Ionosphere Influenced From Lower-Lying Atmospheric Regions

The ionosphere represents part of the upper atmosphere. Its variability is observed on a wide-scale temporal range from minutes, or even shorter, up to scales of the solar cycle and secular variations of solar energy input. Ionosphere behavior is predominantly determined by solar and geomagnetic forcing. However, the lower-lying atmospheric regions can contribute significantly to the resulting energy budget. The energy transfer between distant atmospheric parts happens due to atmospheric waves that propagate from their source region up to ionospheric heights. Experimental observations show the importance of the involvement of the lower atmosphere in ionospheric variability studies in order to accurately capture small-scale features of the upper atmosphere. In the Part I Coupling, we provide a brief overview of the influence of the lower atmosphere on the ionosphere and summarize the current knowledge. In the Part II Coupling Evidences Within Ionospheric Plasma—Experiments in Midlatitudes, we demonstrate experimental evidence from mid-latitudes, particularly those based on observations by instruments operated by the Institute of Atmospheric Physics, Czech Academy of Sciences. The focus will mainly be on coupling by atmospheric waves.

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Variability of Gravity Wave Effects on the Zonal Mean Circulation and Migrating Terdiurnal Tide as Studied With the Middle and Upper Atmosphere Model (MUAM2019) Using a Nonlinear Gravity Wave Scheme

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2020.588956 ◽

2020 ◽

Vol 7 ◽

Author(s):

Friederike Lilienthal ◽

Erdal Yiğit ◽

Nadja Samtleben ◽

Christoph Jacobi

Keyword(s):

Gravity Wave ◽

Strong Dependence ◽

Lower Thermosphere ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Small Scale ◽

Source Level ◽

Atmosphere Model ◽

Hemisphere Winter ◽

Nonlinear Gravity

Implementing a nonlinear gravity wave (GW) parameterization into a mechanistic middle and upper atmosphere model, which extends to the lower thermosphere (160 km), we study the response of the atmosphere in terms of the circulation patterns, temperature distribution, and migrating terdiurnal solar tide activity to the upward propagating small-scale internal GWs originating in the lower atmosphere. We perform three test simulations for the Northern Hemisphere winter conditions in order to assess the effects of variations in the initial GW spectrum on the climatology and tidal patterns of the mesosphere and lower thermosphere. We find that the overall strength of the source level momentum flux has a relatively small impact on the zonal mean climatology. The tails of the GW source level spectrum, however, are crucial for the lower thermosphere climatology. With respect to the terdiurnal tide, we find a strong dependence of tidal amplitude on the induced GW drag, generally being larger when GW drag is increased.

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Modeling the propagation of atmospheric waves from various tropospheric disturbances and studying their influence on the upper atmosphere

10.5194/egusphere-egu2020-459 ◽

2020 ◽

Author(s):

Yuliya Kurdyaeva ◽

Olga Borchevkina ◽

Sergey Kshevetskii

Keyword(s):

Gravity Waves ◽

Coastal Region ◽

Internal Gravity Waves ◽

Travelling Wave ◽

The State ◽

Upper Atmosphere ◽

Small Scale ◽

Research Project ◽

Atmospheric Waves ◽

The Earth

The atmosphere and ionosphere are a complex dynamic system, which is affected by sources, caused both by internal processes and external ones. It is known that atmospheric waves propagating from the troposphere to the upper atmosphere make a significant contribution to the state of this system. One of the regular sources of such waves are various tropospheric disturbances caused, for example, by meteorological processes. Numerical modeling is an effective tool for studying these processes and the effects they cause. However, a number of problems arise, while setting up numerical experiments. The first is that most atmospheric models use hydrostatic approximation (which does not allow the resolution of small-scale perturbations) and work for a limited range of heights (which does not allow studying the relationship between the lower and upper atmosphere). This demands an accurate selection of the model in accordance with the stated research goals. The second problem is the difficulty of direct definition of the wave tropospheric sources, that was mentioned before, due to the lack of experimental information for their detailed description. The authors proposed, researched and tested a way to solve this problem. It was shown that the solution of the problem of waves propagation from a certain tropospheric source is completely determined by the pressure field at the surface of the Earth. This work is devoted to solving various problems using this approach.This study presents the results of calculations of the propagation of infrasound and internal gravity waves from tropospheric disturbances given by pressure variations at the surface of the Earth. The experimental data associated with various meteorological events and the passage of the solar terminator were obtained both directly - by a network of microbarographs in the studied region, and indirectly - based on the data from the LIDAR signal intensity and temperature changes in the coastal region. The calculations were done using the non-hydrostatic numerical model &#8220;AtmoSym&#8221;. The characteristics of atmospheric waves generated by such sources are estimated. The effect from a tropospheric sources on the state of the upper atmosphere and ionosphere is investigated. The physical processes that determine the change in atmospheric parameters are discussed.&#160; It is shown that the main contribution from wave disturbances generated by meteorological sources belongs to infrasound. Infrasound and internal gravity waves can be sources of travelling wave packets and can also cause a sporadic E-layer.The study was funded by RFBR and Kaliningrad region according to the research project&#160; 19-45-390005 (Y. Kurdyaeva) and&#160; RFBR to the research project&#160; 18-05-00184 (O. Borchevkina).

