Journal articles on the topic 'AGWs'
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1
Balthazor, R. L., R. J. Moffett, and G. H. Millward. "A study of the Joule and Lorentz inputs in the production of atmospheric gravity waves in the upper thermosphere." Annales Geophysicae 15, no. 6 (June 30, 1997): 779–85. http://dx.doi.org/10.1007/s00585-997-0779-6.
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Abstract. First results of a modelling study of atmospheric gravity waves (AGWs) are presented. A fully-coupled global thermosphere-ionosphere-plasmasphere model is used to examine the relative importance of Lorentz forcing and Joule heating in the generation of AGWs. It is found that Joule heating is the dominant component above 110km. The effects of the direction of the Lorentz forcing component on the subsequent propagation of the AGW are also addressed. It is found that enhancement of zonal E×B forcing results in AGWs at F-region altitudes of similar magnitudes travelling from the region of forcing in both poleward and equatorward directions, whilst enhancement of equatorward meridional E×B forcing results in AGWs travelling both poleward and equatorward, but with the magnitude of the poleward wave severely attenuated compared with the equatorward wave
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Magalhaes, J. M., I. B. Araújo, J. C. B. da Silva, R. H. J. Grimshaw, K. Davis, and J. Pineda. "Atmospheric gravity waves in the Red Sea: a new hotspot." Nonlinear Processes in Geophysics 18, no. 1 (February 3, 2011): 71–79. http://dx.doi.org/10.5194/npg-18-71-2011.
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Abstract. The region of the Middle East around the Red Sea (between 32° E and 44° E longitude and 12° N and 28° N latitude) is a currently undocumented hotspot for atmospheric gravity waves (AGWs). Satellite imagery shows evidence that this region is prone to relatively high occurrence of AGWs compared to other areas in the world, and reveals the spatial characteristics of these waves. The favorable conditions for wave propagation in this region are illustrated with three typical cases of AGWs propagating in the lower troposphere over the sea. Using weakly nonlinear long wave theory and the observed characteristic wavelengths we obtain phase speeds which are consistent with those observed and typical for AGWs, with the Korteweg-de Vries theory performing slightly better than Benjamin-Davis-Acrivos-Ono theory as far as phase speeds are concerned. ERS-SAR and Envisat-ASAR satellite data analysis between 1993 and 2008 reveals signatures consistent with horizontally propagating large-scale internal waves. These signatures cover the entire Red Sea and are more frequently observed between April and September, although they also occur during the rest of the year. The region's (seasonal) propagation conditions for AGWs, based upon average vertical atmospheric stratification profiles suggest that many of the signatures identified in the satellite images are atmospheric internal waves.
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Yue, Jia, Septi Perwitasari, Shuang Xu, Yuta Hozumi, Takuji Nakamura, Takeshi Sakanoi, Akinori Saito, Steven D. Miller, William Straka, and Pingping Rong. "Preliminary Dual-Satellite Observations of Atmospheric Gravity Waves in Airglow." Atmosphere 10, no. 11 (October 28, 2019): 650. http://dx.doi.org/10.3390/atmos10110650.
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Atmospheric gravity waves (AGWs) are among the important energy and momentum transfer mechanisms from the troposphere to the middle and upper atmosphere. Despite their understood importance in governing the structure and dynamics of these regions, mesospheric AGWs remain poorly measured globally, and largely unconstrained in numerical models. Since late 2011, the Suomi National Polar-orbiting Partnership (NPP) Visible/Infrared Imaging Radiometer Suite (VIIRS) day–night band (DNB) has observed global AGWs near the mesopause by virtue of its sensitivity to weak emissions of the OH* Meinel bands. The wave features, detectable at 0.75 km spatial resolution across its 3000 km imagery swath, are often confused by the upwelling emission of city lights and clouds reflecting downwelling nightglow. The Ionosphere, Mesosphere, upper Atmosphere and Plasmasphere (IMAP)/ Visible and near-Infrared Spectral Imager (VISI) O2 band, an independent measure of the AGW structures in nightglow based on the International Space Station (ISS) during 2012–2015, contains much less noise from the lower atmosphere. However, VISI offers much coarser resolution of 14–16 km and a narrower swath width of 600 km. Here, we present preliminary results of comparisons between VIIRS/DNB and VISI observations of AGWs, focusing on several concentric AGW events excited by the thunderstorms over Eastern Asia in August 2013. The comparisons point toward suggested improvements for future spaceborne airglow sensor designs targeting AGWs.
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Husein-ElAhmed, Husein. "Could the human papillomavirus vaccine prevent recurrence of ano-genital warts?: a systematic review and meta-analysis." International Journal of STD & AIDS 31, no. 7 (May 21, 2020): 606–12. http://dx.doi.org/10.1177/0956462420920142.
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Human papillomavirus (HPV) is the most prevalent sexually transmitted infection worldwide and ano-genital warts (AGWs) are highly infectious. This virus is transmitted through sexual, anal, or oral contact as well as skin-to-skin contacts. Treatment for this condition has significant morbidity and it can be frustrating in certain cases. The HPV vaccination has been demonstrated as a promising strategy of secondary prevention in HPV-related diseases such as head and neck cancers, cervical diseases, and recurrent respiratory papillomatosis. Regarding AGWs, it is unclear whether vaccination can provide analogous clinical benefit. The aim of this work is to systematically review the literature regarding HPV vaccination for secondary disease prevention after treatment of AGWs. From October to December 2018, a systematic search for clinical trials was conducted in five databases: PubMed, MEDLINE, EMBASE, Cochrane, and clinicaltrials.gov using a combination of the following descriptors: ‘gardasil’ OR ‘cervarix’ OR ‘nine-valent’ OR ‘9-valent’ OR ‘vaccine’ AND ‘recurrence’ OR ‘relapse’ AND ‘hpv’ OR ‘papillomavirus’ AND ‘warts’ OR ‘condyloma.’ Data were synthetized and entered in the Review Manager software (RevMan 5.3.5) to perform the meta-analysis. The search yielded 824 potentially relevant studies. Two studies fulfilled the eligibility criteria involving 656 participants. The meta-analysis estimated the rate of recurrence of AGWs was similar between the vaccine group and the control group. The overall effect estimate was 1.02 (0.75–1.38). This is the first meta-analysis exploring the effect of HPV vaccine in preventing the relapse of AGWs. These results suggest that HPV vaccination does not provide secondary benefit in patients with previous AGWs. However, these results cannot be generalized due to the scarce number of RCTs currently available in the literature. The outcomes from future randomized controlled trials (RCTs) are warranted to further clarify the precise effect of the vaccine.
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Barton, Samantha, Victoria Wakefield, Colm O'Mahony, and Steven Edwards. "Effectiveness of topical and ablative therapies in treatment of anogenital warts: a systematic review and network meta-analysis." BMJ Open 9, no. 10 (October 2019): e027765. http://dx.doi.org/10.1136/bmjopen-2018-027765.
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ObjectiveTo generate estimates of comparative clinical effectiveness for interventions used in the treatment of anogenital warts (AGWs) through the systematic review, appraisal and synthesis of data from randomised controlled trials (RCTs).DesignSystematic review and network meta-analysis of RCTs. Search strategies were developed for MEDLINE, Embase, the Cochrane Library and the Web of Science. For electronic databases, searches were run from inception to March 2018. The systematic review was carried out following the general principles recommended in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.ParticipantsPeople aged ≥16 years with clinically diagnosed AGWs (irrespective of biopsy confirmation).InterventionsTopical and ablative treatments recommended by the British Association for Sexual Health and HIV for the treatment of AGWs, either as monotherapy or in combination versus each other.Outcome measuresComplete clearance of AGWs at the end of treatment and at other scheduled visits, and rate of recurrence.ResultsThirty-seven RCTs met inclusion criteria. Twenty studies were assessed as being at unclear risk of bias, with the remaining studies categorised as high risk of bias. Network meta-analysis indicates that, of the treatment options compared, carbon dioxide laser therapy is the most effective treatment for achieving complete clearance of AGWs at the end of treatment. Of patient-applied topical treatments, podophyllotoxin 0.5% solution was found to be the most effective at achieving complete clearance, and was associated with a statistically significant difference compared with imiquimod 5% cream and polyphenon E 10% ointment (p<0.05). Few data were available on recurrence of AGWs after complete clearance. Of the interventions evaluated, surgical excision was the most effective at minimising risk of recurrence.ConclusionOf the studies assessed, as a collective, the quality of the evidence is low. Few studies are available that evaluate treatment options versus each other.Trial registration numberCRD42013005457
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Mercier, C., and A. R. Jacobson. "Observations of atmospheric gravity waves by radio interferometry: are results biased by the observational technique?" Annales Geophysicae 15, no. 4 (April 30, 1997): 430–42. http://dx.doi.org/10.1007/s00585-997-0430-6.
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Abstract. In this paper we present a quantitative comparison between a large data base of medium-scale atmospheric gravity waves (AGWs) observed by radio interferometry of transionospheric radio sources and the results of a numerical simulation of the observed effects. The simulation includes: (i) the propagation and dissipation of AGWs up to ionospheric heights and (ii) the calculation of the subsequent slant TEC perturbations integrated along the path to the radio sources. We show that the observed azimuthal distribution of AGWs can be deeply biased. Predicted results are found to be consistent with previous extensive observations using radio beacons aboard geostationary satellites. These observations are rediscussed in view of the present predictions.
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Didebulidze, Goderdzi G., Giorgi Dalakishvili, and Maya Todua. "Formation of Multilayered Sporadic E under an Influence of Atmospheric Gravity Waves (AGWs)." Atmosphere 11, no. 6 (June 19, 2020): 653. http://dx.doi.org/10.3390/atmos11060653.
