The Turbopause experiment: atmospheric stability and turbulent structure spanning the turbopause altitude

Abstract. Very few sequences of high resolution wind and temperature measurements in the lower thermosphere are available in the literature, which makes it difficult to verify the simulation results of models that would provide better understanding of the complex dynamics of the region. To address this problem the Turbopause experiment used four rockets launched over a period of approximately two hours from Poker Flat Research Range, Alaska (64° N, 147° W) on the night of 17–18 February 2009. All four rocket payloads released trimethyl aluminum trails for neutral wind and turbulence measurements, and two of the rockets carried ionization gauges and fixed-bias Langmuir probes measuring neutral and electron densities, small-scale fluctuations and neutral temperatures. Two lidars monitored temperature structure and sodium densities. The observations were made under quiet geomagnetic conditions and show persistence in the wind magnitudes and shears throughout the observing period while being modulated by inertia-gravity waves. High resolution temperature profiles show the winter polar mesosphere and lower thermosphere in a state of relatively low stability with several quasi-adiabatic layers between 74 and 103 km. Temperature and wind data were combined to calculate Richardson number profiles. Evidence for turbulence comes from simultaneous observations of density fluctuations and downward transport of sodium in a mixed layer near 75 km; the observation of turbulent fluctuations and energy dissipation from 87–90 km; and fast and irregular trail expansion at 90–93 km, and especially between 95 to 103 km. The regions of turbulent trails agree well with regions of quasi-adiabatic temperature gradients. Above 103 km, trail diffusion was mainly laminar; however, unusual features and vortices in the trail diffusion were observed up to 118 km that have not been as prevalent or as clearly evident in earlier trail releases.

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On the short-term variability of turbulence and temperature in the winter mesosphere

Annales Geophysicae ◽

10.5194/angeo-36-1099-2018 ◽

2018 ◽

Vol 36 (4) ◽

pp. 1099-1116

Author(s):

Gerald A. Lehmacher ◽

Miguel F. Larsen ◽

Richard L. Collins ◽

Aroh Barjatya ◽

Boris Strelnikov

Keyword(s):

Attitude Control ◽

Large Scale ◽

Lower Thermosphere ◽

Density Fluctuations ◽

Large Temperature ◽

Small Scale ◽

Spatial And Temporal Variability ◽

Temperature Structure ◽

Wind Shears

Abstract. Four mesosphere–lower thermosphere temperature and turbulence profiles were obtained in situ within ∼30 min and over an area of about 100 by 100 km during a sounding rocket experiment conducted on 26 January 2015 at Poker Flat Research Range in Alaska. In this paper we examine the spatial and temporal variability of mesospheric turbulence in relationship to the static stability of the background atmosphere. Using active payload attitude control, neutral density fluctuations, a tracer for turbulence, were observed with very little interference from the payload spin motion, and with high precision (<0.01 %) at sub-meter resolution. The large-scale vertical temperature structure was very consistent between the four soundings. The mesosphere was almost isothermal, which means more stratified, between 60 and 80 km, and again between 88 and 95 km. The stratified regions adjoined quasi-adiabatic regions assumed to be well mixed. Additional evidence of vertical transport and convective activity comes from sodium densities and trimethyl aluminum trail development, respectively, which were both observed simultaneously with the in situ measurements. We found considerable kilometer-scale temperature variability with amplitudes of 20 K in the stratified region below 80 km. Several thin turbulent layers were embedded in this region, differing in width and altitude for each profile. Energy dissipation rates varied between 0.1 and 10 mW kg−1, which is typical for the winter mesosphere. Very little turbulence was observed above 82 km, consistent with very weak small-scale gravity wave activity in the upper mesosphere during the launch night. On the other hand, above the cold and prominent mesopause at 102 km, large temperature excursions of +40 to +70 K were observed. Simultaneous wind measurements revealed extreme wind shears near 108 km, and combined with the observed temperature gradient, isolated regions of unstable Richardson numbers (0<Ri<0.25) were detected in the lower thermosphere. The experiment was launched into a bright auroral arc under moderately disturbed conditions (Kp∼5).

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Fine Structure, Instabilities, and Turbulence in the Lower Atmosphere: High-Resolution In Situ Slant-Path Measurements with the DataHawk UAV and Comparisons with Numerical Modeling

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-16-0037.1 ◽

2018 ◽

Vol 35 (3) ◽

pp. 619-642 ◽

Cited By ~ 6

Author(s):

Ben B. Balsley ◽

Dale A. Lawrence ◽

David C. Fritts ◽

Ling Wang ◽

Kam Wan ◽

...