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What do 14CO measurements tell us about OH?

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-10405-2007 ◽

2007 ◽

Vol 7 (4) ◽

pp. 10405-10438 ◽

Cited By ~ 2

Author(s):

M. C. Krol ◽

J. Fokke Meirink ◽

P. Bergamaschi ◽

J. E. Mak ◽

D. Lowe ◽

...

Keyword(s):

Source Region ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Atmospheric Measurements ◽

Model Calculations ◽

Mixing Ratios ◽

Short Time Span ◽

The Tropics ◽

Short Time ◽

Model Measurement

Abstract. The possible use of 14CO measurements to constrain hydroxyl radical (OH) concentrations in the atmosphere is investigated.14CO is mainly produced in the upper atmosphere from cosmic radiation. During transport to measurement locations at the Earth's surface 14CO is oxidized by OH. In this paper, the sensitivity of 14CO mixing ratio measurements to the 3-D OH distribution is assessed with the TM5 model. Simulated 14CO mixing ratios compare reasonably well with atmospheric measurements taken at five locations worldwide. As a next step, the sensitivity of 14CO measurements to OH is calculated with the adjoint TM5 model. For our sensitivity calculations the adjoint methodology outlined in the paper offers computational advantages compared to forward model calculations. The results indicate that 14CO measurements, especially those taken in the tropics, are sensitive to OH in a spatially confined region. Moreover, the OH sensitivity at a certain location varies strongly over time due to meteorological variability. On average, 14CO measurements are about 5 times more sensitive to OH at high latitudes than to OH in the tropics. Moreover, the measurements are sensitive to OH in the main 14CO source region in the upper atmosphere. It will therefore be difficult to assign model-measurement discrepancies to either the 14CO source uncertainty or to the OH sink. Nevertheless, the large distance between the 14CO source region and the measurement locations should allow the retrieval of information on OH. Specifically, the sensitivity to OH in the lower atmosphere during a relatively short time span may offer the possibility to constrain local OH. These efforts will strongly depend on the number of measurements available and on our ability to accurately model the 14CO transport.

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Large and small scale changes in the disturbed upper atmosphere

Journal of Atmospheric and Terrestrial Physics ◽

10.1016/0021-9169(76)90163-x ◽

1976 ◽

Vol 38 (6) ◽

pp. 655-659 ◽

Cited By ~ 13

Author(s):

G.W. Prölss ◽

U. Von Zahn

Keyword(s):

Upper Atmosphere ◽

Small Scale

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Global upper-atmospheric heating at Jupiter by the recirculation of auroral energy

10.5194/epsc2021-808 ◽

2021 ◽

Author(s):

James O'Donoghue ◽

Luke Moore ◽

Tanapat Bhakyapaibul ◽

Henrik Melin ◽

Tom Stallard ◽

...

Keyword(s):

