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Title: Lidar Observations of Predawn Thermosphere‐Ionosphere Na (TINa) Layers Over Boulder (40.13°N, 105.24°W): Annual Phase Variations and Correlation With Sunrise and Tidal Winds
Abstract

We have discovered that the peak phase time of predawn thermosphere‐ionosphere Na (TINa) layers (∼110–150 km altitude) undergoes clear annual variations with the earliest occurrence in summer and latest in winter over Boulder (40.13°N, 105.24°W), which are closely correlated to annual phase variations of sunrise and tidal winds. Such discoveries were enabled by the first characterization of 12 monthly composites of TINa layers from January through December using 7 years of lidar observations (2011–2017). Despite their tenuous densities, the predawn TINa layers have nearly 100% occurrence rate (160 out of 164 nights of observations). Monthly composites show downward‐phase‐progression TINa descending at similar phase speeds as Climatological Tidal Model of the Thermosphere tidal winds. These TINa layers occur in ion convergence but neutral divergence regions, modeled using tidal winds. These results support the formation mechanism (neutralization of converged TINa+forming TINa) proposed previously and suggest that migrating tidal winds experience annual phase variations.

 
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Award ID(s):
2110428 2330168 2029162
NSF-PAR ID:
10470947
Author(s) / Creator(s):
 ;  
Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Geophysical Research Letters
Volume:
50
Issue:
18
ISSN:
0094-8276
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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