Articles | Volume 38, issue 1
https://doi.org/10.5194/angeo-38-95-2020
© Author(s) 2020. 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-38-95-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
23 Jan 2020
Regular paper |
| 23 Jan 2020
| 23 Jan 2020
Impact of local gravity wave forcing in the lower stratosphere on the polar vortex stability: effect of longitudinal displacement
Nadja Samtleben
CORRESPONDING AUTHOR
Institute for Meteorology, Universität Leipzig, Stephanstr. 3, 04103 Leipzig, Germany
Aleš Kuchař
Department of Atmospheric Physics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic
Petr Šácha
Institute for Meteorology, Universität für Bodenkultur Wien, Gregor-Mendel-Straße 33, 1180 Vienna, Austria
Department of Atmospheric Physics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic
EPhysLab, Faculty of Sciences, Universidade de Vigo, Campus As Lagoas, s/n, 32004 Ourense, Spain
Petr Pišoft
Department of Atmospheric Physics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 180 00 Prague 8, Czech Republic
Christoph Jacobi
Institute for Meteorology, Universität Leipzig, Stephanstr. 3, 04103 Leipzig, Germany
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Friederike Lilienthal, Erdal Yiğit, Nadja Samtleben, and Christoph Jacobi
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2019-339, https://doi.org/10.5194/gmd-2019-339, 2020
Preprint withdrawn
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Gravity waves are a small-scale but prominent dynamical feature in the Earth's atmosphere. Here, we use a mechanistic nonlinear general circulation model and implement a modern whole atmosphere gravity wave parameterization. We study the response of the atmosphere on several phase speed spectra. We find a large influence of fast travelling waves on the background dynamics in the thermosphere and also a strong dependence of the amplitude of the terdiurnal solar tide, indicating wave interactions.
Nadja Samtleben, Christoph Jacobi, Petr Pišoft, Petr Šácha, and Aleš Kuchař
Ann. Geophys., 37, 507–523, https://doi.org/10.5194/angeo-37-507-2019, https://doi.org/10.5194/angeo-37-507-2019, 2019
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Simulations of locally breaking gravity wave hot spots in the stratosphere show a suppression of wave propagation at midlatitudes, which is partly compensated for by additional wave propagation through the polar region. This leads to a displacement of the polar vortex towards lower latitudes. The effect is highly dependent on the position of the artificial gravity wave forcing. It is strongest (weakest) for hot spots at lower to middle latitudes (higher latitudes).
Yunqian Zhu, Hideharu Akiyoshi, Valentina Aquila, Elisabeth Asher, Ewa M. Bednarz, Slimane Bekki, Christoph Brühl, Amy H. Butler, Parker Case, Simon Chabrillat, Gabriel Chiodo, Margot Clyne, Lola Falletti, Peter R. Colarco, Eric Fleming, Andrin Jörimann, Mahesh Kovilakam, Gerbrand Koren, Ales Kuchar, Nicolas Lebas, Qing Liang, Cheng-Cheng Liu, Graham Mann, Michael Manyin, Marion Marchand, Olaf Morgenstern, Paul Newman, Luke D. Oman, Freja F. Østerstrøm, Yifeng Peng, David Plummer, Ilaria Quaglia, William Randel, Samuel Rémy, Takashi Sekiya, Stephen Steenrod, Timofei Sukhodolov, Simone Tilmes, Kostas Tsigaridis, Rei Ueyama, Daniele Visioni, Xinyue Wang, Shingo Watanabe, Yousuke Yamashita, Pengfei Yu, Wandi Yu, Jun Zhang, and Zhihong Zhuo
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To understand the climate impact of the 2022 Hunga volcanic eruption, we developed a climate model-observation comparison project. The paper describes the protocols and models that participate in the experiments. We designed several experiments to achieve our goal of this activity: 1. evaluate the climate model performance; 2. understand the Earth system responses to this eruption.
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
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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. Discuss., https://doi.org/10.5194/angeo-2024-13, https://doi.org/10.5194/angeo-2024-13, 2024
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Ales Kuchar, Timofei Sukhodolov, Gabriel Chiodo, Andrin Jörimann, Jessica Kult-Herdin, Eugene Rozanov, and Harald Rieder
EGUsphere, https://doi.org/10.5194/egusphere-2024-1909, https://doi.org/10.5194/egusphere-2024-1909, 2024
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In January 2022, the Hunga Tonga-Hunga Ha'apai volcano erupted, sending massive amount of water vapor into the atmosphere. This event had a significant impact on stratospheric and lower mesosphere chemical composition. A year later stratospheric conditions have been disturbed during so-called Sudden Stratospheric. Here we simulate a novel pathway by which the water-rich eruption such as HT may have contributed to conditions during these events and consequently impacted surface climate.
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
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Masatomo Fujiwara, Patrick Martineau, Jonathon S. Wright, Marta Abalos, Petr Šácha, Yoshio Kawatani, Sean M. Davis, Thomas Birner, and Beatriz M. Monge-Sanz
Atmos. Chem. Phys., 24, 7873–7898, https://doi.org/10.5194/acp-24-7873-2024, https://doi.org/10.5194/acp-24-7873-2024, 2024
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A climatology of the major variables and terms of the transformed Eulerian-mean (TEM) momentum and thermodynamic equations from four global atmospheric reanalyses is evaluated. The spread among reanalysis TEM momentum balance terms is around 10 % in Northern Hemisphere winter and up to 50 % in Southern Hemisphere winter. The largest uncertainties in the thermodynamic equation (about 50 %) are in the vertical advection, which does not show a structure consistent with the differences in heating.
