Case Study of Upper Tropospheric Meteorological Systems on South America: Synoptic Analysis

The upper tropospheric cyclonic vortex (VCAN) over northeastern Brazil (NeB) and the Bolivian High (AB) are the South America typical upper level (250 hPa) pressure systems, especially in warmer seasons. Besides these, one can also consider the extratropical VCAN, which has transient feature and is found throughout the year. In this work is presented a synoptic analysis, based on the specialized literature, of a case observed in February 01, 2005, when the three systems occurred simultaneously. Some features found in literature were noted in the systems of this case. The temperature field most associated to the extratropical system was 500 hPa and not 250 hPa. The most significant vertical movements were only found in extratropical system: intense upward movements in the lee of the upper tropospheric trough axis. It has found no system specifically associated to VCAN of NeB, while it was observed the association between the continental low (or Chaco Low) and the Bolivian High and an intense extratropical cyclone associated to extratropical VCAN. Such surface cyclone carries on a southerly and consequent cooling of the layer, what could be observed by the amplitude of the upper tropospheric trough, which is unusual in this season.