@Article{MeriwetherMaHuFiBuMeTa:2011:ClNiEq,
author = "Meriwether, J. W. and Makela, J. J. and Huang, Y. and Fisher, D.
J. and Buriti, Ricardo Arlen and Medeiros, Amauri Fragoso de and
Takahashi, Hisao",
affiliation = "Clemson Univ, Dept Phys \& Astron, Clemson, SC 29634 USA and Univ
Illinois, Dept Elect \& Comp Engn, Urbana, IL 61801 USA and Univ
Illinois, Dept Elect \& Comp Engn, Urbana, IL 61801 USA and Univ
Illinois, Dept Elect \& Comp Engn, Urbana, IL 61801 USA and Univ
Fed Campina Grande, Dept Phys, BR-58109970 Campina Grande, PB,
Brazil and Univ Fed Campina Grande, Dept Phys, BR-58109970 Campina
Grande, PB, Brazil and {Instituto Nacional de Pesquisas Espaciais
(INPE)}",
title = "Climatology of the nighttime equatorial thermospheric winds and
temperatures over Brazil near solar minimum",
journal = "Journal of Applied Geophysics",
year = "2011",
volume = "116",
pages = "A04322",
month = "APRIL",
keywords = "FABRY-PEROT-INTERFEROMETER, F-REGION, SEASONAL-VARIATION, MAXIMUM,
IONOSPHERE, AREQUIPA, TIME, SUPERROTATION, ATMOSPHERE, DYNAMICS.",
abstract = "We report on the climatology of equatorial thermospheric winds and
temperatures based on Fabry-Perot interferometer measurements of
Doppler shifts and Doppler broadenings of the 630.0 nm spectral
emission from the Cajazeiras observatory located in the
northeastern part of Brazil (6.89 degrees S, 38.56 degrees W).
These results apply to the lower thermosphere region near 240 km
and were obtained during a period of weak solar activity with the
solar flux typically within the range of 72 and 82 solar flux
units. Examination of the monthly averaged meridional
thermospheric winds for 1 year of measurement from October 2009 to
September 2010 found the wind direction to be equatorward during
summer months throughout the early evening hours with maximum
speeds reaching similar to 65 ms(-1). During winter months, the
early evening meridional wind direction reversed to poleward with
similar speeds. This result is attributed to the cross-hemispheric
flow from the summer to winter hemisphere. Superimposed upon this
wintertime meridional wind flow was an equatorward surge shortly
before midnight. This surge shifted to earlier local times in the
transition from the vernal equinox to summer and to later local
times between the summer solstice and the autumnal equinox; this
flow feature is attributed to tidal wave forcing. The temperature
observations exhibited the expected behavior, with the midnight
temperature maximum showing a greater amplitude, similar to 120 K,
in the vernal equinox with somewhat weaker amplitudes, similar to
75 K, seen at earlier local times during the summer. Also observed
was a phase lag of 60 to 90 min between the appearance of the
equatorward meridional wind flow and occurrence of the midnight
temperature maximum peak.",
doi = "10.1029/2011JA016477",
url = "http://dx.doi.org/10.1029/2011JA016477",
issn = "0926-9851",
language = "en",
urlaccessdate = "14 fev. 2025"
}