Articles | Volume 40, issue 1
https://doi.org/10.5194/angeo-40-23-2022
© Author(s) 2022. 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-40-23-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
20 Jan 2022
Regular paper |
| 20 Jan 2022
| 20 Jan 2022
Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere
Leibniz Institute of Atmospheric Physics at the University of Rostock, Schloss-Strasse 6, 18225 Kühlungsborn, Germany
Toralf Renkwitz
Leibniz Institute of Atmospheric Physics at the University of Rostock, Schloss-Strasse 6, 18225 Kühlungsborn, Germany
Jorge L. Chau
Leibniz Institute of Atmospheric Physics at the University of Rostock, Schloss-Strasse 6, 18225 Kühlungsborn, Germany
Maosheng He
Leibniz Institute of Atmospheric Physics at the University of Rostock, Schloss-Strasse 6, 18225 Kühlungsborn, Germany
Peter Hoffmann
Leibniz Institute of Atmospheric Physics at the University of Rostock, Schloss-Strasse 6, 18225 Kühlungsborn, Germany
deceased, Peter Hoffmann on 29 October 2020 and Chris Hall on 9 August 2021
Yosuke Yamazaki
GFZ German Research Centre for Geosciences, Potsdam, Germany
Christoph Jacobi
Institute Meteorology, Leipzig University, Stephanstr. 3, 04103 Leipzig, Germany
Masaki Tsutsumi
National Institute of Polar Research, Tokyo, Japan
Vivien Matthias
Institute for Solar-Terrestrial Physics, German Aerospace Center (DLR), Neustrelitz, Germany
Chris Hall
Tromsø Geophysical Observatory, Arctic University of Norway, Tromsø, Norway
deceased, Peter Hoffmann on 29 October 2020 and Chris Hall on 9 August 2021
Related authors
Christoph Jacobi, Ales Kuchar, Toralf Renkwitz, and Juliana Jaen
Adv. Radio Sci., 21, 111–121, https://doi.org/10.5194/ars-21-111-2023, https://doi.org/10.5194/ars-21-111-2023, 2023
Short summary
Short summary
Middle atmosphere long-term changes show the signature of climate change. We analyse 43 years of mesopause region horizontal winds obtained at two sites in Germany. We observe mainly positive trends of the zonal prevailing wind throughout the year, while the meridional winds tend to decrease in magnitude in both summer and winter. Furthermore, there is a change in long-term trends around the late 1990s, which is most clearly visible in summer winds.
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
Short summary
Short summary
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.
Toralf Renkwitz, Mani Sivakandan, Juliana Jaen, and Werner Singer
Atmos. Chem. Phys., 23, 10823–10834, https://doi.org/10.5194/acp-23-10823-2023, https://doi.org/10.5194/acp-23-10823-2023, 2023
Short summary
Short summary
The paper focuses on remote sensing of the lowermost part of the ionosphere (D region) between ca. 50 and 90 km altitude, which overlaps widely with the mesosphere. We present a climatology of electron density over northern Norway, covering solar-maximum and solar-minimum conditions (2014–2022). Excluding detected energetic particle precipitation events, we derived a quiet-profile climatology. We also found a spring–fall asymmetry, while a symmetric solar zenith angle dependence was expected.
Guochun Shi, Hanli Liu, Masaki Tsutsumi, Njål Gulbrandsen, Alexander Kozlovsky, Dimitry Pokhotelov, Mark Lester, Christoph Jacobi, Kun Wu, and Gunter Stober
Atmos. Chem. Phys., 25, 9403–9430, https://doi.org/10.5194/acp-25-9403-2025, https://doi.org/10.5194/acp-25-9403-2025, 2025
Short summary
Short summary
Concerns about climate change are growing due to its widespread impacts, including rising temperatures, extreme weather events, and disruptions to ecosystems. To address these challenges, urgent global action is needed to monitor the distribution of trace gases and understand their effects on the atmosphere.
Sina Mehrdad, Sajedeh Marjani, Dörthe Handorf, and Christoph Jacobi
EGUsphere, https://doi.org/10.5194/egusphere-2025-3612, https://doi.org/10.5194/egusphere-2025-3612, 2025
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
Short summary
Short summary
We studied how strong wind disturbances caused by mountains can disturb the polar vortex, a large pool of cold air high above the North Pole. Using simulations, we boosted these wind disturbances over the Himalayas, North America, and East Asia. We found they can shift, weaken, and mix the vortex in different ways depending on the region. This helps explain how mountains influence the upper atmosphere and improve forecasts of extreme cold weather at the surface.
Daniel J. Emmons, Cornelius Csar Jude H. Salinas, Dong L. Wu, Nimalan Swarnalingam, Eugene V. Dao, Jorge L. Chau, Yosuke Yamazaki, Kyle E. Fitch, and Victoriya V. Forsythe
EGUsphere, https://doi.org/10.5194/egusphere-2025-3731, https://doi.org/10.5194/egusphere-2025-3731, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
Short summary
Short summary
The E-region of the Earth’s ionosphere plays an important role in atmospheric energy balance and High Frequency radio propagation. In this paper, we compare predictions from two recently developed ionospheric models to observations by ionospheric sounders (ionosondes). Overall, the models show reasonable agreement with the observations. However, there are several areas for improvement in the models as well as questions about the accuracy of the automatically processed ionosonde dataset.
