ozone, water vapour and wind measurements.
Cited articles
Akbari, H., Bhatt, A., La Hoz, C., and Semeter, J. L.: Incoherent Scatter Plasma Lines: Observations and Applications, Space Sci. Rev., 212, 249–294, https://doi.org/10.1007/s11214-017-0355-7, 2017. a
Baloukidis, D., Sarris, T., Tourgaidis, S., Pirnaris, P., Aikio, A., Virtanen, I., Buchert, S., and Papadakis, K.: A Comparative Assessment of the Distribution of Joule Heating in Altitude as Estimated in TIE-GCM and EISCAT Over One Solar Cycle, J. Geophys. Res.-Space Phys., 128, e2023JA031526, https://doi.org/10.1029/2023JA031526, 2023. a, b, c
Baumgarten, K. and Stober, G.: On the evaluation of the phase relation between temperature and wind tides based on ground-based measurements and reanalysis data in the middle atmosphere, Ann. Geophys., 37, 581–602, https://doi.org/10.5194/angeo-37-581-2019, 2019. a
Baumjohann, W. and Treumann, R. A.: Basic space plasma physics, World Scientific, 340 pp., https://doi.org/10.1142/p015, 1996. a
Becker, E.: Mean-Flow Effects of Thermal Tides in the Mesosphere and Lower Thermosphere, J. Atmos. Sci., 74, 2043–2063, https://doi.org/10.1175/JAS-D-16-0194.1, 2017. a
Brekke, A. and Kamide, Y.: On the relationship between Joule and frictional heating in the polar ionosphere., J. Atmos. Terr. Phys., 58, 139–143, https://doi.org/10.1016/0021-9169(95)00025-9, 1996. a
Chapman, S.: The electrical conductivity of the ionosphere: A review, Il Nuovo Cimento, 4, 1385–1412, https://doi.org/10.1007/BF02746310, 1956. a, b
Deng, Y., Fuller-Rowell, T. J., Akmaev, R. A., and Ridley, A. J.: Impact of the altitudinal Joule heating distribution on the thermosphere, J. Geophys. Res.-Space Phys., 116, A05313, https://doi.org/10.1029/2010JA016019, 2011. a, b
Emmert, J. T., Drob, D. P., Picone, J. M., Siskind, D. E., Jones, M., Mlynczak, M. G., Bernath, P. F., Chu, X., Doornbos, E., Funke, B., Goncharenko, L. P., Hervig, M. E., Schwartz, M. J., Sheese, P. E., Vargas, F., Williams, B. P., and Yuan, T.: NRLMSIS 2.0: A Whole Atmosphere Empirical Model of Temperature and Neutral Species Densities, Earth Space Sci., 8, e01321, https://doi.org/10.1029/2020EA001321, 2021. a
Fang, X., Randall, C. E., Lummerzheim, D., Wang, W., Lu, G., Solomon, S. C., and Frahm, R. A.: Parameterization of monoenergetic electron impact ionization, Geophys. Res. Lett., 37, L22106, https://doi.org/10.1029/2010GL045406, 2010. a, b
Fang, X., Lummerzheim, D., and Jackman, C. H.: Proton impact ionization and a fast calculation method, J. Geophys. Res.-Space Phys., 118, 5369–5378, https://doi.org/10.1002/jgra.50484, 2013. a, b
Folkestad, K., Hagfors, T., and Westerlund, S.: EISCAT: An updated description of technical characteristics and operational capabilities, Radio Sci., 18, 867–879, https://doi.org/10.1029/RS018i006p00867, 1983. a
Frøystein, I. and Johnsen, M. G.: A critical review and presentation of the complete, historic series of K-indices as determined at Norwegian Magnetic Observatories since 1939, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2024-3254, 2024. a
Gjerloev, J. W.: The SuperMAG data processing technique, J. Geophys. Res.-Space Phys., 117, A09213, https://doi.org/10.1029/2012JA017683, 2012. a
Gledhill, J. A.: The effective recombination coefficient of electrons in the ionosphere between 50 and 150 km, Radio Sci., 21, 399–408, https://doi.org/10.1029/RS021i003p00399, 1986. a, b
Grandin, M., Partamies, N., and Virtanen, I. I.: Statistical comparison of electron precipitation during auroral breakups occurring either near the open–closed field line boundary or in the central part of the auroral oval, Ann. Geophys., 42, 355–369, https://doi.org/10.5194/angeo-42-355-2024, 2024. a
Grassmann, V.: The effect of different collision operators on EISCAT's standard data analysis model, J. Atmos. Terr. Phys., 55, 567–571, https://doi.org/10.1016/0021-9169(93)90005-J, 1993a. a
