author = "M{\"u}ller, Gabriela Viviana and Gan, Manoel Alonso and Piva, 
                         Everson Dal and Silveira, Virginia Piccinini",
          affiliation = "{} and {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Energetics of wave propagation leading to cold event in tropical 
                         latitudes of South America",
              journal = "Climate Dynamics",
                 year = "2015",
               volume = "x",
             keywords = "energetics, wave propagation, frost events, South America.",
             abstract = "This paper presents a new vision on the cold and cool events that 
                         affect the tropical region of South America, considering the 
                         dynamics and the energetics of wave train propagation associated 
                         with these systems. Through a composite analysis of meridional 
                         winds at 300 hPa for cold (T < 0 °C) and cool (0 °C \≤ T 
                         \≤ 2.5 °C) air incursions affecting tropical latitudes and 
                         causing frost are studied. The cold events observed in tropical 
                         latitudes are associated with a single Rossby wave pattern 
                         propagating over the Pacific Ocean which drives the low level 
                         anticyclone from the southwest of the continent to low latitudes. 
                         This propagation involves a southern circulation due to the 
                         meridional wind penetration and consequently cold air advection 
                         causing temperatures to drop below 0 °C. During cool events a 
                         subtropical wave train propagating through the Pacific Ocean is 
                         observed, which merges before the event with a wave coming from 
                         the subpolar latitudes of the South Atlantic Ocean. The zonal 
                         propagation leads to the entrance of the anticyclone from the west 
                         of the continent, and it is strengthened together with the 
                         meridionaly extended cyclone located upstream. This configuration 
                         causes southerly wind advection over central-southeastern Brazil 
                         and consequently causes the temperature decrease. The energetics 
                         shows that the cold events kinetic energy maxima are more intense 
                         than those of cool events. For the cold events three maxima are 
                         observed, the first (K1) and the third (K3) maxima are developed 
                         by baroclinic conversion and ageostrophic flux convergence and the 
                         second one (K2) by ageostrophic flux convergence. For the cool 
                         events two maxima are found, the first maximum (K4) developed by 
                         baroclinic conversion and the second one by ageostrophic flux 
                  doi = "10.1007/s00382-015-2532-2",
                  url = "http://dx.doi.org/10.1007/s00382-015-2532-2",
                 issn = "0930-7575",
           targetfile = "Muller_Energetics.pdf",
        urlaccessdate = "25 nov. 2020"