Heat Source ◽

Acoustic Waves ◽

Temperature Gradients ◽

Upper Atmosphere ◽

Global Temperature ◽

Lower Atmosphere ◽

Polar Regions ◽

High Resolution Data ◽

Coriolis Forces ◽

Global Circulation Models

Jupiter's upper atmosphere is significantly hotter than expected based on the amount of solar heating it receives. This temperature discrepency is known as the 'energy crisis' due to it's nearly 50-year duration and the fact it also occurs at Saturn, Uranus and Neptune. At Jupiter, magnetosphere-ionosphere coupling gives rise to intense auroral emissions and enormous energy deposition in the magnetic polar regions, so it was presumed long ago that redistribution of this energy could heat the rest of the planet. However, most global circulation models have difficulty redistributing auroral energy globally due to the strong Coriolis forces and ion drag on this rapidly rotating planet. Consequently, other possible heat sources have continued to be studied, such as heating by gravity and acoustic waves emanating from the lower atmosphere. Each global heating mechanism would imprint a unique signature on global temperature gradients, thus revealing the dominant heat source, but these gradients have not been determined due a lack of planet-wide, high-resolution data. The last global map of Jovian upper-atmospheric temperatures was produced using ground-based data taken in 1993, in which the region between 45o latitude (north & south) and the poles was represented by just 2 pixels. As a result, those maps did not (or could not) show a clear temperature gradient, and furthermore, they even showed regions of hot atmosphere near the equator, supporting the idea of an equatorial heat source, e.g. gravity and/or acoustic wave heating. Therefore observationally and from a modeling perspective, a concensus has not been reached to date. Here we report new infrared spectroscopy of Jupiter's major upper-atmospheric ion H3+, with a spatial resolution of 2o longitude and latitude extending from pole to equator, capable of tracing the global temperature gradients. We find that temperatures decrease steadily from the auroral polar regions to the equator. Further, during a period of enhanced activity possibly driven by a solar wind compression, a high-temperature planetary-scale structure was observed which may be propagating from the aurora. These observations indicate that Jupiter's upper atmosphere is predominantly heated via the redistribution of auroral energy, and therefore that Coriolis forces and ion drag are observably overcome.

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Radiation in the neighbourhood of a double layer

Annales Geophysicae ◽

10.5194/angeo-32-677-2014 ◽

2014 ◽

Vol 32 (6) ◽

pp. 677-687 ◽

Cited By ~ 7

Author(s):

R. Pottelette ◽

M. Berthomier ◽

J. Pickett

Keyword(s):

Phase Space ◽

Electron Distribution ◽

Electron Distribution Function ◽

Source Region ◽

Double Layers ◽

Small Scale ◽

High Time Resolution ◽

Local Electron ◽

Nonlinear Phase ◽

Electron Holes

Abstract. In the auroral kilometric radiation (AKR) source region, acceleration layers narrow in altitude and associated with parallel field-aligned potential drops of several kV can be identified by using both particles and wave-field high time-resolution measurements from the Fast Auroral SnapshoT explorer spacecraft (FAST). These so-called double layers (DLs) are recorded around density enhancements in the auroral cavity, where the enhancement can be at the edge of the cavity or even within the cavity at a small scale. Once immersed in the plasma, DLs necessarily accelerate particles along the magnetic field lines, thereby generating locally strong turbulent processes leading to the formation of nonlinear phase space holes. The FAST data reveal the asymmetric character of the turbulence: the regions located on the high-potential side of the DLs are characterized by the presence of electron holes, while on the low-potential side, ion holes are recorded. The existence of these nonlinear phase space holes may affect the AKR radiation pattern in the neighbourhood of a DL where the electron distribution function is drastically different from a horseshoe shape. We present some observations which illustrate the systematic generation of elementary radiation events occurring significantly above the local electron gyrofrequency in the presence of electron holes. These fine-scale AKR radiators are associated with a local electron distribution which presents a pronounced beam-like shape.

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On wireless interference phenomena between ground waves and waves deviated by the upper atmosphere

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1926.0164 ◽

1926 ◽

Vol 113 (764) ◽

pp. 450-458 ◽

Cited By ~ 9

Keyword(s):