Grassmann, V.: An incoherent scatter experiment for the measurement of particle collisions, J. Atmos. Terr. Phys., 55, 573–576, https://doi.org/10.1016/0021-9169(93)90006-K, 1993b. a, b, c, d
Günzkofer, F., Pokhotelov, D., Stober, G., Liu, H., Liu, H. L., Mitchell, N. J., Tjulin, A., and Borries, C.: Determining the Origin of Tidal Oscillations in the Ionospheric Transition Region With EISCAT Radar and Global Simulation Data, J. Geophys. Res.-Space Phys., 127, e2022JA030861, https://doi.org/10.1029/2022JA030861, 2022. a, b
Günzkofer, F., Pokhotelov, D., Stober, G., Mann, I., Vadas, S. L., Becker, E., Tjulin, A., Kozlovsky, A., Tsutsumi, M., Gulbrandsen, N., Nozawa, S., Lester, M., Belova, E., Kero, J., Mitchell, N. J., and Borries, C.: Inferring neutral winds in the ionospheric transition region from atmospheric-gravity-wave traveling-ionospheric-disturbance (AGW-TID) observations with the EISCAT VHF radar and the Nordic Meteor Radar Cluster, Ann. Geophys., 41, 409–428, https://doi.org/10.5194/angeo-41-409-2023, 2023a. a
Günzkofer, F., Liu, H., Stober, G., Pokhotelov, D., and Borries, C.: Evaluation of the Empirical Scaling Factor of Joule Heating Rates in TIE-GCM With EISCAT Measurements, Earth Space Sci., 11, e2023EA003447, https://doi.org/10.1029/2023EA003447, 2024. a, b, c
Günzkofer, F., Stober, G., Kero, J., Themens, D., Tjulin, A., Gulbrandsen, N., Tsutsumi, M., and Borries, C.: The impact of particle precipitation on the ion-neutral collision frequency analyzed with EISCAT measurements, Zenodo [data set], https://doi.org/10.5281/zenodo.14646603, 2025. a
Hagan, M. E. and Forbes, J. M.: Migrating and nonmigrating semidiurnal tides in the upper atmosphere excited by tropospheric latent heat release, J. Geophys. Res.-Space Phys., 108, 1062, https://doi.org/10.1029/2002JA009466, 2003. a
Hall, C. M. and Tsutsumi, M.: Changes in mesospheric dynamics at 78° N, 16° E and 70° N, 19° E: 2001–2012, J. Geophys. Res.-Atmos., 118, 2689–2701, https://doi.org/10.1002/jgrd.50268, 2013. a
Hays, P. B., Jones, R. A., and Rees, M. H.: Auroral heating and the composition of the neutral atmosphere, Planet. Space Sci., 21, 559–573, https://doi.org/10.1016/0032-0633(73)90070-6, 1973. a, b
Holdsworth, D. A., Reid, I. M., and Cervera, M. A.: Buckland Park all-sky interferometric meteor radar, Radio Sci., 39, RS5009, https://doi.org/10.1029/2003RS003014, 2004. a
Ieda, A.: Ion-Neutral Collision Frequencies for Calculating Ionospheric Conductivity, J. Geophys. Res.-Space Phys., 125, e27128, https://doi.org/10.1029/2019JA027128, 2020. a, b, c, d
Kurihara, J., Oyama, S., Nozawa, S., Tsuda, T. T., Fujii, R., Ogawa, Y., Miyaoka, H., Iwagami, N., Abe, T., Oyama, K. I., Kosch, M. J., Aruliah, A., Griffin, E., and Kauristie, K.: Temperature enhancements and vertical winds in the lower thermosphere associated with auroral heating during the DELTA campaign, J. Geophys. Res.-Space Phys., 114, A12306, https://doi.org/10.1029/2009JA014392, 2009. a, b, c
Lehtinen, M. S. and Huuskonen, A.: General incoherent scatter analysis and GUISDAP, J. Atmos. Terr. Phys., 58, 435–452, https://doi.org/10.1016/0021-9169(95)00047-X, 1996. a
Lieberman, R. S. and Hays, P. B.: An Estimate of the Momentum Deposition in the Lower Thermosphere by the Observed Diurnal Tide., J. Atmos. Sci., 51, 3094–3108, https://doi.org/10.1175/1520-0469(1994)051<3094:AEOTMD>2.0.CO;2, 1994. a
Lindzen, R. S.: Atmospheric Tides, Annu. Rev. Earth Planet. Sci., 7, 199, https://doi.org/10.1146/annurev.ea.07.050179.001215, 1979. a
Liu, H.-L.: Variability and predictability of the space environment as related to lower atmosphere forcing, Space Weather, 14, 634–658, https://doi.org/10.1002/2016SW001450, 2016. a
Maute, A., Lu, G., Knipp, D. J., Anderson, B. J., and Vines, S. K.: Importance of lower atmospheric forcing and magnetosphere-ionosphere coupling in simulating neutral density during the February 2016 geomagnetic storm, Frontiers in Astronomy and Space Sciences, 9, 932748, https://doi.org/10.3389/fspas.2022.932748, 2022. a
