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Medientyp:
E-Artikel
Titel:
Lunar semidiurnal tide in the thermosphere under solar minimum conditions
Beteiligte:
Forbes, Jeffrey M.;
Zhang, Xiaoli;
Bruinsma, Sean;
Oberheide, Jens
Erschienen:
American Geophysical Union (AGU), 2013
Erschienen in:Journal of Geophysical Research: Space Physics
Sprache:
Englisch
DOI:
10.1029/2012ja017962
ISSN:
2169-9380;
2169-9402
Entstehung:
Anmerkungen:
Beschreibung:
<jats:p>Renewed interest in lunar tidal influences on the ionosphere‐thermosphere (IT) system has emerged in connection with recent studies of possible connections between stratospheric warmings and enhanced lunar tidal perturbations of the equatorial ionosphere. By virtue of its gravitational force, the Moon produces perturbations in the temperature, density, pressure, and winds throughout Earth's atmosphere. Lunar tidal winds in the dynamo region (~100–150 km) can furthermore generate electric fields that map into the <jats:italic>F</jats:italic>‐region and redistribute ionospheric plasma. Direct penetration (propagation) of lunar tides to <jats:italic>F</jats:italic>‐region heights can also transport ionospheric plasma. Decades‐long satellite data sets now exist that can provide a global perspective on lunar tidal oscillations, but this resource has not yet been exploited for this purpose. In this paper, we examine the global structure of the main <jats:italic>M</jats:italic><jats:sub>2</jats:sub> (period = 12.42 h) lunar tide through examination of temperatures measured by the Thermosphere Ionosphere Mesosphere Energetics and Dynamics SABER instrument at 110 km and densities at 360 and 480 km inferred from accelerometers on the CHAMP and Gravity Recovery and Climate Experiment satellites, respectively. Ten year mean SABER <jats:italic>M</jats:italic><jats:sub>2</jats:sub> temperature amplitudes are of order 5–10 K while the corresponding density perturbations during the 2007–2010 solar minimum period approach amplitudes of order 5% at 360 km and 10% at 480 km. The observed amplitudes are large enough to impose non‐negligible day‐to‐day variability on the IT system. Global‐Scale Wave Model simulations provide a theoretical and modeling context for interpreting these data, and moreover enable estimates of <jats:italic>E</jats:italic>‐ and <jats:italic>F</jats:italic>‐region winds.</jats:p>