Ales Kuchar, Gunter Stober, Dimitry Pokhotelov, Huixin Liu, Han-Li Liu, Manfred Ern, Damian Murphy, Diego Janches, Tracy Moffat-Griffin, Nicholas Mitchell, and Christoph Jacobi
EGUsphere, https://doi.org/10.5194/egusphere-2025-2827, https://doi.org/10.5194/egusphere-2025-2827, 2025
This preprint is open for discussion and under review for Annales Geophysicae (ANGEO).
Short summary
Short summary
We studied how the healing of the Antarctic ozone layer is affecting winds high above the South Pole. Using ground-based radar, satellite data, and computer models, we found that winds in the upper atmosphere have become stronger over the past two decades. These changes appear to be linked to shifts in the lower atmosphere caused by ozone recovery. Our results show that human efforts to repair the ozone layer are also influencing climate patterns far above Earth’s surface.
Arthur Gauthier, Claudia Borries, Alexander Kozlovsky, Diego Janches, Peter Brown, Denis Vida, Christoph Jacobi, Damian Murphy, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Johan Kero, Nicholas Mitchell, Tracy Moffat-Griffin, and Gunter Stober
Ann. Geophys., 43, 427–440, https://doi.org/10.5194/angeo-43-427-2025, https://doi.org/10.5194/angeo-43-427-2025, 2025
Short summary
Short summary
This study focuses on a TIMED Doppler Interferometer (TIDI)–meteor radar (MR) comparison of zonal and meridional winds and their dependence on local time and latitude. The correlation calculation between TIDI wind measurements and MR winds shows good agreement. A TIDI–MR seasonal comparison and analysis of the altitude–latitude dependence for winds are performed. TIDI reproduces the mean circulation well when compared with MRs and may be a useful lower boundary for general circulation models.
Florian Günzkofer, Gunter Stober, Johan Kero, David R. Themens, Anders Tjulin, Njål Gulbrandsen, Masaki Tsutsumi, and Claudia Borries
Ann. Geophys., 43, 331–348, https://doi.org/10.5194/angeo-43-331-2025, https://doi.org/10.5194/angeo-43-331-2025, 2025
Short summary
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.
Sina Mehrdad, Sajedeh Marjani, Dörthe Handorf, and Christoph Jacobi
EGUsphere, https://doi.org/10.5194/egusphere-2025-3005, https://doi.org/10.5194/egusphere-2025-3005, 2025
Short summary
Short summary
Wind flowing over mountains creates wave-like patterns aloft that can influence the atmosphere higher up in the stratosphere and mesosphere. In this study, we intensified these waves over specific regions like the Himalayas and Rocky Mountains and examined the resulting climate effects. We found that this can shift global wind patterns and even impact extreme events near the poles, showing how small regional changes in stratospheric wind patterns can influence the broader climate system.
Devin Huyghebaert, Juha Vierinen, Björn Gustavsson, Ralph Latteck, Toralf Renkwitz, Marius Zecha, Claudia C. Stephan, J. Federico Conte, Daniel Kastinen, Johan Kero, and Jorge L. Chau
EGUsphere, https://doi.org/10.5194/egusphere-2025-2323, https://doi.org/10.5194/egusphere-2025-2323, 2025
Short summary
Short summary
The phenomena of meteors occurs at altitudes of 60–120 km and can be used to measure the neutral atmosphere. We use a large high power radar system in Norway (MAARSY) to determine changes to the atmospheric density between the years of 2016–2023 at altitudes of 85–115 km. The same day-of-year is compared, minimizing changes to the measurements due to factors other than the atmosphere. This presents a novel method by which to obtain atmospheric neutral density variations.
Markus Kunze, Christoph Zülicke, Tarique A. Siddiqui, Claudia C. Stephan, Yosuke Yamazaki, Claudia Stolle, Sebastian Borchert, and Hauke Schmidt
Geosci. Model Dev., 18, 3359–3385, https://doi.org/10.5194/gmd-18-3359-2025, https://doi.org/10.5194/gmd-18-3359-2025, 2025
Short summary
Short summary
We present the Icosahedral Nonhydrostatic (ICON) general circulation model with an upper-atmospheric extension with the physics package for numerical weather prediction (UA-ICON(NWP)). We optimized the parameters for the gravity wave parameterizations and achieved realistic modeling of the thermal and dynamic states of the mesopause regions. UA-ICON(NWP) now shows a realistic frequency of major sudden stratospheric warmings and well-represented solar tides in temperature.
J. Federico Conte, Jorge L. Chau, Toralf Renkwitz, Ralph Latteck, Masaki Tsutsumi, Christoph Jacobi, Njål Gulbrandsen, and Satonori Nozawa
EGUsphere, https://doi.org/10.5194/egusphere-2025-1996, https://doi.org/10.5194/egusphere-2025-1996, 2025
Short summary
Short summary
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.
Christoph Jacobi, Khalil Karami, Ales Kuchar, Manfred Ern, Toralf Renkwitz, Ralph Latteck, and Jorge L. Chau
Adv. Radio Sci., 23, 21–31, https://doi.org/10.5194/ars-23-21-2025, https://doi.org/10.5194/ars-23-21-2025, 2025
Short summary
Short summary
Half-hourly mean winds have been obtained using ground-based low-frequency and very high frequency radio observations of the mesopause region at Collm, Germany, since 1984. Long-term changes of wind variances, which are proxies for short-period atmospheric gravity waves, have been analysed. Gravity wave amplitudes increase with time in winter, but mainly decrease in summer. The trends are consistent with mean wind changes according to wave theory.
