Articles | Volume 16, issue 5
https://doi.org/10.5194/acp-16-3279-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/acp-16-3279-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
14 Mar 2016
Research article |
| 14 Mar 2016
Semi-annual oscillation (SAO) of the nighttime ionospheric D region as detected through ground-based VLF receivers
Department of Geosciences, Tel Aviv University, Tel Aviv,
Israel
Colin Price
Department of Geosciences, Tel Aviv University, Tel Aviv,
Israel
Craig J. Rodger
Department of Physics, University of Otago, Dunedin, New
Zealand
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We explore how well clouds are represented in numerical weather prediction over Antarctica, a very difficult environment for field programs where few studies have been conducted. Fortunately, a 2015–2017 field program for West Antarctica supplied observations. We achieve promising results with newer, more advanced cloud schemes. We need to understand the role of clouds and precipitation in the maintenance of the Antarctic ice mass to understand and predict sea level change over the 21st century.
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Peter Kuma, Adrian J. McDonald, Olaf Morgenstern, Richard Querel, Israel Silber, and Connor J. Flynn
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René Sedlak, Alexandra Zuhr, Carsten Schmidt, Sabine Wüst, Michael Bittner, Goderdzi G. Didebulidze, and Colin Price
Atmos. Meas. Tech., 13, 5117–5128, https://doi.org/10.5194/amt-13-5117-2020, https://doi.org/10.5194/amt-13-5117-2020, 2020
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Gravity wave (GW) activity in the UMLT in the period range 6-480 min is calculated by applying a wavelet analysis to nocturnal temperature time series derived from OH* airglow spectrometers. We analyse measurements from eight different locations at different latitudes.
GW activity shows strong period dependence. We find hardly any seasonal variability for periods below 60 min and a semi-annual cycle for periods longer than 60 min that evolves into an annual cycle around a period of 200 min.
Harriet George, Emilia Kilpua, Adnane Osmane, Timo Asikainen, Milla M. H. Kalliokoski, Craig J. Rodger, Stepan Dubyagin, and Minna Palmroth
Ann. Geophys., 38, 931–951, https://doi.org/10.5194/angeo-38-931-2020, https://doi.org/10.5194/angeo-38-931-2020, 2020
Short summary
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We compared trapped outer radiation belt electron fluxes to high-latitude precipitating electron fluxes during two interplanetary coronal mass ejections (ICMEs) with opposite magnetic cloud rotation. The electron response had many similarities and differences between the two events, indicating that different acceleration mechanisms acted. Van Allen Probe data were used for trapped electron flux measurements, and Polar Operational Environmental Satellites were used for precipitating flux data.
Keith M. Hines, David H. Bromwich, Sheng-Hung Wang, Israel Silber, Johannes Verlinde, and Dan Lubin
Atmos. Chem. Phys., 19, 12431–12454, https://doi.org/10.5194/acp-19-12431-2019, https://doi.org/10.5194/acp-19-12431-2019, 2019
Short summary
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We explore how well clouds are represented in numerical weather prediction over Antarctica, a very difficult environment for field programs where few studies have been conducted. Fortunately, a 2015–2017 field program for West Antarctica supplied observations. We achieve promising results with newer, more advanced cloud schemes. We need to understand the role of clouds and precipitation in the maintenance of the Antarctic ice mass to understand and predict sea level change over the 21st century.
Y. Yair, S. Shalev, Z. Erlich, A. Agrachov, E. Katz, H. Saaroni, C. Price, and B. Ziv
Nat. Hazards Earth Syst. Sci., 14, 165–173, https://doi.org/10.5194/nhess-14-165-2014, https://doi.org/10.5194/nhess-14-165-2014, 2014
M. E. Andersson, P. T. Verronen, C. J. Rodger, M. A. Clilverd, and S. Wang
Atmos. Chem. Phys., 14, 1095–1105, https://doi.org/10.5194/acp-14-1095-2014, https://doi.org/10.5194/acp-14-1095-2014, 2014
Related subject area
Subject: Dynamics | Research Activity: Remote Sensing | Altitude Range: Mesosphere | Science Focus: Physics (physical properties and processes)
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Natalie Kaifler, Bernd Kaifler, Markus Rapp, Guiping Liu, Diego Janches, Gerd Baumgarten, and Jose-Luis Hormaechea
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Noctilucent clouds (NLCs) are silvery clouds that can be viewed during twilight and indicate atmospheric conditions like temperature and water vapor in the upper mesosphere. High-resolution measurements from a remote sensing laser instrument provide NLC height, brightness, and occurrence rate since 2017. Most observations occur in the morning hours, likely caused by strong tidal winds, and NLC ice particles are thus transported from elsewhere to the observing location in the Southern Hemisphere.
