Articles | Volume 13, issue 18
27 Sep 2013
Research article | 27 Sep 2013
Mean winds in the MLT, the SQBO and MSAO over Ascension Island (8° S, 14° W)
K. A. Day and N. J. Mitchell
No articles found.
Neil P. Hindley, Neil Cobbett, David C. Fritts, Diego Janchez, Nicholas J. Mitchell, Tracy Moffat-Griffin, Anne K. Smith, and Corwin J. Wright
Atmos. Chem. Phys. Discuss.,
Revised manuscript under review for ACPShort summary
Here we present observations of winds in the mesosphere and lower thermosphere (MLT) from a recently installed meteor radar on the remote island of South Georgia (54° S, 36° W). We characterise mean winds, tides, planetary waves and gravity waves in the MLT at this location and compare our measured winds to a leading climate model. We find that the observed wintertime winds are unexpectedly reversed from model predictions, likely due to missing impacts of secondary gravity waves in the model.
Matthew J. Griffith, Shaun M. Dempsey, David R. Jackson, Tracy Moffat-Griffin, and Nicholas J. Mitchell
Ann. Geophys., 39, 487–514,Short summary
There is great scientific interest in extending atmospheric models upwards to include the upper atmosphere. The Met Office’s Unified Model has recently been successfully extended to include this region. Atmospheric tides are an important driver of atmospheric motion at these greater heights. This paper provides a first comparison of winds and tides produced by the new extended model with meteor radar observations, comparing key tidal properties and discussing their similarities and differences.
Neil P. Hindley, Corwin J. Wright, Alan M. Gadian, Lars Hoffmann, John K. Hughes, David R. Jackson, John C. King, Nicholas J. Mitchell, Tracy Moffat-Griffin, Andrew C. Moss, Simon B. Vosper, and Andrew N. Ross
Atmos. Chem. Phys., 21, 7695–7722,Short summary
One limitation of numerical atmospheric models is spatial resolution. For atmospheric gravity waves (GWs) generated over small mountainous islands, the driving effect of these waves on atmospheric circulations can be underestimated. Here we use a specialised high-resolution model over South Georgia island to compare simulated stratospheric GWs to colocated 3-D satellite observations. We find reasonable model agreement with observations, with some GW amplitudes much larger than expected.
Neil P. Hindley, Corwin J. Wright, Nathan D. Smith, Lars Hoffmann, Laura A. Holt, M. Joan Alexander, Tracy Moffat-Griffin, and Nicholas J. Mitchell
Atmos. Chem. Phys., 19, 15377–15414,Short summary
In this study, a 3–D Stockwell transform is applied to AIRS–Aqua satellite observations in the first extended 3–D study of stratospheric gravity waves over the Southern Ocean during winter. A dynamic environment is revealed that contains some of the most intense gravity wave sources on Earth. A particularly striking result is a large–scale meridional convergence of gravity wave momentum flux towards latitudes near 60 °S, something which is not normally considered in model parameterisations.
Corwin J. Wright, Neil P. Hindley, Lars Hoffmann, M. Joan Alexander, and Nicholas J. Mitchell
Atmos. Chem. Phys., 17, 8553–8575,Short summary
We introduce a novel 3-D method of measuring atmospheric gravity waves, based around a 3-D Stockwell transform. Our method lets us measure new properties, including wave intrinsic frequencies and phase and group velocities. We apply it to data from the AIRS satellite instrument over the Southern Andes for two consecutive winters. Our results show clear evidence that the waves measured are primarily orographic in origin, and that their group velocity vectors are focused into the polar night jet.
Neil P. Hindley, Nathan D. Smith, Corwin J. Wright, D. Andrew S. Rees, and Nicholas J. Mitchell
Atmos. Meas. Tech., 9, 2545–2565,Short summary
Gravity waves are medium-sized momentum-carrying atmospheric waves that nearly all weather and climate models struggle to represent. Thus, the accurate global measurement of gravity-wave properties in the real atmosphere is of key importance. Here we use a new two-dimensional Stockwell transform (2-DST) method to measure key GW properties in 2-D satellite data. We show that our 2-DST approach greatly improves upon current methods, particularly if a new elliptical spectral window is used.
