Articles de revues : « Atmospheric tides »

1

Palumbo, A. « Atmospheric tides ». Journal of Atmospheric and Solar-Terrestrial Physics 60, n^o 3 (février 1998) : 279–87. http://dx.doi.org/10.1016/s1364-6826(97)00078-3.

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Auclair-Desrotour, P., S. Mathis et J. Laskar. « Atmospheric thermal tides and planetary spin ». Astronomy & ; Astrophysics 609 (janvier 2018) : A118. http://dx.doi.org/10.1051/0004-6361/201731540.

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Context. Thermal atmospheric tides can torque telluric planets away from spin-orbit synchronous rotation, as observed in the case of Venus. They thus participate in determining the possible climates and general circulations of the atmospheres of these planets. Aims. The thermal tidal torque exerted on an atmosphere depends on its internal structure and rotation and on the tidal frequency. Particularly, it strongly varies with the convective stability of the entropy stratification. This dependence has to be characterized to constrain and predict the rotational properties of observed telluric exoplanets. Moreover, it is necessary to validate the approximations used in global modelings such as the traditional approximation, which is used to obtain separable solutions for tidal waves. Methods. We wrote the equations governing the dynamics of thermal tides in a local vertically stratified section of a rotating planetary atmosphere by taking into account the effects of the complete Coriolis acceleration on tidal waves. This allowed us to analytically derive the tidal torque and the tidally dissipated energy, which we used to discuss the possible regimes of tidal dissipation and to examine the key role played by stratification. Results. In agreement with early studies, we find that the frequency dependence of the thermal atmospheric tidal torque in the vicinity of synchronization can be approximated by a Maxwell model. This behavior corresponds to weakly stably stratified or convective fluid layers, as observed previously. A strong stable stratification allows gravity waves to propagate, and makes the tidal torque negligible. The transition is continuous between these two regimes. The traditional approximation appears to be valid in thin atmospheres and in regimes where the rotation frequency is dominated by the forcing or the buoyancy frequencies. Conclusions. Depending on the stability of their atmospheres with respect to convection, observed exoplanets can be tidally driven toward synchronous or asynchronous final rotation rates. The domain of applicability of the traditional approximation is rigorously constrained by calculations.

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Auclair-Desrotour, P., J. Laskar et S. Mathis. « Atmospheric tides in Earth-like planets ». Astronomy & ; Astrophysics 603 (juillet 2017) : A107. http://dx.doi.org/10.1051/0004-6361/201628252.

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Context. Atmospheric tides can strongly affect the rotational dynamics of planets. In the family of Earth-like planets, which includes Venus, this physical mechanism coupled with solid tides makes the angular velocity evolve over long timescales and determines the equilibrium configurations of their spin. Aims. Unlike the solid core, the atmosphere of a planet is subject to both tidal gravitational potential and insolation flux coming from the star. The complex response of the gas is intrinsically linked to its physical properties. This dependence has to be characterized and quantified for application to the wide variety of extrasolar planetary systems. Methods. We develop a theoretical global model where radiative losses, which are predominant in slowly rotating atmospheres, are taken into account. We analytically compute the perturbation of pressure, density, temperature, and velocity field caused by a thermogravitational tidal perturbation. From these quantities, we deduce the expressions of atmospheric Love numbers and tidal torque exerted on the fluid shell by the star. The equations are written for the general case of a thick envelope and the simplified one of a thin isothermal atmosphere. Results. The dynamics of atmospheric tides depends on the frequency regime of the tidal perturbation: the thermal regime near synchronization and the dynamical regime characterizing fast-rotating planets. Gravitational and thermal perturbations imply different responses of the fluid, i.e. gravitational tides and thermal tides, which are clearly identified. The dependence of the torque on the tidal frequency is quantified using the analytic expressions of the model for Earth-like and Venus-like exoplanets and is in good agreement with the results given by global climate models (GCM) simulations.Introducing dissipative processes such as radiation regularizes the tidal response of the atmosphere, otherwise it is singular at synchronization. Conclusions. We demonstrate the important role played by the physical and dynamical properties of a super-Earth atmosphere (e.g. Coriolis, stratification, basic pressure, density, temperature, radiative emission) in its response to a tidal perturbation. We point out the key parameters defining tidal regimes (e.g. inertia, Brunt-Väisälä, radiative frequencies, tidal frequency) and characterize the behaviour of the fluid shell in the dissipative regime, which cannot be studied without considering the radiative losses.

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Navarro, Thomas, Timothy M. Merlis, Nicolas B. Cowan et Natalya Gomez. « Atmospheric Gravitational Tides of Earth-like Planets Orbiting Low-mass Stars ». Planetary Science Journal 3, n^o 7 (1 juillet 2022) : 162. http://dx.doi.org/10.3847/psj/ac76cd.

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Abstract Temperate terrestrial planets orbiting low-mass stars are subject to strong tidal forces. The effects of gravitational tides on the solid planet and that of atmospheric thermal tides have been studied, but the direct impact of gravitational tides on the atmosphere itself has so far been ignored. We first develop a simplified analytic theory of tides acting on the atmosphere of a planet. We then implement gravitational tides into a general circulation model of a static-ocean planet in a short-period orbit around a low-mass star—the results agree with our analytic theory. Because atmospheric tides and solid-body tides share a scaling with the semimajor axis, we show that there is a maximum amplitude of the atmospheric tide that a terrestrial planet can experience while still having a solid surface; Proxima Centauri b is the poster child for a planet that could be geophysically Earth-like but with atmospheric tides more than 500× stronger than Earth’s. In this most extreme scenario, we show that atmospheric tides significantly impact the planet’s meteorology—but not its climate. Two possible modest climate impacts are enhanced longitudinal heat transport and cooling of the lowest atmospheric layers. The strong radiative forcing of such planets dominates over gravitational tides, unlike moons of cold giant planets, such as Titan. We speculate that atmospheric tides could be climatologically important on planets where the altitude of maximal tidal forcing coincides with the altitude of cloud formation and that the effect could be detectable for non-Earth-like planets subject to even greater tides.