McCrea, I., Aikio, A., Alfonsi, L., Belova, E., Buchert, S., Clilverd, M., Engler, N., Gustavsson, B., Heinselman, C., Kero, J., Kosch, M., Lamy, H., Leyser, T., Ogawa, Y., Oksavik, K., Pellinen-Wannberg, A., Pitout, F., Rapp, M., Stanislawska, I., and Vierinen, J.: The science case for the EISCAT_3D radar, Prog. Earth Planet. Sci, 2, 21, https://doi.org/10.1186/s40645-015-0051-8, 2015. a
Mironova, I. A., Aplin, K. L., Arnold, F., Bazilevskaya, G. A., Harrison, R. G., Krivolutsky, A. A., Nicoll, K. A., Rozanov, E. V., Turunen, E., and Usoskin, I. G.: Energetic Particle Influence on the Earth's Atmosphere, Space Sci. Rev., 194, 1–96, https://doi.org/10.1007/s11214-015-0185-4, 2015. a
Monro, P. E., Nisbet, J. S., and Stick, T. L.: Effects of tidal oscillations in the neutral atmosphere on electron densities in the E-region, J. Atmos. Terr. Phys., 38, 523–528, https://doi.org/10.1016/0021-9169(76)90010-6, 1976. a
Newell, P. T. and Gjerloev, J. W.: Evaluation of SuperMAG auroral electrojet indices as indicators of substorms and auroral power, J. Geophys. Res.-Space Phys., 116, A12211, https://doi.org/10.1029/2011JA016779, 2011. a
Nicolls, M. J., Bahcivan, H., Häggström, I., and Rietveld, M.: Direct measurement of lower thermospheric neutral density using multifrequency incoherent scattering, Geophys. Res. Lett., 41, 8147–8154, https://doi.org/10.1002/2014GL062204, 2014. a, b, c
Nozawa, S., Ogawa, Y., Oyama, S., Fujiwara, H., Tsuda, T., Brekke, A., Hall, C. M., Murayama, Y., Kawamura, S., Miyaoka, H., and Fujii, R.: Tidal waves in the polar lower thermosphere observed using the EISCAT long run data set obtained in September 2005, J. Geophys. Res.-Space Phys., 115, A08312, https://doi.org/10.1029/2009JA015237, 2010. a
Nygrén, T.: Studies of the E-region ion-neutral collision frequency using the EISCAT incoherent scatter radar, Adv. Space Res., 18, 79–82, https://doi.org/10.1016/0273-1177(95)00843-4, 1996. a
Nykiel, G., Ferreira, A., Günzkofer, F., Iochem, P., Tasnim, S., and Sato, H.: Large-Scale Traveling Ionospheric Disturbances Over the European Sector During the Geomagnetic Storm on March 23-24, 2023: Energy Deposition in the Source Regions and the Propagation Characteristics, J. Geophys. Res.-Space Phys., 129, e2023JA032145, https://doi.org/10.1029/2023JA032145, 2024. a
Olson, W. P. and Moe, K.: Influence of precipitating charged particles on the high latitude thermosphere, J. Atmos. Terr. Phys., 36, 1715, https://doi.org/10.1016/0021-9169(74)90156-1, 1974. a
Oyama, S., Watkins, B. J., Maeda, S., Shinagawa, H., Nozawa, S., Ogawa, Y., Brekke, A., Lathuillere, C., and Kofman, W.: Generation of the lower-thermospheric vertical wind estimated with the EISCAT KST radar at high latitudes during periods of moderate geomagnetic disturbance, Ann. Geophys., 26, 1491–1505, https://doi.org/10.5194/angeo-26-1491-2008, 2008. a, b, c, d
Oyama, S., Kurihara, J., Watkins, B. J., Tsuda, T. T., and Takahashi, T.: Temporal variations of the ion-neutral collision frequency from EISCAT observations in the polar lower ionosphere during periods of geomagnetic disturbances, J. Geophys. Res.-Space Phys., 117, A05308, https://doi.org/10.1029/2011JA017159, 2012. a, b, c
Qian, L. and Solomon, S. C.: Thermospheric Density: An Overview of Temporal and Spatial Variations, Space Sci. Rev., 168, 147–173, https://doi.org/10.1007/s11214-011-9810-z, 2012. a
Rees, D., Tobiska, K., Bowman, B., Vaughan, B., and Owens, J.: The New COSPAR International Reference Atmosphere (CIRA2014): Overview, Space Research Today, 188, 4–8, https://doi.org/10.1016/j.srt.2013.11.005, 2013. a
Schunk, R. W. and Walker, J. C. G.: Transport processes in the E region of the ionosphere, J. Geophys. Res., 76, 6159–6171, https://doi.org/10.1029/JA076i025p06159, 1971. a, b