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The formation of multilayered sporadic E by atmospheric gravity waves (AGWs), propagating in the mid-latitude lower thermosphere, is shown theoretically and numerically. AGWs with a vertical wavelength smaller than the width of the lower thermosphere lead to the appearance of vertical drift velocity nodes (regions where the ions’ vertical drift velocity, caused by these waves, is zero) of heavy metallic ions (Fe+). The distance between the nearest nodes is close to the AGWs’ vertical wavelength. When the divergence of the ion vertical drift velocity at its nodes has a minimal negative value, then these charged particles can accumulate into Es-type thin layers and the formation of multilayered sporadic E is possible. We showed the importance of the ions’ ambipolar diffusion in the formation of Es layers and control of their densities. Oblique downward or upward propagation of AGWs causes downward or upward motion of the ion vertical drift velocity nodes by the vertical propagation phase velocity of these waves. In this case, the formed Es layers also descend or move upward with the same phase velocity. The condition, when the horizontal component of AGWs’ intrinsic phase velocity (phase velocity relative to the wind) and background wind velocity have same magnitudes but opposite directions, is favorable for the formation of the multilayered sporadic E at fixed heights of the sublayers. When the AGWs are absent, then horizontal homogeneous wind causes the formation of sporadic E but with a single peak. In the framework of the suggested theory, it is shown that, in the lower thermosphere, the wind direction, magnitude, and shear determine the development of the processes of ion/electron convergence into the Es-type layer, as well as their density divergence. Consideration of arbitrary height profiles of the meridional and zonal components of the horizontal wind velocity, in case of AGW propagation, should be important for the investigation of the distribution and behavior of heavy metallic ions on regional and global scales.
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Zhao, Weibo, Xiong Hu, Zhaoai Yan, Weilin Pan, Wenjie Guo, Junfeng Yang, and Xiaoyong Du. "Atmospheric Gravity Wave Potential Energy Observed by Rayleigh Lidar above Jiuquan (40° N, 95° E), China." Atmosphere 13, no. 7 (July 13, 2022): 1098. http://dx.doi.org/10.3390/atmos13071098.
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Two years of observational data from the 532 nm Rayleigh lidar were used to study the vertical profile characteristics of atmospheric gravity wave potential energy density (GWPED) between 40–80 km above Jiuquan (40° N, 95° E) for the first time. The atmospheric gravity waves (AGWs) characteristics are presented in terms of the atmospheric relative temperature perturbation, along with the estimated annual and seasonal GWPED with high spatial and temporal resolution (0.5 km and 1 h). The annual potential energy mass density Epm and volume density Epv vertical profiles show that the GWPED in the upper mesosphere is close to the adiabatic growth rate. The seasonal vertical profiles result shows that Epm is higher in autumn–winter than in spring–summer in all the observed altitudes. The GWPED approaches adiabatic growth above 61 and 65 km in spring–summer and autumn–winter, respectively. The AGWs severely dissipate below the turning altitudes and transfer energy into the background atmosphere. The GWPED scale heights show that the AGWs dissipation rate of spring–summer is close to that of autumn–winter. Furthermore, based on the wind data from SD–WACCM, the influence of critical level filtering on AGWs is discussed. It plays an important role in affecting the seasonal variation in GWPED.
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Fedorenko, A. K., E. I. Kryuchkov, and O. K. Cheremnykh. "Influence of vertical heterogeneity of the atmosphere temperature on the propagation of acoustic-gravity waves." Kinematika i fizika nebesnyh tel (Online) 36, no. 6 (November 1, 2020): 3–21. http://dx.doi.org/10.15407/kfnt2020.06.003.
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A new approach to the study of acoustic-gravity waves (AGW) in the Earth’s atmosphere in the presence of a vertical temperature inhomogeneity is proposed. Using this approach, the local AGW dispersion equation is obtained for an atmosphere with a small vertical temperature gradient. The modification of acoustic and gravitational regions of freely propagating AGWs on the spectral plane is studied depending on the temperature gradient. It is shown that, the acoustic and gravitational regions approach each other with a positive temperature gradient and the distance between them increases with a negative gradient. On the spectral plane, the dispersion curves of non-divergent and anelastic horizontal wave modes are the indicators of location of the acoustic and the gravitational regions of freely propagating AGWs. The possibility of overlapping the acoustic and the gravitational regions of AGWs in non-isothermal atmosphere is investigated.
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Thurgar, Elizabeth, Samantha Barton, Charlotta Karner, and Steven J. Edwards. "Clinical effectiveness and cost-effectiveness of interventions for the treatment of anogenital warts: systematic review and economic evaluation." Health Technology Assessment 20, no. 24 (March 2016): 1–486. http://dx.doi.org/10.3310/hta20240.
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BackgroundTypically occurring on the external genitalia, anogenital warts (AGWs) are benign epithelial skin lesions caused by human papillomavirus infection. AGWs are usually painless but can be unsightly and physically uncomfortable, and affected people might experience psychological distress. The evidence base on the clinical effectiveness and cost-effectiveness of treatments for AGWs is limited.ObjectivesTo systematically review the evidence on the clinical effectiveness of medical and surgical treatments for AGWs and to develop an economic model to estimate the cost-effectiveness of the treatments.Data sourcesElectronic databases (MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, The Cochrane Library databases and Web of Science) were searched from inception (or January 2000 for Web of Science) to September 2014. Bibliographies of relevant systematic reviews were hand-searched to identify potentially relevant studies. The World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov were searched for ongoing and planned studies.Review methodsA systematic review of the clinical effectiveness literature was carried out according to standard methods and a mixed-treatment comparison (MTC) undertaken. The model implemented for each outcome was that with the lowest deviance information criterion. A de novo economic model was developed to assess cost-effectiveness from the perspective of the UK NHS. The model structure was informed through a systematic review of the economic literature and in consultation with clinical experts. Effectiveness data were obtained from the MTC. Costs were obtained from the literature and standard UK sources.ResultsOf 4232 titles and abstracts screened for inclusion in the review of clinical effectiveness, 60 randomised controlled trials (RCTs) evaluating 19 interventions were included. Analysis by MTC indicated that ablative techniques were typically more effective than topical interventions at completely clearing AGWs at the end of treatment. Podophyllotoxin 0.5% solution (Condyline®, Takeda Pharmaceutical Company Ltd; Warticon®solution, Stiefel Laboratories Ltd) was found to be the most effective topical treatment evaluated. Networks for other outcomes included fewer treatments, which restrict conclusions on the comparative effectiveness of interventions. In total, 84 treatment strategies were assessed using the economic model. Podophyllotoxin 0.5% solution first line followed by carbon dioxide (CO2) laser therapy second line if AGWs did not clear was most likely to be considered a cost-effective use of resources at a willingness to pay of £20,000–30,000 per additional quality-adjusted life-year gained. The result was robust to most sensitivity analyses conducted.LimitationsLimited reporting in identified studies of baseline characteristics for the enrolled population generates uncertainty around the comparability of the study populations and therefore the generalisability of the results to clinical practice. Subgroup analyses were planned based on type, number and size of AGWs, all of which are factors thought to influence treatment effect. Lack of data on clinical effectiveness based on these characteristics precluded analysis of the differential effects of treatments in the subgroups of interest. Despite identification of 60 studies, most comparisons in the MTC are informed by only one RCT. Additionally, lack of head-to-head RCTs comparing key treatments, together with minimal reporting of results in some studies, precluded comprehensive analysis of all treatments for AGWs.ConclusionsThe results generated by the MTC are in agreement with consensus opinion that ablative techniques are clinically more effective at completely clearing AGWs after treatment. However, the evidence base informing the MTC is limited. A head-to-head RCT that evaluates the comparative effectiveness of interventions used in clinical practice would help to discern the potential advantages and disadvantages of the individual treatments. The results of the economic analysis suggest that podophyllotoxin 0.5% solution is likely to represent a cost-effective first-line treatment option. More expensive effective treatments, such as CO2laser therapy or surgery, may represent cost-effective second-line treatment options. No treatment and podophyllin are unlikely to be considered cost-effective treatment options. There is uncertainty around the cost-effectiveness of treatment with imiquimod, trichloroacetic acid and cryotherapy.Study registrationThis study is registered as PROSPERO CRD42013005457.FundingThe National Institute for Health Research Health Technology Assessment programme.
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Yang, Shih-Sian, Stelios M. Potirakis, Sudipta Sasmal, and Masashi Hayakawa. "Natural Time Analysis of Global Navigation Satellite System Surface Deformation: The Case of the 2016 Kumamoto Earthquakes." Entropy 22, no. 6 (June 17, 2020): 674. http://dx.doi.org/10.3390/e22060674.
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In order to have further evidence of the atmospheric oscillation channel of the lithosphere-atmosphere-ionosphere coupling (LAIC), we have studied criticality in global navigation satellite system (GNSS) surface deformation as a possible agent for exciting atmospheric gravity waves (AGWs) in the atmosphere and GNSS fluctuations in the frequency range of AGWs with the use of the natural time (NT) method. The target earthquake (EQ) is the 2016 Kumamoto EQ with its main shock on 15 April 2016 (M = 7.3, universal time). As the result of the application of the NT method to GNSS data, we found that for the one-day sampled GNSS deformation data and its fluctuations in two AGW bands of 20–100 and 100–300 min, we could detect a criticality in the period of 1–14 April, which was one day to two weeks before the EQ. These dates of criticalities are likely to overlap with the time periods of previous results on clear AGW activity in the stratosphere and on the lower ionospheric perturbation. Hence, we suggest that the surface deformation could be a possible candidate for exciting those AGWs in the stratosphere, leading to the lower ionospheric perturbation, which lends further support to the AGW hypothesis of the LAIC process.
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Fedorenko, A. K., A. V. Bespalova, O. K. Cheremnykh, and E. I. Kryuchkov. "A dominant acoustic-gravity mode in the polar thermosphere." Annales Geophysicae 33, no. 1 (January 27, 2015): 101–8. http://dx.doi.org/10.5194/angeo-33-101-2015.