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Auclair-Desrotour, P., J. Laskar et S. Mathis. « Atmospheric tides and their consequences on the rotational dynamics of terrestrial planets ». EAS Publications Series 82 (2019) : 81–90. http://dx.doi.org/10.1051/eas/1982008.

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Atmospheric tides can have a strong impact on the rotational dynamics of planets. They are of most importance for terrestrial planets located in the habitable zone of their host star, where their competition with solid tides is likely to drive the body towards non-synchronized rotation states of equilibrium, as observed in the case of Venus. Contrary to other planetary layers, the atmosphere is sensitive to both gravitational and thermal forcings, through a complex dynamical coupling involving the effects of Coriolis acceleration and characteristics of the atmospheric structure. These key physics are usually not taken into account in modelings used to compute the evolution of planetary systems, where tides are described with parametrised prescriptions. In this work, we present a new ab initio modeling of atmospheric tides adapting the theory of the Earth’s atmospheric tides (Chapman & Lindzen 1970) to other terrestrial planets. We derive analytic expressions of the tidal torque, as a function of the tidal frequency and parameters characterizing the internal structure (e.g. the Brunt-Väisälä frequency, the radiative frequency, the pressure heigh scale). We show that stratification plays a key role, the tidal torque being strong in the case of convective atmospheres (i.e. with a neutral stratification) and weak in case of atmosphere convectively stable. In a second step, the model is used to determine the non-synchronized rotation states of equilibrium of Venus-like planets as functions of the physical parameters of the system. These results are detailed in Auclair-Desrotour et al. (2016a) and Auclair-Desrotour et al. (2016b).

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Brahde, R. « Lunisolar Atmospheric Tides. II ». Australian Journal of Physics 42, n^o 4 (1989) : 439. http://dx.doi.org/10.1071/ph890439.

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In an earlier paper (Brahde 1988) it was shown that series of measurements of the atmospheric pressure in Oslo contained information about a one�day oscillation with mean amplitude 0�17 mb. The data consisted of measurements every second hour during the years 1957-67, 1969 and 1977. In the present paper the intervening years plus 1978 and 1979 have been included, increasing the basis from 13 to 23 years. In addition the phase shift occurring when the Moon crosses the celestial equator has been defined precisely, thus making it possible to include all the data.

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Brahde, R. « Lunisolar Atmospheric Tides. III ». Australian Journal of Physics 44, n^o 1 (1991) : 87. http://dx.doi.org/10.1071/ph910087.

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In two earlier papers (Brahde 1988, 1989) the atmospheric tide in Oslo (Norway) was studied using pressure data for 23 continuous years. In the present paper a similar study based on pressure data from Batavia (now Jakarta in Indonesia, latitude 6�08'S, longitude 106�45'E) is presented. The result is that the tidal wave caused by the lunisolar tide is represented by a one-day and a half-day oscillation with mean amplitudes of 0 �11 and 0�33 mb respectively. The amplitude spectrum reveals amplitudes of up to 1 mb of dynamiC origin. The 'thermal' tide is also studied and the connection between the thermal and dynamic effects is discussed.

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FORBES, Jeffrey M. « Middle Atmosphere Tides and Coupling between Atmospheric Regions ». Journal of geomagnetism and geoelectricity 43, Supplement2 (1991) : 597–609. http://dx.doi.org/10.5636/jgg.43.supplement2_597.

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Hagen, Jonas, Klemens Hocke, Gunter Stober, Simon Pfreundschuh, Axel Murk et Niklaus Kämpfer. « First measurements of tides in the stratosphere and lower mesosphere by ground-based Doppler microwave wind radiometry ». Atmospheric Chemistry and Physics 20, n^o 4 (28 février 2020) : 2367–86. http://dx.doi.org/10.5194/acp-20-2367-2020.

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Abstract. Atmospheric tides are important for vertical coupling in the atmosphere, from the stratosphere down to the troposphere and up to the thermosphere. They are planetary-scale gravity waves with well-known periods that are integer fractions of a day and can be observed in the temperature or wind fields in the atmosphere. Most lidar techniques and satellites measure atmospheric tides only in the temperature field and continuous measurements of the tides in the wind field of the stratosphere and lower mesosphere are rare, even though, with modern lidars, they would be feasible. In this study, we present measurements of the diurnal tide in the wind field in the stratosphere and lower mesosphere by ground-based microwave wind radiometry for two different campaigns in tropical and polar regions. Further, we compare our measurements to MERRA-2 reanalysis data. In the tri-monthly mean, we find a good correspondence in the amplitude and phase of the diurnal tide between measurements and reanalysis with the most important features of the diurnal tides represented in both data sets. When looking at shorter timescales, we find significant differences in the data sets. We make an attempt to examine these differences and discriminate between atmospheric variability and noise, and we present some hints for intermittent diurnal tides. We conclude that continuous ground-based observations of tides in the middle atmospheric wind field are feasible, and they deliver consistent results for the mean amplitude and phase of the diurnal tide in the tri-monthly mean. We further discuss the limitations in regards to short timescale observations of tides and the possibility to provide additional insight into middle atmospheric dynamics that is complementary to temperature observations and reanalysis data.

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Forbes, Jeffrey M., et Gerald V. Groves. « Atmospheric tides below 80 km ». Advances in Space Research 10, n^o 12 (janvier 1990) : 119–25. http://dx.doi.org/10.1016/0273-1177(90)90391-c.