Sina Mehrdad, Dörthe Handorf, Ines Höschel, Khalil Karami, Johannes Quaas, Sudhakar Dipu, and Christoph Jacobi
Weather Clim. Dynam., 5, 1223–1268, https://doi.org/10.5194/wcd-5-1223-2024, https://doi.org/10.5194/wcd-5-1223-2024, 2024
Short summary
Short summary
This study introduces a novel deep learning (DL) approach to analyze how regional radiative forcing in Europe impacts the Arctic climate. By integrating atmospheric poleward energy transport with DL-based clustering of atmospheric patterns and attributing anomalies to specific clusters, our method reveals crucial, nuanced interactions within the climate system, enhancing our understanding of intricate climate dynamics.
Ales Kuchar, Maurice Öhlert, Roland Eichinger, and Christoph Jacobi
Weather Clim. Dynam., 5, 895–912, https://doi.org/10.5194/wcd-5-895-2024, https://doi.org/10.5194/wcd-5-895-2024, 2024
Short summary
Short summary
Exploring the polar vortex's impact on climate, the study evaluates model simulations against the ERA5 reanalysis data. Revelations about model discrepancies in simulating disruptive stratospheric warmings and vortex behavior highlight the need for refined model simulations of past climate. By enhancing our understanding of these dynamics, the research contributes to more reliable climate projections of the polar vortex with the impact on surface climate.
Gunter Stober, Sharon L. Vadas, Erich Becker, Alan Liu, Alexander Kozlovsky, Diego Janches, Zishun Qiao, Witali Krochin, Guochun Shi, Wen Yi, Jie Zeng, Peter Brown, Denis Vida, Neil Hindley, Christoph Jacobi, Damian Murphy, Ricardo Buriti, Vania Andrioli, Paulo Batista, John Marino, Scott Palo, Denise Thorsen, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Kathrin Baumgarten, Johan Kero, Evgenia Belova, Nicholas Mitchell, Tracy Moffat-Griffin, and Na Li
Atmos. Chem. Phys., 24, 4851–4873, https://doi.org/10.5194/acp-24-4851-2024, https://doi.org/10.5194/acp-24-4851-2024, 2024
Short summary
Short summary
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.
Jennifer Hartisch, Jorge L. Chau, Ralph Latteck, Toralf Renkwitz, and Marius Zecha
Ann. Geophys., 42, 29–43, https://doi.org/10.5194/angeo-42-29-2024, https://doi.org/10.5194/angeo-42-29-2024, 2024
Short summary
Short summary
Scientists are studying the mesosphere and lower thermosphere using radar in northern Norway. They found peculiar events with strong upward and downward air movements, happening frequently (up to 2.5 % per month) from 2015 to 2021. Over 700 such events were noted, lasting around 20 min and expanding the studied layer. A total of 17 % of these events had extreme vertical speeds, showing their unique nature.
Christoph Jacobi, Ales Kuchar, Toralf Renkwitz, and Juliana Jaen
Adv. Radio Sci., 21, 111–121, https://doi.org/10.5194/ars-21-111-2023, https://doi.org/10.5194/ars-21-111-2023, 2023
Short summary
Short summary
Middle atmosphere long-term changes show the signature of climate change. We analyse 43 years of mesopause region horizontal winds obtained at two sites in Germany. We observe mainly positive trends of the zonal prevailing wind throughout the year, while the meridional winds tend to decrease in magnitude in both summer and winter. Furthermore, there is a change in long-term trends around the late 1990s, which is most clearly visible in summer winds.
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
Short summary
Short summary
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
Short summary
Short summary
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.
Toralf Renkwitz, Mani Sivakandan, Juliana Jaen, and Werner Singer
Atmos. Chem. Phys., 23, 10823–10834, https://doi.org/10.5194/acp-23-10823-2023, https://doi.org/10.5194/acp-23-10823-2023, 2023
Short summary
Short summary
The paper focuses on remote sensing of the lowermost part of the ionosphere (D region) between ca. 50 and 90 km altitude, which overlaps widely with the mesosphere. We present a climatology of electron density over northern Norway, covering solar-maximum and solar-minimum conditions (2014–2022). Excluding detected energetic particle precipitation events, we derived a quiet-profile climatology. We also found a spring–fall asymmetry, while a symmetric solar zenith angle dependence was expected.
Olivia Linke, Johannes Quaas, Finja Baumer, Sebastian Becker, Jan Chylik, Sandro Dahlke, André Ehrlich, Dörthe Handorf, Christoph Jacobi, Heike Kalesse-Los, Luca Lelli, Sina Mehrdad, Roel A. J. Neggers, Johannes Riebold, Pablo Saavedra Garfias, Niklas Schnierstein, Matthew D. Shupe, Chris Smith, Gunnar Spreen, Baptiste Verneuil, Kameswara S. Vinjamuri, Marco Vountas, and Manfred Wendisch
Atmos. Chem. Phys., 23, 9963–9992, https://doi.org/10.5194/acp-23-9963-2023, https://doi.org/10.5194/acp-23-9963-2023, 2023
Short summary
Short summary
Lapse rate feedback (LRF) is a major driver of the Arctic amplification (AA) of climate change. It arises because the warming is stronger at the surface than aloft. Several processes can affect the LRF in the Arctic, such as the omnipresent temperature inversion. Here, we compare multimodel climate simulations to Arctic-based observations from a large research consortium to broaden our understanding of these processes, find synergy among them, and constrain the Arctic LRF and AA.
Yosuke Yamazaki
Geosci. Model Dev., 16, 4749–4766, https://doi.org/10.5194/gmd-16-4749-2023, https://doi.org/10.5194/gmd-16-4749-2023, 2023
Short summary
Short summary
The Earth's atmosphere can support various types of global-scale waves. Some waves propagate eastward and others westward, and they can have different zonal wavenumbers. The Fourier–wavelet analysis is a useful technique for identifying different components of global-scale waves and their temporal variability. This paper introduces an easy-to-implement method to derive Fourier–wavelet spectra from 2-D space–time data. Application examples are presented using atmospheric models.