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Abstract. The article presents a summary of the main findings of the systematic study of acoustic-gravity waves (AGWs) in the polar thermosphere. This study was based on the in situ measurements made by the Dynamics Explorer 2 (DE2) spacecraft late in its mission when it descended low enough (250–400 km). It was found out that AGWs in the polar thermosphere are observed within a narrow frequency band close to the Brunt–Väisälä frequency and with horizontal wavelengths about 500–600 km. The broadband spectrum of travelling ionospheric disturbance (TID) frequencies observed by radars is caused by the Doppler effect. The AGW amplitudes do not depend on the altitude, but grow almost linearly with the wind velocity. They propagate towards the wind.
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Kryuchkov, E. I., I. T. Zhuk, and O. K. Cheremnykh. "Two-frequency acoustic-gravitational waves, simulation of satellite measurements." Kinematika i fizika nebesnyh tel (Online) 36, no. 6 (November 1, 2020): 22–36. http://dx.doi.org/10.15407/kfnt2020.06.022.
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The theory of acoustic gravity waves (AGW) considers free disturbances of the atmosphere within the framework of a single-frequency approach. In this case, the theory implies the existence of two separate types of waves with different natural frequencies - acoustic and gravitational. In the single-frequency approach, wave fluctuations of density, temperature, and velocity are related to each other through the spectral characteristics of the wave, and these relationships are unchanged. However, satellite observations of AGW parameters cannot always be explained within the framework of a single-frequency approach. This paper presents a two-frequency approach to the study of AGWs using the model of two coupled oscillators. It is shown that the perturbed movements of the elementary volume of the medium occur simultaneously at two natural frequencies. In this case, the connections between the wave fluctuations of the parameters are determined by the initial conditions, which can be arbitrary. Solutions in real functions for an isothermal atmosphere are obtained. The conditions under which single-frequency AGWs are obtained from the general two-frequency solution are investigated. The AGW waveforms measured from the satellite for velocities and displacements in single-frequency and dual-frequency modes are numerically simulated. The results of simulating two-frequency AGWs agree with the data of satellite measurements. Two-frequency AGWs are not always implemented at two different frequencies. It is shown that when the frequencies approach each other, the beat effect occurs and two closely related modes become indistinguishable. At the same wavelength, they have one center frequency and one phase velocity. The main feature of the two-frequency approach to the study of AGW is the expansion of the relationships between the wave parameters of the medium. This makes it possible to achieve satisfactory agreement of the model waveforms with the data of satellite measurements. Thus, the use of a two-frequency AGW treatment opens up new possibilities in the interpretation of experimental data.
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Snively, Jonathan B., Roberto Sabatini, Donna A. Calhoun, Christopher J. Heale, Pavel A. Inchin, and Matthew D. Zettergren. "Modeling of acoustic and gravity wave interactions, coupling, and observables above meteorological systems." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A161. http://dx.doi.org/10.1121/10.0010975.
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Meteorology, especially strong tropospheric convection, is widely appreciated to generate broad spectra of acoustic and gravity waves (AWs and GWs or, together, AGWs). These include GWs with scales of tens to hundreds of kilometers and periods of ∼5 min to hours, that readily propagate upward, reach high altitudes (often to the lower-thermosphere), and grow to large amplitudes so that they may evolve nonlinearly prior to being overcome by dissipation. Strong convective dynamics, e.g., thunderstorms and tornadoes, are also known to radiate AWs at very low infrasonic frequencies (e.g., 0.1 Hz down to ∼4 mHz) that reach high altitudes and may be detectable in fluctuations of the atmosphere and ionosphere [e.g., Nishioka et al. (2013); Heale et al. (2019)]. The breaking of strong GW fields may also generate secondary AWs and, more generally, AGWs [Snively (2017); Heale et al. (2021)]. Together, convection and secondary AGW processes contribute to a broad spectrum of AWs with ∼mHz periods that are readily detectable at high altitudes and in pressure signals also measured at ground. Although AWs are excluded from traditional numerical weather prediction models, we report on models and simulation experiments designed to capture AW/AGW evolutions and their resulting observable signatures. In particular, we review and highlight scenarios by which ∼mHz AWs may reveal source processes of interest, as well as the opportunities to use atmospheric and ionospheric signals of AWs/AGWs as complement to ground-based infrasound recordings.
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Godin, Oleg A. "Wentzel–Kramers–Brillouin approximation for atmospheric waves." Journal of Fluid Mechanics 777 (July 16, 2015): 260–90. http://dx.doi.org/10.1017/jfm.2015.367.
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Ray and Wentzel–Kramers–Brillouin (WKB) approximations have long been important tools in understanding and modelling propagation of atmospheric waves. However, contradictory claims regarding the applicability and uniqueness of the WKB approximation persist in the literature. Here, we consider linear acoustic–gravity waves (AGWs) in a layered atmosphere with horizontal winds. A self-consistent version of the WKB approximation is systematically derived from first principles and compared to ad hoc approximations proposed earlier. The parameters of the problem are identified that need to be small to ensure the validity of the WKB approximation. Properties of low-order WKB approximations are discussed in some detail. Contrary to the better-studied cases of acoustic waves and internal gravity waves in the Boussinesq approximation, the WKB solution contains the geometric, or Berry, phase. The Berry phase is generally non-negligible for AGWs in a moving atmosphere. In other words, knowledge of the AGW dispersion relation is not sufficient for calculation of the wave phase.
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Galushko, V. G., V. V. Paznukhov, Y. M. Yampolski, and J. C. Foster. "Incoherent scatter radar observations of AGW/TID events generated by the moving solar terminator." Annales Geophysicae 16, no. 7 (July 31, 1998): 821–27. http://dx.doi.org/10.1007/s00585-998-0821-3.
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Abstract. Observations of traveling ionospheric disturbances (TIDs) associated with atmospheric gravity waves (AGWs) generated by the moving solar terminator have been made with the Millstone Hill incoherent scatter radar. Three experiments near 1995 fall equinox measured the AGW/TID velocity and direction of motion. Spectral and cross-correlation analysis of the ionospheric density observations indicates that ST-generated AGWs/TIDs were observed during each experiment, with the more-pronounced effect occurring at sunrise. The strongest oscillations in the ionospheric parameters have periods of 1.5 to 2 hours. The group and phase velocities have been determined and show that the disturbances propagate in the horizontal plane perpendicular to the terminator with the group velocity of 300-400 m s-1 that corresponds to the ST speed at ionospheric heights. The high horizontal group velocity seems to contradict the accepted theory of AGW/TID propagation and indicates a need for additional investigation.Key words. Ionosphere (wave propagation) · Meteorology and atmospheric dynamics (waves and tides)
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Klymenko, Yurij, Oleg Cheremnykh, Alla Fedorenko, and Anna Voitsekhovska. "RECOVERY OF SPECTRAL PROPERTIES OF ACOUSTIC-GRAVITY WAVES IN SATELLITE MEASUREMENTS." International Scientific Technical Journal "Problems of Control and Informatics 67, no. 3 (June 1, 2022): 124–34. http://dx.doi.org/10.34229/2786-6505-2022-3-10.
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Acoustic-gravity waves (AGWs) are the important mechanism for transferring energy in the atmosphere from the Earth and space disturbances. Theresult of the expansion of AGWs is the fluctuations of atmospheric parameters, which can be registered by ground-based and satellite measurements.However, each of the methods has certain limitations on obtaining information about the properties of the waves. In this regard, it is important thedevelopment of methods which allow us to recover the spectral properties ofAGWs on the basis of limited experimental data. In this article, an analyticalmethod for determining the spectral properties of acoustic-gravity wavesfrom direct satellite measurements is proposed. The method is based on polarization relations, which connect the wave fluctuations of different atmospheric parameters (temperature, density and velocity of particles). It is basedon the determination of the phase shifts between oscillations of some physical parameters of the atmosphere, which are available in satellite measurements. Simple analytical relations are obtained, which allow us to determinethe spectral characteristics of AGW, the nature of wave propagation (horizontal or freely propagated at an angle to the horizontal plane) and their direction relative to the satellite. It is shown that the feature of evanescentwaves is in-phase or anti-phase oscillations of density and temperature. Infreely propagating AGH, these oscillations have a certain phase shift, themagnitude of which depends on the spectral properties. The results obtainedin this work allow us to determine immediately the type of the waves towhich the observed atmospheric perturbation belongs. According to the experimental data, the proposed method for determining the AGW spectralcharacteristics of AGWs has been tested. For this purpose, the measurements of atmospheric AGW parameters in the polar regions on the Dynamics Explorer 2 satellite were used.
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Mercier, Claude. "Some characteristics of atmospheric gravity waves observed by radio-interferometry." Annales Geophysicae 14, no. 1 (January 31, 1996): 42–58. http://dx.doi.org/10.1007/s00585-996-0042-6.
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Abstract. Observations of atmospheric acoustic-gravity waves (AGWs) are considered through their effect on the horizontal gradient G of the slant total electron content (slant TEC), which can be directly obtained from two-dimensional radio-interferometric observations of cosmic radio-sources with the Nançay radioheligraph (2.2°E, 47.3°N). Azimuths of propagation can be deduced (modulo 180°). The total database amounts to about 800 h of observations at various elevations, local time and seasons. The main results are: a) AGWs are partially directive, confirming our previous results. b) The propagation azimuths considered globally are widely scattered with a preference towards the south. c) They show a bimodal time distribution with preferential directions towards the SE during daytime and towards the SW during night-time (rather than a clockwise rotation as reported by previous authors). d) The periods are scattered but are larger during night-time than during daytime by about 60%. e) The effects observed with the solar radio-sources are significantly stronger than with other radio-sources (particularly at higher elevations), showing the role of the geometry in line of sight-integrated observations.
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Xie, Jinlai, Xunren Yang, and Qitai Li. "The Correlations Between Acoustical Gravity Waves Caused by Solar Eclipse and the Solar Radiation." Journal of Low Frequency Noise, Vibration and Active Control 11, no. 2 (June 1992): 37–41. http://dx.doi.org/10.1177/026309239201100201.