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Biagi, P. F., R. Piccolo, V. Capozzi, A. Ermini, S. Martellucci et C. Bellecci. « Exalting in atmospheric tides as earthquake precursor ». Natural Hazards and Earth System Sciences 3, n^o 3/4 (31 août 2003) : 197–201. http://dx.doi.org/10.5194/nhess-3-197-2003.

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Abstract. During February–March 1998, we observed a significant increase (6–8 dB) in the electric field of the CZE (f = 270 kHz, Czech Republic) broadcasting station at a site named AS and located in central Italy. On 13 March 1998 an earthquake (M = 5.2) occurred in Slovenia, starting a strong seismic crisis (M = 6.0 on 12 April, M = 5.1 on 6 May). The distances of the epicentres from the radio receiver were over 400 km, but the epicentres are located in a zone that is in the middle of the CZE-AS path. Previously, we advanced the hypothesis that the increase of radio-signal electric field detected could be a precursor of the Slovenia seismic crisis. At the purpose to precise the connection between this radio anomaly and the preparatory phase of the earthquakes, we analysed in detail the data collected. At first we carried out a FFT on the data and clear harmonic components with period 0.5d, 1d, 14d, 28d and 365d were revealed. These periods are characteristic of gravity tides and therefore, it seems reasonable to consider the previous harmonics in the electric field of the radio signal as components related to tides of the atmosphere, assuming as tides of the atmosphere only the linear action of gravity tides on atmosphere. Then, we carried out band pass filters on our data and we discovered that the February–March 1998 increase is mainly related to an exalting of the harmonics with period 0.5d, 1d, 14d and 28d, i.e. of the (semi)monthly and (semi)diurnal atmospheric tidal components in the radio signal. Supposing that this exalting is produced by a corresponding exalting of the atmospheric tides we propose a model able to explain the production of such an effect during the preparatory phase of the Slovenia earthquakes.

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Cunha, Diana, Alexandre C. M. Correia et Jacques Laskar. « Spin evolution of Earth-sized exoplanets, including atmospheric tides and core–mantle friction ». International Journal of Astrobiology 14, n^o 2 (30 juillet 2014) : 233–54. http://dx.doi.org/10.1017/s1473550414000226.

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AbstractPlanets with masses between 0.1 and 10 M⊕ are believed to host dense atmospheres. These atmospheres can play an important role on the planet's spin evolution, since thermal atmospheric tides, driven by the host star, may counterbalance gravitational tides. In this work, we study the long-term spin evolution of Earth-sized exoplanets. We generalize previous works by including the effect of eccentric orbits and obliquity. We show that under the effect of tides and core–mantle friction, the obliquity of the planets evolves either to 0° or 180°. The rotation of these planets is also expected to evolve into a very restricted number of equilibrium configurations. In general, none of these equilibria is synchronous with the orbital mean motion. The role of thermal atmospheric tides becomes more important for Earth-sized planets in the habitable zones of their systems; so they cannot be neglected when we search for their potential habitability.

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Griffith, Matthew J., et Nicholas J. Mitchell. « Analysis of migrating and non-migrating tides of the Extended Unified Model in the mesosphere and lower thermosphere ». Annales Geophysicae 40, n^o 3 (1 juin 2022) : 327–58. http://dx.doi.org/10.5194/angeo-40-327-2022.

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Abstract. Atmospheric tides play a key role in coupling the lower, middle, and upper atmosphere/ionosphere. The tides reach large amplitudes in the mesosphere and lower thermosphere (MLT), where they can have significant fluxes of energy and momentum, and so strongly influence the coupling and dynamics. The tides must therefore be accurately represented in general circulation models (GCMs) that seek to model the coupling of atmospheric layers and impacts on the ionosphere. The tides consist of both migrating (sun-following) and non-migrating (not sun-following) components, both of which have important influences on the atmosphere. The Extended Unified Model (ExUM) is a recently developed version of the Met Office's GCM (the Unified Model) which has been extended to include the MLT. Here, we present the first in-depth analysis of migrating and non-migrating components in the ExUM. We show that the ExUM produces both non-migrating and migrating tides in the MLT of significant amplitude across a rich spectrum of spatial and temporal components. The dominant non-migrating components in the MLT are found to be DE3, DW2, and DW3 in the diurnal tide and S0, SW1, and SW3 in the semidiurnal tide. These components in the model can have monthly mean amplitudes at a height of 95 km as large as 35 m s−1/10 K. All the non-migrating components exhibit a strong seasonal variability in amplitude, and a significant short-term variability is evident. Both the migrating and non-migrating components exhibit notable variation with latitude. For example, the temperature and wind diurnal tides maximise at low latitudes and the semidiurnal tides include maxima at high latitudes. A comparison against published satellite and ground-based observations shows generally good agreement in latitudinal tidal structure, with more differences in seasonal tidal structure. Our results demonstrate the capability of the ExUM for modelling atmospheric migrating and non-migrating tides, and this lays the foundation for its future development into a whole atmosphere model. To this end, we make specific recommendations on further developments which would improve the capability of the model.

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Lindzen, Richard S. « Richard J. Reed and Atmospheric Tides ». Meteorological Monographs 53 (1 décembre 2003) : 85–89. http://dx.doi.org/10.1175/0065-9401-31.53.85.

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Palumbo, A. « Reply to comments on "Atmospheric Tides" ». Journal of Atmospheric and Solar-Terrestrial Physics 60, n^o 18 (décembre 1998) : 1793. http://dx.doi.org/10.1016/s1364-6826(98)00148-5.

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Price, Colin, Ron Maor et Hofit Shachaf. « Using smartphones for monitoring atmospheric tides ». Journal of Atmospheric and Solar-Terrestrial Physics 174 (septembre 2018) : 1–4. http://dx.doi.org/10.1016/j.jastp.2018.04.015.