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
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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.
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
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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
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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.
Roland Eichinger, Sebastian Rhode, Hella Garny, Peter Preusse, Petr Pisoft, Aleš Kuchař, Patrick Jöckel, Astrid Kerkweg, and Bastian Kern
Geosci. Model Dev., 16, 5561–5583, https://doi.org/10.5194/gmd-16-5561-2023, https://doi.org/10.5194/gmd-16-5561-2023, 2023
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The columnar approach of gravity wave (GW) schemes results in dynamical model biases, but parallel decomposition makes horizontal GW propagation computationally unfeasible. In the global model EMAC, we approximate it by GW redistribution at one altitude using tailor-made redistribution maps generated with a ray tracer. More spread-out GW drag helps reconcile the model with observations and close the 60°S GW gap. Polar vortex dynamics are improved, enhancing climate model credibility.
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
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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.
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
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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
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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
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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.
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.
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
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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.
Rudolf Brázdil, Petr Dobrovolný, Jiří Mikšovský, Petr Pišoft, Miroslav Trnka, Martin Možný, and Jan Balek
Clim. Past, 18, 935–959, https://doi.org/10.5194/cp-18-935-2022, https://doi.org/10.5194/cp-18-935-2022, 2022
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The paper deals with 520-year series (1501–2020 CE) of temperature, precipitation, and four drought indices reconstructed from documentary evidence and instrumental observations for the Czech Lands. Basic features of their fluctuations, long-term trends, and periodicities as well as attribution to changes in external forcings and climate variability modes are analysed. Representativeness of Czech reconstructions at European scale is evaluated. The paper shows extreme character of past decades.
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, 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.
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
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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
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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.
Arseniy Karagodin-Doyennel, Eugene Rozanov, Ales Kuchar, William Ball, Pavle Arsenovic, Ellis Remsberg, Patrick Jöckel, Markus Kunze, David A. Plummer, Andrea Stenke, Daniel Marsh, Doug Kinnison, and Thomas Peter
Atmos. Chem. Phys., 21, 201–216, https://doi.org/10.5194/acp-21-201-2021, https://doi.org/10.5194/acp-21-201-2021, 2021
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The solar signal in the mesospheric H2O and CO was extracted from the CCMI-1 model simulations and satellite observations using multiple linear regression (MLR) analysis. MLR analysis shows a pronounced and statistically robust solar signal in both H2O and CO. The model results show a general agreement with observations reproducing a negative/positive solar signal in H2O/CO. The pattern of the solar signal varies among the considered models, reflecting some differences in the model setup.
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
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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
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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.
Christoph Geißler, Christoph Jacobi, and Friederike Lilienthal
Ann. Geophys., 38, 527–544, https://doi.org/10.5194/angeo-38-527-2020, https://doi.org/10.5194/angeo-38-527-2020, 2020
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This is an extensive model study to analyze the migrating quarterdiurnal solar tide (QDT) and its forcing mechanisms in the middle atmosphere. We first show a climatology of the QDT amplitudes and examine the contribution of the different forcing mechanisms, including direct solar, nonlinear and gravity wave forcing, on the QDT amplitude. We then investigate the destructive interference between the individual forcing mechanisms.
Peter Huszar, Jan Karlický, Jana Ďoubalová, Kateřina Šindelářová, Tereza Nováková, Michal Belda, Tomáš Halenka, Michal Žák, and Petr Pišoft
Atmos. Chem. Phys., 20, 1977–2016, https://doi.org/10.5194/acp-20-1977-2020, https://doi.org/10.5194/acp-20-1977-2020, 2020
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Urban surfaces alter meteorological conditions which consequently alter air pollution due to modified transport and chemical reactions. Here, we focus on a major component of this influence, enhanced vertical eddy diffusion. Using a regional climate model coupled to a chemistry transport model, we investigate how different representations of turbulent transport translate to urban canopy impact on ozone and PM2.5 concentrations and whether turbulence remains the most important component.
Friederike Lilienthal, Erdal Yiğit, Nadja Samtleben, and Christoph Jacobi
Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2019-339, https://doi.org/10.5194/gmd-2019-339, 2020
Preprint withdrawn
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Gravity waves are a small-scale but prominent dynamical feature in the Earth's atmosphere. Here, we use a mechanistic nonlinear general circulation model and implement a modern whole atmosphere gravity wave parameterization. We study the response of the atmosphere on several phase speed spectra. We find a large influence of fast travelling waves on the background dynamics in the thermosphere and also a strong dependence of the amplitude of the terdiurnal solar tide, indicating wave interactions.
Erik Schmölter, Jens Berdermann, Norbert Jakowski, and Christoph Jacobi
Ann. Geophys., 38, 149–162, https://doi.org/10.5194/angeo-38-149-2020, https://doi.org/10.5194/angeo-38-149-2020, 2020
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This study correlates ionospheric parameters with the integrated solar radiation for an analysis of the delayed ionospheric response in order to confirm previous studies on the delay and to further specify variations of the delay (seasonal and spatial). Results also indicate the dependence on the geomagnetic activity as well as on the 11-year solar cycle. The results are important for the understanding of ionospheric processes and could be used for the validation of ionospheric models.