Sandra Wallis, Matthew DeLand, and Christian von Savigny
EGUsphere, https://doi.org/10.5194/egusphere-2024-2165, https://doi.org/10.5194/egusphere-2024-2165, 2024
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The 2022 Hunga eruption emitted about 150 Tg H2O that partly reached the upper polar SH mesosphere in the beginning of 2024. Noctilucent clouds (NLC) did not show a clear perturbation in their occurrence frequency, but the slight increase from mid-January to February could potentially be caused by the additional H2O. It needs 2 years to reach the summer polar mesopause region, analogous to the 1883 Krakatau eruption that is argued to have caused the first sightings of NCLs.
Qinzeng Li, Jiyao Xu, Aditya Riadi Gusman, Hanli Liu, Wei Yuan, Weijun Liu, Yajun Zhu, and Xiao Liu
Atmos. Chem. Phys., 24, 8343–8361, https://doi.org/10.5194/acp-24-8343-2024, https://doi.org/10.5194/acp-24-8343-2024, 2024
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The 2022 Hunga Tonga–Hunga Ha’apai (HTHH) volcanic eruption not only triggered broad-spectrum atmospheric waves but also generated unusual tsunamis which can generate atmospheric gravity waves (AGWs). Multiple strong atmospheric waves were observed in the far-field area of the 2022 HTHH volcano eruption in the upper atmosphere by a ground-based airglow imager network. AGWs caused by tsunamis can propagate to the mesopause region; there is a good match between atmospheric waves and tsunamis.
Prosper K. Nyassor, Cristiano M. Wrasse, Igo Paulino, Cosme A. O. B. Figueiredo, Ricardo A. Buriti, Hisao Takahashi, Delano Gobbi, and Gabriel A. Giongo
EGUsphere, https://doi.org/10.5194/egusphere-2024-1982, https://doi.org/10.5194/egusphere-2024-1982, 2024
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This work studies the dynamics of momentum and energy of upward and downward GW. From photometer, the vertical component of GWs were observed and horizontal component from an all-sky imager. Using these parameters from these two instruments and wind from meteor radar, the momentum flux and energy of the waves were determined and studied. It was observed that the dynamics of the downward GWs is opposite to that of the upward GWs.
Klemens Hocke, Wenyue Wang, and Guanyi Ma
Atmos. Chem. Phys., 24, 5837–5846, https://doi.org/10.5194/acp-24-5837-2024, https://doi.org/10.5194/acp-24-5837-2024, 2024
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We find a sudden stratospheric warming (SSW) effect in the F2 critical frequency (foF2) series for Okinawa. Across 29 SSW events, the amplitude of the semidiurnal cycle of foF2 peaks at the SSW onset in the SSW years. In these years, we find, for the first time, a lunar terdiurnal component with a relative amplitude of about 5 %, and lunar diurnal and semidiurnal components have relative amplitudes of about 10 %. The periods of lunar ionospheric tidal variations align with those of ocean tides.
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.
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.
Jan Laštovička
Atmos. Chem. Phys., 23, 5783–5800, https://doi.org/10.5194/acp-23-5783-2023, https://doi.org/10.5194/acp-23-5783-2023, 2023
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Increasing concentration of greenhouse gases, particularly of CO2, in the atmosphere causes well-known heating of the troposphere and surface. However, the increasing concentration of CO2 also affects higher levels of the atmosphere, the stratosphere, mesosphere, thermosphere, and ionosphere, where it results in remarkable long-term trends. This article reviews significant progress in investigations of long-term trends in the mesosphere, thermosphere, and ionosphere during the period 2018–2022.
Cornelius Csar Jude H. Salinas, Dong L. Wu, Jae N. Lee, Loren C. Chang, Liying Qian, and Hanli Liu
Atmos. Chem. Phys., 23, 1705–1730, https://doi.org/10.5194/acp-23-1705-2023, https://doi.org/10.5194/acp-23-1705-2023, 2023
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Upper mesospheric carbon monoxide's (CO) photochemical lifetime is longer than dynamical timescales. This work uses satellite observations and model simulations to establish that the migrating diurnal tide and its seasonal and interannual variabilities drive CO primarily through vertical advection. Vertical advection is a transport process that is currently difficult to observe. This work thus shows that we can use CO as a tracer for vertical advection across seasonal and interannual timescales.
