Remote sensing lower thermosphere wind profiles using non‐specular meteor echoes

Oppenheim, M. M.; Sugar, Glenn; Slowey, Nicholas O.; Bass, Elizabeth; Chau, Jorge L.; Close, Sigrid

doi:10.1029/2009gl037353

Cited by 40 publications

(61 citation statements)

References 13 publications

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“…In the chemical release experiment by sounding rockets at different latitudes, longitudes, seasons, and local times, large horizontal winds and strong vertical shears have been measured (e.g., Wu and Widdel, 1992;Larsen, 2000Larsen, , 2002Larsen et al, 2005;Larsen and Fesen, 2009;Koizumi et al, 2009). Moreover, both the magnitudes and vertical structures of winds and shears measured by the sodium lidar and non-specular meteor radar are in line with those obtained by sounding rocket measurements (e.g., Larsen et al, 2003Larsen et al, , 2004Larsen and Fesen, 2009;Oppenheim et al, 2009Oppenheim et al, , 2014. Various wind measurement techniques indicated that large winds and wind shears occur frequently in the MLT region regardless of local times, seasons, latitudes, and longitudes (Larsen, 2002).…”

Section: Introductionsupporting

confidence: 63%

Simulations of large winds and wind shears induced by gravity wave breaking in the mesosphere and lower thermosphere (MLT) region

Liu

et al. 2014

Ann. Geophys.

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Abstract. Using a fully nonlinear two-dimensional (2-D) numerical model, we simulated gravity waves (GWs) breaking and their contributions to the formation of large winds and wind shears in the mesosphere and lower thermosphere (MLT). An eddy diffusion coefficient is used in the 2-D numerical model to parameterize realistic turbulent mixing. Our study shows that the momentum deposited by breaking GWs accelerates the mean wind. The resultant large background wind increases the GW's apparent horizontal phase velocity and decreases the GW's intrinsic frequency and vertical wavelength. Both the accelerated mean wind and the decreased GW vertical wavelength contribute to the enhancement of wind shears. This, in turn, creates a background condition that favors the occurrence of GW instability, breaking, and momentum deposition, as well as mean wind acceleration, which further enhances the wind shears. We find that GWs with longer vertical wavelengths and faster horizontal phase velocity can induce larger winds, but they may not necessarily induce larger wind shears. In addition, the background temperature can affect the time and height of GW breaking, thus causing accelerated mean winds and wind shears.

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Section: Introductionsupporting

confidence: 63%

Simulations of large winds and wind shears induced by gravity wave breaking in the mesosphere and lower thermosphere (MLT) region

Liu

et al. 2014

Ann. Geophys.

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“…These trails have also been referred to as range-spread echoes [Malhotra et al, 2008;Mathews et al, 2008], spread meteor echoes [Reddi et al, 2002], and turbulent trail echoes, and they typically endure for less than a few seconds. They have been detected using both HPLA radars [Chapin and Kudeki, 1994;Oppenheim et al, 2009] and, less frequently, lowpower radars and are thought to result from Bragg scattering from field aligned irregularities (FAIs) in the trail [Heritage et al, 1962]; detection results from the growth of plasma instabilities. The time sequence associated with this process was summarized by Oppenheim et al [2000], who showed that an ambipolar E field (perpendicular to both the geomagnetic field and the trail) first develops, followed by a growth of plasma concentration waves on the edges of the trail that arise from the gradient drift/Farley Buneman instability and then, finally, plasma turbulence.…”

Section: Introductionmentioning

confidence: 99%

Polarization and scattering of a long-duration meteor trail

Kelley

Vertatschitsch

et al. 2011

J. Geophys. Res.

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[1] High-power, large-aperture (HPLA) radars have been used over the past two decades to characterize the plasmas formed both around and behind meteoroids as they enter Earth's atmosphere. These plasmas, referred to as heads and trails, respectively, occur with relative frequency (peak head echo detection rate of ∼1/s) but are extremely diverse and have been difficult to define in a general sense. One particular type of plasma, referred to as the nonspecular trail, occurs when the meteoroid travels quasi-parallel to the radar beam with the radar beam lying quasi-perpendicular to the background magnetic field. Reflection is believed to occur from field-aligned irregularities (FAIs) that form after the trail becomes unstable. While FAI scattering pertains to the majority of nonspecular trails that are short in duration, a subset of these trails, referred to as long-duration trails, still remains open to interpretation. In this paper we present a case study analysis of a longduration, nonspecular trail and its associated head echo detected with the Advanced Research Project Agency (ARPA) Long-Range Tracking and Identification Radar (ALTAIR), which is an HPLA radar. These data are unique in that they are high resolution (with monopulse angles), dual frequency, and, most importantly, dual polarized, which allows for unprecedented insight into the scattering process from both heads and trails. First, we determine the velocity and mass of the parent meteoroid, which is a particle weighing more than a milligram and is one of the largest meteoroids ever detected by ALTAIR. Second, we determine the peak plasma density and polarization of the head echo and characterize the unique, yet strong returns in the opposite polarization, which may be due to multiple scattering centers within the range gate. Finally, we examine the polarization properties of the trail and discuss the first conclusive evidence of polarization flipping along the trail striations, which we believe corresponds to sharp gradients at the edges of the trail related to turbulent mixing of a dusty plasma that is elongating along the magnetic field. We look into a new idea, namely, the notion that some nonspecular echoes might correspond to a high Schmidt number, dusty plasma, as is found in and above noctilucent clouds. Our results show how polarized return can aid in scattering diagnostics and that single polarization radars must be used with caution for determining head and trail plasma densities given that some of the return can occur in the "unexpected" channel.