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
Short summary
Short summary
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).
Khalil Karami, Rolando Garcia, Christoph Jacobi, Jadwiga H. Richter, and Simone Tilmes
Atmos. Chem. Phys., 23, 3799–3818, https://doi.org/10.5194/acp-23-3799-2023, https://doi.org/10.5194/acp-23-3799-2023, 2023
Short summary
Short summary
Alongside mitigation and adaptation efforts, stratospheric aerosol intervention (SAI) is increasingly considered a third pillar to combat dangerous climate change. We investigate the teleconnection between the quasi-biennial oscillation in the equatorial stratosphere and the Arctic stratospheric polar vortex under a warmer climate and an SAI scenario. We show that the Holton–Tan relationship weakens under both scenarios and discuss the physical mechanisms responsible for such changes.
Christoph Jacobi, Kanykei Kandieva, and Christina Arras
Adv. Radio Sci., 20, 85–92, https://doi.org/10.5194/ars-20-85-2023, https://doi.org/10.5194/ars-20-85-2023, 2023
Short summary
Short summary
Sporadic E (Es) layers are thin regions of accumulated ions in the lower ionosphere. They can be observed by disturbances of GNSS links between low-Earth orbiting satellites and GNSS satellites. Es layers are influenced by neutral atmospheric tides and show the coupling between the neutral atmosphere and the ionosphere. Here we analyse migrating (sun-synchronous) and non-migrating tidal components in Es. The main signatures are migrating Es, but nonmigrating components are found as well.
Gerhard Georg Bruno Schmidtke, Raimund Brunner, and Christoph Jacobi
EGUsphere, https://doi.org/10.5194/egusphere-2023-139, https://doi.org/10.5194/egusphere-2023-139, 2023
Preprint withdrawn
Short summary
Short summary
The instrument records annual changes in Spectral Outgoing Radiation from 200–1100 nm, with 60 photomultiplier tubes simultaneously providing spectrometer and photometer data. Using Total Solar Irradiance data with a stability of 0.01 Wm-2 per year to recalibrate the established instruments, stable data of ~0.1 Wm-2 over a solar cycle period is expected. Determination of the changes in the global green Earth coverage and mapping will also assess the impact of climate engineering actions.
Gabriele Messori, Marlene Kretschmer, Simon H. Lee, and Vivien Wendt
Weather Clim. Dynam., 3, 1215–1236, https://doi.org/10.5194/wcd-3-1215-2022, https://doi.org/10.5194/wcd-3-1215-2022, 2022
Short summary
Short summary
Over 10 km above the ground, there is a region of the atmosphere called the stratosphere. While there is very little air in the stratosphere itself, its interactions with the lower parts of the atmosphere – where we live – can affect the weather. Here we study a specific example of such an interaction, whereby processes occurring at the boundary of the stratosphere can lead to a continent-wide drop in temperatures in North America during winter.
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
Short summary
Short summary
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.
Ales Kuchar, Petr Sacha, Roland Eichinger, Christoph Jacobi, Petr Pisoft, and Harald Rieder
EGUsphere, https://doi.org/10.5194/egusphere-2022-474, https://doi.org/10.5194/egusphere-2022-474, 2022
Preprint archived
Short summary
Short summary
We focus on the impact of small-scale orographic gravity waves (OGWs) above the Himalayas. The interaction of GWs with the large-scale circulation in the stratosphere is not still well understood and can have implications on climate projections. We use a chemistry-climate model to show that these strong OGW events are associated with anomalously increased upward planetary-scale waves and in turn affect the circumpolar circulation and have the potential to alter ozone variability as well.
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
Short summary
Short summary
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.
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
Short summary
Short summary
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.
Ryan Volz, Jorge L. Chau, Philip J. Erickson, Juha P. Vierinen, J. Miguel Urco, and Matthias Clahsen
Atmos. Meas. Tech., 14, 7199–7219, https://doi.org/10.5194/amt-14-7199-2021, https://doi.org/10.5194/amt-14-7199-2021, 2021
Short summary
Short summary
We introduce a new way of estimating winds in the upper atmosphere (about 80 to 100 km in altitude) from the observed Doppler shift of meteor trails using a statistical method called Gaussian process regression. Wind estimates and, critically, the uncertainty of those estimates can be evaluated smoothly (i.e., not gridded) in space and time. The effective resolution is set by provided parameters, which are limited in practice by the number density of the observed meteors.
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.
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
Short summary
Short summary
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.
Fabio Vargas, Jorge L. Chau, Harikrishnan Charuvil Asokan, and Michael Gerding
Atmos. Chem. Phys., 21, 13631–13654, https://doi.org/10.5194/acp-21-13631-2021, https://doi.org/10.5194/acp-21-13631-2021, 2021
Short summary
Short summary
We study large- and small-scale gravity wave cases observed in both airglow imagery and meteor radar data obtained during the SIMONe campaign carried out in early November 2018. We calculate the intrinsic features of several waves and estimate their impact in the mesosphere and lower thermosphere region via transferring energy and momentum to the atmosphere. We also associate cases of large-scale waves with secondary wave generation in the stratosphere.
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.