Rajesh Vaishnav, Christoph Jacobi, and Jens Berdermann
Ann. Geophys., 37, 1141–1159, https://doi.org/10.5194/angeo-37-1141-2019, https://doi.org/10.5194/angeo-37-1141-2019, 2019
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We investigate the ionospheric response to the temporal and spatial dynamics of the solar activity using total electron content (TEC) maps and multiple solar proxies. The maximum correlation at a 16–32-d timescale is observed between the He-II, Mg-II, and F30 with respect to global mean TEC, with an effective time delay of about 1 d. The most suitable proxy to represent the solar activity at the timescales of 16–32 d and 32–64 d is He-II.
Friederike Lilienthal and Christoph Jacobi
Ann. Geophys., 37, 943–953, https://doi.org/10.5194/angeo-37-943-2019, https://doi.org/10.5194/angeo-37-943-2019, 2019
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We analyzed the forcing mechanisms of the migrating terdiurnal solar tide in the middle atmosphere, focusing the impact on the zonal mean circulation. We show that the primary solar forcing is the most dominant one but secondary wave–wave interactions also contribute in the lower thermosphere region. We further demonstrate that small-scale gravity waves can strongly and irregularly influence the amplitude of the terdiurnal tide as well as the background circulation in the thermosphere.
Christoph Jacobi and Christina Arras
Adv. Radio Sci., 17, 213–224, https://doi.org/10.5194/ars-17-213-2019, https://doi.org/10.5194/ars-17-213-2019, 2019
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We analyze tidal phases and related wind shear in the mesosphere and
lower thermosphere as observed by a meteor radar. The wind shear phases are compared with those of sporadic E occurrence rates, which were derived from GPS radio occultation observations. We find good correspondence between radar derived wind shear and sporadic E phases for the semidiurnal, terdiurnal, and quarterdiurnal tidal components, but not for the diurnal tide.
Nadja Samtleben, Christoph Jacobi, Petr Pišoft, Petr Šácha, and Aleš Kuchař
Ann. Geophys., 37, 507–523, https://doi.org/10.5194/angeo-37-507-2019, https://doi.org/10.5194/angeo-37-507-2019, 2019
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Simulations of locally breaking gravity wave hot spots in the stratosphere show a suppression of wave propagation at midlatitudes, which is partly compensated for by additional wave propagation through the polar region. This leads to a displacement of the polar vortex towards lower latitudes. The effect is highly dependent on the position of the artificial gravity wave forcing. It is strongest (weakest) for hot spots at lower to middle latitudes (higher latitudes).
Petr Šácha, Roland Eichinger, Hella Garny, Petr Pišoft, Simone Dietmüller, Laura de la Torre, David A. Plummer, Patrick Jöckel, Olaf Morgenstern, Guang Zeng, Neal Butchart, and Juan A. Añel
Atmos. Chem. Phys., 19, 7627–7647, https://doi.org/10.5194/acp-19-7627-2019, https://doi.org/10.5194/acp-19-7627-2019, 2019
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Climate models robustly project a Brewer–Dobson circulation (BDC) acceleration in the course of climate change. Analyzing mean age of stratospheric air (AoA) from a subset of climate projection simulations, we find a remarkable agreement in simulating the largest AoA trends in the extratropical stratosphere. This is shown to be related with the upward shift of the circulation, resulting in a so-called stratospheric shrinkage, which could be one of the so-far-omitted BDC acceleration drivers.
Christoph Jacobi, Christina Arras, Christoph Geißler, and Friederike Lilienthal
Ann. Geophys., 37, 273–288, https://doi.org/10.5194/angeo-37-273-2019, https://doi.org/10.5194/angeo-37-273-2019, 2019
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Sporadic E (Es) layers in the Earth's ionosphere are produced by ion convergence due to vertical wind shear in the presence of a horizontal component of the Earth's magnetic field. We present analyses of the 6 h tidal signatures in ES occurrence rates derived from GPS radio observations. Times of maxima in ES agree well with those of negative wind shear obtained from radar observation. The global distribution of ES amplitudes agrees with wind shear amplitudes from numerical modeling.
Jiří Mikšovský, Rudolf Brázdil, Miroslav Trnka, and Petr Pišoft
Clim. Past, 15, 827–847, https://doi.org/10.5194/cp-15-827-2019, https://doi.org/10.5194/cp-15-827-2019, 2019
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To reveal sources of variability imprinted in central European drought records, regression and wavelet analysis were applied to 5 centuries of reconstructed data characterizing Czech climate. Mid- to long-term changes in temperature in the North Atlantic and North Pacific were identified as one of the potential sources of drought variations; transient colder and wetter episodes were linked to the effects of large volcanic eruptions.
Daniel Mewes and Christoph Jacobi
Atmos. Chem. Phys., 19, 3927–3937, https://doi.org/10.5194/acp-19-3927-2019, https://doi.org/10.5194/acp-19-3927-2019, 2019
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Horizontal moist static energy (MSE) transport patterns were extracted from reanalysis data using an artificial neuronal network for the winter months. The results show that during the last 30 years transport pathways that favour MSE transport through the North Atlantic are getting more frequent. This North Atlantic pathway is connected to positive temperature anomalies over the central Arctic, which implies a connection between Arctic amplification and the change in horizontal heat transport.