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“…However, a more detailed analysis of one of these fragmentation events and its corresponding trail revealed that these fragmentation influences do not account for all of the variation. Another suggestion could be that the neutral winds suddenly changed directions and caused the meteor trail to be "dragged" in the opposite direction of the original diffusion [Oppenheim et al, 2009], thereby causing an inflection point in the average variation of the meteor trail. However, we believe that the main factor for these large varying portions are due to detection of the meteor plasma in the initial stages of turbulence after the instabilities have grown large enough.…”

Section: Diffusion Perpendicular and Parallel To The Magnetic Fieldmentioning

confidence: 99%

“…Not only can we study the plasma from the meteors but we can also derive ambient ionosphere conditions. For example, Oppenheim et al [2009] developed a technique by which nonspecular meteor trails could be used to compute neutral wind measurements by comparing the phase differences between detection channels from the Jicamarca Radio Observatory [Oppenheim et al, 2009]. With these measurements, Oppenheim et al [2009] was able to discuss the influence of these neutral winds on the bulk fluid motion of the meteor trails in the ionosphere.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Oppenheim et al [2009] developed a technique by which nonspecular meteor trails could be used to compute neutral wind measurements by comparing the phase differences between detection channels from the Jicamarca Radio Observatory [Oppenheim et al, 2009]. With these measurements, Oppenheim et al [2009] was able to discuss the influence of these neutral winds on the bulk fluid motion of the meteor trails in the ionosphere. In addition to helping with the prediction and understanding of neutral winds and other atmospheric phenomena, meteor research provides insight into understanding space plasmas including plasmas that are generated from meteoroid impacts on satellites [Close et al, 2010;Lee et al, 2012].…”

Section: Introductionmentioning

confidence: 99%

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Plasma turbulence of nonspecular trail plasmas as measured by a high‐power large‐aperture radar

Yee

2013

JGR Atmospheres

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[1] High-power, large-aperture radars have been used to characterize plasmas formed as meteoroids ablate in Earth's atmosphere. These plasmas are referred to as heads, the plasmas surrounding the meteoroids, and trails, the plasmas left behind by the meteoroids. A subset of trails is nonspecular trails, which are detected when the radar beam is quasi-perpendicular to the magnetic field. Radar returns from trail plasma are thought to originate from field-aligned irregularity reflections that form due to turbulence within the trail. In this paper, we present theory and analysis of plasma trail diffusion using nonspecular trails detected by the Advanced Research Project Agency Long-range Tracking and Identification Radar. These data include dual frequency, dual polarized, and high-range resolution in-phase and quadrature returns with azimuth and elevation data. We present turbulence onset times for nonspecular trails and derive comparisons to models. We compare diffusion coefficients calculated from the decay in signal return with ambipolar diffusion coefficients derived for specular meteor trails. These results, in conjunction with an analysis of the diffusion perpendicular and parallel to the magnetic field, demonstrate that the ambipolar diffusion coefficient is not a sufficient description of the turbulent diffusion in nonspecular trails and that other influences, such as external electric fields and anomalous cross-field diffusion, must be considered when calculating the diffusion coefficients of nonspecular trails. In addition, we examined these results with respect to the polarization of the returns and found similar trends between all polarizations with slight differences for the right circular return.Citation: Yee, J., and S. Close (2013), Plasma turbulence of nonspecular trail plasmas as measured by a high-power large-aperture radar,

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Remote sensing lower thermosphere wind profiles using non‐specular meteor echoes

Cited by 40 publications

References 13 publications

Simulations of large winds and wind shears induced by gravity wave breaking in the mesosphere and lower thermosphere (MLT) region

Simulations of large winds and wind shears induced by gravity wave breaking in the mesosphere and lower thermosphere (MLT) region

Polarization and scattering of a long-duration meteor trail

Plasma turbulence of nonspecular trail plasmas as measured by a high‐power large‐aperture radar

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