Rajesh Vaishnav, Christoph Jacobi, Jens Berdermann, Mihail Codrescu, and Erik Schmölter
Ann. Geophys., 39, 641–655, https://doi.org/10.5194/angeo-39-641-2021, https://doi.org/10.5194/angeo-39-641-2021, 2021
Short summary
Short summary
We investigate the role of eddy diffusion in the delayed ionospheric response against solar flux changes in the solar rotation period using the CTIPe model. The study confirms that eddy diffusion is an important factor affecting the delay of the total electron content. An increase in eddy diffusion leads to faster transport processes and an increased loss rate, resulting in a decrease in the ionospheric delay.
Rajesh Vaishnav, Erik Schmölter, Christoph Jacobi, Jens Berdermann, and Mihail Codrescu
Ann. Geophys., 39, 341–355, https://doi.org/10.5194/angeo-39-341-2021, https://doi.org/10.5194/angeo-39-341-2021, 2021
Short summary
Short summary
We investigate the delayed ionospheric response using the observed and CTIPe-model-simulated TEC against the solar EUV flux. The ionospheric delay estimated using model-simulated TEC is in good agreement with the delay estimated for observed TEC. The study confirms the model's capabilities to reproduce the delayed ionospheric response against the solar EUV flux. Results also indicate that the average delay is higher in the Northern Hemisphere as compared to the Southern Hemisphere.
Johann Stamm, Juha Vierinen, Juan M. Urco, Björn Gustavsson, and Jorge L. Chau
Ann. Geophys., 39, 119–134, https://doi.org/10.5194/angeo-39-119-2021, https://doi.org/10.5194/angeo-39-119-2021, 2021
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
Harikrishnan Charuvil Asokan, Jorge L. Chau, Raffaele Marino, Juha Vierinen, Fabio Vargas, Juan Miguel Urco, Matthias Clahsen, and Christoph Jacobi
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-974, https://doi.org/10.5194/acp-2020-974, 2020
Preprint withdrawn
Short summary
Short summary
This paper explores the dynamics of gravity waves and turbulence present in the mesosphere and lower thermosphere (MLT) region. We utilized two different techniques on meteor radar observations and simulations to obtain power spectra at different horizontal scales. The techniques are applied to a special campaign conducted in northern Germany in November 2018. The study revealed the dominance of large-scale structures with horizontal scales larger than 500 km during the campaign period.
Ales Kuchar, Petr Sacha, Roland Eichinger, Christoph Jacobi, Petr Pisoft, and Harald E. Rieder
Weather Clim. Dynam., 1, 481–495, https://doi.org/10.5194/wcd-1-481-2020, https://doi.org/10.5194/wcd-1-481-2020, 2020
Short summary
Short summary
Our study focuses on the impact of topographic structures such as the Himalayas and Rocky Mountains, so-called orographic gravity-wave hotspots. These hotspots play an important role in the dynamics of the middle atmosphere, in particular in the lower stratosphere. We study intermittency and zonally asymmetric character of these hotspots and their effects on the upper stratosphere and mesosphere using a new detection method in various modeling and observational datasets.
Cited articles
Andrews, D. G., Holton, J. R., and Leovy, C. B.: Middle Atmosphere Dynamics, vol. 40 – 1st edn., Academic Press, ISBN 0-12-058576-6, 1987. a
Baldwin, M. P., Gray, L. J., Dunkerton, T. J., Hamilton, K., Haynes, P. H.,
Randel, W. J., Holton, J. R., Alexander, M. J., Hirota, I., Horinouchi, T.,
Jones, D. B. A., Kinnersley, J. S., Marquardt, C., Sato, K., and Takahashi,
M.: The quasi-biennial oscillation, Rev. Geophys., 39, 179–229,
https://doi.org/10.1029/1999RG000073, 2001. a
Baumgarten, G., Fiedler, J., Lübken, F.-J., and von Cossart, G.:
Particle properties and water content of noctilucent clouds and their
interannual variation, J. Geophys. Res., 113, D06203,
https://doi.org/10.1029/2007JD008884, 2008. a
Butler, A. H., Seidel, D. J., Hardiman, S. C., Butchart, N., Birner, T., and
Match, A.: Defining sudden stratospheric warmings, B. Am.