Sven Wilhelm, Gunter Stober, Vivien Matthias, Christoph Jacobi, and Damian J. Murphy
Ann. Geophys., 37, 1–14, https://doi.org/10.5194/angeo-37-1-2019, https://doi.org/10.5194/angeo-37-1-2019, 2019
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This study shows that the mesospheric winds are affected by an expansion–shrinking of the mesosphere and lower thermosphere that takes place due to changes in the intensity of the solar radiation, which affects the density within the atmosphere. On seasonal timescales, an increase in the neutral density occurs together with a decrease in the eastward-directed zonal wind. Further, even after removing the seasonal and the 11-year solar cycle variations, we show a connection between them.
Friederike Lilienthal, Christoph Jacobi, and Christoph Geißler
Atmos. Chem. Phys., 18, 15725–15742, https://doi.org/10.5194/acp-18-15725-2018, https://doi.org/10.5194/acp-18-15725-2018, 2018
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The terdiurnal solar tide is an atmospheric wave, owing to the daily variation of solar heating with a period of 8 h. Here, we present model simulations of this tide and investigate the relative importance of possible forcing mechanisms because they are still under debate. These are, besides direct solar heating, nonlinear interactions between other tides and gravity wave–tide interactions. As a result, solar heating is most important and nonlinear effects partly counteract this forcing.
Peter Huszar, Michal Belda, Jan Karlický, Tatsiana Bardachova, Tomas Halenka, and Petr Pisoft
Atmos. Chem. Phys., 18, 14059–14078, https://doi.org/10.5194/acp-18-14059-2018, https://doi.org/10.5194/acp-18-14059-2018, 2018
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The impact of meteorological changes introduced by urbanization on aerosol concentration using a regional climate model and a chemistry transport model over central Europe is investigated. We found a strong increase of temperature and turbulence and a decrease of humidity and wind speed due to urban surfaces. This resulted in a clear decrease of aerosol concentrations near the surface: PM2.5 concentrations were reduced by 3 μg/m3. The dominating effect is the increased turbulent transport.
Christoph Jacobi, Christoph Geißler, Friederike Lilienthal, and Amelie Krug
Adv. Radio Sci., 16, 141–147, https://doi.org/10.5194/ars-16-141-2018, https://doi.org/10.5194/ars-16-141-2018, 2018
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The possible sources of the quarterdiurnal tide (QDT) in the middle atmosphere are still under discussion. Therefore, meteor radar winds were analyzed with respect to non-linear interaction, which probably plays a role in winter, but to a lesser degree in summer. Numerical model experiments lead to the conclusion that, although non-linear tidal interaction is indeed one source of the QDT, the major source is direct solar forcing of the 6-hr tidal components.
Erik Schmölter, Jens Berdermann, Norbert Jakowski, Christoph Jacobi, and Rajesh Vaishnav
Adv. Radio Sci., 16, 149–155, https://doi.org/10.5194/ars-16-149-2018, https://doi.org/10.5194/ars-16-149-2018, 2018
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Physical and chemical processes in the ionosphere are driven by complex interactions with the solar radiation. The ionospheric plasma is in particular sensitive to solar variations with a time delay between one and two days.
Here we present preliminary results of the ionospheric delay based on a comprehensive and reliable database consisting of GNSS TEC Maps and EUV spectral flux data.
Rajesh Vaishnav, Christoph Jacobi, Jens Berdermann, Erik Schmölter, and Mihail Codrescu
Adv. Radio Sci., 16, 157–165, https://doi.org/10.5194/ars-16-157-2018, https://doi.org/10.5194/ars-16-157-2018, 2018
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We investigate the ionospheric response to solar Extreme Ultraviolet (EUV) variations using different solar proxies and IGS TEC maps. An ionospheric delay in GTEC is observed at the 27 days solar rotation period with the time scale of about ~ 1–2 days. Here we present preliminary results from the CTIPe model simulations which qualitatively reproduce the observed ~1-2 days delay in GTEC, which is might be due to vertical transport processes.
Gunter Stober, Jorge L. Chau, Juha Vierinen, Christoph Jacobi, and Sven Wilhelm
Atmos. Meas. Tech., 11, 4891–4907, https://doi.org/10.5194/amt-11-4891-2018, https://doi.org/10.5194/amt-11-4891-2018, 2018
Jan Karlický, Peter Huszár, Tomáš Halenka, Michal Belda, Michal Žák, Petr Pišoft, and Jiří Mikšovský
Atmos. Chem. Phys., 18, 10655–10674, https://doi.org/10.5194/acp-18-10655-2018, https://doi.org/10.5194/acp-18-10655-2018, 2018
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Our work presents a comparison of modelled and observed urban-induced meteorological changes in long-term perspective using 10-year simulations. It contains an evaluation of models' urban parameterizations, investigations of the benefits of more sophisticated urban parameterizations with respect to simple approaches and evaluation of urban-induced meteorological changes from the perspective of pollutant dispersion.
Petr Šácha, Jiri Miksovsky, and Petr Pisoft
Earth Syst. Dynam., 9, 647–661, https://doi.org/10.5194/esd-9-647-2018, https://doi.org/10.5194/esd-9-647-2018, 2018
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The paper investigates variability in the gravity wave drag in the stratosphere in connection with climate phenomena like the El Niño–Southern Oscillation. This link represents a possible mechanism of tropospheric influence on the higher atmospheric layers, a mechanism of utmost importance that has not been studied in detail yet. The results illustrate that there are indeed significant changes in the gravity wave drag distribution and strength depending on the phase of the studied oscillations.