Corwin J. Wright, Neil P. Hindley, Andrew C. Moss, and Nicholas J. Mitchell
Atmos. Meas. Tech., 9, 877–908,Short summary
Seven gravity-wave-resolving instruments (satellites, radiosondes and a meteor radar) are used to compare gravity-wave energy and vertical wavelength over the Southern Andes hotspot. Several conclusions are drawn, including that limb sounders and the radar show strong positive correlations. Radiosondes and AIRS weakly anticorrelate with other instruments and we see strong correlations with local stratospheric winds. Short-timescale variability is larger than the seasonal cycle.
Andrew C. Moss, Corwin J. Wright, Robin N. Davis, and Nicholas J. Mitchell
Ann. Geophys., 34, 323–330,Short summary
Gravity waves are fundamental to the dynamics of the mesosphere. In some years very strong winds are observed in the first phase of the MSAO. It has been proposed that this is due to filtering of ascending gravity waves. We report the first gravity-wave momentum flux observations from the Ascension Island (8° S, 14° W) meteor radar and show that anomalous fluxes were observed during one such event in 2002. Analysis of the underlying winds suggests the wave-filtering hypothesis is not valid.
H. Iimura, D. C. Fritts, D. Janches, W. Singer, and N. J. Mitchell
Ann. Geophys., 33, 1349–1359,Short summary
The quasi-5-day wave at mid- and high-latitudes in the mesosphere and lower-thermosphere was compared between the hemispheres using meteor radar horizontal wind measurements, spanning June 2010 to December 2012. Variances of the quasi-5-day wave showed a wave activity from July to August in both hemispheres and in April 2012 in the Northern Hemisphere and November 2012 in the Southern Hemisphere with unique characteristics at each site.
N. P. Hindley, C. J. Wright, N. D. Smith, and N. J. Mitchell
Atmos. Chem. Phys., 15, 7797–7818,Short summary
In nearly all GCMs, unresolved gravity wave (GW) drag may cause the southern stratospheric winter polar vortex to break down too late. Here, we characterise GWs in this region of the atmosphere using GPS radio occultation. We find GWs may propagate into the region from other latitudes. We develop a new quantitative wave identification method to learn about regional wave populations. We also find intense GW momentum fluxes over the southern Andes and Antarctic Peninsula GW hot spot.
R. N. Davis, J. Du, A. K. Smith, W. E. Ward, and N. J. Mitchell
Atmos. Chem. Phys., 13, 9543–9564,
Related subject area
Subject: Dynamics | Research Activity: Remote Sensing | Altitude Range: Mesosphere | Science Focus: Physics (physical properties and processes)Interhemispheric differences of mesosphere–lower thermosphere winds and tides investigated from three whole-atmosphere models and meteor radar observationsThe semiannual oscillation (SAO) in the tropical middle atmosphere and its gravity wave driving in reanalyses and satellite observationsMesospheric gravity wave activity estimated via airglow imagery, multistatic meteor radar, and SABER data taken during the SIMONe–2018 campaignInterhemispheric transport of metallic ions within ionospheric sporadic E layers by the lower thermospheric meridional circulationFormation of an additional density peak in the bottom side of the sodium layer associated with the passage of multiple mesospheric frontal systemsGravity-wave-perturbed wind shears derived from SABER temperature observationsComparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere regionAnalysis of 24 years of mesopause region OH rotational temperature observations at Davis, Antarctica – Part 2: Evidence of a quasi-quadrennial oscillation (QQO) in the polar mesosphereThe MATS satellite mission – gravity wave studies by Mesospheric Airglow/Aerosol Tomography and SpectroscopyWinter 2018 major sudden stratospheric warming impact on midlatitude mesosphere from microwave radiometer measurementsClimatology of the mesopause relative density using a global distribution of meteor radarsObservations of OH airglow from ground, aircraft, and satellite: investigation of wave-like structures before a minor stratospheric warmingMesospheric semidiurnal tides and near-12 h waves through jointly analyzing observations of five specular meteor radars from three longitudinal sectors at boreal midlatitudesStatistical climatology of mid-latitude mesospheric summer echoes characterised by OSWIN (Ostsee-Wind) radar observationsCan