Meteorol. Soc., 96, 1913–1928, https://doi.org/10.1175/BAMS-D-13-00173.1,
2015. a
Climate Prediction Center: Cold & Warm Episodes by Season, NOAA/National Weather Service, National Centers for Environmental Prediction [data set], available at: https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php, last access: 20 July 2021. a
Chau, J. L., Stober, G., Hall, C. M., Tsutsumi, M., Laskar, F. I., and
Hoffmann, P.: Polar mesospheric horizontal divergence and relative vorticity
measurements using multiple specular meteor radars, Radio Sci., 52,
811–828, https://doi.org/10.1002/2016RS006225, 2017. a
Chen, L., Huang, J., Ma, Q., Hänninen, H., Tremblay, F., and Bergeron,
Y.: Long‐term changes in the impacts of global warming on leaf phenology
of four temperate tree species, Glob. Change Biol., 25, 997–1004,
https://doi.org/10.1111/gcb.14496, 2019. a, b
Conte, J. F., Chau, J. L., Laskar, F. I., Stober, G., Schmidt, H., and Brown, P.: Semidiurnal solar tide differences between fall and spring transition times in the Northern Hemisphere, Ann. Geophys., 36, 999–1008, https://doi.org/10.5194/angeo-36-999-2018, 2018. a, b
Conte, J. F., Chau, J. L., and Peters, D. H.: Middle‐ and High‐Latitude
Mesosphere and Lower Thermosphere Mean Winds and Tides in Response to Strong
Polar‐Night Jet Oscillations, J. Geophys. Res.-Atmos., 124, 9262–9276, https://doi.org/10.1029/2019JD030828, 2019. a
Free University of Berlin: QBO winds [data set], available at:
https://www.geo.fu-berlin.de/en/met/ag/strat/produkte/qbo/index.html, last access: 20 July 2021. a
French, W. J. R., Klekociuk, A. R., and Mulligan, F. J.: Analysis of 24 years of mesopause region OH rotational temperature observations at Davis, Antarctica – Part 2: Evidence of a quasi-quadrennial oscillation (QQO) in the polar mesosphere, Atmos. Chem. Phys., 20, 8691–8708, https://doi.org/10.5194/acp-20-8691-2020, 2020. a, b
Fukao, S. and Hamazu, K.: Radar for Meteorological and Atmospheric
Observations, Springer Japan, Tokyo, ISBN 978-4-431-54333-6, https://doi.org/10.1007/978-4-431-54334-3, 2014. a
Fung, I. Y., Tucker, C. J., and Prentice, K. C.: Application of Advanced Very High Resolution Radiometer vegetation index to study atmosphere-biosphere exchange of CO2, J. Geophys. Res., 92, 2999–3015,
https://doi.org/10.1029/JD092iD03p02999, 1987. a
Hall, C. M. and Tsutsumi, M.: Neutral temperatures at 90 km altitude over
Svalbard (78∘ N 16∘ E), 2002–2019, derived from meteor radar observations, Polar Sci., 24, 100530, https://doi.org/10.1016/j.polar.2020.100530, 2020. a, b, c, d
Hall, C. M., Aso, T., Tsutsumi, M., Nozawa, S., Manson, A. H., and Meek, C. E.: A comparison of mesosphere and lower thermosphere neutral winds as
determined by meteor and medium-frequency radar at 70∘N, Radio Sci., 40, RS4001, https://doi.org/10.1029/2004RS003102, 2005. a
Hervig, M., Thompson, R. E., McHugh, M., Gordley, L. L., Russell, J. M., and
Summers, M. E.: First confirmation that water ice is the primary component
of polar mesospheric clouds, Geophys. Res. Lett., 28, 971–974,
https://doi.org/10.1029/2000GL012104, 2001. a
Hocking, W., Fuller, B., and Vandepeer, B.: Real-time determination of
meteor-related parameters utilizing modern digital technology, J.
Atmos. Sol.-Terr. Phy., 63, 155–169,
https://doi.org/10.1016/S1364-6826(00)00138-3, 2001. a
Hoffmann, P., Singer, W., and Keuer, D.: Variability of the mesospheric wind
field at middle and Arctic latitudes in winter and its relation to
stratospheric circulation disturbances, J. Atmos. Sol.-Terr. Phy., 64, 1229–1240, https://doi.org/10.1016/S1364-6826(02)00071-8, 2002. a, b, c
Huang, B., Thorne, P. W., Banzon, V. F., Boyer, T., Chepurin, G., Lawrimore, J. H., Menne, M. J., Smith, T. M., Vose, R. S., and Zhang, H.: Extended Reconstructed Sea Surface Temperature, Version 5 (ERSSTv5): Upgrades, Validations, and Intercomparisons, J. Climate, 30, 8179–8205, https://doi.org/10.1175/JCLI-D-16-0836.1, 2017. a
Hurdebise, Q., Aubinet, M., Heinesch, B., and Vincke, C.: Increasing
temperatures over an 18-year period shortens growing season length in a beech
(Fagus sylvatica L.)-dominated forest, Ann. For. Sci., 76, 75,
https://doi.org/10.1007/s13595-019-0861-8, 2019. a, b
Jacobi, C., Lilienthal, F., Geißler, C., and Krug, A.: Long-term
variability of mid-latitude mesosphere-lower thermosphere winds over Collm
(51∘ N, 13∘ E), J. Atmos. Sol.-Terr. Phy., 136,
174–186, https://doi.org/10.1016/j.jastp.2015.05.006, 2015. a, b
Jaen, J., Renkwitz, T., Chau, J. L., He, M., Hoffmann, P., Yamazaki, Y., Jacobi, C., Tsutsumi, M., Matthias, V., and Hall, C.: JaenANGEO2021, Leibniz Institute of Atmospheric Physics at the University of Rostock [data set], https://doi.org/10.22000/513, 2022. a
Jolliffe, I. T.: Principal Component Analysis, Springer Series in Statistics, Springer-Verlag, New York, https://doi.org/10.1007/b98835, 2002. a