Keyword(s):

High Resolution ◽

Mechanical Energy ◽

Potential Temperature ◽

Lower Troposphere ◽

Lower Atmosphere ◽

Horizontal Wind ◽

Small Scale ◽

Temperature Structure ◽

Temperature Structure Parameter

AbstractA new platform for high-resolution in situ measurements in the lower troposphere is described and its capabilities are demonstrated. The platform is the small GPS-controlled DataHawk unmanned aerial system (UAS), and measurements were performed under stratified atmospheric conditions at Dugway Proving Ground, Utah, on 11 October 2012. The measurements included spiraling vertical profiles of temperature and horizontal wind vectors, from which the potential temperature θ, mechanical energy dissipation rate ε, Brunt–Väsälä frequency N, temperature structure parameter CT2, Thorpe and Ozmidov scales LT and LO, and Richardson number Ri were inferred. Profiles of these quantities from ~50 to 400 m reveal apparent gravity wave modulation at larger scales, persistent sheet-and-layer structures at scales of ~30–100 m, and several layers exhibiting significant correlations of large ε, CT2, LT, and small Ri. Smaller-scale flow features suggest local gravity waves and Kelvin–Helmholtz instabilities exhibiting strong correlations, yielding significant vertical displacements and inducing turbulence and mixing at smaller scales. Comparisons of these results with a direct numerical simulation (DNS) of similar multiscale dynamics indicate close agreement between measured and modeled layer character and evolution, small-scale dynamics, and turbulence intensities. In particular, a detailed examination of the potential biases in inferred quantities and/or misinterpretation of the underlying dynamics as a result of the specific DataHawk sampling trajectory is carried out using virtual sampling paths through the DNS and comparing these with the DataHawk measurements.

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Simultaneous in situ measurements of small-scale structures in neutral, plasma, and atomic oxygen densities during the WADIS sounding rocket project

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11443-2019 ◽

2019 ◽

Vol 19 (17) ◽

pp. 11443-11460 ◽

Cited By ~ 5

Author(s):

Boris Strelnikov ◽

Martin Eberhart ◽

Martin Friedrich ◽

Jonas Hedin ◽

Mikhail Khaplanov ◽

...

Keyword(s):

Atomic Oxygen ◽

Lower Thermosphere ◽

Density Fluctuations ◽

Sounding Rocket ◽

Small Scale ◽

Scale Structures ◽

Small Scale Structures ◽

Mlt Region ◽

Diffusion Properties

Abstract. In this paper we present an overview of measurements conducted during the WADIS-2 rocket campaign. We investigate the effect of small-scale processes like gravity waves and turbulence on the distribution of atomic oxygen and other species in the mesosphere–lower thermosphere (MLT) region. Our analysis suggests that density fluctuations of atomic oxygen are coupled to fluctuations of other constituents, i.e., plasma and neutrals. Our measurements show that all measured quantities, including winds, densities, and temperatures, reveal signatures of both waves and turbulence. We show observations of gravity wave saturation and breakdown together with simultaneous measurements of generated turbulence. Atomic oxygen inside turbulence layers shows two different spectral behaviors, which might imply a change in its diffusion properties.

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Density Fluctuations in the Lower Thermosphere of Mars Retrieved From the ExoMars Trace Gas Orbiter (TGO) Aerobraking

Atmosphere ◽

10.3390/atmos10100620 ◽

2019 ◽

Vol 10 (10) ◽

pp. 620 ◽

Cited By ~ 2

Author(s):

David Jesch ◽

Alexander S. Medvedev ◽

Francesco Castellini ◽

Erdal Yiğit ◽

Paul Hartogh

Keyword(s):

Gravity Waves ◽

Lower Thermosphere ◽

Wave Activity ◽

Density Fluctuations ◽

Statistical Characteristics ◽

Trace Gas ◽

Small Scale ◽

Data Set ◽

Diurnal Variability ◽

Winter Hemisphere

The upper atmosphere of Mars is constantly perturbed by small-scale gravity waves propagating from below. As gravity waves strongly affect the large-scale dynamics and thermal state, constraining their statistical characteristics is of great importance for modeling the atmospheric circulation. We present a new data set of density perturbation amplitudes derived from accelerometer measurements during aerobraking of the European Space Agency’s Trace Gas Orbiter. The obtained data set presents features found by three previous orbiters: the lower thermosphere polar warming in the winter hemisphere, and the lack of links between gravity wave activity and topography. In addition, the orbits allowed for demonstrating a very weak diurnal variability in wave activity at high latitudes of the southern winter hemisphere for the first time. The estimated vertical damping rates of gravity waves agree well with theoretical predictions. No clear anticorrelation between perturbation amplitudes and the background temperature has been found. This indicates differences in dissipation mechanisms of gravity waves in the lower and upper thermosphere.

