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Browsing by Author "Yu, Zhibin"

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    First Simultaneous Lidar Observations of Thermosphere-Ionosphere Fe and Na (TIFe and TINa) Layers at McMurdo (77.84 degrees S, 166.67 degrees E), Antarctica With Concurrent Measurements of Aurora Activity, Enhanced Ionization Layers, and Converging Electric Field
    Chu, Xinzhao; Nishimura, Yukitoshi; Xu, Zhonghua; Yu, Zhibin; Plane, John M. C.; Gardner, Chester S.; Ogawa, Yasunobu (2020-10-28)
    We report the first simultaneous, common-volume lidar observations of thermosphere-ionosphere Fe (TIFe) and Na (TINa) layers in Antarctica. We also report the observational discovery of nearly one-to-one correspondence between TIFe and aurora activity, enhanced ionization layers, and converging electric fields. Distinctive TIFe layers have a peak density of similar to 384 cm(-3) and the TIFe mixing ratio peaks around 123 km, similar to 5 times the mesospheric layer maximum. All evidence shows that Fe+ ion-neutralization is the major formation mechanism of TIFe layers. The TINa mixing ratio often exhibits a broad peak at TIFe altitudes, providing evidence for in situ production via Na+ neutralization. However, the tenuous TINa layers persist long beyond TIFe disappearance and reveal gravity wave perturbations, suggesting a dynamic background of neutral Na, but not Fe, above 110 km. The striking differences between distinct TIFe and diffuse TINa suggest differential transport between Fe and Na, possibly due to mass separation.
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    Mid-Latitude Thermosphere-Ionosphere Na (TINa) Layers Observed With High-Sensitivity Na Doppler Lidar Over Boulder (40.13 degrees N, 105.24 degrees W)
    Chu, Xinzhao; Chen, Yingfei; Cullens, Chihoko Y.; Yu, Zhibin; Xu, Zhonghua; Zhang, Shun-Rong; Huang, Wentao; Jandreau, Jackson; Immel, Thomas J.; Richmond, Arthur D. (2021-06-16)
    We report the first lidar observations of regular occurrence of mid-latitude thermosphere-ionosphere Na (TINa) layers over Boulder (40.13 degrees N, 105.24 degrees W), Colorado. Detection of tenuous Na layers (similar to 0.1-1 cm(-3) from 150 to 130 km) was enabled by high-sensitivity Na Doppler lidar. TINa layers occur regularly in various months and years, descending from similar to 125 km after dusk and from similar to 150 km before dawn. The downward-progression phase speeds are similar to 3 m/s above 120 km and similar to 1 m/s below 115 km, consistent with semidiurnal tidal phase speeds. One or more layers sometimes occur across local midnight. Elevated volume mixing ratios above the turning point (similar to 105-110 km) of Na density slope suggest in situ production of the dawn/dusk layers via neutralization of converged Na+ layers. Vertical drift velocity of TINa+ calculated with the Ionospheric Connection Explorer Hough Mode Extension tidal winds shows convergent ion flow phases aligned well with TINa, supporting this formation hypothesis.