Affiliation:
1. Cooperative Institute of Research in Environmental Sciences & Department of Aerospace Engineering Sciences University of Colorado Boulder Boulder CO USA
Abstract
AbstractWe 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.
Funder
National Science Foundation
National Aeronautics and Space Administration
Publisher
American Geophysical Union (AGU)
Subject
General Earth and Planetary Sciences,Geophysics
Cited by
1 articles.
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