Mesocale Reanalysis of the LLJ along the Andes during the WETAMC/LBA - TRMM: comparison with observations

The northerly low level jet along the Andes provides an important mechanism for moisture transport from the Amazon to the higher latitudes of S.America. Based on the mesoscale reanalysis of the WETAMC/LBA-TRMM/Brazil campaign, performed with the RAMS assimilation module, the LLJ was particularly intense during 4 episodes during the: (a) Period I from 18 to 22 January, (b) Period II from 27 to 28 January, c) Period III from 30 January to February 03 and (d) Period IV from 11 to 14 February. The mesoscale reanalysis shows acceptable agreement with the observations. The mechanism for the diurnal variation of the LLJ is discussed. A significant impact of the heat source on the higher slopes of the Andes is identified besides the traditional mechanisms for the LLJ formation.