ATMOSPHERIC BLOCKINGS IN THE PACIFIC SOUTHEAST AND ATLANTIC SOUTH OCEANS AND THEIR INFLUENCE ON THE CLIMATE OF URUGUAY
Gianina Giacosa, Madeleine Renom y Marcelo Barreiro
Instituto Uruguayo de Meteorología, Uruguay.
Departamento de Ciencias de la Atmósfera, Universidad de la República, Montevideo, Uruguay.
Manuscript received on August 3th, 2018, on final form on January 16th, 2019.
In this work blocking patterns in the Southern Hemisphere are identified between 1980 and 2016 in the Southeast Pacific (PAS region) and South Atlantic (ATS region) Oceans in order to determine their influence on the climate of Uruguay. The ocurrence of a block event is identified following a classical methodology for blocking detection where time persistence conditions are imposed to the gradient of the geopotential height in a band of at least 15o of longitude. Blocking patterns are classified by region
of ocurrence and composites are constructed to determine the upper level and surface circulation anomalies as well as their consecuences on temperature (maximum and minimum) and precipitation in Uruguay. Blocking events ocurred in the PAS region had opposite effects during warm and cold months, causing significant negative anomalies in temperature and precipitation during summer and leading to significant positive anomalies of temperature in the uruguayan coast during autumn and winter. ATS region shows a lower frecuency of 1 events resulting in temperatures below the mean troughout the year. These temperature anomalies are statistically significant in autumn, a period also characterized by significant rainfall anomalies below the normal.