Jolliffe, I. T. and Jackson, J. E.: A User's Guide to Principal Components., Statistician, 42, 76–77, https://doi.org/10.2307/2348121, 1993. a
Keuer, D., Hoffmann, P., Singer, W., and Bremer, J.: Long-term variations of the mesospheric wind field at mid-latitudes, Ann. Geophys., 25, 1779–1790, https://doi.org/10.5194/angeo-25-1779-2007, 2007. a, b
Laskar, F. I., Chau, J. L., St.-Maurice, J. P., Stober, G., Hall, C. M.,
Tsutsumi, M., Höffner, J., and Hoffmann, P.: Experimental Evidence of
Arctic Summer Mesospheric Upwelling and Its Connection to Cold Summer
Mesopause, Geophys. Res. Lett., 44, 9151–9158,
https://doi.org/10.1002/2017GL074759, 2017. a, b
Laštovička, J. and Jelínek, Š.: Problems in
calculating long-term trends in the upper atmosphere, J. Atmos. Sol.-Terr. Phy., 189, 80–86, https://doi.org/10.1016/j.jastp.2019.04.011, 2019. a
Liu, R. Q., Jacobi, C., Hoffmann, P., Stober, G., and Merzlyakov, E. G.: A
piecewise linear model for detecting climatic trends and their structural
changes with application to mesosphere/lower thermosphere winds over Collm,
Germany, J. Geophys. Res., 115, D22105, https://doi.org/10.1029/2010JD014080, 2010. a
Livesey, N. J., Read, G., W., Wagner, P. A., Froidevaux, L., Lambert, A.,
Manney, G. L., Millán Valle, L. F., Pumphrey, H. C., Santee, M. L., Schwartz, M. J., Wang, S., Fuller, R. A., Jarnot, R. F., Knosp, B. W., Martinez, E., and Lay, R. R.: EOS MLS Version 4.2x Level 2 data quality and
description document, available at: https://mls.jpl.nasa.gov/data/v4-2_data_quality_document.pdf (last access: 10 May 2021), 2015. a
Machol, J., Snow, M., Woodraska, D., Woods, T., Viereck, R., and Coddington,
O.: An Improved Lyman‐Alpha Composite, Earth Space Sci., 6,
2263–2272, https://doi.org/10.1029/2019EA000648, 2019. a
Manney, G. L. and Lawrence, Z. D.: The major stratospheric final warming in 2016: dispersal of vortex air and termination of Arctic chemical ozone loss, Atmos. Chem. Phys., 16, 15371–15396, https://doi.org/10.5194/acp-16-15371-2016, 2016. a
NASA: OMNIWeb, available at: https://omniweb.gsfc.nasa.gov/form/dx1.html, last access: 17 March 2021. a
Naujokat, B.: An Update of the Observed Quasi-Biennial Oscillation of the Stratospheric Winds over the Tropics, J. Atmos. Sci., 43, 1873–1877, https://doi.org/10.1175/1520-0469(1986)043<1873:AUOTOQ>2.0.CO;2, 1986. a
Offermann, D., Donner, M., Knieling, P., and Naujokat, B.: Middle atmosphere
temperature changes and the duration of summer, J. Atmos. Sol.-Terr. Phy., 66, 437–450, https://doi.org/10.1016/j.jastp.2004.01.028,
2004. a, b, c
Offermann, D., Jarisch, M., Donner, M., Oberheide, J., Wohltmann, I., Garcia,
R., Marsh, D., Naujokat, B., and Winkler, P.: Middle atmosphere summer
duration as an indicator of long-term circulation changes, Adv. Space
Res., 35, 1416–1422, https://doi.org/10.1016/j.asr.2005.02.065, 2005. a, b
Offermann, D., Jarisch, M., Donner, M., Steinbrecht, W., and Semenov, A.: OH
temperature re-analysis forced by recent variance increases, J. Atmos. Sol.-Terr. Phy., 68, 1924–1933,
https://doi.org/10.1016/j.jastp.2006.03.007, 2006. a
Offermann, D., Hoffmann, P., Knieling, P., Koppmann, R., Oberheide, J., and
Steinbrecht, W.: Long-term trends and solar cycle variations of mesospheric
temperature and dynamics, J. Geophys. Res.-Atmos., 115,
D18 127, https://doi.org/10.1029/2009JD013363, 2010. a, b, c
Offermann, D., Goussev, O., Kalicinsky, C., Koppmann, R., Matthes, K., Schmidt, H., Steinbrecht, W., and Wintel, J.: Journal of Atmospheric and
Solar-Terrestrial Physics A case study of multi-annual temperature
oscillations in the atmosphere : Middle Europe, J. Atmos. Sol.-Terr. Phy., 135, 1–11, https://doi.org/10.1016/j.jastp.2015.10.003, 2015. a, b
Pedatella, N. M. and Liu, H.-L.: Tidal variability in the mesosphere and lower thermosphere due to the El Niño-Southern Oscillation, Geophys. Res. Lett., 39, 1–7, https://doi.org/10.1029/2012GL053383, 2012. a
Peters, D. H., Schneidereit, A., and Karpechko, A.: Enhanced
Stratosphere/Troposphere Coupling During Extreme Warm Stratospheric Events
with Strong Polar-Night Jet Oscillation, Atmosphere, 9, 467,
https://doi.org/10.3390/atmos9120467, 2018. a
Pokhotelov, D., Becker, E., Stober, G., and Chau, J. L.: Seasonal variability of atmospheric tides in the mesosphere and lower thermosphere: meteor radar data and simulations, Ann. Geophys., 36, 825–830, https://doi.org/10.5194/angeo-36-825-2018, 2018. a
Portnyagin, Y. I., Merzlyakov, E. G., Solovjova, T. V., Jacobi, C.,
Kürschner, D., Manson, A., and Meek, C.: Long-term trends and
year-to-year variability of mid-latitude mesosphere/lower thermosphere
winds, J. Atmos. Sol.-Terr. Phy., 68, 1890–1901,
https://doi.org/10.1016/j.jastp.2006.04.004, 2006. a