Sabine Wüst, Michael Bittner, Patrick J. Espy, W. John R. French, and Frank J. Mulligan
Atmos. Chem. Phys., 23, 1599–1618, https://doi.org/10.5194/acp-23-1599-2023, https://doi.org/10.5194/acp-23-1599-2023, 2023
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Ground-based OH* airglow measurements have been carried out for almost 100 years. Advanced detector technology has greatly simplified the automatic operation of OH* airglow observing instruments and significantly improved the temporal and/or spatial resolution. Studies based on long-term measurements or including a network of instruments are reviewed, especially in the context of deriving gravity wave properties. Scientific and technical challenges for the next few years are described.
Natalie Kaifler, Bernd Kaifler, Markus Rapp, and David C. Fritts
Atmos. Chem. Phys., 23, 949–961, https://doi.org/10.5194/acp-23-949-2023, https://doi.org/10.5194/acp-23-949-2023, 2023
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We used a lidar to measure polar mesospheric clouds from a balloon floating in the upper stratosphere. The thin-layered ice clouds at 83 km altitude are perturbed by waves. The high-resolution lidar soundings reveal small-scale structures induced by the breaking of those waves. We study these patterns and find that they occur very often. We show their morphology and discuss associated dynamical physical processes, which help to interpret case studies and to guide modelling.
Prosper K. Nyassor, Cristiano M. Wrasse, Igo Paulino, Eliah F. M. T. São Sabbas, José V. Bageston, Kleber P. Naccarato, Delano Gobbi, Cosme A. O. B. Figueiredo, Toyese T. Ayorinde, Hisao Takahashi, and Diego Barros
Atmos. Chem. Phys., 22, 15153–15177, https://doi.org/10.5194/acp-22-15153-2022, https://doi.org/10.5194/acp-22-15153-2022, 2022
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This work investigates the sources of concentric gravity waves (CGWs) excited by a moving system of clouds with several overshooting regions on 1–2 October 2019 at São Martinho da Serra. The parameters of these waves were estimated using 2D spectral analysis and their source locations identified using backward ray tracing. Furthermore, the sources of these waves were properly identified by tracking the individual overshooting regions in space and time since the system of clouds was moving.
Qinzeng Li, Jiyao Xu, Hanli Liu, Xiao Liu, and Wei Yuan
Atmos. Chem. Phys., 22, 12077–12091, https://doi.org/10.5194/acp-22-12077-2022, https://doi.org/10.5194/acp-22-12077-2022, 2022
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We use ground-based airglow network observations, reanalysis data, and satellite observations to explore the propagation process of concentric gravity waves (CGWs) excited by a typhoon between the troposphere, stratosphere, mesosphere, and thermosphere. We find that CGWs in the mesosphere are generated directly by the typhoon but the CGW observed in the thermosphere may be excited by CGW dissipation in the mesosphere, rather than directly excited by a typhoon and propagated to the thermosphere.
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.
Manfred Ern, Mohamadou Diallo, Peter Preusse, Martin G. Mlynczak, Michael J. Schwartz, Qian Wu, and Martin Riese
Atmos. Chem. Phys., 21, 13763–13795, https://doi.org/10.5194/acp-21-13763-2021, https://doi.org/10.5194/acp-21-13763-2021, 2021
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Details of the driving of the semiannual oscillation (SAO) of the tropical winds in the middle atmosphere are still not known. We investigate the SAO and its driving by small-scale gravity waves (GWs) using satellite data and different reanalyses. In a large altitude range, GWs mainly drive the SAO westerlies, but in the upper mesosphere GWs seem to drive both SAO easterlies and westerlies. Reanalyses reproduce some features of the SAO but are limited by model-inherent damping at upper levels.
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
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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.
Bingkun Yu, Xianghui Xue, Christopher J. Scott, Jianfei Wu, Xinan Yue, Wuhu Feng, Yutian Chi, Daniel R. Marsh, Hanli Liu, Xiankang Dou, and John M. C. Plane
Atmos. Chem. Phys., 21, 4219–4230, https://doi.org/10.5194/acp-21-4219-2021, https://doi.org/10.5194/acp-21-4219-2021, 2021
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A long-standing mystery of metal ions within Es layers in the Earth's upper atmosphere is the marked seasonal dependence, with a summer maximum and a winter minimum. We report a large-scale winter-to-summer transport of metal ions from 6-year multi-satellite observations and worldwide ground-based stations. A global atmospheric circulation is responsible for the phenomenon. Our results emphasise the effect of this atmospheric circulation on the transport of composition in the upper atmosphere.