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Brahde, R. « Lunisolar Atmospheric Tides : A New Approach ». Australian Journal of Physics 41, n^o 6 (1988) : 807. http://dx.doi.org/10.1071/ph880807.

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In records of the atmospheric pressure in Oslo, at 60' latitude, a one-day oscillation caused by the lunisolar tide has been detected. The amplitude has a mean value of O� 17 mb. This oscillation appears during intervals when the declination of the Moon has high numerical values. When the Moon passes through the equator, the one-day oscillation disappears and only the half-day mode continues. If a maximum coincides with upper culmination, it reappears during the next fortnight at lower culmination. This means that the phase changes approximately 180' or 12h every time the Moon crosses the equator, and this is the main reason why it has not been detected by means of traditional harmonic analysis of the atmospheric pressure oscillations. By means of the correlation between the pressure variation and the magnitude of the tidal acceleration, it was possible to separate the dynamic one-day oscillation from terms of thermal origin.

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French, Richard G., Anthony D. Toigo, Peter J. Gierasch, Candice J. Hansen, Leslie A. Young, Bruno Sicardy, Alex Dias-Oliveira et Scott D. Guzewich. « Seasonal variations in Pluto’s atmospheric tides ». Icarus 246 (janvier 2015) : 247–67. http://dx.doi.org/10.1016/j.icarus.2014.05.017.

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Guzewich, Scott D., C. E. Newman, M. de la Torre Juárez, R. J. Wilson, M. Lemmon, M. D. Smith, H. Kahanpää et A. M. Harri. « Atmospheric tides in Gale Crater, Mars ». Icarus 268 (avril 2016) : 37–49. http://dx.doi.org/10.1016/j.icarus.2015.12.028.

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Wergen, W. « Normal mode initialization and atmospheric tides ». Quarterly Journal of the Royal Meteorological Society 115, n^o 487 (avril 1989) : 535–45. http://dx.doi.org/10.1002/qj.49711548706.

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Tokioka, Tatsushi, et Isamu Yagai. « Atmospheric Tides Appearing in a Global Atmospheric General Circulation Model ». Journal of the Meteorological Society of Japan. Ser. II 65, n^o 3 (1987) : 423–38. http://dx.doi.org/10.2151/jmsj1965.65.3_423.

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Harris, M. J., N. F. Arnold et A. D. Aylward. « A study into the effect of the diurnal tide on the structure of the background mesosphere and thermosphere using the new coupled middle atmosphere and thermosphere (CMAT) general circulation model ». Annales Geophysicae 20, n^o 2 (28 février 2002) : 225–35. http://dx.doi.org/10.5194/angeo-20-225-2002.

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Abstract. A new coupled middle atmosphere and thermosphere general circulation model has been developed, and some first results are presented. An investigation into the effects of the diurnal tide upon the mean composition, dynamics and energetics was carried out for equinox conditions. Previous studies have shown that tides deplete mean atomic oxygen in the upper mesosphere-lower thermosphere due to an increased recombination in the tidal displaced air parcels. The model runs presented suggest that the mean residual circulation associated with the tidal dissipation also plays an important role. Stronger lower boundary tidal forcing was seen to increase the equatorial local diurnal maximum of atomic oxygen and the associated 0(1S) 557.7 nm green line volume emission rates. The changes in the mean background temperature structure were found to correspond to changes in the mean circulation and exothermic chemical heating.Key words. Atmospheric composition and structure (middle atmosphere – composition and chemistry) Meterology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

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Hupe, Patrick, Lars Ceranna et Christoph Pilger. « Using barometric time series of the IMS infrasound network for a global analysis of thermally induced atmospheric tides ». Atmospheric Measurement Techniques 11, n^o 4 (10 avril 2018) : 2027–40. http://dx.doi.org/10.5194/amt-11-2027-2018.

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Abstract. The International Monitoring System (IMS) has been established to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty and comprises four technologies, one of which is infrasound. When fully established, the IMS infrasound network consists of 60 sites uniformly distributed around the globe. Besides its primary purpose of determining explosions in the atmosphere, the recorded data reveal information on other anthropogenic and natural infrasound sources. Furthermore, the almost continuous multi-year recordings of differential and absolute air pressure allow for analysing the atmospheric conditions. In this paper, spectral analysis tools are applied to derive atmospheric dynamics from barometric time series. Based on the solar atmospheric tides, a methodology for performing geographic and temporal variability analyses is presented, which is supposed to serve for upcoming studies related to atmospheric dynamics. The surplus value of using the IMS infrasound network data for such purposes is demonstrated by comparing the findings on the thermal tides with previous studies and the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2), which represents the solar tides well in its surface pressure fields. Absolute air pressure recordings reveal geographical characteristics of atmospheric tides related to the solar day and even to the lunar day. We therefore claim the chosen methodology of using the IMS infrasound network to be applicable for global and temporal studies on specific atmospheric dynamics. Given the accuracy and high temporal resolution of the barometric data from the IMS infrasound network, interactions with gravity waves and planetary waves can be examined in future for refining the knowledge of atmospheric dynamics, e.g. the origin of tidal harmonics up to 9 cycles per day as found in the barometric data sets. Data assimilation in empirical models of solar tides would be a valuable application of the IMS infrasound data.

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Braswell, William D., et Richard S. Lindzen. « Anomalous short wave absorption and atmospheric tides ». Geophysical Research Letters 25, n^o 9 (1 mai 1998) : 1293–96. http://dx.doi.org/10.1029/98gl01031.

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Andruk, V., G. Butenko, V. Kostyuchenko et L. Svachij. « The relation between extinction and atmospheric tides ». Journal of Physical Studies 11, n^o 4 (2007) : 432–37. http://dx.doi.org/10.30970/jps.11.432.