Sabine Wüst, Thomas Offenwanger, Carsten Schmidt, Michael Bittner, Christoph Jacobi, Gunter Stober, Jeng-Hwa Yee, Martin G. Mlynczak, and James M. Russell III
Atmos. Meas. Tech., 11, 2937–2947, https://doi.org/10.5194/amt-11-2937-2018, https://doi.org/10.5194/amt-11-2937-2018, 2018
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OH*-spectrometer measurements allow the analysis of gravity wave ground-based periods, but spatial information cannot necessarily be deduced. We combine the approach of Wachter at al. (2015) in order to derive horizontal wavelengths (but based on only one OH* spectrometer) with additional information about wind and temperature and compute vertical wavelengths. Knowledge of these parameters is a precondition for the calculation of further information such as the wave group velocity.
Petr Pisoft, Petr Sacha, Jiri Miksovsky, Peter Huszar, Barbara Scherllin-Pirscher, and Ulrich Foelsche
Atmos. Meas. Tech., 11, 515–527, https://doi.org/10.5194/amt-11-515-2018, https://doi.org/10.5194/amt-11-515-2018, 2018
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We revise selected findings regarding utilization of Global Positioning System radio occultation density profiles for analysis of internal gravity waves. The results show that previously published results are valid only for one specific data version only. Using radiosonde profiles, we also analyze a nonhydrostatic component in temperature profiles. The last part presents detailed study on the utilization of density profiles for characterization of the wave field stability.
Christoph Jacobi, Tatiana Ermakova, Daniel Mewes, and Alexander I. Pogoreltsev
Adv. Radio Sci., 15, 199–206, https://doi.org/10.5194/ars-15-199-2017, https://doi.org/10.5194/ars-15-199-2017, 2017
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There is continuous interest in coupling processes between the lower and middle atmosphere. Here we analyse midlatitude winds measured by radar at 82–97 km and find that especially in February they are positively correlated with El Niño. The signal is strong for the upper altitudes accessible to the radar, but weakens below. The observations can be qualitatively reproduced by numerical experiments using a mechanistic global circulation model.
Friederike Lilienthal, Christoph Jacobi, Torsten Schmidt, Alejandro de la Torre, and Peter Alexander
Ann. Geophys., 35, 785–798, https://doi.org/10.5194/angeo-35-785-2017, https://doi.org/10.5194/angeo-35-785-2017, 2017
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Gravity waves (GWs) are one of the most important dynamical features of the middle atmosphere that extends from the tropopause to the lower thermosphere. They originate from the troposphere and propagate upward. Here, we show the impact of the horizontal GW distribution in the lower atmosphere on the dynamics of the middle atmosphere using a global circulation model. As a result, we find that non-zonal GW structures can force additional stationary planetary waves.
Gunter Stober, Vivien Matthias, Christoph Jacobi, Sven Wilhelm, Josef Höffner, and Jorge L. Chau
Ann. Geophys., 35, 711–720, https://doi.org/10.5194/angeo-35-711-2017, https://doi.org/10.5194/angeo-35-711-2017, 2017
Petr Šácha, Friederike Lilienthal, Christoph Jacobi, and Petr Pišoft
Atmos. Chem. Phys., 16, 15755–15775, https://doi.org/10.5194/acp-16-15755-2016, https://doi.org/10.5194/acp-16-15755-2016, 2016
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With a mechanistic model for the middle and upper atmosphere we performed sensitivity simulations to study a possible impact of a localized GW breaking hotspot in the eastern Asia–northern Pacific region and also the possible influence of the spatial distribution of gravity wave activity on the middle atmospheric circulation and transport. We show implications for polar vortex stability, in situ PW generation and longitudinal variability and strength of the Brewer–Dobson circulation.
William T. Ball, Aleš Kuchař, Eugene V. Rozanov, Johannes Staehelin, Fiona Tummon, Anne K. Smith, Timofei Sukhodolov, Andrea Stenke, Laura Revell, Ancelin Coulon, Werner Schmutz, and Thomas Peter
Atmos. Chem. Phys., 16, 15485–15500, https://doi.org/10.5194/acp-16-15485-2016, https://doi.org/10.5194/acp-16-15485-2016, 2016
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We find monthly, mid-latitude temperature changes above 40 km are related to ozone and temperature variations throughout the middle atmosphere. We develop an index to represent this atmospheric variability. In statistical analysis, the index can account for up to 60 % of variability in tropical temperature and ozone above 27 km. The uncertainties can be reduced by up to 35 % and 20 % in temperature and ozone, respectively. This index is an important tool to quantify current and future ozone recovery.
Peter Huszár, Michal Belda, Jan Karlický, Petr Pišoft, and Tomáš Halenka
Atmos. Chem. Phys., 16, 12993–13013, https://doi.org/10.5194/acp-16-12993-2016, https://doi.org/10.5194/acp-16-12993-2016, 2016
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Using an online coupled system of a regional climate model and chemistry transport model we investigated the radiative/climate impact of short-lived pollutants directly emitted by urban areas and those secondarily formed, focusing on the area of central Europe. We found that the direct/indirect effects of aerosols dominate, causing small but statistically significant cooling in summer and winter (up to −0.04 K). The radiative impact of ozone changes remains negligible.
