Intense turbulence observed above a mesospheric temperature inversion at equatorial latitude

Lehmacher, G. A.; Croskey, C. L.; Mitchell, John; Friedrich, Martin; Lübken, Franz‐Josef; Rapp, Markus; Kudeki, Erhan; Fritts, David C.

doi:10.1029/2005gl024345

Cited by 28 publications

(39 citation statements)

References 25 publications

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“…Anomalous diffusion occurred also in the trail near 105 and 110 km analyzed by . Strong layering in the lower thermosphere with stable and unstable regions has also been observed in high resolution temperature profiles (Philbrick et al, 1985;Hillert et al, 1994;Lehmacher et al, 2006). Our wind, temperature and trail observations confirm that the lower thermosphere is highly structured and shows clear deviations from laminar behavior.…”

Section: Anomalous Diffusion From 103 To 118 Kmsupporting

confidence: 70%

“…Individual values show large variations, and strong turbulence has also been observed at other latitudes. Lehmacher et al (2006) report a single observation at low latitudes with 170 mW kg −1 between 92 and 95 km associated with a tidal inversion layer. Bishop et al (2004) identified a turbulent layer near 87 km with 130 mW kg −1 derived from TMA trail observations at midlatitudes.…”

Section: Mixed Layer At 90 Kmmentioning

confidence: 99%

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

et al. 2011

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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 Correspondence to: G. A. Lehmacher (glehmac@clemson.edu) 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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Section: Anomalous Diffusion From 103 To 118 Kmsupporting

confidence: 70%

Section: Mixed Layer At 90 Kmmentioning

confidence: 99%

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

et al. 2011

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“…Favorably, as shown in Fig. 1, during the daytime, such a static vertical gradient of N e exists above 60 km (Rastogi and Bowhill, 1976;Lehmacher et al, 2006). Consequently, electrons can comove with ions vertically.…”

Section: Rri Perturbation By Turbulencementioning

confidence: 99%

“…In addition to radar observations, an important in situ observation has recently been performed, obtaining a turbulence spectrum of the electron density ( Fig. 3; Lehmacher et al, 2006). This electron density was deduced from the electron density measurement of the Langmuir probe onboard the rockets although the electron density was also measured by incoherent scatter radar by the Altair radar at the Kwajalein Atoll and by the Faraday rotation in radio transmission between the ground and the rockets.…”

Section: Observation Of Turbulence With Radarsmentioning

confidence: 99%

Validity on radar observation of middle- and upper-atmosphere dynamics

Katō

2009

Earth Planet Sp

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Doppler radar observations have made a large contribution towards improving our understanding of middleand upper-atmosphere dynamics. This radar echo is mainly due to radiowave scattering by atmospheric turbulence, which occurs almost universally throughout the atmosphere as a result of gravity wave (GW) breaking. In the strictness sense, the radar pulse is back-scattered by radio refractive index (RRI) perturbations caused by turbulence whose size along the radar beam is half of the radar wavelength. Understanding of the validity of the MST (mesosphere, stratosphere and troposphere)-radar observation requires a precise knowledge of how RRI perturbations are formed and behave. A basic property of the RRI of the atmosphere is that it has a static vertical gradient in terms of distribution and the turbulence velocity is divergence-free. The RRI depends on three atmospheric properties-humidity, air density and electron density. These three elements each have a static vertical gradient along which turbulence transports each element, hereby perturbing the density distribution of each element; that is to say, it produces the RRI irregularity for scattering the radar pulse. Since the turbulence motion and winds are divergence-free, PRI perturbation co-moves with the total air flow, i.e. turbulence motion plus winds. This can be true even in the mesosphere where the perturbation is controlled electromagnetically. Co-movement of turbulence with local winds has been shown from a comparison of observations with radars and radiosondes. In addition to tracking turbulence as wind-tracers, MST-radar observations provide important data in the study of atmosphere turbulence dynamics.

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“…The experiment consisted of an instrumented rocket launch from Roi-Namur island of the Kwajalein Atoll, the site of the ALTAIR radar, and UHF zenith scan measurements by ALTAIR along the azimuth plane of the rocket trajectory. The rocket measurements are discussed by Friedrich et al [2006], as well as Lehmacher et al [2006], while ALTAIR results are the main focus of this paper.…”

Section: Introductionmentioning

confidence: 99%

ALTAIR incoherent scatter observations of the equatorial daytime ionosphere

Kudeki

Milla

Friedrich

et al. 2006

Geophysical Research Letters

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The first high‐resolution electron density maps of the low‐latitude D‐ and E‐region ionosphere in the Pacific sector acquired with ALTAIR UHF measurements are presented. The electron density data were collected in connection with a rocket based common volume experiment described by Friedrich et al. (2006). The observed phenomena in the density maps include E‐region density layers of tidal origin, shorter lived layers with small vertical scales, and lower E‐region electron density enhancement in response to enhanced X‐ray flux.

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Intense turbulence observed above a mesospheric temperature inversion at equatorial latitude

Cited by 28 publications

References 25 publications

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

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

Validity on radar observation of middle- and upper-atmosphere dynamics

ALTAIR incoherent scatter observations of the equatorial daytime ionosphere

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