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Can solar eclipses generate AGWs? If so, how are they excited? This is still an open question and a long-standing dispute within academic circles. The annular solar eclipse which traversed the Chinese mainland on September 23rd 1987 afforded a rare and excellent opportunity to study this problem. Vast amounts of data of microbarometric pressure at ground level, radio-sondage, solar radiation and ionospheric probing were obtained from various observation stations. By making use of these abundant data synthetically, an important conclusion has been reached: there is an obvious accord between the period of the solar eclipse, AGW and the fluctuation period of solar direct radiation. All the solar eclipse AGWs in different places come from two different kinds of atmospheric oscillation, i.e., the forced oscillation generated directly by changes in direct solar radiation and the buoyancy oscillation in the local atmosphere above various spots. The former has a longer wave period and a larger amplitude, depending directly upon the radiation change during the solar eclipse; the latter has a shorter period and smaller amplitude, depending upon thermodynamic stability in the local atmosphere during the solar eclipse and the atmospheric moisture condition.
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Snively, Jonathan B., Donna A. Calhoun, Pavel A. Inchin, Roberto Sabatini, Christopher J. Heale, and Matthew D. Zettergren. "Modeling of infrasonic and acoustic-gravity wave propagation, nonlinear evolution, and observable effects." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A165. http://dx.doi.org/10.1121/10.0015898.
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Mechanical disturbances associated with hazardous events—e.g., earthquakes, explosions (volcanic or man-made)—and severe weather – generate broad spectra of infrasound and acoustic-gravity waves (AGWs). These wave signals may provide diagnostic insight into the processes that generated them. They are routinely detected as fluctuations in atmospheric pressure, measured at ground or from balloon-borne platforms; at lower frequencies (<1 Hz), and where they may attain sufficient amplitudes at high altitudes, they may also be measured via the fluctuations that they impose in densities of layered species throughout the atmosphere and ionosphere. Thus, they provide complementary remote sensing opportunities, where waves and their effects, especially above and surrounding larger sources, may be diagnosed as they propagate. We review recent progress and techniques for high-fidelity modeling and simulation, to capture the propagation and evolution of low-frequency infrasound and AGWs throughout the atmosphere, from 0–500 km altitude (from surface to exobase). Strategies to (1) efficiently extend model simulation domains well into the diffusive thermosphere, to (2) connect models of atmospheric dynamics to those for other measurable processes (e.g., the ionosphere), and to (3) construct simulations that extend from source processes to specific remote sensing methodologies are discussed.
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Godin, Oleg A., and Iosif M. Fuks. "Transmission of acoustic-gravity waves through gas–liquid interfaces." Journal of Fluid Mechanics 709 (August 10, 2012): 313–40. http://dx.doi.org/10.1017/jfm.2012.336.
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AbstractIt was demonstrated recently that gas–liquid interfaces, which are usually almost perfect reflectors of acoustic waves, become anomalously transparent, and the power flux in the wave transmitted into the gas increases dramatically, when a compact sound source in the liquid approaches the interface within a fraction of the wavelength (Godin, Phys. Rev. Lett., vol. 97, 2006b, 164301). Powerful underwater explosions and certain natural sources, such as underwater landslides, generate very low-frequency waves in water and air, for which fluid buoyancy and compressibility simultaneously serve as restoring forces. In this paper, analysis of sound transmission through gas–liquid interfaces is extended to acoustic-gravity waves (AGWs) and applied to the air–water interface. It is found that, as for sound, the interface becomes anomalously transparent for sufficiently shallow compact sources of AGWs. Depending on the source type, the increase of a wave power flux into gas due to diffraction effects can reach several orders of magnitude. The physical mechanisms responsible for the anomalous transparency are discussed. Excitation of an interface wave by a point source in the liquid is shown to be an important channel of AGW transmission into the gas, which has no counterpart in the case of sound.
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Li, Q., J. Xu, J. Yue, W. Yuan, and X. Liu. "Statistical characteristics of gravity wave activities observed by an OH airglow imager at Xinglong, in northern China." Annales Geophysicae 29, no. 8 (August 23, 2011): 1401–10. http://dx.doi.org/10.5194/angeo-29-1401-2011.
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Abstract. An all-sky airglow imager (ASAI) was installed at Xinglong, in northern China (40.2° N, 117.4° E) in November 2009 to study the morphology of atmospheric gravity waves (AGWs) in the mesosphere and lower thermosphere (MLT) region. Using one year of OH airglow imager data from December 2009 to November 2010, the characteristics of short-period AGWs are investigated and a yearlong AGW climatology in northern China is first ever reported. AGW occurrence frequency in summer and winter is higher than that in equinoctial months. Observed bands mainly have horizontal wavelengths from 10 to 35 km, observed periods from 4 to 14 min and observed horizontal phase speeds in the range of 30 to 60 m s−1. Most of the bands propagate in the meridional direction. The propagation directions of the bands show a strong southwestward preference in winter, while almost all bands propagate northeastward in summer. Although the wind filtering in the middle atmosphere may control AGW propagations in the zonal direction, the non-uniform distribution of wave sources in the lower atmosphere may contribute to the anisotropy in the meridional direction in different seasons. Additionally, as an indication of local instability, the characteristics of ripples are also analyzed. It also shows seasonal variations, occurring more often in summer and winter and mainly moving westward in summer and eastward in winter.
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Gong, Shaohua, Guotao Yang, Jiyao Xu, Xiao Liu, and Qinzeng Li. "Gravity Wave Propagation from the Stratosphere into the Mesosphere Studied with Lidar, Meteor Radar, and TIMED/SABER." Atmosphere 10, no. 2 (February 16, 2019): 81. http://dx.doi.org/10.3390/atmos10020081.
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A low-frequency inertial atmospheric gravity wave (AGW) event was studied with lidar (40.5° N, 116° E), meteor radar (40.3° N, 116.2° E), and TIMED/SABER at Beijing on 30 May 2012. Lidar measurements showed that the atmospheric temperature structure was persistently perturbed by AGWs propagating upward from the stratosphere into the mesosphere (35–86 km). The dominant contribution was from the waves with vertical wavelengths λ z = 8 − 10 km and wave periods T ob = 6.6 ± 0.7 h . Simultaneous observations from a meteor radar illustrated that MLT horizontal winds were perturbed by waves propagating upward with an azimuth angle of θ = 247 ° , and the vertical wavelength ( λ z = 10 km ) and intrinsic period ( T in = 7.4 h ) of the dominant waves were inferred with the hodograph method. TIMED/SABER measurements illustrated that the vertical temperature profiles were also perturbed by waves with dominant vertical wavelength λ z = 6 − 9 km . Observations from three different instruments were compared, and it was found that signatures in the temperature perturbations and horizontal winds were induced by identical AGWs. According to these coordinated observation results, the horizontal wavelength and intrinsic phase speed were inferred to be ~560 km and ~21 m/s, respectively. Analyses of the Brunt-Väisälä frequency and potential energy illustrated that this persistent wave propagation had good static stability.
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Gavrilov, N. M., and S. P. Kshevetskii. "Verifications of the nonlinear numerical model and polarization relations of atmospheric acoustic-gravity waves." Geoscientific Model Development Discussions 7, no. 6 (November 18, 2014): 7805–22. http://dx.doi.org/10.5194/gmdd-7-7805-2014.
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Abstract. Comparisons of amplitudes of wave variations of atmospheric characteristics simulated using direct numerical simulation models with polarization relations given by conventional theories of linear acoustic-gravity waves (AGWs) could be helpful for testing these numerical models. In this study, we performed high-resolution numerical simulations of nonlinear AGW propagation at altitudes 0–500 km from a plane wave forcing at the Earth's surface and compared them with analytical polarization relations of linear AGW theory. After some transition time te (increasing with altitude) subsequent to triggering the wave source, initial wave pulse disappear and the main spectral components of the wave source dominate. The numbers of numerically simulated and analytical pairs of AGW parameters, which are equal with confidence 95%, are largest at altitudes 30–60 km at t > te. At low and high altitudes and at t < te numbers of equal pairs are smaller, because of influence of the lower boundary conditions, strong dissipation and AGW transience making substantial inclinations from conditions, assumed in conventional theories of linear nondissipative stationary AGWs in the free atmosphere. Reasonable agreements between simulated and analytical wave parameters satisfying the scope the limitations of the AGW theory proof adequacy of the used nonlinear numerical model. Significant differences between numerical and analytical AGW parameters reveal circumstances, when analytical theories give substantial errors and numerical simulations of wave fields are required. In addition, direct numerical AGW simulations may be useful tools for testing simplified parameterizations of wave effects in the atmosphere.
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Gavrilov, N. M., S. P. Kshevetskii, and A. V. Koval. "Verifications of the high-resolution numerical model and polarization relations of atmospheric acoustic-gravity waves." Geoscientific Model Development 8, no. 6 (June 22, 2015): 1831–38. http://dx.doi.org/10.5194/gmd-8-1831-2015.
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Abstract. Comparisons of amplitudes of wave variations of atmospheric characteristics obtained using direct numerical simulation models with polarization relations given by conventional theories of linear acoustic-gravity waves (AGWs) could be helpful for testing these numerical models. In this study, we performed high-resolution numerical simulations of nonlinear AGW propagation at altitudes 0–500 km from a plane wave forcing at the Earth's surface and compared them with analytical polarization relations of linear AGW theory. After some transition time te (increasing with altitude) subsequent to triggering the wave source, the initial wave pulse disappears and the main spectral components of the wave source dominate. The numbers of numerically simulated and analytical pairs of AGW parameters, which are equal with confidence of 95 %, are largest at altitudes 30–60 km at t > te. At low and high altitudes and at t < te, numbers of equal pairs are smaller, because of the influence of the lower boundary conditions, strong dissipation and AGW transience making substantial inclinations from conditions, assumed in conventional theories of linear nondissipative stationary AGWs in the free atmosphere. Reasonable agreements between simulated and analytical wave parameters satisfying the scope of the limitations of the AGW theory prove the adequacy of the used wave numerical model. Significant differences between numerical and analytical AGW parameters reveal circumstances when analytical theories give substantial errors and numerical simulations of wave fields are required. In addition, direct numerical AGW simulations may be useful tools for testing simplified parameterizations of wave effects in the atmosphere.
