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@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"
}


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