Viswanathan Lakshmi Narayanan, Satonori Nozawa, Shin-Ichiro Oyama, Ingrid Mann, Kazuo Shiokawa, Yuichi Otsuka, Norihito Saito, Satoshi Wada, Takuya D. Kawahara, and Toru Takahashi
Atmos. Chem. Phys., 21, 2343–2361, https://doi.org/10.5194/acp-21-2343-2021, https://doi.org/10.5194/acp-21-2343-2021, 2021
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In the past, additional sodium peaks occurring above the main sodium layer of the upper mesosphere were discussed. Here, formation of an additional sodium peak below the main sodium layer peak is discussed in detail. The event coincided with passage of multiple mesospheric bores, which are step-like disturbances occurring in the upper mesosphere. Hence, this work highlights the importance of such mesospheric bores in causing significant changes to the minor species concentration in a short time.
Xiao Liu, Jiyao Xu, Jia Yue, and Hanli Liu
Atmos. Chem. Phys., 20, 14437–14456, https://doi.org/10.5194/acp-20-14437-2020, https://doi.org/10.5194/acp-20-14437-2020, 2020
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Large wind shears in the mesosphere and lower thermosphere are recognized as a common phenomenon. Simulation and ground-based observations show that the main contributor of large wind shears is gravity waves. We present a method of deriving wind shears induced by gravity waves according to the linear theory and using the global temperature observations by SABER (Sounding of the Atmosphere using Broadband Emission Radiometry). Our results agree well with observations and model simulations.
Gunter Stober, Kathrin Baumgarten, John P. McCormack, Peter Brown, and Jerry Czarnecki
Atmos. Chem. Phys., 20, 11979–12010, https://doi.org/10.5194/acp-20-11979-2020, https://doi.org/10.5194/acp-20-11979-2020, 2020
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This paper presents a first cross-comparison of meteor ground-based observations and a meteorological analysis (NAVGEM-HA) to compare a seasonal climatology of winds and temperatures at the mesosphere/lower thermosphere. The validation is insofar unique as we not only compare the mean state but also provide a detailed comparison of the short time variability of atmospheric tidal waves. Our analysis questions previous results claiming the importance of lunar tides.
W. John R. French, Andrew R. Klekociuk, and Frank J. Mulligan
Atmos. Chem. Phys., 20, 8691–8708, https://doi.org/10.5194/acp-20-8691-2020, https://doi.org/10.5194/acp-20-8691-2020, 2020
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We explore a quasi-quadrennial oscillation (QQO; 3–4 K amplitude, ~ 4-year period) in mesopause region temperatures observed in 24 years of hydroxyl airglow measurements over Davis, Antarctica (68° S, 78° E). Correlation and composite analysis using meteorological reanalysis and satellite data reveals complex patterns on the QQO timescale in both hemispheres. Modulation of the meridional circulation, linked to the propagation of gravity waves, plays a significant role in producing the QQO response.
Jörg Gumbel, Linda Megner, Ole Martin Christensen, Nickolay Ivchenko, Donal P. Murtagh, Seunghyuk Chang, Joachim Dillner, Terese Ekebrand, Gabriel Giono, Arvid Hammar, Jonas Hedin, Bodil Karlsson, Mikael Krus, Anqi Li, Steven McCallion, Georgi Olentšenko, Soojong Pak, Woojin Park, Jordan Rouse, Jacek Stegman, and Georg Witt
Atmos. Chem. Phys., 20, 431–455, https://doi.org/10.5194/acp-20-431-2020, https://doi.org/10.5194/acp-20-431-2020, 2020
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Gravity waves can link together atmospheric conditions over large distances. MATS is a new Swedish satellite that will study gravity waves at altitudes around 80–110 km. MATS will take images of emissions from excited molecules, so-called airglow, and of the highest clouds in our atmosphere, so-called noctilucent clouds. These measurements will be analysed to provide three-dimensional wave structures and a comprehensive picture of wave interactions in the atmosphere.
Yuke Wang, Valerii Shulga, Gennadi Milinevsky, Aleksey Patoka, Oleksandr Evtushevsky, Andrew Klekociuk, Wei Han, Asen Grytsai, Dmitry Shulga, Valery Myshenko, and Oleksandr Antyufeyev
Atmos. Chem. Phys., 19, 10303–10317, https://doi.org/10.5194/acp-19-10303-2019, https://doi.org/10.5194/acp-19-10303-2019, 2019
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The major sudden stratospheric warming (SSW) dramatically changed atmospheric conditions. This event is accompanied by a sharp increase in the polar stratosphere temperature, zonal wind reverse, and strong changes in the polar mesosphere. These changes affect even the midlatitude mesosphere, which is not widely covered by observations. Our newly installed microwave radiometer allowed for studying mesospheric zonal wind and CO variations to understand the SSW 2018 effects at midlatitudes.