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Balthazor, R. L., and R. J. Moffett. "A study of atmospheric gravity waves and travelling ionospheric disturbances at equatorial latitudes." Annales Geophysicae 15, no. 8 (August 31, 1997): 1048–56. http://dx.doi.org/10.1007/s00585-997-1048-4.
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Abstract. A global coupled thermosphere-ionosphere-plasmasphere model is used to simulate a family of large-scale imperfectly ducted atmospheric gravity waves (AGWs) and associated travelling ionospheric disturbances (TIDs) originating at conjugate magnetic latitudes in the north and south auroral zones and subsequently propagating meridionally to equatorial latitudes. A 'fast' dominant mode and two slower modes are identified. We find that, at the magnetic equator, all the clearly identified modes of AGW interfere constructively and pass through to the opposite hemisphere with unchanged velocity. At F-region altitudes the 'fast' AGW has the largest amplitude, and when northward propagating and southward propagating modes interfere at the equator, the TID (as parameterised by the fractional change in the electron density at the F2 peak) increases in magnitude at the equator. The amplitude of the TID at the magnetic equator is increased compared to mid-latitudes in both upper and lower F-regions with a larger increase in the upper F-region. The ionospheric disturbance at the equator persists in the upper F-region for about 1 hour and in the lower F-region for 2.5 hours after the AGWs first interfere, and it is suggested that this is due to enhancements of the TID by slower AGW modes arriving later at the magnetic equator. The complex effects of the interplays of the TIDs generated in the equatorial plasmasphere are analysed by examining neutral and ion winds predicted by the model, and are demonstrated to be consequences of the forcing of the plasmasphere along the magnetic field lines by the neutral air pressure wave.
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Prikryl, P., D. B. Muldrew, and G. J. Sofko. "The influence of solar wind on extratropical cyclones – Part 2: A link mediated by auroral atmospheric gravity waves?" Annales Geophysicae 27, no. 1 (January 6, 2009): 31–57. http://dx.doi.org/10.5194/angeo-27-31-2009.
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Abstract. Cases of mesoscale cloud bands in extratropical cyclones are observed a few hours after atmospheric gravity waves (AGWs) are launched from the auroral ionosphere. It is suggested that the solar-wind-generated auroral AGWs contribute to processes that release instabilities and initiate slantwise convection thus leading to cloud bands and growth of extratropical cyclones. Also, if the AGWs are ducted to low latitudes, they could influence the development of tropical cyclones. The gravity-wave-induced vertical lift may modulate the slantwise convection by releasing the moist symmetric instability at near-threshold conditions in the warm frontal zone of extratropical cyclones. Latent heat release associated with the mesoscale slantwise convection has been linked to explosive cyclogenesis and severe weather. The circumstantial and statistical evidence of the solar wind influence on extratropical cyclones is further supported by a statistical analysis of high-level clouds (<440 mb) extracted from the International Satellite Cloud Climatology Project (ISCCP) D1 dataset. A statistically significant response of the high-level cloud area index (HCAI) to fast solar wind from coronal holes is found in mid-to-high latitudes during autumn-winter and in low latitudes during spring-summer. In the extratropics, this response of the HCAI to solar wind forcing is consistent with the effect on tropospheric vorticity found by Wilcox et al. (1974) and verified by Prikryl et al. (2009). In the tropics, the observed HCAI response, namely a decrease in HCAI at the arrival of solar wind stream followed by an increase a few days later, is similar to that in the northern and southern mid-to-high latitudes. The amplitude of the response nearly doubles for stream interfaces associated with the interplanetary magnetic field BZ component shifting southward. When the IMF BZ after the stream interface shifts northward, the autumn-winter effect weakens or shifts to lower (mid) latitudes and no statistically significant response is found at low latitudes in spring-summer. The observed effect persists through years of low and high volcanic aerosol loading. The similarity of the response in mid-to-high and low latitudes, the lack of dependence upon aerosol loading, and the enhanced amplitude of the effect when IMF BZ component shifts southward, favor the proposed AGW link over the atmospheric electric circuit (AEC) mechanism (Tinsley et al., 1994). The latter requires the presence of stratospheric aerosols for a significant effect and should produce negative and positive cloud anomalies in mid-to-high and low latitudes, respectively. However, if the requirement of aerosols for the AEC mechanism can be relaxed, the AGW and AEC mechanisms should work in synergy at least in mid-to-high latitudes.
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Bourdillon, A., E. Lefur, C. Haldoupis, Y. Le Roux, J. Ménard, and J. Delloue. "Decameter mid-latitude sporadic-E irregularities in relation with gravity waves." Annales Geophysicae 15, no. 7 (July 31, 1997): 925–34. http://dx.doi.org/10.1007/s00585-997-0925-1.
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Abstract. HF radar observations of mid-latitude spo- radic-E irregularities carried out with the Valensole radar in South France are compared with simultaneous ionosonde measurements underneath the irregularity zones. In a previous study of Valensole radar data, it has been shown that HF backscatter from the night-time mid-latitude E region is usually associated with large- scale wave-like modulations. To obtain more informa- tion on the geophysical conditions prevailing during backscatter events, a new experiment was performed which also included a vertical ionosonde beneath the scattering region. The data to be presented here are from two periods when radar scattering appeared simulta- neously with large variations in the virtual height and the Doppler velocity of F-layer re¯ected echoes mea- sured with the vertical ionosonde, indicating very clearly the passage of atmospheric gravity waves (AGWs). The e.ect of the atmospheric waves on the sporadic-E layer is not always as marked as it is in the F region. In the ®rst event, the passage of the AGWs is accompanied by an upward followed by a downward movement of the Es-layer. The apparent descending movement of the Es-layer from 135 to 110 km in less than 10 min corresponded to a positive (downward) Doppler velocity of 35 m/s measured by the vertical ionosonde, and was accompanied by a range variation in the radar scattering region with a negative rate of about 90±110 m/s. In the second event, the Es-layer is not as strongly disturbed as in the previous one, but, nevertheless, the range varia- tions of the scattering region can still be associated with height ¯uctuations of the Es-layer.
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Guerra, Fiona M., Laura C. Rosella, Sheila Dunn, Sarah E. Wilson, Cynthia Chen, and Shelley L. Deeks. "Early impact of Ontario’s human papillomavirus (HPV) vaccination program on anogenital warts (AGWs): A population-based assessment." Vaccine 34, no. 39 (September 2016): 4678–83. http://dx.doi.org/10.1016/j.vaccine.2016.08.020.
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Didebulidze, G. G., G. Dalakishvili, L. Lomidze, and G. Matiashvili. "Formation of sporadic-E (Es) layers under the influence of AGWs evolving in a horizontal shear flow." Journal of Atmospheric and Solar-Terrestrial Physics 136 (December 2015): 163–73. http://dx.doi.org/10.1016/j.jastp.2015.09.012.
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Perwitasari, Septi, Takuji Nakamura, Masaru Kogure, Yoshihiro Tomikawa, Mitsumu K. Ejiri, and Kazuo Shiokawa. "Comparison of gravity wave propagation directions observed by mesospheric airglow imaging at three different latitudes using the M-transform." Annales Geophysicae 36, no. 6 (November 30, 2018): 1597–605. http://dx.doi.org/10.5194/angeo-36-1597-2018.
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Abstract. We developed user-friendly software based on Matsuda et al.'s (2014) 3D-FFT method (Matsuda-transform, M-transform) for airglow imaging data analysis as a function of Interactive Data Language (IDL). Users can customize the range of wave parameters to process when executing the program. The input for this function is a 3-D array of a time series of a 2-D airglow image in geographical coordinates. We applied this new function to mesospheric airglow imaging data with slightly different observation parameters obtained for the period of April–May at three different latitudes: Syowa Station, the Antarctic (69∘ S, 40∘ E); Shigaraki, Japan (35∘ N, 136∘ E); and Tomohon, Indonesia (1∘ N, 122∘ E). The day-to-day variation of the phase velocity spectrum at the Syowa Station is smaller and the propagation direction is mainly westward. In Shigaraki, the day-to-day variation of the horizontal propagation direction is larger than that at the Syowa Station; the variation in Tomohon is even larger. In Tomohon, the variation of the nightly power spectrum magnitude is remarkable, which indicates the intermittency of atmospheric gravity waves (AGWs). The average nightly spectrum obtained from April–May shows that the dominant propagation is westward with a phase speed <50 m s−1 at the Syowa Station and east-southeastward with a phase speed of up to ∼80 m s−1 in Shigaraki. The day-to-day variation in Tomohon is too strong to discuss average characteristics; however, a phase speed of up to ∼100 m s−1 and faster is observed. The corresponding background wind profiles derived from MERRA-2 indicate that wind filtering plays a significant role in filtering out waves that propagate eastward at the Syowa Station. On the other hand, the background wind is not strong enough to filter out relatively high-speed AGWs in Shigaraki and Tomohon and the dominant propagation direction is likely related to the distribution and characteristics of the source region, at least in April and May.
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A. Morse, Carol, and Voula Messimeri-Kianidis. "Issues of Women Carers in Australian-Greek Families." Australian Journal of Primary Health 4, no. 3 (1998): 203. http://dx.doi.org/10.1071/py98050.
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Several myths prevail regarding family-based caregiving in migrant groups from non-English-speaking backgrounds (NESB): i) a low need for formal services because of extensive family networks (i.e. informal assistance); ii) NESB groups prefer to 'look after their own' to a greater extent than do Anglo-Australian communities; and iii) caregiving is a 'natural' role for women in migrant families. In 1995 a survey was undertaken of 150 care-giving families in the Australian Greek community in Melbourne, identified from the register of the Australian Greek Welfare Society (AGWS), matched by age and gender with 150 Australian Greeks with no caregiving roles. Health status and social experiences were examined of providing family-based caregiving for a co-resident member with developmental delay, physical and/or mental disorder or frail age.