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Arabelos, D., G. Asteriadis, M. E. Contadakis, S. D. Spatalas et H. Sachsamanoglou. « Atmospheric tides in the area of Thessaloniki ». Journal of Geodynamics 23, n^o 1 (janvier 1997) : 65–75. http://dx.doi.org/10.1016/s0264-3707(96)00018-x.

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Zharov, V. E., et D. Gambis. « Atmospheric tides and rotation of the Earth ». Journal of Geodesy 70, n^o 6 (juin 1996) : 321–26. http://dx.doi.org/10.1007/bf00868183.

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Zharov, V. E., et D. Gambis. « Atmospheric tides and rotation of the Earth ». Journal of Geodesy 70, n^o 6 (1 mars 1996) : 321–26. http://dx.doi.org/10.1007/s001900050022.

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Balcerak, Ernie. « Atmospheric tides link stratosphere and ionosphere changes ». Eos, Transactions American Geophysical Union 95, n^o 24 (17 juin 2014) : 208. http://dx.doi.org/10.1002/2014eo240008.

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Charnay, B., G. Tobie, S. Lebonnois et R. D. Lorenz. « Gravitational atmospheric tides as a probe of Titan’s interior : Application to Dragonfly ». Astronomy & ; Astrophysics 658 (février 2022) : A108. http://dx.doi.org/10.1051/0004-6361/202141898.

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Context. Saturn’s massive gravity is expected to causes a tide in Titan’s atmosphere, producing a surface pressure variation through the orbit of Titan and tidal winds in the troposphere. The future Dragonfly mission could analyse this exotic meteorological phenomenon. Aims. We aim to analyse the effect of Saturn’s tides on Titan’s atmosphere and interior to determine how pressure measurements by Dragonfly could constrain Titan’s interior. Methods. We model atmospheric tides with analytical calculations and with a 3D global climate model (the IPSL-Titan GCM), including the tidal response of the interior. Results. We predict that the Love numbers of Titan’s interior should verify 1 + ℜ(k2 − h2) ~ 0.02–0.1 and ℑ(k2 − h2) < 0.04. The deformation of Titan’s interior should therefore strongly weaken gravitational atmospheric tides, yielding a residual surface pressure amplitude of only ~5 Pa, with a phase shift of 5–20 h. Tidal winds are very weak, of the order of 3 × 10−4 m s−1 in the lower troposphere. Finally, constraints from Dragonfly data may permit the real and the imaginary parts of k2 − h2 to be estimated with a precision of ±0.01–0.03. Conclusions. Measurements of pressure variations by Dragonfly over the whole mission could give valuable constraints on the thickness of Titan’s ice shell, and, via geophysical models, its heat flux and the density of its internal ocean.

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Covey, Curt, Aiguo Dai, Dan Marsh et Richard S. Lindzen. « The Surface-Pressure Signature of Atmospheric Tides in Modern Climate Models ». Journal of the Atmospheric Sciences 68, n^o 3 (1 mars 2011) : 495–514. http://dx.doi.org/10.1175/2010jas3560.1.

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Abstract Although atmospheric tides driven by solar heating are readily detectable at the earth’s surface as variations in air pressure, their simulations in current coupled global climate models have not been fully examined. This work examines near-surface-pressure tides in climate models that contributed to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC); it compares them with tides both from observations and from the Whole Atmosphere Community Climate Model (WACCM), which extends from the earth’s surface to the thermosphere. Surprising consistency is found among observations and all model simulations, despite variation of the altitudes of model upper boundaries from 32 to 76 km in the IPCC models and at 135 km for WACCM. These results are consistent with previous suggestions that placing a model’s upper boundary at low altitude leads to partly compensating errors—such as reducing the forcing of the tides by ozone heating, but also introducing spurious waves at the upper boundary, which propagate to the surface.

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Covey, Curt, Aiguo Dai, Richard S. Lindzen et Daniel R. Marsh. « Atmospheric Tides in the Latest Generation of Climate Models* ». Journal of the Atmospheric Sciences 71, n^o 6 (30 mai 2014) : 1905–13. http://dx.doi.org/10.1175/jas-d-13-0358.1.

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Abstract For atmospheric tides driven by solar heating, the database of climate model output used in the most recent assessment report of the Intergovernmental Panel on Climate Change (IPCC) confirms and extends the authors’ earlier results based on the previous generation of models. Both the present study and the earlier one examine the surface pressure signature of the tides, but the new database removes a shortcoming of the earlier study in which model simulations were not strictly comparable to observations. The present study confirms an approximate consistency among observations and all model simulations, despite variation of model tops from 31 to 144 km. On its face, this result is surprising because the dominant (semidiurnal) component of the tides is forced mostly by ozone heating around 30–70-km altitude. Classical linear tide calculations and occasional numerical experimentation have long suggested that models with low tops achieve some consistency with observations by means of compensating errors, with wave reflection from the model top making up for reduced ozone forcing. Future work with the new database may confirm this hypothesis by additional classical calculations and analyses of the ozone heating profiles and wave reflection in Coupled Model Intercomparison Project (CMIP) models. The new generation of models also extends CMIP's purview to free-atmosphere fields including the middle atmosphere and above.

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Sakazaki, T., et K. Hamilton. « Physical Processes Controlling the Tide in the Tropical Lower Atmosphere Investigated Using a Comprehensive Numerical Model ». Journal of the Atmospheric Sciences 74, n^o 8 (21 juillet 2017) : 2467–87. http://dx.doi.org/10.1175/jas-d-17-0080.1.