Rapp, M., Lübken, F.-J., and Blix, T.: The role of charged ice particles for the creation of PMSE: A review of recent developments, Adv. Space Res., 31, 2033–2043, https://doi.org/10.1016/S0273-1177(03)00226-6, 2003. a
Reid, I. M.: MF and HF radar techniques for investigating the dynamics and
structure of the 50 to 110 km height region: a review, Prog. Earth Planet. Sci., 2, 33, https://doi.org/10.1186/s40645-015-0060-7, 2015. a
Renkwitz, T. and Latteck, R.: Variability of virtual layered phenomena in the mesosphere observed with medium frequency radars at 69∘N, J. Atmos. Sol.-Terr. Phy., 163, 38–45, https://doi.org/10.1016/j.jastp.2017.05.009, 2017. a
Santer, B. D., Wigley, T. M., Boyle, J. S., Gaffen, D. J., Hnilo, J. J.,
Nychka, D., Parker, D. E., and Taylor, K. E.: Statistical significance of
trends and trend differences in layer-average atmospheric temperature time
series, J. Geophys. Res.-Atmos., 105, 7337–7356,
https://doi.org/10.1029/1999JD901105, 2000. a
Savenkova, E., Kanukhina, A., Pogoreltsev, A., and Merzlyakov, E.: Variability of the springtime transition date and planetary waves in the stratosphere, J. Atmos. Sol.-Terr. Phy., 90-91, 1–8,
https://doi.org/10.1016/j.jastp.2011.11.001, 2012. a
Singer, W., von Zahn, U., and Weiß, J.: Diurnal and annual variations of meteor rates at the arctic circle, Atmos. Chem. Phys., 4, 1355–1363, https://doi.org/10.5194/acp-4-1355-2004, 2004. a
Singer, W., Latteck, R., Friedrich, M., Dalin, P., Kirkwood, S., Engler, N.,
and Holdsworth, D.: D-region electron densities obtained by differential
absorption and phase measurements with a 3-MHz-Doppler radar, in: 17th ESA Symposium on European Rocket and Balloon Programmes and Related Research, 30 May–2 June 2005, Sandefjord, Norway, edited by: Warmbein, B., ESA SP-590, ESA Publications Division, Noordwijk, ISBN 92-9092-901-4, 233–237, 2005. a
Wang, C. and Picaut, J.: Understanding ENSO physics—a review, Geophys.
Monogr. Ser., 147, 21–48, https://doi.org/10.1029/147GM02, 2004. a
Waters, J. W., Froidevaux, L., Harwood, R. S., Jarnot, R. F., Pickett, H. M.,
Read, W. G., Siegel, P. H., Cofield, R. E., Filipiak, M. J., Flower, D. A.,
Holden, J. R., Lau, G. K., Livesey, N. J., Manney, G. L., Pumphrey, H. C.,
Santee, M. L., Wu, D. L., Cuddy, D. T., Lay, R. R., Loo, M. S., Perun, V. S.,
Schwartz, M. J., Stek, P. C., Thurstans, R. P., Boyles, M. A., Chandra,
K. M., Chavez, M. C., Chen, G. S., Chudasama, B. V., Dodge, R., Fuller,
R. A., Girard, M. A., Jiang, J. H., Jiang, Y., Knosp, B. W., Labelle, R. C.,
Lam, J. C., Lee, K. A., Miller, D., Oswald, J. E., Patel, N. C., Pukala,
D. M., Quintero, O., Scaff, D. M., Van Snyder, W., Tope, M. C., Wagner,
P. A., and Walch, M. J.: The Earth Observing System Microwave Limb Sounder
(EOS MLS) on the aura satellite, IEEE T. Geosci. Remote, 44, 1075–1092, https://doi.org/10.1109/TGRS.2006.873771, 2006.
a, b
Wilhelm, S., Stober, G., and Chau, J. L.: A comparison of 11-year mesospheric and lower thermospheric winds determined by meteor and MF radar at 69∘ N, Ann. Geophys., 35, 893–906, https://doi.org/10.5194/angeo-35-893-2017, 2017. a, b
Wilhelm, S., Stober, G., and Brown, P.: Climatologies and long-term changes in mesospheric wind and wave measurements based on radar observations at high and mid latitudes, Ann. Geophys., 37, 851–875, https://doi.org/10.5194/angeo-37-851-2019, 2019. a
Wu, D. L., Schwartz, M. J., Waters, J. W., Limpasuvan, V., Wu, Q., and Killeen, T. L.: Mesospheric doppler wind measurements from Aura Microwave Limb Sounder (MLS), Adv. Space Res., 42, 1246–1252,
https://doi.org/10.1016/j.asr.2007.06.014, 2008. a
Yamazaki, Y. and Matthias, V.: Large‐Amplitude Quasi‐10‐Day Waves in the
Middle Atmosphere During Final Warmings, J. Geophys. Res.-Atmos., 124, 9874–9892, https://doi.org/10.1029/2019JD030634, 2019. a, b, c
Yiğit, E., Koucká Knížová, P., Georgieva, K., and
Ward, W.: A review of vertical coupling in the Atmosphere-Ionosphere system:
Effects of waves, sudden stratospheric warmings, space weather, and of solar
activity, J. Atmos. Sol.-Terr. Phy., 141, 1–12,
https://doi.org/10.1016/j.jastp.2016.02.011, 2016. a
Younger, P. T., Astin, I., Sandford, D. J., and Mitchell, N. J.: The sporadic radiant and distribution of meteors in the atmosphere as observed by VHF radar at Arctic, Antarctic and equatorial latitudes, Ann. Geophys., 27, 2831–2841, https://doi.org/10.5194/angeo-27-2831-2009, 2009. a
Zhou, L., Tucker, C. J., Kaufmann, R. K., Slayback, D., Shabanov, N. V., and
Myneni, R. B.: Variations in northern vegetation activity inferred from
satellite data of vegetation index during 1981 to 1999, J. Geophys. Res.-Atmos., 106, 20069–20083, https://doi.org/10.1029/2000JD000115, 2001. a, b
Short summary
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.
To study long-term trends in the mesosphere and lower thermosphere (70–100 km), we established...
