Book•
Waves in the atmosphere : atmospheric infrasound and gravity waves : their generation and propagation
01 Jan 1975-Vol. 2
TL;DR: In this paper, the authors provide an introduction to the theory of propagation and the dynamics of mesoscale atmospheric masses and wave propagation in the field of radiophysics, as well as their role in the generation of clear air turbulence (CAT).
Abstract: Development in Atmospheric Science, 2
In recent years 'here has been increased
interest in mesoscale atmospheric waves as
newly developed atmospheric probes such as
radars and acoustic echo sounders have
made it possible to study these waves in
great detail. Numerous observations reported
in a rapidly expending literature on the
subject have demonstrated that these waves
are more than mere curiosities; in fact, they
can play an essential role in the generation of
some kinds of clear air turbulence (CAT), .
thus Creating a hazard to commercial aircraft;,
and they may be very important to the very
dynamics of the larger-scale atmospheric
circulation, This timely book provides the
interested meteorologist, radiophysicist. and
graduate student with a self-contained
introduction to the theory of propagation and
the dynamics of mesoscale atmospheric
waves.
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TL;DR: In this paper, the air pressure head at the water surface in the well must be added to measured water levels, even though the resulting values may have larger temporal and spatial variability than the original water level measurements.
Abstract: Failing to account for barometric pressure effects in water level measurements can introduce errors by misestimating the total head and by adding noise to water level measurements. For determining the total head in an aquifer, we assert that the air pressure head at the water surface in the well must be added to measured water levels (equivalent to using an absolute pressure transducer) even though the resulting values may have larger temporal and spatial variability than the original water level measurements. At the Savannah River Site in South Carolina, the average barometric pressure variation is 6 to 7 cm, with a range of over 30 cm. Failure to account for barometric pressure variability could result in misestimation of the direction and magnitude of the hydraulic gradient at the site. We also demonstrate procedures for removing barometric effects, such as to reduce noise during an aquifer pumping test, and to identify mechanisms by which barometric pressure affects water levels. Three mechanisms are summarized including: an instantaneous response for confined aquifers; a delayed response due to borehole storage in confined and unconfined aquifers; and a delayed response in unconfined aquifers due to the passage of barometric pressure changes through the unsaturated zone. Using data from the Savannah River Site, barometric efficiencies are estimated using linear regression and a modification of Clark's Method. Delayed responses are estimated using regression deconvolution. The type of barometric effect provides diagnostic information about whether the aquifer is confined or not, the presence of borehole storage or skin effects, and the air diffusivity coefficient within the unsaturated zone. We also show how removal of barometric pressure effects improves the ability to observe otherwise unnoticeable effects.
160 citations
TL;DR: The 15 January 2022 climactic eruption of Hunga volcano, Tonga, produced an explosion in the atmosphere of a size that has not been documented in the modern geophysical record as mentioned in this paper .
Abstract: The 15 January 2022 climactic eruption of Hunga volcano, Tonga, produced an explosion in the atmosphere of a size that has not been documented in the modern geophysical record. The event generated a broad range of atmospheric waves observed globally by various ground-based and spaceborne instrumentation networks. Most prominent was the surface-guided Lamb wave (≲0.01 hertz), which we observed propagating for four (plus three antipodal) passages around Earth over 6 days. As measured by the Lamb wave amplitudes, the climactic Hunga explosion was comparable in size to that of the 1883 Krakatau eruption. The Hunga eruption produced remarkable globally detected infrasound (0.01 to 20 hertz), long-range (~10,000 kilometers) audible sound, and ionospheric perturbations. Seismometers worldwide recorded pure seismic and air-to-ground coupled waves. Air-to-sea coupling likely contributed to fast-arriving tsunamis. Here, we highlight exceptional observations of the atmospheric waves. Description Going on the lamb The Hunga Tonga undersea volcanic eruption was one of the most powerful recorded, with audible sound detected more than 10,000 kilometers from the source. Matoza et al. present infrasound and seismic recordings, along with other geophysical observations, that help to describe this event. An atmospheric lamb wave, characteristic of energetic atmospheric events, circled the planet four times and was similar to the 1883 Krakatau eruption. Kubota et al. detail how this lamb wave contributed to the global tsunami waves arriving much earlier than expected. The eruption also generated long-range infrasounds and ionospheric interations, along with a global tsunami. This set of observations will be helpful for disentangling the event and understanding the propagation of waves through the atmosphere and ocean (see the Perspective by Brodsky and Lay). —BG Observations of the Hunga Tonga volcanic eruption show a complex main event that was as energetic as the Krakatau eruption.
156 citations
TL;DR: In this paper, the authors proposed a possible use of VLF/LF (very low frequency (3-30 kHz) /low frequency (30-300 kHz)) radio sounding of the seismo-ionospheric perturbations.