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Abstract The lower-atmospheric circulation in the tropics is strongly influenced by large-scale daily variations referred to as atmospheric solar tides. Most earlier studies have used simplified linear theory to explain daily variations in the tropics. The present study employs a comprehensive limited-area atmospheric model and revisits some longstanding issues related to atmospheric tidal dynamics. The tides in the tropical lower atmosphere are realistically simulated in the control experiment with a near-global (75°S–75°N) version of the model. Sensitivity experiments with different aspects of the solar heating suppressed showed that the semidiurnal (S2) tide near the surface can be attributed roughly equally to stratospheric and tropospheric direct solar heating and that the diurnal (S1) tide is excited almost entirely by tropospheric direct solar heating as well as solar heating of Earth’s surface. Linear theory with forcing only by direct radiative heating predicts the phase of the S2 barometric oscillation should be ~0910 LT versus the ~0945 LT phase seen in low-latitude observations. The roles of (i) convective and latent heating and (ii) mechanical dissipation, in determining the S2 phase, are assessed in the model. It is found that the former effect delays the phase by ~25 min and the latter by ~5 min; these two effects together explain the observed phase. When the model is run in limited-area domains comparable to those used in typical regional climate studies the S2, but not S1, tide is found to be significantly weaker than observed, even using atmospheric reanalysis data to drive the lateral boundaries.

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Griffith, Matthew J., Shaun M. Dempsey, David R. Jackson, Tracy Moffat-Griffin et Nicholas J. Mitchell. « Winds and tides of the Extended Unified Model in the mesosphere and lower thermosphere validated with meteor radar observations ». Annales Geophysicae 39, n^o 3 (10 juin 2021) : 487–514. http://dx.doi.org/10.5194/angeo-39-487-2021.

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Abstract. The mesosphere and lower thermosphere (MLT) is a critical region that must be accurately reproduced in general circulation models (GCMs) that aim to include the coupling between the lower and middle atmosphere and the thermosphere. An accurate representation of the MLT is thus important for improved climate modelling and the development of a whole atmosphere model. This is because the atmospheric waves at these heights are particularly large, and so the energy and momentum they carry is an important driver of climatological phenomena through the whole atmosphere, affecting terrestrial and space weather. The Extended Unified Model (ExUM) is the recently developed version of the Met Office's Unified Model which has been extended to model the MLT. The capability of the ExUM to model atmospheric winds and tides in the MLT is currently unknown. Here, we present the first study of winds and tides from the ExUM. We make a comparison against meteor radar observations of winds and tides from 2006 between 80 and 100 km over two radar stations – Rothera (68∘ S, 68∘ W) and Ascension Island (8∘ S, 14∘ W). These locations are chosen to study tides in two very different tidal regimes – the equatorial regime, where the diurnal (24 h) tide dominates, and the polar regime, where the semi-diurnal (12 h) tide dominates. The results of this study illustrate that the ExUM is capable of reproducing atmospheric winds and tides that capture many of the key characteristics seen in meteor radar observations, such as zonal and meridional wind maxima and minima, the increase in tidal amplitude with increasing height, and the decrease in tidal phase with increasing height. In particular, in the equatorial regime some essential characteristics of the background winds, tidal amplitudes and tidal phases are well captured but with significant differences in detail. In the polar regime, the difference is more pronounced. The ExUM zonal background winds in austral winter are primarily westward rather than eastward, and in austral summer they are larger than observed above 90 km. The ExUM tidal amplitudes here are in general consistent with observed values, but they are also larger than observed values above 90 km in austral summer. The tidal phases are generally well replicated in this regime. We propose that the bias in background winds in the polar regime is a consequence of the lack of in situ gravity wave generation to generate eastward fluxes in the MLT. The results of this study indicate that the ExUM has a good natural capability for modelling atmospheric winds and tides in the MLT but that there is room for improvement in the model physics in this region. This highlights the need for modifications to the physical parameterization schemes used in the model in this region – such as the non-orographic spectral gravity wave scheme – to improve aspects such as polar circulation. To this end, we make specific recommendations of changes that can be implemented to improve the accuracy of the ExUM in the MLT.

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Wang, Zewei, Cunying Xiao, Xiong Hu, Junfeng Yang, Xuan Cheng, Qingchen Xu, Luo Xiao et Xiaoqi Wu. « Short-Period Variation of the Activity of Atmospheric Turbulence in the MLT Region over Langfang ». Atmosphere 14, n^o 6 (17 juin 2023) : 1045. http://dx.doi.org/10.3390/atmos14061045.

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In this paper, we investigate the activity of atmospheric turbulence in the MLT region and the relationship between the activity of atmospheric turbulence and atmospheric wave activity. We use data from the Langfang MF radar (39.4∘N, 116.7∘E) from July 2019 to June 2020 and NRLMSIS 2.0 to calculate the parameters of atmospheric wave activity and atmospheric turbulence energy dissipation rate (ε). Atmospheric ε is modulated by different periods at different altitudes, and while there are 12 h and 24 h periods at all altitudes, the main period is different at different altitudes. A comparison of the ε with atmospheric tide activity shows that tides have an effect on ε, and the influence of tides on ε may be different at different altitudes. The pattern of variation in ε is similar to that of the atmospheric activity of the gravity wave, with both ε and the atmospheric activity of the gravity wave showing significant semi-annual variation.

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Pan, Q. W., J. E. Allnutt et C. Tsui. « Evidence of atmospheric tides from satellite beacon experiment ». Electronics Letters 42, n^o 12 (2006) : 706. http://dx.doi.org/10.1049/el:20060408.

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Vial, François. « Numerical simulations of atmospheric tides for solstice conditions ». Journal of Geophysical Research 91, A8 (1986) : 8955. http://dx.doi.org/10.1029/ja091ia08p08955.

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Forbes, Jeffrey M. « Atmospheric tides between 80 km and 120 km ». Advances in Space Research 10, n^o 12 (janvier 1990) : 127–40. http://dx.doi.org/10.1016/0273-1177(90)90392-d.

