Case Study of a Cold air Outbreak Incursion Extreme Event in July 2013 on Brazilian Amazon Basin

Abstract The Amazon basin is located in the tropical region whose main characteristics are the high values of temperature and humidity of the air. However, cold and dry air incursions also penetrate the region, as occurred in July 2013. This fourth cold wave that affected the South American continent caused snow in cities of the South region, characterizing an intense polar mass with displacement to the North. The present work analyzed the behavior of meteorological variables in order to investigate the intensity of this effect. The dataset used were observations and reanalyses. The negative anomaly of the maximum temperature in Rio Branco was 15.9 °C, in Manicoré of 6.7 °C and Manaus of 2,0 °C. In this event, the most expressive values occurred at the maximum temperature. Also worth mentioning is a monthly contribution in precipitation rates, whose values were higher than 13.0 mm.day-1. Thus, it is concluded that the event of July 2013 was a case of intense cold, due to the fact that it moved to the central region of Amazonia and caused abrupt drops, mainly in maximum temperature, favoring rainfall in the tropical regions, as well as changes in surface pressure, humidity and wind.