Ch. Jacobi, N. Samtleben, and G. Stober
Adv. Radio Sci., 14, 169–174, https://doi.org/10.5194/ars-14-169-2016, https://doi.org/10.5194/ars-14-169-2016, 2016
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VHF meteor radar observations of mesosphere/lower thermosphere daily temperatures have been performed at Collm, Germany. The data have been analyzed with respect to long-period oscillations at time scales of 2 to 30 days. The results reveal that oscillations with periods of up to 6 days are more frequently observed during summer, while those with longer periods have larger amplitudes during winter. The results are comparable with analyses from radar wind measurements.
Christoph Jacobi, Norbert Jakowski, Gerhard Schmidtke, and Thomas N. Woods
Adv. Radio Sci., 14, 175–180, https://doi.org/10.5194/ars-14-175-2016, https://doi.org/10.5194/ars-14-175-2016, 2016
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The ionospheric response to solar extreme ultraviolet variability is shown by simple proxies based on Solar Dynamics Observatory/Extreme Ultraviolet Variability Experiment solar spectra. The daily proxies are compared with global mean total electron content. At time scales of the solar rotation up to about 40 days there is a time lag between EUV and TEC variability of about one day, with a tendency to increase for longer time scales.
Jiří Mikšovský, Eva Holtanová, and Petr Pišoft
Earth Syst. Dynam., 7, 231–249, https://doi.org/10.5194/esd-7-231-2016, https://doi.org/10.5194/esd-7-231-2016, 2016
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Using regression analysis, near-surface temperatures from several gridded data sets were investigated for the presence of components attributable to external climate forcings and to major internal climate variability modes, over the 1901–2010 period. The spatial patterns of local temperature response and their combination in globally averaged temperature were shown and discussed, with special focus on highlighting the inter-dataset contrasts.
P. Šácha, A. Kuchař, C. Jacobi, and P. Pišoft
Atmos. Chem. Phys., 15, 13097–13112, https://doi.org/10.5194/acp-15-13097-2015, https://doi.org/10.5194/acp-15-13097-2015, 2015
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In this study, we present a discovery of an internal gravity wave activity and breaking hotspot collocated with an area of anomalously low annual cycle amplitude and specific dynamics in the stratosphere over the Northeastern Pacific/Eastern Asia coastal region. The reasons why this particular IGW activity hotspot was not discovered before nor the specific dynamics of this region pointed out are discussed together with possible consequences on the middle atmospheric dynamics and transport.
F. Lilienthal and Ch. Jacobi
Atmos. Chem. Phys., 15, 9917–9927, https://doi.org/10.5194/acp-15-9917-2015, https://doi.org/10.5194/acp-15-9917-2015, 2015
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The quasi 2-day wave (QTDW), one of the most striking features in the mesosphere/lower thermosphere, is analyzed using meteor radar measurements at Collm (51°N, 13°E) during 2004-2014. The QTDW has periods lasting between 43 and 52h during strong summer bursts, and weaker enhancements are found during winter. A correlation between QTDW amplitudes and wind shear suggests baroclinic instability to be a likely forcing mechanism.
A. Kuchar, P. Sacha, J. Miksovsky, and P. Pisoft
Atmos. Chem. Phys., 15, 6879–6895, https://doi.org/10.5194/acp-15-6879-2015, https://doi.org/10.5194/acp-15-6879-2015, 2015
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We have studied the solar cycle manifestation in the latest generation of the reanalysed data sets by the means of both linear and nonlinear attribution analyses. The study is supplemented by the discussion of the dynamical implications.
P. Šácha, U. Foelsche, and P. Pišoft
Atmos. Meas. Tech., 7, 4123–4132, https://doi.org/10.5194/amt-7-4123-2014, https://doi.org/10.5194/amt-7-4123-2014, 2014
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In the presented paper, we introduce a method for the density background separation and a methodology for internal gravity waves analysis using the GPS RO density profiles. Various background choices are discussed, and the correspondence between analytical forms of the density and dry temperature background profiles is examined. Finally the advantages of the density instead of dry temperature GPS RO data utilization are listed (e.g. inclusion of non-hydrostatic waves).
G. Schmidtke, Ch. Jacobi, B. Nikutowski, and Ch. Erhardt
Adv. Radio Sci., 12, 251–260, https://doi.org/10.5194/ars-12-251-2014, https://doi.org/10.5194/ars-12-251-2014, 2014
F. Lilienthal and Ch. Jacobi
Adv. Radio Sci., 12, 205–210, https://doi.org/10.5194/ars-12-205-2014, https://doi.org/10.5194/ars-12-205-2014, 2014
Ch. Jacobi
Adv. Radio Sci., 12, 161–165, https://doi.org/10.5194/ars-12-161-2014, https://doi.org/10.5194/ars-12-161-2014, 2014
Related subject area
Subject: Terrestrial atmosphere and its relation to the sun | Keywords: Middle atmosphere dynamics
The Role of Gravity Waves in the Mesosphere Inversion Layers (MILs) over low-latitude (3–15° N) Using SABER Satellite Observations
Propagating characteristics of mesospheric gravity waves observed by an OI 557.7 nm airglow all-sky camera at Mt. Bohyun (36.2° N, 128.9° E)
Modelling the residual mean meridional circulation at different stages of sudden stratospheric warming events
Stratospheric influence on the mesosphere–lower thermosphere over mid latitudes in winter observed by a Fabry–Perot interferometer
Migrating and non-migrating tides observed in the stratosphere from FORMOSAT-3/COSMIC temperature retrievals
Local stratopause temperature variabilities and their embedding in the global context
Relation between the interannual variability in the stratospheric Rossby wave forcing and zonal mean fields suggesting an interhemispheric link in the stratosphere
Stratospheric observations of noctilucent clouds: a new approach in studying middle- and large-scale mesospheric dynamics
High-resolution Beijing mesosphere–stratosphere–troposphere (MST) radar detection of tropopause structure and variability over Xianghe (39.75° N, 116.96° E), China
Effect of latitudinally displaced gravity wave forcing in the lower stratosphere on the polar vortex stability
Global analysis for periodic variations in gravity wave squared amplitudes and momentum fluxes in the middle atmosphere
Notes on the correlation between sudden stratospheric warmings and solar activity
Connection between the length of day and wind measurements in the mesosphere and lower thermosphere at mid- and high latitudes
Semidiurnal solar tide differences between fall and spring transition times in the Northern Hemisphere
Chalachew Lingerew and Jaya Prakash Raju
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2023-34, https://doi.org/10.5194/angeo-2023-34, 2023
Revised manuscript accepted for ANGEO
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The study uses SABER data to analyze the MIL phenomenon and its causative gravity wave potential energy and instability. The upper MLT inversion frequency is below 40 %, while lower inversions are below 20 %. The high potential energy (~100 J/kg) of gravity waves in the upper MLT region (85 and 90 km) is due to instability, causing large inversion phenomena. while the reverse is true in the lower MLT regions.