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Bartzokas, A., C. C. Repapis et D. A. Metaxas. « Temporal variations of atmospheric tides over Athens, Greece ». Meteorology and Atmospheric Physics 55, n^o 1-2 (1995) : 113–23. http://dx.doi.org/10.1007/bf01029606.

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Bills, Bruce G., Thomas Navarro, Gerald Schubert, Anton Ermakov et Krzysztof M. Górski. « Gravitational signatures of atmospheric thermal tides on Venus ». Icarus 340 (avril 2020) : 113568. http://dx.doi.org/10.1016/j.icarus.2019.113568.

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Palus, Shannon. « Role of lunar atmospheric tides in thermosphere density ». Eos, Transactions American Geophysical Union 95, n^o 47 (25 novembre 2014) : 444. http://dx.doi.org/10.1002/2014eo470012.

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Min, J. E., S. K. Lee et J. H. Ryu. « ADVANCED SURFACE-REFLECTED RADIANCE CORRECTION FOR AIRBORNE HYPERSPECTRAL IMAGERY IN COASTAL RED TIDE DETECTION ». ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences V-3-2021 (17 juin 2021) : 73–80. http://dx.doi.org/10.5194/isprs-annals-v-3-2021-73-2021.

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Abstract. Red tides are among the most common coastal hazards, causing serious damage to the coastal environment. Many satellite sensors can detect red tide blooms, but are limited in their detection of the exact area of the bloom and biological abundance in terms of spatial and spectral resolution. The high spatial and spectral resolutions of hyperspectral airborne remote sensing data may help overcome these limitations to analyze red tide blooms more effectively. To identify potential applications of hyperspectral airborne data in red tide detection, an integrated field campaign was performed in September 2016 off the coast of Tongyeong, South Korea. An AisaEAGLE sensor was installed on a Cessna 208B crewed aircraft to obtain hyperspectral images of an 18 km × 18 km coastal area. To assess the atmospheric correction of the hyperspectral data, in situ optical data and water samples were measured on two vessels concurrent with the flight path. Advanced surface-reflected radiance (Lr) correction and basic atmospheric path radiance (La) correction were performed on the hyperspectral images. Of these, Lr correction comprised a large proportion of the atmospheric correction. The atmosphere-corrected remote sensing reflectance data of the hyperspectral images closely matched the in-situ measurements. The data were assessed for red tide events using ratio analysis and the fluorescence line height technique; the ratio analysis more effectively detected regions with suspected red tides.

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Williams, Joanne, Maialen Irazoqui Apecechea, Andrew Saulter et Kevin J. Horsburgh. « Radiational tides : their double-counting in storm surge forecasts and contribution to the Highest Astronomical Tide ». Ocean Science 14, n^o 5 (14 septembre 2018) : 1057–68. http://dx.doi.org/10.5194/os-14-1057-2018.

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Abstract. Tide predictions based on tide-gauge observations are not just the astronomical tides; they also contain radiational tides – periodic sea-level changes due to atmospheric conditions and solar forcing. This poses a problem of double-counting for operational forecasts of total water level during storm surges. In some surge forecasting, a regional model is run in two modes: tide only, with astronomic forcing alone; and tide and surge, forced additionally by surface winds and pressure. The surge residual is defined to be the difference between these configurations and is added to the local harmonic predictions from gauges. Here we use the Global Tide and Surge Model (GTSM) based on Delft-FM to investigate this in the UK and elsewhere, quantifying the weather-related tides that may be double-counted in operational forecasts. We show that the global S2 atmospheric tide is captured by the tide-and-surge model and observe changes in other major constituents, including M2. The Lowest and Highest Astronomical Tide levels, used in navigation datums and design heights, are derived from tide predictions based on observations. We use our findings on radiational tides to quantify the extent to which these levels may contain weather-related components.

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Ray, Richard D. « Decadal Climate Variability : Is There a Tidal Connection ? » Journal of Climate 20, n^o 14 (15 juillet 2007) : 3542–60. http://dx.doi.org/10.1175/jcli4193.1.

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Abstract A possible connection between oceanic tides and climate variability arises from modulations in tidally induced vertical mixing. The idea is reexamined here with emphasis on near-decadal time scales. Occasional extreme tides caused by unusually favorable alignments of the moon and sun are unlikely to influence decadal climate, since these tides are of short duration and, in fact, are barely larger than the typical spring tide near lunar perigee. The argument by Keeling and Whorf in favor of extreme tides is further handicapped by an insufficiently precise catalog of extreme tides. A more plausible connection between tides and near-decadal climate is through “harmonic beating” of nearby tidal spectral lines. The 18.6-yr modulation of diurnal tides is the most likely to be detectable. Possible evidence for this is reviewed. Some of the most promising candidates rely on temperature data in the vicinity of the North Pacific Ocean where diurnal tides are large, but definitive detection is hindered by the shortness of the time series. Paleoclimate temperature data deduced from tree rings are suggestive, but one of the best examples shows a phase reversal, which is evidence against a tidal connection.

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Hocke, K., et K. Igarashi. « Diurnal and semidiurnal tide in the upper middle atmosphere during the first year of simultaneous MF radar observations in northern and southern Japan (45°N and 31°N) ». Annales Geophysicae 17, n^o 3 (31 mars 1999) : 405–14. http://dx.doi.org/10.1007/s00585-999-0405-x.