Wen Yi, Xianghui Xue, Iain M. Reid, Damian J. Murphy, Chris M. Hall, Masaki Tsutsumi, Baiqi Ning, Guozhu Li, Robert A. Vincent, Jinsong Chen, Jianfei Wu, Tingdi Chen, and Xiankang Dou
Atmos. Chem. Phys., 19, 7567–7581, https://doi.org/10.5194/acp-19-7567-2019, https://doi.org/10.5194/acp-19-7567-2019, 2019
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The seasonal variations in the mesopause densities, especially with regard to its global structure, are still unclear. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars from Arctic to Antarctic latitudes. The results reveal a significant AO and SAO in mesopause density, an asymmetry between the two polar regions and evidence of intraseasonal oscillations (ISOs), perhaps associated with the ISOs of the troposphere.
Sabine Wüst, Carsten Schmidt, Patrick Hannawald, Michael Bittner, Martin G. Mlynczak, and James M. Russell III
Atmos. Chem. Phys., 19, 6401–6418, https://doi.org/10.5194/acp-19-6401-2019, https://doi.org/10.5194/acp-19-6401-2019, 2019
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In winter 2016, the camera system FAIM derived information about the OH* airglow at ca. 86 km height during six flights on board the research aircraft FALCON in northern Scandinavia. Coincident ground- and satellite-based measurements (GRIPS and TIMED-SABER) complete the data set. The data are analysed with respect to the temporal and spatial evolution of small-scale atmospheric dynamics just before a minor stratospheric warming. Special emphasis is placed on possible instability features.
Maosheng He and Jorge Luis Chau
Atmos. Chem. Phys., 19, 5993–6006, https://doi.org/10.5194/acp-19-5993-2019, https://doi.org/10.5194/acp-19-5993-2019, 2019
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We propose an approach to resolve waves with multiple spatial scales at a given frequency using ground-based detectors from few longitudinal sectors. The approach is used to investigate near-12 h waves. Results suggest that broadly reported enhancements of two solar nonmigrating tides during sudden stratospheric warming events are just low-frequency-resolved signatures of two neighboring waves. The tides do not enhance.
Dimitry Pokhotelov, Gunter Stober, and Jorge Luis Chau
Atmos. Chem. Phys., 19, 5251–5258, https://doi.org/10.5194/acp-19-5251-2019, https://doi.org/10.5194/acp-19-5251-2019, 2019
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Twelve years of radar observations from a mid-latitude location in Kühlungsborn, Germany have been analysed to study characteristics of mesospheric summer echoes (MSEs). The statistical analysis shows that MSEs have a strong daytime preference and early summer seasonal preference. It is demonstrated that the meridional wind transport from polar regions is the important controlling factor for MSEs, while no clear connection to geomagnetic and solar activity is found.
Nikoloz Gudadze, Gunter Stober, and Jorge L. Chau
Atmos. Chem. Phys., 19, 4485–4497, https://doi.org/10.5194/acp-19-4485-2019, https://doi.org/10.5194/acp-19-4485-2019, 2019
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We show a possibility of measuring mean vertical winds during the summer months using polar mesosphere summer echo (PMSE) observations. Middle Atmosphere Alomar Radar System observations of PMSE five-beam radial velocities are analysed to obtain the results. We found that sampling issues are the reason for bias in vertical wind measurements at the edges of PMSE altitudes. However, the PMSE is a good tracer for the mean vertical wind estimation at the central altitudes with its peak occurrence.
Bingkun Yu, Xianghui Xue, Xin'an Yue, Chengyun Yang, Chao Yu, Xiankang Dou, Baiqi Ning, and Lianhuan Hu
Atmos. Chem. Phys., 19, 4139–4151, https://doi.org/10.5194/acp-19-4139-2019, https://doi.org/10.5194/acp-19-4139-2019, 2019
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It reports the long-term climatology of the intensity of Es layers from COSMIC satellites. The global Es maps present high-resolution spatial distributions and seasonal dependence. It mainly occurs at mid-latitudes and polar regions. Based on wind shear theory, simulation results indicate the convergence of vertical ion velocity could partially explain the Es seasonal dependence and some disagreements between observations and simulations suggest other processes play roles in the Es variations.
Xianchang Yue, Jonathan S. Friedman, Qihou Zhou, Xiongbin Wu, and Jens Lautenbach
Atmos. Chem. Phys., 19, 3207–3221, https://doi.org/10.5194/acp-19-3207-2019, https://doi.org/10.5194/acp-19-3207-2019, 2019
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Using 11 years of lidar temperature data, the seasonal variations (SVs) of gravity waves (GWs) are addressed in the tropical mesopause region, shown to be clearly associated with the SVs of zonal winds reported in the literature. The SVs of GWs are determined by the filtering effect of the local background wind. The altitudes of GW potential energy have a close relation to the upper mesospheric temperature inversion layers (TILs), which provides support for the formation mechanism of TILs.