Jun-Young Hwang, Young-Sook Lee, Yong Ha Kim, Hosik Kam, Seok-Min Song, Young-Sil Kwak, and Tae-Yong Yang
Ann. Geophys., 40, 247–257, https://doi.org/10.5194/angeo-40-247-2022, https://doi.org/10.5194/angeo-40-247-2022, 2022
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We analysed all-sky camera images observed at Mt. Bohyun observatory (36.2° N, 128.9° E) for the period of 2017–2019. We retrieved gravity wave parameters including horizontal wavelength, phase velocity and period from the image data. The horizontally propagating directions of the wave were biased according to their seasons, exerted with filtering effect by prevailing background winds. We also evaluated the nature of vertical propagation of the wave for each season.
Andrey V. Koval, Wen Chen, Ksenia A. Didenko, Tatiana S. Ermakova, Nikolai M. Gavrilov, Alexander I. Pogoreltsev, Olga N. Toptunova, Ke Wei, Anna N. Yarusova, and Anton S. Zarubin
Ann. Geophys., 39, 357–368, https://doi.org/10.5194/angeo-39-357-2021, https://doi.org/10.5194/angeo-39-357-2021, 2021
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Numerical modelling is used to simulate atmospheric circulation and calculate residual mean meridional circulation (RMC) during sudden stratospheric warming (SSW) events. Calculating the RMC is used to take into account wave effects on the transport of atmospheric quantities and gas species in the meridional plane. The results show that RMC undergoes significant changes at different stages of SSW and contributes to SSW development.
Olga S. Zorkaltseva and Roman V. Vasilyev
Ann. Geophys., 39, 267–276, https://doi.org/10.5194/angeo-39-267-2021, https://doi.org/10.5194/angeo-39-267-2021, 2021
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One of the fundamental tasks of atmospheric physics is the study of the processes of vertical interaction of atmospheric layers. We carried out observations with a Fabry–Perot interferometer at an altitude of 90–100 km. We have shown that sudden stratospheric warming and active planetary waves have an impact on the dynamics of the upper atmosphere. That is, the green line airglow decreases and the temperature rises. Major warming causes the reversal of the zonal wind in the upper atmosphere.
Uma Das, William E. Ward, Chen Jeih Pan, and Sanat Kumar Das
Ann. Geophys., 38, 421–435, https://doi.org/10.5194/angeo-38-421-2020, https://doi.org/10.5194/angeo-38-421-2020, 2020
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Temperatures obtained from FORMOSAT-3 and COSMIC observations in the stratosphere are analysed for tidal variations. It is seen that non-migrating tides are not very significant in the high-latitude winter stratosphere. It is shown that the observed amplitudes of these tides in earlier studies are most probably a result of aliasing and are not geophysical in nature. Thus, the process of non-linear interactions through which it was believed that they are produced seems to be unimportant.
Ronald Eixmann, Vivien Matthias, Josef Höffner, Gerd Baumgarten, and Michael Gerding
Ann. Geophys., 38, 373–383, https://doi.org/10.5194/angeo-38-373-2020, https://doi.org/10.5194/angeo-38-373-2020, 2020
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The aim of this study is to bring local variabilities into a global context. To qualitatively study the impact of global waves on local measurements in winter, we combine local lidar measurements with global MERRA-2 reanalysis data. Our results show that about 98 % of the local day-to-day variability can be explained by the variability of waves with zonal wave numbers 1, 2 and 3. Thus locally measured effects which are not based on global wave variability can be investigated much better.
Yuki Matsushita, Daiki Kado, Masashi Kohma, and Kaoru Sato
Ann. Geophys., 38, 319–329, https://doi.org/10.5194/angeo-38-319-2020, https://doi.org/10.5194/angeo-38-319-2020, 2020
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Interannual variabilities of the zonal mean wind and temperature related to the Rossby wave forcing in the winter stratosphere of the Southern Hemisphere are studied using 38-year reanalysis data. Correlation of the mean fields to the wave forcing is extended to the subtropics of the Northern Hemisphere. This interhemispheric link is caused by the wave forcing which reduces the meridional gradient of the angular momentum and drives the meridional circulation over the Equator in the stratosphere.
