Tidal wind shear observed by meteor radar and comparison with sporadic E occurrence rates based on GPS radio occultation observations

Jacobi, Ch.; Arras, Christina

doi:10.5194/ars-17-213-2019

Cited by 15 publications

(10 citation statements)

References 66 publications

(99 reference statements)

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“…It is well known that the diurnal tide play a significant role in ionospheric E‐region (Gong & Zhou, 2011; Pignalberi et al., 2014; Jacobi & Arras, 2019). The monthly variation of the tidal amplitude in Figure 5 is in direct proportion to the seasonal occurrence rate of the E‐layer daytime irregularities in Figure 2, also implying the close relationship between diurnal tide and E‐region irregularities.…”

Section: Analysis and Discussionmentioning

confidence: 99%

Statistical Characteristics of the Low‐Latitude E‐Region Irregularities Observed by the HCOPAR in South China

et al. 2021

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Sporadic-E (Es) between 90 and 120 km is a very special layer of Earth's ionosphere. It is considered as a sporadic concentration of the E-layer plasma into thin layers of high electron density (Mathews, 1998;Whitehead, 1989). It is believed that the wind shear together with the Earth's geomagnetic field compresses the E-region ions into a thin, ion-rich layer, approximately one to two km in thickness (Chu et al., 2014;Cosgrove & Tsunoda, 2002). The steep density gradient in Es creates a favorable environment for gradient drift instability, which is widely believed responsible for the E-region Field-Aligned Irregularities (FAIs) (Ecklund et al., 1981;Kagan & Kelley, 1998;Larsen, 2000). The earliest report of the scattered echoes from E-region FAIs was published in the middle of last century (Bailey et al., 1955). When the Quasi Periodic (QP) scattered echoes from Es layer were recorded by the MU radar (Middle and Upper Atmosphere Radar) in 1989 (Yamamoto et al., 1991), these plasma structures aligned along the geomagnetic fields have drawn a lot of attention of the space physics community. And then the observations of the FAIs were widely carried out all over the world (e.g.,

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Section: Analysis and Discussionmentioning

confidence: 99%

Statistical Characteristics of the Low‐Latitude E‐Region Irregularities Observed by the HCOPAR in South China

et al. 2021

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“…Examination of wind‐shears in the lower thermosphere over approximately 100–120 km altitude is not possible from the majority of ground‐based lidar and radar systems (e.g., Jacobi & Arras, 2019). Altitude‐resolved horizontal wind observations, suitable for determining vertical shears, can be made in this range from ground‐based systems such as incoherent scatter radars (e.g., Djuth et al., 2010; Hysell et al., 2014) lidars (e.g., Fritts et al., 2004; Gardner & Papen, 1995; Yue et al., 2010) and VHF radars (e.g., Oppenheim et al., 2009).…”

Section: Introductionmentioning

confidence: 99%

Vertical Shears of Horizontal Winds in the Lower Thermosphere Observed by ICON

England

Englert

Harding

et al. 2022

Geophysical Research Letters

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Vertical shears of horizontal winds play an important role in the dynamics of the upper atmosphere. Prior observations have indicated that these shears predominantly occur in the lower thermosphere. MIGHTI observations from the Ionospheric Connection Explorer indicate that strong wind shears are a common feature of the lower thermosphere between 100–130 km, varying greatly between orbits. This work focuses on these strong shears, and examines their occurrences, horizontal scales and underlying organization. The wind shears can persist for 1000s km horizontally. Over a large data set, no preferred direction for the strong wind shears is found. The shears that persist for a short horizontal extent are slightly larger in amplitude and more numerous than those that persist across large horizontal scales. The altitude at which the strongest shears occur, regardless of the horizontal extent, show a downward progression with local time, following the climatological winds and upward propagating tides.

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“…Direct observational evidence for the wind shear theory is limited due to the lack of neutral wind measurements from the lower thermosphere. Es layers mostly occur above the height range where ground‐based radars can reliably determine the wind velocity (e.g., Jacobi & Arras, 2019). Sounding rockets have sometimes provided simultaneous measurements of plasma densities and neutral winds suitable for testing the wind shear theory.…”

Section: Introductionmentioning

confidence: 99%

Examining the Wind Shear Theory of Sporadic E With ICON/MIGHTI Winds and COSMIC‐2 Radio Occultation Data

Yamazaki

Arras

Andoh

et al. 2021

Geophysical Research Letters

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Metallic ion layers are commonly observed in the ionosphere. In particular, those which occur at E-region heights show high plasma concentrations, and they can cause anomalous high frequency (HF) radio propagation, known as Es. The characterization of the phenomenon and the formation mechanism for Es layers have been a subject of study for many decades (see, e.g., reviews by Haldoupis, 2011;Mathews, 1998;Whitehead, 1989). Observations of Es have been made using various instruments and techniques, including ionosondes (e.g., Taguchi, 1961), sounding rockets (e.g., Smith, 1966), incoherent scatter radars (e.g., Miller & Smith, 1978), lidars (e.g., Gardner et al., 1993, and radio occultation measurements (e.g., Hocke et al., 2001). It is now well established that Es layers occur most frequently at mid latitudes (20°-50° latitude) in the summer hemisphere at altitudes of 90-120 km.The formation of an Es layer requires the convergence of ion flux. The wind shear theory (Axford, 1963;Whitehead, 1961) suggests that the required ion flux convergence can be realized by the vertical shear of horizontal neutral winds. The following simple expression can be obtained for the vertical component of the ion velocity, under the assumption of balance between the Lorentz force due to ion motions across the ambient geomagnetic field and the frictional force due to ion-neutral collisions (e.g., Haldoupis, 2011):

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Tidal wind shear observed by meteor radar and comparison with sporadic E occurrence rates based on GPS radio occultation observations

Cited by 15 publications

References 66 publications

Statistical Characteristics of the Low‐Latitude E‐Region Irregularities Observed by the HCOPAR in South China

Statistical Characteristics of the Low‐Latitude E‐Region Irregularities Observed by the HCOPAR in South China

Vertical Shears of Horizontal Winds in the Lower Thermosphere Observed by ICON

Examining the Wind Shear Theory of Sporadic E With ICON/MIGHTI Winds and COSMIC‐2 Radio Occultation Data

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