An episode of intense Low Level Jet (LLJ) was identified during the period 6-7 March 1999, at the end of the TRMM-Brazil and WET AMC/LBA campaigns. The LLJ is a circulation feature characteristics of the summer circulation east of the Andes in South America, and has been identified using global reanalysis, while the lack of continuos observations of radiosonde on the Bolivia-Paraguay-Southern Brazil region makes the systematic identification of this feature very difficult. A LLJ refers to a wind system with maximum strength within the lowest one or two km, possessing a horizontal extent that is commonly of sub synoptic dimension. This jet transports water vapor from tropical to higher latitudes, from the warm tropical Amazon region to regions of heavy convective weather of northern Argentina-southern Brazil.
The diurnal cycle of zonal and meridional circulation, together with its influence in convection rainfall and low level circulation are analyzed here, for the LLJ episode of March 7 1999. We used the network of raingauges and radiosonde observations from TRMM-Brazil. Additional radiosonde and pilot balloon observations made in Bolivia by the PACS-SONET network during that period was also used.
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