Peter Dalin, Nikolay Pertsev, Vladimir Perminov, Denis Efremov, and Vitaly Romejko
Ann. Geophys., 38, 61–71, https://doi.org/10.5194/angeo-38-61-2020, https://doi.org/10.5194/angeo-38-61-2020, 2020
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A unique stratospheric balloon-borne observation of noctilucent clouds (NLCs) was performed at night on 5–6 July 2018. A sounding balloon, carrying the NLC camera, reached 20.4 km altitude. NLCs were observed from the stratosphere at large scales (100–1500 km) for the first time. Propagations of gravity waves of various scales were registered. This experiment is rather simple and can be reproduced by the broad geoscience community and amateurs, providing a new technique in NLC observations.
Feilong Chen, Gang Chen, Yufang Tian, Shaodong Zhang, Kaiming Huang, Chen Wu, and Weifan Zhang
Ann. Geophys., 37, 631–643, https://doi.org/10.5194/angeo-37-631-2019, https://doi.org/10.5194/angeo-37-631-2019, 2019
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Using the Beijing MST radar echo-power observations collected during the period November 2011–May 2017, the structure and variability of the tropopause over Xianghe, China (39.75° N, 116.96° E), was presented. Our comparison results showed a good agreement between the radar and thermal tropopauses during all seasons. In contrast, the consistency between the radar and dynamical tropopauses is poor during summer. Diurnal oscillation in tropopause height is commonly observed during all seasons.
Nadja Samtleben, Christoph Jacobi, Petr Pišoft, Petr Šácha, and Aleš Kuchař
Ann. Geophys., 37, 507–523, https://doi.org/10.5194/angeo-37-507-2019, https://doi.org/10.5194/angeo-37-507-2019, 2019
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Simulations of locally breaking gravity wave hot spots in the stratosphere show a suppression of wave propagation at midlatitudes, which is partly compensated for by additional wave propagation through the polar region. This leads to a displacement of the polar vortex towards lower latitudes. The effect is highly dependent on the position of the artificial gravity wave forcing. It is strongest (weakest) for hot spots at lower to middle latitudes (higher latitudes).
Dan Chen, Cornelia Strube, Manfred Ern, Peter Preusse, and Martin Riese
Ann. Geophys., 37, 487–506, https://doi.org/10.5194/angeo-37-487-2019, https://doi.org/10.5194/angeo-37-487-2019, 2019
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In this paper, for the first time, absolute gravity wave momentum flux (GWMF) on temporal scales from terannual variation up to solar cycle length is investigated. The systematic spectral analysis of SABER absolute GWMF is presented and physically interpreted. The various roles of filtering and oblique propagating are discussed, which is likely an important factor for MLT dynamics, and hence can be used as a stringent test bed of the reproduction of such features in global models.
Ekaterina Vorobeva
Ann. Geophys., 37, 375–380, https://doi.org/10.5194/angeo-37-375-2019, https://doi.org/10.5194/angeo-37-375-2019, 2019
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We investigated the statistical relationship between solar activity and the occurrence rate of major sudden stratospheric warmings (MSSWs). For this purpose, the 10.7 cm radio flux (F10.7) has been used as a proxy for solar activity. The calculations have been performed based on two datasets of central day (NCEP–NCAR-I and combined ERA) for the period from 1958 to 2013. The analysis revealed a positive correlation between MSSW events and solar activity.
Sven Wilhelm, Gunter Stober, Vivien Matthias, Christoph Jacobi, and Damian J. Murphy
Ann. Geophys., 37, 1–14, https://doi.org/10.5194/angeo-37-1-2019, https://doi.org/10.5194/angeo-37-1-2019, 2019
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This study shows that the mesospheric winds are affected by an expansion–shrinking of the mesosphere and lower thermosphere that takes place due to changes in the intensity of the solar radiation, which affects the density within the atmosphere. On seasonal timescales, an increase in the neutral density occurs together with a decrease in the eastward-directed zonal wind. Further, even after removing the seasonal and the 11-year solar cycle variations, we show a connection between them.
J. Federico Conte, Jorge L. Chau, Fazlul I. Laskar, Gunter Stober, Hauke Schmidt, and Peter Brown
Ann. Geophys., 36, 999–1008, https://doi.org/10.5194/angeo-36-999-2018, https://doi.org/10.5194/angeo-36-999-2018, 2018
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Based on comparisons of meteor radar measurements with HAMMONIA model simulations, we show that the differences exhibited by the semidiurnal solar tide (S2) observed at middle and high latitudes of the Northern Hemisphere between equinox times are mainly due to distinct behaviors of the migrating semidiurnal (SW2) and the non-migrating westward-propagating wave number 1 semidiurnal (SW1) tidal components.
Cited articles
Albers, J. R. and Birner, T.: Vortex Preconditioning due to Planetary and
Gravity Waves prior to Sudden Stratospheric Warmings, J. Atmos. Sci., 71,
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Short summary
The additional transfer of momentum and energy induced by locally breaking gravity wave hotspots in the lower stratosphere may lead to a destabilization of the polar vortex, which is strongly dependent on the position of the hotspot. The simulations with a global circulation model show that hotspots located above Eurasia cause a total decrease in the stationary planetary wave (SPW) activity, while the impact of hotspots located in North America mostly increase the SPW activity.
The additional transfer of momentum and energy induced by locally breaking gravity wave hotspots...