Robert Menke, Nikola Vasiljević, Jakob Mann, and Julie K. Lundquist
Atmos. Chem. Phys., 19, 2713–2723, https://doi.org/10.5194/acp-19-2713-2019, https://doi.org/10.5194/acp-19-2713-2019, 2019
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This research utilizes several months of lidar measurements from the Perdigão 2017 campaign to investigate flow recirculation zones that occur at the two parallel ridges at the measurement site in Portugal. We found that recirculation occurs in over 50 % of the time when the wind direction is perpendicular to the direction of the ridges. Moreover, we show three-dimensional changes of the zones along the ridges and the implications of recirculation on wind turbines that are operating downstream.
Christian von Savigny, Dieter H. W. Peters, and Günter Entzian
Atmos. Chem. Phys., 19, 2079–2093, https://doi.org/10.5194/acp-19-2079-2019, https://doi.org/10.5194/acp-19-2079-2019, 2019
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This study investigates solar effects in radio reflection height observations in the ionospheric D region at an altitude of about 80 km at northern midlatitudes. The analyzed time series covers almost six solar cycles. Statistically significant solar 27-day and 11-year signatures are identified. However, the driving mechanisms are not fully understood. We also provide evidence for dynamical effects on the radio reflection heights with periods close to the solar rotational cycle.
Yuta Hozumi, Akinori Saito, Takeshi Sakanoi, Atsushi Yamazaki, and Keisuke Hosokawa
Atmos. Chem. Phys., 18, 16399–16407, https://doi.org/10.5194/acp-18-16399-2018, https://doi.org/10.5194/acp-18-16399-2018, 2018
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Spatial structures of wave disturbances in the upper atmosphere were investigated with space-borne imaging from the International Space Station. The wave disturbance occurred around an altitude of 100 km, and is called a mesospheric bore. The large-scale structure of mesospheric bores has not been fully captured by previous ground-based imagers, but the space-borne imaging captured a bore with a wide field of view, and showed that bores can have a large undulating wave front as long as 2000 km.
Michael Gerding, Jochen Zöllner, Marius Zecha, Kathrin Baumgarten, Josef Höffner, Gunter Stober, and Franz-Josef Lübken
Atmos. Chem. Phys., 18, 15569–15580, https://doi.org/10.5194/acp-18-15569-2018, https://doi.org/10.5194/acp-18-15569-2018, 2018
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We describe the first comparative study of noctilucent clouds (NLCs) and mesospheric summer echoes at midlatitudes. Therefore, this study compares fresh clouds (small particles) with fully evolved clouds in the mesosphere, hinting at their evolution. It is shown that, in contrast to higher latitudes, here only a thin layer of fresh particles exist above the NLCs. This gives evidence that NLCs are not formed locally but are typically advected. This needs to be acknowledged in trend studies.
Martin Lainer, Klemens Hocke, and Niklaus Kämpfer
Atmos. Chem. Phys., 18, 12061–12074, https://doi.org/10.5194/acp-18-12061-2018, https://doi.org/10.5194/acp-18-12061-2018, 2018
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A long continuous record (in total 7 years) of middle atmospheric water vapor at the midlatitude NDACC station in Bern is investigated to study quasi 2-day wave oscillations (Q2DWs). We present monthly climatologies of the wave amplitudes and show the periods that the Q2DWs developed. What we observe is very-high-frequency variability. An autobicoherence analysis revealed nonlinear phase couplings between Q2DWs and other atmospheric waves. Our results are useful for model validation purposes.
Tao Li, Chao Ban, Xin Fang, Jing Li, Zhaopeng Wu, Wuhu Feng, John M. C. Plane, Jiangang Xiong, Daniel R. Marsh, Michael J. Mills, and Xiankang Dou
Atmos. Chem. Phys., 18, 11683–11695, https://doi.org/10.5194/acp-18-11683-2018, https://doi.org/10.5194/acp-18-11683-2018, 2018
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A total of 154 nights of observations by the USTC Na temperature and wind lidar (32° N, 117° E) suggest significant seasonal variability in the mesopause. Chemistry plays an important role in Na atom formation. More than half of the observed gravity wave (GW) momentum flux (MF), whose divergence determines the GW forcing, is induced by short-period (10 min–2 h) waves. The anticorrelation between MF and zonal wind (U) suggests strong filtering of short-period GWs by semiannual oscillation U.