Sheng, C., Deng, Y., Zhang, S.-R., Nishimura, Y., and Lyons, L. R.: Relative Contributions of Ion Convection and Particle Precipitation to Exciting Large-Scale Traveling Atmospheric and Ionospheric Disturbances, J. Geophys. Res.-Space Phys., 125, e27342, https://doi.org/10.1029/2019JA027342, 2020. a
Smith, M. F., Rees, D., and Fuller-Rowell, T. J.: The consequences of high latitude particle precipitation on global thermospheric dynamics, Planet. Space Sci., 30, 1259–1267, https://doi.org/10.1016/0032-0633(82)90099-X, 1982. a
Stober, G., Baumgarten, K., McCormack, J. P., Brown, P., and Czarnecki, J.: Comparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere region, Atmos. Chem. Phys., 20, 11979–12010, https://doi.org/10.5194/acp-20-11979-2020, 2020. a
Stober, G., Kozlovsky, A., Liu, A., Qiao, Z., Tsutsumi, M., Hall, C., Nozawa, S., Lester, M., Belova, E., Kero, J., Espy, P. J., Hibbins, R. E., and Mitchell, N.: Atmospheric tomography using the Nordic Meteor Radar Cluster and Chilean Observation Network De Meteor Radars: network details and 3D-Var retrieval, Atmos. Meas. Tech., 14, 6509–6532, https://doi.org/10.5194/amt-14-6509-2021, 2021a. a
Stober, G., Kuchar, A., Pokhotelov, D., Liu, H., Liu, H.-L., Schmidt, H., Jacobi, C., Baumgarten, K., Brown, P., Janches, D., Murphy, D., Kozlovsky, A., Lester, M., Belova, E., Kero, J., and Mitchell, N.: Interhemispheric differences of mesosphere–lower thermosphere winds and tides investigated from three whole-atmosphere models and meteor radar observations, Atmos. Chem. Phys., 21, 13855–13902, https://doi.org/10.5194/acp-21-13855-2021, 2021b. a
Stober, G., Liu, A., Kozlovsky, A., Qiao, Z., Kuchar, A., Jacobi, C., Meek, C., Janches, D., Liu, G., Tsutsumi, M., Gulbrandsen, N., Nozawa, S., Lester, M., Belova, E., Kero, J., and Mitchell, N.: Meteor radar vertical wind observation biases and mathematical debiasing strategies including the 3DVAR+DIV algorithm, Atmos. Meas. Tech., 15, 5769–5792, https://doi.org/10.5194/amt-15-5769-2022, 2022. a
Tjulin, A.: EISCAT Experiments, Tech. rep., EISCAT AB, https://eiscat.se/wp-content/uploads/2024/08/Experiments_v20240807.pdf (last access: 25 June 2025), 2024. a
Truskowski, A. O., Forbes, J. M., Zhang, X., and Palo, S. E.: New perspectives on thermosphere tides: 1. Lower thermosphere spectra and seasonal-latitudinal structures, Earth Planet. Space, 66, 136, https://doi.org/10.1186/s40623-014-0136-4, 2014. a
Waldteufel, P.: A study of seasonal changes in the lower thermosphere and their implications, Planet. Space Sci., 18, 741–748, https://doi.org/10.1016/0032-0633(70)90055-3, 1970. a
Watson, C., Themens, D. R., and Jayachandran, P. T.: Development and Validation of Precipitation Enhanced Densities for the Empirical Canadian High Arctic Ionospheric Model, Space Weather, 19, e2021SW002779, https://doi.org/10.1029/2021SW002779, 2021. a
Yue, J., Yu, W., Pedatella, N., Bruinsma, S., Wang, N., and Liu, H.: Contribution of the lower atmosphere to the day-to-day variation of thermospheric density, Adv. Space Res., 72, 5460–5475, https://doi.org/10.1016/j.asr.2022.06.011, 2023. a
Zhang, Y., Paxton, L. J., Lu, G., and Yee, S.: Impact of nitric oxide, solar EUV and particle precipitation on thermospheric density decrease, J. Atmos. Solar-Terr. Phy., 182, 147–154, https://doi.org/10.1016/j.jastp.2018.11.016, 2019. a
Short summary
The Earth’s magnetic field is not closed at high latitudes. Electrically charged particles can penetrate the Earth’s atmosphere, deposit their energy, and heat the local atmosphere–ionosphere. This presumably causes an upwelling of the neutral atmosphere, which affects the atmosphere–ionosphere coupling. We apply a new analysis technique to infer the atmospheric density from incoherent scatter radar measurements. We identify signs of particle precipitation impact on the neutral atmosphere.
The Earth’s magnetic field is not closed at high latitudes. Electrically charged particles can...