VHF radars at polar latitudes measure mean vertical winds in the presence of PMSE?The global climatology of the intensity of the ionospheric sporadic E layerLong-term lidar observations of the gravity wave activity near the mesopause at AreciboCharacterization of flow recirculation zones at the Perdigão site using multi-lidar measurementsSolar 27-day signatures in standard phase height measurements above central EuropeMesospheric bores at southern midlatitudes observed by ISS-IMAP/VISI: a first report of an undulating wave frontSimultaneous observations of NLCs and MSEs at midlatitudes: implications for formation and advection of ice particlesLong-term observation of midlatitude quasi 2-day waves by a water vapor radiometerClimatology of mesopause region nocturnal temperature, zonal wind and sodium density observed by sodium lidar over Hefei, China (32° N, 117° E)Multi-static spatial and angular studies of polar mesospheric summer echoes combining MAARSY and KAIRAObservation of Kelvin–Helmholtz instabilities and gravity waves in the summer mesopause above Andenes in Northern NorwayTemporal variability of tidal and gravity waves during a record long 10-day continuous lidar soundingQuasi 18 h wave activity in ground-based observed mesospheric H2O over Bern, SwitzerlandWinds and temperatures of the Arctic middle atmosphere during January measured by Doppler lidarShort-period mesospheric gravity waves and their sources at the South PoleLong-term dynamics of OH * temperatures over central Europe: trends and solar correlationsMIPAS observations of longitudinal oscillations in the mesosphere and the lower thermosphere: climatology of odd-parity daily frequency modesNeutral atmosphere temperature trends and variability at 90 km, 70 °N, 19 °E, 2003–2014Response of OH airglow emissions to mesospheric gravity waves and comparisons with full-wave model simulation at a low-latitude Indian stationFirst continuous ground-based observations of long period oscillations in the vertically resolved wind field of the stratosphere and mesosphereSemi-annual oscillation (SAO) of the nighttime ionospheric D region as detected through ground-based VLF receiversMeteor radar quasi 2-day wave observations over 10 years at Collm (51.3° N, 13.0° E)Observations of planetary waves in the mesosphere-lower thermosphere during stratospheric warming eventsEvidence for tropospheric wind shear excitation of high-phase-speed gravity waves reaching the mesosphere using the ray-tracing techniqueThe quasi 16-day wave in mesospheric water vapor during boreal winter 2011/2012Quantification of waves in lidar observations of noctilucent clouds at scales from seconds to minutesThe diurnal and semidiurnal tides over Ascension Island (° S, 14° W) and their interaction with the stratospheric quasi-biennial oscillation: studies with meteor radar, eCMAM and WACCMThe roles of vertical advection and eddy diffusion in the equatorial mesospheric semi-annual oscillation (MSAO)Transport of mesospheric H2O during and after the stratospheric sudden warming of January 2010: observation and simulationFirst detection of tidal behaviour in polar mesospheric water vapour by ground based microwave spectroscopyThe climatology, propagation and excitation of ultra-fast Kelvin waves as observed by meteor radar, Aura MLS, TRMM and in the Kyushu-GCMMean winds, temperatures and the 16- and 5-day planetary waves in the mesosphere and lower thermosphere over Bear Lake Observatory (42° N, 111° W)Aura MLS observations of the westward-propagating s=1, 16-day planetary wave in the stratosphere, mesosphere and lower thermosphereDynamics of the Antarctic and Arctic mesosphere and lower thermosphere – Part 1: Mean windsStudy on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar measurementsThe 16-day wave in the Arctic and Antarctic mesosphere and lower 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,Short summary
Little is known about the climate change of wind systems in the mesosphere and lower thermosphere at the edge of space at altitudes from 70–110 km. Meteor radars represent a well-accepted remote sensing technique to measure winds at these altitudes. Here we present a state-of-the-art climatological interhemispheric comparison using continuous and long-lasting observations from worldwide distributed meteor radars from the Arctic to the Antarctic and sophisticated general circulation models.
