Browsing by Author "Cullens, Chihoko Y."
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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.
- Sensitivity study for ICON tidal analysisCullens, Chihoko Y.; Immel, Thomas J.; Triplett, Colin C.; Wu, Yen-Jung; England, Scott L.; Forbes, Jeffrey M.; Liu, Guiping (2020-05-22)Retrieval of the properties of the middle and upper atmosphere can be performed using several different interferometric and photometric methods. The emission-shape and Doppler shift of both atomic and molecular emissions can be observed from the ground and space to provide temperature and bulk velocity. These instantaneous measurements can be combined over successive times/locations along an orbit track, or successive universal/local times from a ground station to quantify the motion and temperature of the atmosphere needed to identify atmospheric tides. In this report, we explore how different combinations of space-based wind and temperature measurements affect the retrieval of atmospheric tides, a ubiquitous property of planetary atmospheres. We explore several scenarios informed by the use of a tidally forced atmospheric circulation model, an empirically based emissions reference, and a low-earth orbit satellite observation geometry based on the ICON mission design. This capability provides a necessary tool for design of an optimal mission concept for retrieval of atmospheric tides from ICON remote-sensing observations. Here it is used to investigate scenarios of limited data availability and the effects of rapid changes in the total wave spectrum on the retrieval of the correct tidal spectrum. An approach such as that described here could be used in the design of future missions, such as the NASA DYNAMIC mission (National Research Council, Solar and space physics: a science for a technological society, 2013).