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Abstract. The climatology of mean wind, diurnal and semidiurnal tide during the first year (1996-1997) of simultaneous wind observations at Wakkanai (45.4°N, 141.7°E) and Yamagawa (31.2°N, 130.6°E) is presented. The locations of the radars allow us to describe the latitudinal dependence of the tides. Tidal amplitude and phase profiles are compared with those of the global scale wave model (GSWM). While the observed amplitude profiles of the diurnal tide agree well with the GSWM values, the observed phase profiles often indicate longer vertical wavelengths than the GSWM phase profiles. In contrast to the GSWM simulation, the observations show a strong bimodal structure of the diurnal tide, with the phase advancing about 6 hours from summer to winter.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

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Zhao, Zhongxiang. « Development of the Yearly Mode-1 M2 Internal Tide Model in 2019 ». Journal of Atmospheric and Oceanic Technology 39, n^o 4 (avril 2022) : 463–78. http://dx.doi.org/10.1175/jtech-d-21-0116.1.

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Abstract The yearly mode-1 M2 internal tide model in 2019 is constructed using sea surface height measurements made by six concurrent satellite altimetry missions: Jason-3, Sentinel-3A, Sentinel-3B, CryoSat-2, Haiyang-2A, and SARAL/AltiKa. The model is developed following a three-step procedure consisting of two rounds of plane wave analysis with a spatial bandpass filter in between. Prior mesoscale correction is made on the altimeter data using AVISO gridded mesoscale fields. The model is labeled Y2019, because it represents the 1-yr-coherent internal tide field in 2019. In contrast, the model developed using altimeter data from 1992 to 2017 is labeled MY25, because it represents the multiyear-coherent internal tide field in 25 years. Thanks to the new mapping technique, model errors in Y2019 are as low as those in MY25. Evaluation using independent altimeter data confirms that Y2019 reduces slightly less variance (∼6%) than MY25. Further analysis reveals that the altimeter data from five missions (without Jason-3) can yield an internal tide model of almost the same quality. Comparing Y2019 and MY25 shows that mode-1 M2 internal tides are subject to significant interannual variability in both amplitude and phase, and their interannual variations are a function of location. Along southward internal tides from Amukta Pass, the energy flux in Y2019 is 2 times larger and the phase speed is about 1.1% faster. This mapping technique has been applied successfully to 2017 and 2018. This work demonstrates that yearly internal tides can be observed by concurrent altimetry missions and their interannual variations can be determined. Significance Statement This work is motivated to study the interannual variations of internal tides using observation-based yearly internal tide models from satellite altimetry. Previous satellite observations of internal tides are usually based on 25 years of altimeter data from 1993 to 2017. The yearly subsetted altimeter data are short, so that the resultant yearly models are overwhelmed by noise. A new mapping technique is developed and demonstrated in this paper. It paves a path to study the interannual and decadal variations of internal tides on a global scale and monitor the global ocean changes by tracking long-range internal tides.

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REDDY, S. JEEV ANANDA. « Lunar and solar atmospheric tides in surface winds and rainfall ». MAUSAM 25, n^o 3 (21 février 2022) : 499–502. http://dx.doi.org/10.54302/mausam.v25i3.5264.

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Lunar and solar atmospheric tides in surface winds and rainfall data at 4 stations have been determined following Chapman-Miller method as detailed by Malin and Chapman. Using the similar results obtained by Rao and Reddy (1972) for other stations a synthesis of the lunar and solar tides in surface winds and rainfall data for Indian stations have been made.

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Shved, G. M., L. N. Petrova et O. S. Polyakova. « Penetration of the Earth's free oscillations at 54 minute period into the atmosphere ». Annales Geophysicae 18, n^o 5 (31 mai 2000) : 566–72. http://dx.doi.org/10.1007/s00585-000-0566-0.

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Abstract. It is known that the fundamental spheroidal mode 0S2 of the Earth free oscillation with a period of about 54 min forces atmospheric oscillations. We present a certain phase relationship for components of the 0S2 multiplet, which is based on synchronous collocated microbarograph and seismograph observations. This relationship is both the first observational manifestation of the Pekeris mode of global atmospheric oscillations with the 54 min period and a further proof of the Earth's 0S2 mode penetrating into the atmosphere. We show that the linear non-dissipative model of steady forced oscillations in isothermal atmosphere at rest does not describe the penetration of the 0S2 mode into the atmosphere adequately.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

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Jones, Graham B., et Anne J. Trevena. « The influence of coral reefs on atmospheric dimethylsulphide over the Great Barrier Reef, Coral Sea, Gulf of Papua and Solomon and Bismarck Seas ». Marine and Freshwater Research 56, n^o 1 (2005) : 85. http://dx.doi.org/10.1071/mf04097.

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Marked regional differences in dissolved dimethylsulphide (DMS), atmospheric DMS and DMS flux were recorded during July 1997 through the northern Great Barrier Reef, Coral Sea, Gulf of Papua, Solomon and Bismarck Seas. Highest concentrations of dissolved DMS occurred in the Coral Sea, Gulf of Papua and Bismarck Sea, with lower concentrations in the Great Barrier Reef and Solomon Sea. Elevated levels of atmospheric DMS often occurred in south-easterly to southerly trade winds sampled in the region 18°32′–8°12′S to 145°–151°E, where the highest biomass of coral reefs occurred. Atmospheric DMS often increased in the day after low tides and was positively correlated with tidal height in the northern Great Barrier Reef (r = 0.91, P < 0.05). For tides less than 1.6 m, atmospheric DMS increased on the rising tide for the northern GBR and NW Coral Sea (r = 0.66; P < 0.05) and for the whole voyage (r = 0.25; P < 0.05). As coral reefs have been identified as significant sources of DMS, it is suggested that the daytime increase in atmospheric DMS over much of the study area was mainly a result of high winds and extremely low tides in July, which exposed the reefs during the day.

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Volland, Hans. « Comments on "Atmosphereic Tides" by A.Palumbo ». Journal of Atmospheric and Solar-Terrestrial Physics 60, n^o 18 (décembre 1998) : 1791–92. http://dx.doi.org/10.1016/s1364-6826(98)00147-3.

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