Manfred Ern, Mohamadou Diallo, Peter Preusse, Martin G. Mlynczak, Michael J. Schwartz, Qian Wu, and Martin Riese
Atmos. Chem. Phys., 21, 13763–13795,Short summary
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,Short summary
We study large- and small-scale gravity wave cases observed in both airglow imagery and meteor radar data obtained during the SIMONe campaign carried out in early November 2018. We calculate the intrinsic features of several waves and estimate their impact in the mesosphere and lower thermosphere region via transferring energy and momentum to the atmosphere. We also associate cases of large-scale waves with secondary wave generation in the stratosphere.
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
The seasonal variations in the mesopause densities, especially with regard to its global structure, are still unclear. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars from Arctic to Antarctic latitudes. The results reveal a significant AO and SAO in mesopause density, an asymmetry between the two polar regions and evidence of intraseasonal oscillations (ISOs), perhaps associated with the ISOs of the troposphere.
Sabine Wüst, Carsten Schmidt, Patrick Hannawald, Michael Bittner, Martin G. Mlynczak, and James M. Russell III
Atmos. Chem. Phys., 19, 6401–6418,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,
Kathrin Baumgarten, Michael Gerding, Gerd Baumgarten, and Franz-Josef Lübken
Atmos. Chem. Phys., 18, 371–384,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
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,Short summary
Atmospheric temperatures at 90 km height above Tromsø, Norway, from 2003 to 2014 have been determined using meteor radar. Periodic oscillations ranging from ~ 9 days to a year were found in the dataset, which were related to the large-scale circulation in the middle atmosphere and with wave activity. A trend analysis was performed, revealing an overall weak cooling trend from 2003 to 2014, which is in line with other recent studies on mesopause region (~ 90 km) temperature trends.
Rupesh N. Ghodpage, Michael P. Hickey, Alok K. Taori, Devendraa Siingh, and Parashram T. Patil
Atmos. Chem. Phys., 16, 5611–5621,Short summary
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,Short summary
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.
Israel Silber, Colin Price, and Craig J. Rodger
Atmos. Chem. Phys., 16, 3279–3288,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.
F. Lilienthal and Ch. Jacobi
Atmos. Chem. Phys., 15, 9917–9927,Short summary
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,Short summary
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,Short summary
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.
D. Scheiben, B. Tschanz, K. Hocke, N. Kämpfer, S. Ka, and J. J. Oh
Atmos. Chem. Phys., 14, 6511–6522,
N. Kaifler, G. Baumgarten, J. Fiedler, and F.-J. Lübken
Atmos. Chem. Phys., 13, 11757–11768,
R. N. Davis, J. Du, A. K. Smith, W. E. Ward, and N. J. Mitchell
Atmos. Chem. Phys., 13, 9543–9564,
R. L. Gattinger, E. Kyrölä, C. D. Boone, W. F. J. Evans, K. A. Walker, I. C. McDade, P. F. Bernath, and E. J. Llewellyn
Atmos. Chem. Phys., 13, 7813–7824,
C. Straub, B. Tschanz, K. Hocke, N. Kämpfer, and A. K. Smith
Atmos. Chem. Phys., 12, 5413–5427,
K. Hallgren and P. Hartogh
Atmos. Chem. Phys., 12, 3753–3759,
R. N. Davis, Y.-W. Chen, S. Miyahara, and N. J. Mitchell
Atmos. Chem. Phys., 12, 1865–1879,
K. A. Day, M. J. Taylor, and N. J. Mitchell
Atmos. Chem. Phys., 12, 1571–1585,
K. A. Day, R. E. Hibbins, and N. J. Mitchell
Atmos. Chem. Phys., 11, 4149–4161,
D. J. Sandford, C. L. Beldon, R. E. Hibbins, and N. J. Mitchell
Atmos. Chem. Phys., 10, 10273–10289,
N. Mbatha, V. Sivakumar, S. B. Malinga, H. Bencherif, and S. R. Pillay
Atmos. Chem. Phys., 10, 3397–3404,
K. A. Day and N. J. Mitchell
Atmos. Chem. Phys., 10, 1461–1472,
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