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Essien, Patrick, Igo Paulino, Cristiano Max Wrasse, Jose Andre V. Campos, Ana Roberta Paulino, Amauri F. Medeiros, Ricardo Arlen Buriti, Hisao Takahashi, Ebenezer Agyei-Yeboah, and Aline N. Lins. "Seasonal characteristics of small- and medium-scale gravity waves in the mesosphere and lower thermosphere over the Brazilian equatorial region." Annales Geophysicae 36, no. 3 (June 21, 2018): 899–914. http://dx.doi.org/10.5194/angeo-36-899-2018.
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Abstract. The present work reports seasonal characteristics of small- and medium-scale gravity waves in the mesosphere and lower thermosphere (MLT) region. All-sky images of the hydroxyl (NIR-OH) airglow emission layer over São João do Cariri (7.4∘ S, 36.5∘ W; hereafter Cariri) were obtained from September 2000 to December 2010, during a total of 1496 nights. For investigation of the characteristics of small-scale gravity waves (SSGWs) and medium-scale gravity waves (MSGWs), we employed the Fourier two-dimensional (2-D) spectrum and keogram fast Fourier transform (FFT) techniques, respectively. From the 11 years of data, we could observe 2343 SSGW and 537 MSGW events. The horizontal wavelengths of the SSGWs were concentrated between 10 and 35 km, while those of the MSGWs ranged from 50 to 200 km. The observed periods for SSGWs were concentrated around 5 to 20 min, whereas the MSGWs ranged from 20 to 60 min. The observed horizontal phase speeds of SSGWs were distributed around 10 to 60 m s−1, and the corresponding MSGWs were around 20 to 120 m s−1. In summer, autumn, and winter both SSGWs and MSGWs propagated preferentially northeastward and southeastward, while in spring the waves propagated in all directions. The critical level theory of atmospheric gravity waves (AGWs) was applied to study the effects of wind filtering on SSGW and MSGW propagation directions. The SSGWs were more susceptible to wind filtering effects than MSGWs. The average of daily mean outgoing longwave radiation (OLR) was also used to investigate the possible wave source region in the troposphere. The results showed that in summer and autumn, deep convective regions were the possible source mechanism of the AGWs. However, in spring and winter the deep convective regions did not play an important role in the waves observed at Cariri, because they were too far away from the observatory. Therefore, we concluded that the horizontal propagation directions of SSGWs and MSGWs show clear seasonal variations based on the influence of the wind filtering process and wave source location. Keywords. Atmospheric composition and structure (airglow and aurora) – electromagnetics (wave propagation) – history of geophysics (atmospheric sciences)
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Rapoport, Yuriy G., Oleg K. Cheremnykh, Volodymyr V. Koshovy, Mykola O. Melnik, Oleh L. Ivantyshyn, Roman T. Nogach, Yuriy A. Selivanov, et al. "Ground-based acoustic parametric generator impact on the atmosphere and ionosphere in an active experiment." Annales Geophysicae 35, no. 1 (January 5, 2017): 53–70. http://dx.doi.org/10.5194/angeo-35-53-2017.
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Abstract. We develop theoretical basics of active experiments with two beams of acoustic waves, radiated by a ground-based sound generator. These beams are transformed into atmospheric acoustic gravity waves (AGWs), which have parameters that enable them to penetrate to the altitudes of the ionospheric E and F regions where they influence the electron concentration of the ionosphere. Acoustic waves are generated by the ground-based parametric sound generator (PSG) at the two close frequencies. The main idea of the experiment is to design the output parameters of the PSG to build a cascade scheme of nonlinear wave frequency downshift transformations to provide the necessary conditions for their vertical propagation and to enable penetration to ionospheric altitudes. The PSG generates sound waves (SWs) with frequencies f1 = 600 and f2 = 625 Hz and large amplitudes (100–420 m s−1). Each of these waves is modulated with the frequency of 0.016 Hz. The novelty of the proposed analytical–numerical model is due to simultaneous accounting for nonlinearity, diffraction, losses, and dispersion and inclusion of the two-stage transformation (1) of the initial acoustic waves to the acoustic wave with the difference frequency Δf = f2 − f1 in the altitude ranges 0–0.1 km, in the strongly nonlinear regime, and (2) of the acoustic wave with the difference frequency to atmospheric acoustic gravity waves with the modulational frequency in the altitude ranges 0.1–20 km, which then reach the altitudes of the ionospheric E and F regions, in a practically linear regime. AGWs, nonlinearly transformed from the sound waves, launched by the two-frequency ground-based sound generator can increase the transparency of the ionosphere for the electromagnetic waves in HF (MHz) and VLF (kHz) ranges. The developed theoretical model can be used for interpreting an active experiment that includes the PSG impact on the atmosphere–ionosphere system, measurements of electromagnetic and acoustic fields, study of the variations in ionospheric transparency for the radio emissions from galactic radio sources, optical measurements, and the impact on atmospheric aerosols. The proposed approach can be useful for better understanding the mechanism of the acoustic channel of seismo-ionospheric coupling.
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Piersanti, Mirko, William Jerome Burger, Vincenzo Carbone, Roberto Battiston, Roberto Iuppa, and Pietro Ubertini. "On the Geomagnetic Field Line Resonance Eigenfrequency Variations during Seismic Event." Remote Sensing 13, no. 14 (July 19, 2021): 2839. http://dx.doi.org/10.3390/rs13142839.
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In this paper, we report high statistical evidence for a seismo–ionosphere effects occurring in conjunction with an earthquake. This finding supports a lithosphere-magnetosphere coupling mechanism producing a plasma density variation along the magnetic field lines, mechanically produced by atmospheric acoustic gravity waves (AGWs) impinging the ionosphere. We have analysed a large sample of earthquakes (EQ) using ground magnetometers data: in 28 of 42 analysed case events, we detect a temporary stepwise decrease (Δf) of the magnetospheric field line resonance (FLR) eigenfrequency (f*). Δf decreases of ∼5–25 mHz during ∼20–35 min following the time of the EQ. We present an analytical model for f*, able to reproduce the behaviour observed during the EQ. Our work is in agreement with recent results confirming co-seismic direct coupling between lithosphere, ionosphere and magnetosphere opening the way to new remote sensing methods, from space/ground, of the earth seismic activity.
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Захаров, Виктор, Viktor Zakharov, Вячеслав Пилипенко, Vyacheslav Pilipenko, Валерий Грушин, Valeriy Grushin, Аскар Хамидуллин, and Askar Khamidullin. "Impact of typhoon Vongfong 2014 on the ionosphere and geomagnetic field according to Swarm satellite data: 1. Wave disturbances of ionospheric plasma." Solar-Terrestrial Physics 5, no. 2 (June 28, 2019): 101–8. http://dx.doi.org/10.12737/stp-52201914.
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The article considers the influence of large atmospheric processes on the ionosphere by the example of tropical typhoon Vongfong 2014. We use data obtained from three SWARM satellite missions (450–500 km altitude). We discuss two possible mechanisms of transfer of atmospheric disturbances to ionospheric heights. The first mechanism is the generation of acoustic-gravity waves (AGWs); the second mechanism considers the excitation of electric fields in the atmosphere. We propose new techniques for detecting the ionospheric response to AGW, which rely on low-orbit satellite data. The first technique is based on determination of relative electron density variations in the frequency band from 15 to 150–180 s, corresponding to certain scales of AGW. The second technique estimates space-time derivatives of the electron density, measured by two nearby SWARM satellites. We present and estimate the characteristic magnitudes of ionospheric response effects, their localization and spatial-temporal characteristics for the large tropical cyclone under study.
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Захаров, Виктор, Viktor Zakharov, Вячеслав Пилипенко, Vyacheslav Pilipenko, Валерий Грушин, Valeriy Grushin, Аскар Хамидуллин, and Askar Khamidullin. "Impact of typhoon Vongfong 2014 on the ionosphere and geomagnetic field according to Swarm satellite data: 1. Wave disturbances of ionospheric plasma." Solnechno-Zemnaya Fizika 5, no. 2 (June 28, 2019): 114–23. http://dx.doi.org/10.12737/szf-52201914.
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The article considers the influence of large atmospheric processes on the ionosphere by the example of tropical typhoon Vongfong 2014. We use data obtained from three SWARM satellite missions (450–500 km altitude). We discuss two possible mechanisms of transfer of atmospheric disturbances to ionospheric heights. The first mechanism is the generation of acoustic-gravity waves (AGWs); the second mechanism considers the excitation of electric fields in the atmosphere. We propose new techniques for detecting the ionospheric response to AGW, which rely on low-orbit satellite data. The first technique is based on determination of relative electron density variations in the frequency band from 15 to 150–180 s, corresponding to certain scales of AGW. The second technique estimates space-time derivatives of the electron density, measured by two nearby SWARM satellites. We present and estimate the characteristic magnitudes of ionospheric response effects, their localization and spatial-temporal characteristics for the large tropical cyclone under study.
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Zhang, Ruijiao, Gang Chen, Yaxian Li, Shaodong Zhang, Wanlin Gong, Zhiqiu He, and Min Zhang. "Long-Term Observation of the Quasi-3-Hour Large-Scale Traveling Ionospheric Disturbances by the Oblique-Incidence Ionosonde Network in North China." Sensors 22, no. 1 (December 29, 2021): 233. http://dx.doi.org/10.3390/s22010233.