Abstract: It is recently recognized that the ionosphere is very sensitive to seismic effects, and the detection of ionospheric perturbations associated with earthquakes, seems to be very promising for short-term earthquake prediction. We have proposed a possible use of VLF/LF (very low frequency (3-30 kHz) /low frequency (30-300 kHz)) radio sounding of the seismo-ionospheric perturbations. A brief history of the use of subionospheric VLF/LF propagation for the short-term earthquake prediction is given, followed by a significant finding of ionospheric perturbation for the Kobe earthquake in 1995. After showing previous VLF/LF results, we present the latest VLF/LF findings; One is the statistical correlation of the ionospheric perturbation with earthquakes and the second is a case study for the Sumatra earthquake in December, 2004, indicating the spatical scale and dynamics of ionospheric perturbation for this earthquake.
135 citations
National Center for Atmospheric Research1, Monash University2, University of Zagreb3, Pennsylvania State University4, National Scientific and Technical Research Council5, United States Naval Research Laboratory6, Complutense University of Madrid7, University of South Florida St. Petersburg8, Yale University9, CSIRO Marine and Atmospheric Research10, California State University, Chico11, Stockholm University12, Cooperative Institute for Research in Environmental Sciences13
TL;DR: In this article, a review of wave-turbulence interactions in stable atmospheric boundary layer (SABL) flows is presented, focusing on the nocturnal SABL.
Abstract: Flow in a stably stratified environment is characterized by anisotropic and intermittent turbulence and wavelike motions of varying amplitudes and periods. Understanding turbulence intermittency and wave-turbulence interactions in a stably stratified flow remains a challenging issue in geosciences including planetary atmospheres and oceans. The stable atmospheric boundary layer (SABL) commonly occurs when the ground surface is cooled by longwave radiation emission such as at night over land surfaces, or even daytime over snow and ice surfaces, and when warm air is advected over cold surfaces. Intermittent turbulence intensification in the SABL impacts human activities and weather variability, yet it cannot be generated in state-of-the-art numerical forecast models. This failure is mainly due to a lack of understanding of the physical mechanisms for seemingly random turbulence generation in a stably stratified flow, in which wave-turbulence interaction is a potential mechanism for turbulence intermittency. A workshop on wave-turbulence interactions in the SABL addressed the current understanding and challenges of wave-turbulence interactions and the role of wavelike motions in contributing to anisotropic and intermittent turbulence from the perspectives of theory, observations, and numerical parameterization. There have been a number of reviews on waves, and a few on turbulence in stably stratified flows, but not much on wave-turbulence interactions. This review focuses on the nocturnal SABL; however, the discussions here on intermittent turbulence and wave-turbulence interactions in stably stratified flows underscore important issues in stably stratified geophysical dynamics in general.
123 citations
TL;DR: In this article, Taylor et al. examined the properties of small-scale features known as ripple features and concluded that these features are not AGW but are rather instability features generated in situ, and they concluded that while there is support for the instability hypothesis as the origin of ripple features, the exact nature of the instabilities causing these features is not known.
Abstract: [1] For over 30 years it has been recognized that atmospheric gravity waves (AGWs) in the 80–110 km region significantly perturb the basic atmospheric state, perhaps causing instability regions and subsequent turbulence. It has also been recognized for nearly as long that AGWs cause strong fluctuations in the airglow emissions that originate in this altitude region. Airglow images have been obtained since 1973, and they have shown structures that have mainly been attributed to the passage of AGWs through this region as predicted theoretically. The AGWs have been assumed to originate largely in the troposphere because of either convective activity or the flow of air over large mountain ranges. However, intensive analysis of the properties of a class of small-scale features currently known as ripples [Taylor et al., 1997; Nakamura et al., 1999] suggests that these features are not AGWs but are rather instability features generated in situ. The basis for this hypothesis is examined in this review, and it is concluded that while there is support for the instability hypothesis as the origin of ripple features, at present the exact nature of the instabilities causing these features is not known.
115 citations
Cites background or methods from "Waves in the atmosphere : atmospher..."
...The importance of critical levels in the dynamics of the atmosphere has long been recognized [e.g., Bretherton, 1966; Booker and Bretherton, 1967; Hines, 1968; Breeding, 1971; Gossard and Hooke, 1975; Huang et al., 1998; Gardner and Taylor, 1998]....
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...[12] When Ri becomes less than 0.25 but greater than zero, Kelvin-Helmholtz billows form from the dynamical instability [e.g., Hauritz, 1964; Lloyd et al., 1973; Gossard and Hooke, 1975; Chandrasekhar, 1981]....
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...While the basic nature of KH billows is well known [Gossard and Hooke, 1975], the wave-caused convective instability has only recently been well characterized [Fritts et al., 1997] using three-dimensional modeling....
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...It was even questioned as to whether such an instability would form since it was felt that the dynamical instability might preempt the convective instability because the latter occurred first [see, e.g., Gossard and Hooke, 1975]....
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...[6] The stability of atmospheric regions is most easily quantified by the Richardson number [Richardson, 1920; Beer, 1974;Gossard and Hooke, 1975], Ri, which is given by Ri ¼ w 2 B dU=dzð Þ2 ð1aÞ Ri ¼ g=Tð Þ dT=dzþ g=Cp dU=dzð Þ2 ; ð1bÞ where wB is the Brunt-Vaisala frequency and dU/dz is the…...
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