Jorge L. Chau, Derek McKay, Juha P. Vierinen, Cesar La Hoz, Thomas Ulich, Markku Lehtinen, and Ralph Latteck
Atmos. Chem. Phys., 18, 9547–9560, https://doi.org/10.5194/acp-18-9547-2018, https://doi.org/10.5194/acp-18-9547-2018, 2018
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Combining a phased-array power radar and a phased-array radio telescope, we have been able to identify and characterized horizontal structures and movement of noctilucent clouds, but at 3 m scales instead of optical scales. As a byproduct of our observations, we have studied their angular dependence. We show a new alternative to study these clouds on routine basis and therefore study the atmospheric dynamics that modulate them.
Gunter Stober, Svenja Sommer, Carsten Schult, Ralph Latteck, and Jorge L. Chau
Atmos. Chem. Phys., 18, 6721–6732, https://doi.org/10.5194/acp-18-6721-2018, https://doi.org/10.5194/acp-18-6721-2018, 2018
Kathrin Baumgarten, Michael Gerding, Gerd Baumgarten, and Franz-Josef Lübken
Atmos. Chem. Phys., 18, 371–384, https://doi.org/10.5194/acp-18-371-2018, https://doi.org/10.5194/acp-18-371-2018, 2018
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Gravity waves (GWs) as well as solar tides are a key driving mechanism for the circulation in the Earth's atmosphere. The temporal variation of these waves is studied using a record long 10-day continuous Rayleigh–Mie–Raman lidar sounding at midlatitudes. This data set shows a large variability of these waves on timescales of a few days and therefore provides new insights into wave intermittency phenomena, which can help to improve model simulations.
Martin Lainer, Klemens Hocke, Rolf Rüfenacht, and Niklaus Kämpfer
Atmos. Chem. Phys., 17, 14905–14917, https://doi.org/10.5194/acp-17-14905-2017, https://doi.org/10.5194/acp-17-14905-2017, 2017
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We report on middle-atmospheric water vapor measurements above Bern from the ground-based microwave radiometer MIAWARA (NDACC affiliated) during two winter periods of 6 months. Quasi 18 h oscillations of mesospheric water vapor above 0.1 hPa are observed. Further, the 18 h wave is seen in a zonal wind data set from the Doppler wind radiometer WIRA. Inertia-gravity-wave-induced fluctuations or a nonlinear coupling between tides and quasi 2-day waves are considered as possible drivers.
Jens Hildebrand, Gerd Baumgarten, Jens Fiedler, and Franz-Josef Lübken
Atmos. Chem. Phys., 17, 13345–13359, https://doi.org/10.5194/acp-17-13345-2017, https://doi.org/10.5194/acp-17-13345-2017, 2017
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We present altitude profiles of winds and temperatures in the Arctic strato- and mesosphere obtained during three Januaries. The data show large year-to-year variations. We compare the observations to model data. For monthly mean profiles we find good agreement below 55 km altitude but also differences of up to 20 K and 20 m s-1 above. The fluctuations during single nights indicate gravity waves. The kinetic energy of such waves is typically 5 to 10 times larger than their potential energy.
Dhvanit Mehta, Andrew J. Gerrard, Yusuke Ebihara, Allan T. Weatherwax, and Louis J. Lanzerotti
Atmos. Chem. Phys., 17, 911–919, https://doi.org/10.5194/acp-17-911-2017, https://doi.org/10.5194/acp-17-911-2017, 2017
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This paper presents an investigation into the sources of atmospheric gravity waves observed at 90 km above Amundsen-Scott South Pole Station, Antarctica. By combining gravity wave characteristics obtained from imager data and a numerical model for 3-D wave propagation through the atmosphere, we find that the development of baroclinic instabilities via displacement of the polar vortex is a significant and unique source of vertically propagating, short-period (< 1 h) gravity waves in the region.
Christoph Kalicinsky, Peter Knieling, Ralf Koppmann, Dirk Offermann, Wolfgang Steinbrecht, and Johannes Wintel
Atmos. Chem. Phys., 16, 15033–15047, https://doi.org/10.5194/acp-16-15033-2016, https://doi.org/10.5194/acp-16-15033-2016, 2016
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The analysis of temperatures in the mesopause region between 1988 to 2015 shows, besides the known correlation with the 11-year solar activity cycle, a trend reversal in 2008 that can be described by a long-term oscillation. Understanding such long periodic oscillations in the atmosphere is of prime importance for climate modelling and predictions of future trends.