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The oblique-incidence ionosonde network in North China is a very unique system for regional ionospheric observation. It contains 5 transmitters and 20 receivers, and it has 99 ionospheric observation points between 22.40° N and 33.19° N geomagnetic latitudes. The data of the ionosonde network were used to investigate the statistical characteristics of the quasi-3-h large-scale traveling ionospheric disturbances (LSTIDs). From September 2009 to August 2011, 157 cases of the quiet-time LSTIDs were recorded; 110 cases traveled southward, 46 cases traveled southwestward and only 1 case traveled southeastward. The LSTIDs mainly appeared between 10:00 and 19:00 LT in the months from September to the following May. We compared the data of the Beijing, Mohe and Yakutsk digisondes and found that the LSTIDs are most likely to come from the northern auroral region. These LSTIDs may be induced by the atmospheric gravity waves (AGWs) and presented obvious seasonal and diurnal varying features, indicating that the thermospheric wind field has played an important role.
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Lue, H. Y., and F. S. Kuo. "Comparative studies of methods of obtaining AGW's propagation properties." Annales Geophysicae 30, no. 3 (March 19, 2012): 557–70. http://dx.doi.org/10.5194/angeo-30-557-2012.
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Abstract. Three among the existing methods of obtaining the properties (intrinsic period, wavelength, propagation direction) of atmospheric gravity waves (AGWs) were compared and studied by numerical method to simulate radar data. Three-dimensional fluctuation velocity satisfying dispersion equation and polarization relation of atmospheric gravity wave were generated, then the numerical data were analysed by these methods to obtain the properties of waves. We found that, hodograph analysis was accurate for a monochromatic wave in obtaining its wave period and propagation direction, but the analysis became erratic for the case of multiple waves' superposition. The error was especially large when data consisted of both upward propagating waves and downward propagating waves. The hodograph method became meaningful again if all the component waves propagated in the same direction and the resulting period was dominantly decided by the lowest frequency wave. Stokes parameters method would obtain statistically meaningful values of wave period and azimuth if the spreading of the azimuths among the component waves did not exceed 90° and the resulting period and azimuth were dominated by the lowest frequency wave component as well, irrespective of the vertical sense of propagation. Another method called phase and group velocity tracing technique was reconfirmed to be meaningful in measuring the characteristic wave period and vertical group and phase velocities of a wave packet: the characteristic wave period and vertical wavelength was dominated by the wave with the highest frequency among the component waves in the wave packet. Based on these numerical results, a composite procedure of data analysis for wave propagation was proposed and an example of real data analysis was presented.
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Didebulidze, G. G., and L. N. Lomidze. "The formation of sporadic E layers by a vortical perturbation excited in a horizontal wind shear flow." Annales Geophysicae 26, no. 7 (June 24, 2008): 1741–49. http://dx.doi.org/10.5194/angeo-26-1741-2008.
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Abstract. The formation of the mid-latitude sporadic E layers (Es layers) by an atmospheric vortical perturbation excited in a horizontal shear flow (horizontal wind with a horizontal linear shear) is investigated. A three-dimensional atmospheric vortical perturbation (atmospheric shear waves), whose velocity vector is in the horizontal plane and has a vertical wavenumber kz≠0, can provide a vertical shear of the horizontal wind. The shear waves influence the vertical transport of heavy metallic ions and their convergence into thin and dense horizontal layers. The proposed mechanism takes into account the dynamical influence of the shear wave velocity in the horizontal wind on the vertical drift velocity of the ions. It also can explain the multi-layer structure of Es layers. The pattern of the multi-layer structure depends on the value of the shear-wave vertical wavelength, the ion-neutral collision frequency and the direction of the background horizontal wind. The modelling of formation of sporadic E layers with a single and a double peak is presented. Also, the importance of shear wave coupling with short-period atmospheric gravity waves (AGWs) on the variations of sporadic E layer ion density is examined and discussed.
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Hu, Huimin, Yu Ling, Xuan Wang, Hao Wang, Niannan Zhu, Yumei Li, and Hui Xu. "Viral Metagenomics Reveals a Putative Novel HPV Type in Anogenital Wart Tissues." Pathogens 11, no. 12 (December 1, 2022): 1452. http://dx.doi.org/10.3390/pathogens11121452.
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Viral metagenomics is widely employed to identify novel viruses in biological samples. Recently, although numerous novel human papillomavirus (HPV) types have been identified in clinical samples including anogenital warts (AGWs), many novel HPV sequences remain to be discovered. In this study, a putative novel HPV type designated as HPV-JDFY01 was discovered from library GW05 with 63 sequence reads by the viral metagenomic technique. Its complete genomic sequence was determined by PCR to bridge the gaps between contigs combining Sanger sequencing. The complete genome of HPV-JDFY01 is a 7186 bp encoding 7 open reading frames (ORFs) (E6, E7, E1, E2, E4, L2 and L1) and contains a 487 bp long control region (LCR) between L1 and E6. Sequence and phylogeny analysis indicated that HPV-JDFY01 shared the highest sequence identity of 74.2% with HPV-mSK_244 (MH777383) and well clustered into the genus Gammapapillomavirus. It has the classical genomic organization of Gammapapillomaviruses. Epidemiological investigation showed that one out of the 413 AGW tissue samples was positive for HPV-JDFY01. Further research with large size and different type of samples should be performed to elucidate the epidemiologic status of HPV-JDFY01.
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Zhao, Weibo, Xiong Hu, Weilin Pan, Zhaoai Yan, and Wenjie Guo. "Mesospheric Gravity Wave Potential Energy Density Observed by Rayleigh Lidar above Golmud (36.25° N, 94.54° E), Tibetan Plateau." Atmosphere 13, no. 7 (July 9, 2022): 1084. http://dx.doi.org/10.3390/atmos13071084.
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Rayleigh lidar data in 2013–2015 is used to describe the characteristics of gravity wave potential energy density in the mesosphere above Golmud (36.25° N, 94.54° E) of the Tibetan Plateau. In this study, the vertical profiles of the atmospheric gravity wave potential energy density between 50–80 km above the region are presented, including the potential energy mass density Epm and the potential energy volume density Epv. It shows the mathematical characteristics of the atmospheric gravity wave potential energy density vertical distribution, which also indicate the gravity waves are obviously dissipated in the lower mesosphere and close to conservative growth in the upper mesosphere (the turning point is around 61 km). A total of 1174 h of data covers seasonal changes, which reveals the seasonal characteristics of the potential energy density. The Epm increases faster with altitude in summer than others. All seasons of the potential energy density profiles show that gravity waves are dissipated in the lower mesosphere, among which spring and winter are the most severe and summer is weakest. The Epm is higher in spring and winter below 55 km. Above 55 km, it is the maximum in winter, followed by summer. Then, the AGWs activities between the location with mid–latitudes and different longitudes are compared and discussed.
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Gavrilov, Nikolai M., Sergey P. Kshevetskii, and Andrey V. Koval. "Decay times of atmospheric acoustic–gravity waves after deactivation of wave forcing." Atmospheric Chemistry and Physics 22, no. 20 (October 24, 2022): 13713–24. http://dx.doi.org/10.5194/acp-22-13713-2022.
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Abstract. High-resolution numerical simulations of non-stationary, nonlinear acoustic–gravity waves (AGWs) propagating upwards from surface wave sources are performed for different temporal intervals relative to activation and deactivation times of the wave forcing. After activating surface wave sources, amplitudes of AGW spectral components reach a quasi-stationary state. Then the surface wave forcing is deactivated in the numerical model, and amplitudes of vertically traveling AGW modes quickly decrease at all altitudes due to discontinuations of the upward propagation of wave energy from the wave sources. However, later the standard deviation of residual and secondary wave perturbations experiences a slower quasi-exponential decrease. High-resolution simulations allowed, for the first time, for the estimation of the decay times of this wave noise produced by slow residual, quasi-standing and secondary AGW spectral components, which vary between 20 and 100 h depending on altitude and the rate of wave source activation and deactivation. The standard deviations of the wave noise are larger for the case of sharp activation and deactivation of the wave forcing compared to the steep processes. These results show that transient wave sources may create long-lived wave perturbations, which can form a background level of wave noise in the atmosphere. This should be taken into account in parameterizations of atmospheric AGW impacts.
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Scharl, Anton J. "„Quidquid agis, prudenter agas et respice finem“." Geburtshilfe und Frauenheilkunde 79, no. 08 (August 2019): 745–46. http://dx.doi.org/10.1055/a-0925-4569.
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Luo, Y., L. F. Chernogor, and K. P. Garmash. "GEOMAGNETIC EFFECT OF TURKISH EARTHQUAKE OF JANUARY 24, 2020." Radio physics and radio astronomy 25, no. 4 (December 2, 2020): 276–89. http://dx.doi.org/10.15407/rpra25.04.276.