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High Resolution Diffraction Imaging of Small Scale Fractures in Shale and Carbonate Reservoirs

Proceedings of the 3rd Unconventional Resources Technology Conference ◽

10.15530/urtec-2015-2153238 ◽

2015 ◽

Author(s):

Alexander M. Popovici ◽

Ioan Sturzu ◽

Tijmen J. Moser

Keyword(s):

High Resolution ◽

Carbonate Reservoirs ◽

Small Scale ◽

Diffraction Imaging

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Circum-nuclear molecular disks: Role in AGN fueling and feedback

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320001544 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 312-317

Author(s):

Francoise Combes

Keyword(s):

Black Hole ◽

Angular Momentum ◽

High Resolution ◽

Large Scale ◽

Active Galaxy ◽

Small Scale ◽

Massive Black Hole ◽

Molecular Outflows ◽

Molecular Outflow

AbstractGas fueling AGN (Active Galaxy Nuclei) is now traceable at high-resolution with ALMA (Atacama Large Millimeter Array) and NOEMA (NOrthern Extended Millimeter Array). Dynamical mechanisms are essential to exchange angular momentum and drive the gas to the super-massive black hole. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching 10pc scale (50mas), may bring smoking gun evidence of fueling, within a randomly oriented nuclear gas disk. AGN feedback is also observed, in the form of narrow and collimated molecular outflows, which point towards the radio mode, or entrainment by a radio jet. Precession has been observed in a molecular outflow, indicating the precession of the radio jet. One of the best candidates for precession is the Bardeen-Petterson effect at small scale, which exerts a torque on the accreting material, and produces an extended disk warp. The misalignment between the inner and large-scale disk, enhances the coupling of the AGN feedback, since the jet sweeps a large part of the molecular disk.

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Impact of Miniaturized Fixed-Bias Multineedle Langmuir Probes on CubeSats

IEEE Transactions on Plasma Science ◽

10.1109/tps.2019.2915810 ◽

2019 ◽

Vol 47 (8) ◽

pp. 3658-3666 ◽

Cited By ~ 1

Author(s):

Sigvald Marholm ◽

Richard Marchand ◽

Diako Darian ◽

Wojciech J. Miloch ◽

Mikael Mortensen

Keyword(s):

Langmuir Probes ◽

Fixed Bias

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High resolution observations of spectral width features associatedwith ULF wave signatures in artificial HF radar backscatter

Annales Geophysicae ◽

10.5194/angeo-22-169-2004 ◽

2004 ◽

Vol 22 (1) ◽

pp. 169-182 ◽

Cited By ~ 4

Author(s):

D. M. Wright ◽

T. K. Yeoman ◽

L. J. Baddeley ◽

J. A. Davies ◽

R. S. Dhillon ◽

...

Keyword(s):

High Resolution ◽

Plasma Source ◽

Spectral Width ◽

Hf Radar ◽

Mhd Waves ◽

Small Scale ◽

Ulf Waves ◽

Source Population ◽

Radar Backscatter ◽

Field Lines

Abstract. The EISCAT high power heating facility at Tromsø, northern Norway, has been utilised to generate artificial radar backscatter in the fields of view of the CUTLASS HF radars. It has been demonstrated that this technique offers a means of making very accurate and high resolution observations of naturally occurring ULF waves. During such experiments, the usually narrow radar spectral widths associated with artificial irregularities increase at times when small scale-sized (high m-number) ULF waves are observed. Possible mechanisms by which these particle-driven high-m waves may modify the observed spectral widths have been investigated. The results are found to be consistent with Pc1 (ion-cyclotron) wave activity, causing aliasing of the radar spectra, in agreement with previous modelling work. The observations also support recent suggestions that Pc1 waves may be modulated by the action of longer period ULF standing waves, which are simultaneously detected on the magnetospheric field lines. Drifting ring current protons with energies of ∼ 10keV are indicated as a common plasma source population for both wave types. Key words. Magnetospheric physics (MHD waves and instabilities) – Space plasma physics (wave-particle interactions) – Ionosphere (active experiments)

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