Maya García-Comas, Francisco González-Galindo, Bernd Funke, Angela Gardini, Aythami Jurado-Navarro, Manuel López-Puertas, and William E. Ward
Atmos. Chem. Phys., 16, 11019–11041, https://doi.org/10.5194/acp-16-11019-2016, https://doi.org/10.5194/acp-16-11019-2016, 2016
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In this paper, for the first time, temperature longitudinal oscillations are derived from 20 to 150 km from a single instrument. A climatology of amplitudes and phases of zonal waves with odd daily frequencies is presented on a global scale. The interannual variability in amplitudes of the migrating modes shows a QBO in the MLT, which is probably originated in the stratosphere. The results are useful for testing general circulation models considering tidal effects in the MLT region.
Silje Eriksen Holmen, Chris M. Hall, and Masaki Tsutsumi
Atmos. Chem. Phys., 16, 7853–7866, https://doi.org/10.5194/acp-16-7853-2016, https://doi.org/10.5194/acp-16-7853-2016, 2016
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Atmospheric temperatures at 90 km height above Tromsø, Norway, from 2003 to 2014 have been determined using meteor radar. Periodic oscillations ranging from ~ 9 days to a year were found in the dataset, which were related to the large-scale circulation in the middle atmosphere and with wave activity. A trend analysis was performed, revealing an overall weak cooling trend from 2003 to 2014, which is in line with other recent studies on mesopause region (~ 90 km) temperature trends.
Rupesh N. Ghodpage, Michael P. Hickey, Alok K. Taori, Devendraa Siingh, and Parashram T. Patil
Atmos. Chem. Phys., 16, 5611–5621, https://doi.org/10.5194/acp-16-5611-2016, https://doi.org/10.5194/acp-16-5611-2016, 2016
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Gravity-wave-induced oscillations have been characterized over Kolhapur (16.8°N and 74.2°E), India, using the adiabatic variations in OH airglow intensity and temperature data. The results show that there exist large deviations from one investigation to the other. We also use a full-wave model to simulate the response of OH emission to the wave motion and compare the results with observed values. This report discusses the observed wave characteristics and cause of the noted difference.
Rolf Rüfenacht, Klemens Hocke, and Niklaus Kämpfer
Atmos. Chem. Phys., 16, 4915–4925, https://doi.org/10.5194/acp-16-4915-2016, https://doi.org/10.5194/acp-16-4915-2016, 2016
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We quantitatively analyze oscillations with periods from 5 to 50 days in horizontal wind profiles between mid-stratosphere and mesopause based on more than 44 months of data from high, mid- and low latitudes measured by a novel instrument. For the first time, long time series of continuous wind measurements allow direct observations of dynamics throughout this altitude range. The observations agree remarkably well with the ECMWF model in the stratosphere but discrepancies exist in the mesosphere.
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.
N. H. Stray, Y. J. Orsolini, P. J. Espy, V. Limpasuvan, and R. E. Hibbins
Atmos. Chem. Phys., 15, 4997–5005, https://doi.org/10.5194/acp-15-4997-2015, https://doi.org/10.5194/acp-15-4997-2015, 2015
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Planetary wave activity measured in the mesosphere to lower thermosphere is shown to increase drastically after strong stratospheric polar cap wind reversals associated with sudden stratospheric warmings. In addition, a moderate but significant correlation was found between planetary wave enhancement in the mesosphere to lower thermosphere and all stratospheric polar cap wind reversals, irrespective of the strength of the reversal.
M. Pramitha, M. Venkat Ratnam, A. Taori, B. V. Krishna Murthy, D. Pallamraju, and S. Vijaya Bhaskar Rao
Atmos. Chem. Phys., 15, 2709–2721, https://doi.org/10.5194/acp-15-2709-2015, https://doi.org/10.5194/acp-15-2709-2015, 2015
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Sources and propagation characteristics of high-frequency gravity waves observed in the mesosphere using airglow emissions from Gadanki and Hyderabad, India, are investigated using reverse ray tracing. Wave amplitudes are also traced back, including both radiative and diffusive damping. Interestingly, large vertical shears in the horizontal wind are noticed near the ray terminal points (at 10-12km altitude) and are thus identified to be the source for generating the observed gravity waves.
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Short summary
We report for the first time that the semi-annual oscillation (SAO) is one of the dominant oscillations in the nighttime lower ionosphere, using ground-based measurements of VLF signals reflected off the lower part of the ionosphere. We conclude that the origins of this oscillation are oscillatory changes of the D region's electrical characteristics, driven by NOx transport from the lower thermosphere. This oscillation should be considered in lower ionospheric and VLF wave propagation models.
We report for the first time that the semi-annual oscillation (SAO) is one of the dominant...
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