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Purpose:The main cause of geomagnetic disturbances are cosmic sources, processes acting in the solar wind and in the interplanetary medium, as well as large celestial bodies entering the terrestrial atmosphere. Earthquakes (EQs) also act to produce geomagnetic effects. In accordance with the systems paradigm, the Earth–atmosphere–ionosphere–magnetosphere system (EAIMS) constitute a unified system, where positive and negative couplings among the subsystems, as well as feedbacks and precondition among the system components take place. The mechanisms for the action of EQs and processes acting in the lithosphere on the geomagnetic field are poorly understood. It is considered that the EQ action is caused by cracking of rocks, fluctuating motion in the pore fluid, static electricity discharges, etc. In the course of EQs, the seismic, acoustic, atmospheric gravity waves (AGWs), and magnetohydrodynamic (MHD) waves are generated. The purpose of this paper is to describe the magnetic effects of the EQ, which took place in Turkey on 24 January 2020. Design/methodology/approach: The measurements are taken with the fluxmeter magnetometer delivering 0.5-500 pT sensitivity in the 1-1000 s period range, respectively, and in a wide enough studied frequency band within 0.001 to 1 Hz. The EM-II magnetometer with the embedded microcontroller digitizes the magnetometer signals and performs preliminary filtering over 0.5 s time intervals, while the external flash memory is used to store the filtered out magnetometer signals and the times of their acquisition. To investigate quasi-periodic processes in detail, the temporal variations in the level of the H and D components of the geomagnetic field were applied to the systems spectral analysis, which makes use of the short-time Fourier transform, the wavelet transform using the Morlet wavelet as a basis function, and the Fourier transform in a sliding window with a width adjusted to be equal to a fixed number of harmonic periods. Findings: The train of oscillations in the level of the D component observed 25.5 h before the EQ on 23 January 2020 is supposed to be associated with the magnetic precursor. The bidirectional pulse in the H component observed on 24 January 2020 could be due to the piston action of the EQ, which had generated an MHD pulse. The quasi-periodic variations in the level of the H and D components of the geomagnetic field, which followed 75 min after the EQ, were caused by a magnetic disturbance produced by the traveling ionospheric disturbances due to the AGWs launched by the EQ. The magnetic effect amplitude was estimated to be close to 0.3 nT, and the quasi-period to be 700-900 s. The amplitude of the disturbances in the electron density in the AGW field was estimated to be about 8 % and the period of 700-900 s. Damping oscillations in both components of the magnetic field were detected to occur with a period of approximately 120 s. This effect is supposed to be due to the shock wave generated in the atmosphere in the course of the EQ. Conclusions: The magnetic variations associated with the EQ and occurring before and during the EQ have been studied in the 1-1000 s period range. Key words: earthquake, fluxmeter magnetometer, quasi-periodic disturbance, seismic wave, acoustic-gravity wave, MHD pulse
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Kshevetskii, Sergey P., Yuliya A. Kurdyaeva, and Nikolai M. Gavrilov. "Spectra of Acoustic-Gravity Waves in the Atmosphere with a Quasi-Isothermal Upper Layer." Atmosphere 12, no. 7 (June 25, 2021): 818. http://dx.doi.org/10.3390/atmos12070818.
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In this paper, we study, in theoretical terms, the structure of the spectrum of acoustic-gravity waves (AGWs) in the nonisothermal atmosphere having asymptotically constant temperature at high altitudes. A mathematical problem of wave propagation from arbitrary initial perturbations in the half-infinite nonisothermal atmosphere is formulated and analyzed for a system of linearized hydrodynamic equations for small-amplitude waves. Besides initial and lower boundary conditions at the ground, wave energy conservation requirements are applied. In this paper, we show that this mathematical problem belongs to the class of wave problems having self-adjoint evolution operators, which ensures the correctness and existence of solutions for a wide range of atmospheric temperature stratifications. A general solution of the problem can be built in the form of basic eigenfunction expansions of the evolution operator. The paper shows that wave frequencies considered as eigenvalues of the self-adjoint evolution operator are real and form two global branches corresponding to high- and low-frequency AGW modes. These two branches are separated since the Brunt–Vaisala frequency is smaller than the acoustic cutoff frequency at the upper boundary of the model. Wave modes belonging to the low-frequency global spectral branch have properties of internal gravity waves (IGWs) at all altitudes. Wave modes of the high-frequency spectral branch at different altitudes may have properties of IGWs or acoustic waves depending on local stratification. The results of simulations using a high-resolution nonlinear numerical model confirm possible changes of AGW properties at different altitudes in the nonisothermal atmosphere.
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Liu, Jing, Dong-He Zhang, Anthea J. Coster, Shun-Rong Zhang, Guan-Yi Ma, Yong-Qiang Hao, and Zuo Xiao. "A case study of the large-scale traveling ionospheric disturbances in the eastern Asian sector during the 2015 St. Patrick's Day geomagnetic storm." Annales Geophysicae 37, no. 4 (August 5, 2019): 673–87. http://dx.doi.org/10.5194/angeo-37-673-2019.
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Abstract. This study presents a comprehensive observation of the large-scale traveling ionospheric disturbances (LSTIDs) in the eastern Asian sector during the 2015 St. Patrick's Day (17 March 2015) geomagnetic storm. For the first time, three dense networks of GPS receivers in China and Japan are combined together to obtain the two-dimensional (2-D) vertical total electron content (VTEC) perturbation maps in a wider longitudinal range than previous studies in this region. Results show that an LSTID spanning at least 60∘ in longitude (80–140∘ E) occurs as a result of possible atmospheric gravity waves (AGWs) propagating from high to lower latitudes at around 09:40–11:40 UT (universal time), and the crest of this LSTID shows a tendency of dissipation starting from the eastern side. The manifestation of the 2-D VTEC perturbation maps is in good agreement with the recordings from two high-frequency Doppler sounders and the iso-frequency lines from eight ionosondes. Then, the propagation parameters of the LSTIDs are estimated by applying least-square fitting methods to the distinct structures in the 2-D VTEC perturbation plots. In general, the propagation parameters are observably longitudinally dependent. For example, the propagation direction is almost due southward between 105 and 115∘ E, while it is slightly southwest and southeast in the western and eastern sides of this region. This feature is probably related to the regional geomagnetic declination. The mean values of the period, trough velocity (Vt), crest velocity (Vc), and wavelength of the LSTIDs in the studied longitudinal bands are 74.8±1.4 min, 578±16 m s−1, 617±23 m s−1, and 2691±80 km, respectively. Finally, using the VTEC map data from the Madrigal database of the MIT Haystack Observatory, the characteristics of the ionospheric disturbances over the European sector (30–70∘ N, 10–20∘ E) are also studied. The results are very different from those in the eastern Asian sector in parameters like the occurrence time, oscillation period, and propagation velocities.
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Politis, Dimitrios Z., Stelios M. Potirakis, Subrata Kundu, Swati Chowdhury, Sudipta Sasmal, and Masashi Hayakawa. "Critical Dynamics in Stratospheric Potential Energy Variations Prior to Significant (M > 6.7) Earthquakes." Symmetry 14, no. 9 (September 18, 2022): 1939. http://dx.doi.org/10.3390/sym14091939.
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Lithosphere–atmosphere–ionosphere coupling (LAIC) is studied through various physical or chemical quantities, obtained from different sources, which are observables of the involved complex processes. LAIC has been proposed to be achieved through three major channels: the chemical, the acoustic, and the electromagnetic. Accumulated evidence supporting the acoustic channel hypothesis has been published, while atmospheric gravity waves (AGWs) play a key role in LAIC as the leading mechanism for the transmission of energy from the lower atmosphere to the stratosphere and mesosphere, associated with atmospheric disturbances observed prior to strong earthquakes (EQs). The seismogenic AGW is the result of temperature disturbances, usually studied through stratospheric potential energy (EP). In this work, we examined 11 cases of significant EQs (M > 6.7) that occurred during the last 10 years at different geographic areas by analyzing the temperature profile at the wider location of each one of the examined EQs. The “Sounding of the Atmosphere using Broadband Emission Radiometry” (SABER) instrument, part of the “Thermosphere Ionosphere Mesosphere Energetics Dynamics” (TIMED) satellite, data were employed to compute the potential energy (EP) of the AGW. Using the temperature profile, we first calculated EP and determined the altitudes’ range for which prominent pre-seismic disturbances were observed. Subsequently, the EP time series at specific altitudes, within the determined “disturbed” range, were for the first time analyzed using the criticality analysis method termed the “natural time” (NT) method in order to find any evidence of an approach to a critical state (during a phase transition from a symmetric phase to a low symmetry phase) prior to the EQ occurrence. Our results show criticality indications in the fluctuation of EP a few days (1 to 15 days) prior to the examined EQs, except from one case. In our study, we also examined all of the temperature-related extreme phenomena that have occurred near the examined geographic areas, in order to take into account any possible non-seismic influence on the obtained results.
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Westfechtel, Lukas, Ricardo Niklas Werner, Corinna Dressler, Matthew Gaskins, and Alexander Nast. "Adjuvant treatment of anogenital warts with systemic interferon: a systematic review and meta-analysis." Sexually Transmitted Infections 94, no. 1 (August 17, 2017): 21–29. http://dx.doi.org/10.1136/sextrans-2017-053150.
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BackgroundInterferons are natural messenger proteins that are used to treat various disease entities. Due to their immunomodulating, antiviral and antiproliferative effects, the systemic administration of interferons after ablative treatment for anogenital warts (AGWs) has been advocated to increase clearance and decrease recurrence rates. However, studies investigating the efficacy of adjuvant systemic interferon have yielded inconsistent results. The objective of this systematic review and meta-analysis was to comprehensively assess and evaluate the available evidence from randomised controlled trials.MethodsA literature search was conducted in Cochrane Central Register of Controlled Trials, Embase and MEDLINE. Available data were classified according to the interferon type and dosage. Pooled effect estimates were calculated for predefined outcomes. The Cochrane Collaboration’s risk of bias tool was used to assess the included trials and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to evaluate our confidence in the effect estimates.ResultsTwelve trials were identified that met the inclusion criteria and assessed immunocompetent patients with external AGW. Compared with placebo, adjuvant alpha-, beta- and gamma-interferon were generally not significantly superior in terms of complete clearance over the short, intermediate or long term, nor with regard to intermediate- or long-term recurrence. However, the low-dose subgroup of adjuvant alpha-interferon was significantly superior compared with placebo regarding intermediate-term complete clearance and recurrence. Further data were available for the comparison of different dosages of alpha- and beta-interferon and for comparisons of the three interferon types. No significant differences were seen in these comparisons regarding efficacy. Data on quality of life were not available.ConclusionsThe GRADE quality of the evidence ranged from ‘very low’ to ‘high’. The significantly higher efficacy of low-dose alpha-interferon compared with placebo was based on a single trial, and our confidence in the effect estimates rated as ‘low’. Overall, we found no reliable evidence favouring the systemic use of interferon after ablative treatment of AGW.
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Sidorowicz-Mulak, Dorota. "Quidquid agis, prudenter agas et respice finem. Odpowiedź na recenzję Haliny Mieczkowskiej." Roczniki Biblioteczne 63 (April 14, 2020): 241–53. http://dx.doi.org/10.19195/0080-3626.63.9.
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