author = "Venturini, Mateus S. and Bageston, Jos{\'e} Valentin and Caetano, 
                         Nattan R. and Peres, Lucas V. and Bencherif, Hassan and Schuch, 
                         Nelson Jorge",
          affiliation = "{Universidade Federal de Santa Maria (UFSM)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Universidade Federal 
                         de Santa Maria (UFSM)} and {Universidade Federal do Oeste do 
                         Par{\'a}} and {Universit{\'e} de La R{\'e}union} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)}",
                title = "Mesopause region temperature variability and its trend in southern 
              journal = "Annales Geophysicae",
                 year = "2018",
               volume = "36",
               number = "2",
                pages = "301--310",
                month = "Mar.",
             keywords = "Atmospheric composition and structure (middle atmosphere - 
                         composition and chemistry, pressure density and temperature), 
                         meteorology and atmospheric dynamics (climatology).",
             abstract = "Nowadays, the study of the upper atmosphere is increasing, mostly 
                         because of the need to understand the patterns of Earth's 
                         atmosphere. Since studies on global warming have become very 
                         important for the development of new technologies, understanding 
                         all regions of the atmosphere becomes an unavoidable task. In this 
                         paper, we aim to analyze the temperature variability and its trend 
                         in the mesosphere and lower thermosphere (MLT) region during a 
                         period of 12 years (from 2003 to 2014). For this purpose, three 
                         different heights, i.e., 85, 90 and 95 km, were focused on in 
                         order to investigate the upper atmosphere, and a geographic region 
                         different to other studies was chosen, in the southern region of 
                         Brazil, centered in the city of Santa Maria, RS (29 degrees 4'02 
                         '' S; 53 degrees 48'25 '' W). In order to reach the objectives of 
                         this work, temperature data from the SABER instrument (Sounding of 
                         the Atmosphere using Broadband Emission Radiometry), aboard NASA's 
                         Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) 
                         satellite, were used. Finally, two cases were studied related to 
                         distinct grids of latitude/longitude used to obtain the mean 
                         temperature profiles. The first case considered a grid of 20 
                         degrees x 20 degrees lat/long, centered in Santa Maria, RS, 
                         Brazil. In the second case, the region was reduced to a size of 15 
                         degrees x 15 degrees in order to compare the results and discuss 
                         the two cases in terms of differences or similarities in 
                         temperature trends. Observations show that the size of the 
                         geographical area used for the average temperature profiles can 
                         influence the results of variability and trend of the temperature. 
                         In addition, reducing the time duration of analyses from 24 to 12 
                         h a day also influences the trend significantly. For the smaller 
                         ge-ographical region (15 degrees x 15 degrees) and the 12 h daily 
                         time window (09:00-21:00 UT) it was found that the main 
                         contributions for the temperature variability at the three heights 
                         were the annual and semi-annual cycles and the solar flux 
                         influence. A smaller trend (-0.02 +/- 0.16% decade(-1)) was found 
                         at 90 km height and small positive trends (0.58 +/- 0.26% and 0.41 
                         +/- 0.19% decade(-1)) were found at altitudes of 85 and 95 km, 
                  doi = "10.5194/angeo-36-301-2018",
                  url = "http://dx.doi.org/10.5194/angeo-36-301-2018",
                 issn = "0992-7689",
             language = "en",
           targetfile = "venturini_mesopause.pdf",
        urlaccessdate = "16 abr. 2021"