author = "Andrioli, V{\^a}nia F{\'a}tima and Batista, Paulo Prado and Xu, 
                         Jiyao and Yang, Guotao and Chi, Wang and Zhengkuan, Liu",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Chinese Academy of 
                         Sciences} and {Chinese Academy of Sciences} and {Chinese Academy 
                         of Sciences} and {Chinese Academy of Sciences}",
                title = "Strong temperature gradients and vertical wind shear on MLT region 
                         associated to instability source at 23S",
              journal = "Journal of Geophysical Research: Space Physics",
                 year = "2017",
               volume = "122",
               number = "4",
                pages = "4500--4511",
                month = "Apr.",
             keywords = "convective instability, dynamical instability, mesopause 
                         instabilities, meteor radar wind, Na lidar temperature.",
             abstract = "Na lidar temperature measurements were taken successfully from 
                         2007 to 2009 in the mesopause region over S{\~a}o Jos{\'e} dos 
                         Campos (23.1S, 45.9W). Strong gradients on these vertical 
                         temperature profiles are often observed. A simple theoretical 
                         study has shown that temperature gradient of at least \−8 
                         K/km is required concurrently with the typical tidal wind shear in 
                         order to generate dynamical instability in the MLT region. We have 
                         studied vertical shear in horizontal wind related to atmospheric 
                         tides, inferred by meteor radar, with the aim of analyzing 
                         instability occurrence. These wind measurements were taken from an 
                         all-sky meteor radar at Cachoeira Paulista (22.7S, 45W). Two 
                         years of simultaneous data, wind and temperature, were used in 
                         this analysis which represent 79 days, totalizing 589 h of 
                         simultaneous observations. We realize that the condition for the 
                         local Richardson number (Ri) dropping below the critical value of 
                         instability (Ri < 0.25) is often reached in 98% of the analyzed 
                         cases. The mean probabilities for occurrence of convective and 
                         dynamical instabilities, in the altitude region between 82 and 98 
                         km, were observed to be about 3% and 17.5%, respectively. 
                         Additionally, vertical distribution of these probabilities has 
                         revealed a weak occurrence of dynamical instability around 90 km, 
                         and this fact can be related to the double mesopause typically 
                         observed in this site.",
                  doi = "10.1002/2016JA023638",
                  url = "http://dx.doi.org/10.1002/2016JA023638",
                 issn = "2169-9402",
             language = "en",
           targetfile = "andrioli_strong.pdf",
        urlaccessdate = "26 nov. 2020"