Short Distance ◽

Wave Length ◽

Path Difference ◽

Upper Atmosphere ◽

Wireless Transmission ◽

Continuous Change ◽

Carrier Wave ◽

Night Time ◽

Side Band ◽

Atmospheric Waves

In previous communications we have outlined two experimental methods of examining the effects of the atmospheric ionized layer in short-distance wireless transmission. In the first type of experiment the existence of night-time interference phenomena between two sets of waves was demonstrated by changing the wave-length of the transmitter continuously through a small range and observing the resultant maxima and minima of signal intensity. It was suggested that such interference took place between ground waves and waves deviated through large angles by the upper atmosphere. In the second type of experiment the angle of incidence of such atmospheric waves at the earth’s surface was measured by comparing the magnitude of the electric and magnetic forces in the stationary wave system produced at the ground. The results of these experiments were interpreted as yielding a direct experimental proof of the existence of the Kennelly-Heaviside layer, and also as demonstrating that the “fading” of broadcasting signals at moderate distances from the transmitter was due mainly to interference phenomena between two sets of waves arriving at a receiver with an appreciable path difference. But there still remained the problem of the cause of the natural succession of interference effects which constitutes fading at moderate distances, and which takes place continuously throughout the night-time. These variations indicate either that the phase relation between the ground and atmospheric waves is continually changing at night, or that intensity or polarization changes of the atmospheric waves are taking place. In considering possible causes of phase variations, let us examine the relation between the path difference and the wave-length for a typical case of short-distance transmission. Let D represent the path-difference between the ground and atmospheric rays. Then the atmospheric ray arrives n wavelengths behind the ground ray at the receiver, where n = D/ λ , and λ is the wave-length. It has been mentioned above that a possible cause of the natural signal variations which occur at night is a continuous change of phase which would be produced by a change in n . Such a change might be brought about by changes in D, or in λ , or in both simultaneously, and it is necessary to decide between these possibilities. Changes in D might be brought about by a variation in the height of the layer, so that a Döppler effect at "reflection” is produced. In such a case the signal variation might be regarded as the beating between the ground-ray frequency and the reflected-ray frequency. On the other hand, if there is a slow variation of transmitter frequency, the frequency of the atmospheric ray would be different from that of the ground ray, because of the difference in times of emission from the transmitter, and, again, the natural changes might be regarded as beats. The suggestion has already been made by Breit that fading is due to the modulation of the carrier wave, and thus to change of wave-length. In the latter connection we have to consider the variation of both carrier wave and side-band frequencies. The results of our earlier experiments suggested that the change of side-band frequency necessary for the wireless transmission of music is sufficient to produce selective frequency fading, and thus a certain amount of distortion. But with the normal type of modulation the signal intensity is chiefly dependent on the intensity of the carrier wave, and the question whether a slow “swing” of the carrier wave is responsible for such fading (which is observed whether the carrier wave is modulated or unmodulated) seems still unanswered. The question, of course, is equally of interest in both continuous wave telegraphy and wireless telephony.

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Theory of the rocket-grenade method of measuring temperature, pressure, density and wind velocity in the upper atmosphere

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1966.0038 ◽

1966 ◽

Vol 290 (1420) ◽

pp. 44-73 ◽

Cited By ~ 2

Keyword(s):

Experimental Data ◽

Least Squares ◽

Wind Velocity ◽

Speed Of Sound ◽

Vertical Component ◽

Second Order ◽

Upper Atmosphere ◽

Lower Atmosphere ◽

Travel Times ◽

Sound Waves

A theory is presented for deriving the speed of sound and wind velocity as a function of height in the upper atmosphere from observations on the travel times of sound waves from accurately located grenades, released during rocket flight, to microphones at surveyed positions on the ground. The theory is taken to a second order of approximation, which can be utilized in practice if lower atmosphere (balloon) measurements are available. By means of the gas law and the vertical equation of motion of the atmosphere, formulae are obtained for deriving temperature, pressure and density from the speed-of-sound profile, and these also may be evaluated to a higher accuracy if lower atmosphere measurements are available. An outline is given of the computational procedure followed in the processing of data on the basis of this theory by means of the Pegasus computer. Methods of calculating the correction to travel times due to the finite wave amplitude are discussed and compared, and the effect of neglecting this correction in a particular set of experimental data is examined. Other errors which may affect the determination of pressure are also discussed. Consistency between the theory and experimental data obtained in 13 Skylark rocket flights at Woomera is checked in two ways: by examining least squares residuals associated with the sound arrivals at various microphones; and by treating the vertical component of air motion as unknown and examining its distribution about zero. The reduction in the least squares residuals which occurs when account is taken of second order terms is evaluated on the basis of these sets of experimental data.

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Leveraging the Cloud for Large-Scale Software Testing – A Case Study

Software Testing in the Cloud - Advances in Computer and Electrical Engineering ◽

10.4018/978-1-4666-2536-5.ch012 ◽

2012 ◽

pp. 252-279 ◽

Cited By ~ 1

Author(s):

Anjan Pakhira ◽

Peter Andras

Keyword(s):

Large Scale ◽

Analysis Data ◽

System Level ◽

Small Scale ◽

Test Cases ◽

Software Life Cycle ◽

Technical Issues ◽

Wide Scale ◽

Set Up

Testing is a critical phase in the software life-cycle. While small-scale component-wise testing is done routinely as part of development and maintenance of large-scale software, the system level testing of the whole software is much more problematic due to low level of coverage of potential usage scenarios by test cases and high costs associated with wide-scale testing of large software. Here, the authors investigate the use of cloud computing to facilitate the testing of large-scale software. They discuss the aspects of cloud-based testing and provide an example application of this. They describe the testing of the functional importance of methods of classes in the Google Chrome software. The methods that we test are predicted to be functionally important with respect to a functionality of the software. The authors use network analysis applied to dynamic analysis data generated by the software to make these predictions. They check the validity of these predictions by mutation testing of a large number of mutated variants of the Google Chrome. The chapter provides details of how to set up the testing process on the cloud and discusses relevant technical issues.

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