Variability of Deep Convection over the South American Region during the southern summer

High resolution infrared (IR) data, measured by the geostationary satellites, and outgoing longwave radiation (OLR) data, obtained from the NOAA polar-orbiting satellites, are used to describe the pattern of warm season convection over South America. General features include an area of maximum convection over the southern and central Amazon Basin, a southeastward extension of the strong convection to Southeast Brazil, and intense convection over the Andes mountains and Altiplano region of Bolivia. The presentation will focus on patterns observed during December 1998-February 1999. Variability of the intensity and distribution of convection over South America occurs on all time scales from the diurnal to the interannual. Each day convective activity is strongly modulated by the diurnal cycle in heating. Deep convection is often a maximum near 1700 LT and a minimum near 0900 LT. However, in the vicinity of elevated terrain and coasts the timing of the maximum and minimum may be quite different. During the period of study strong intraseasonal variability was observed on the eastern and southern flanks of the convective core region, which includes the region of the South Atlantic Convergence Zone (SACZ). This resulted partly due to Madden-Julian Oscillation (MJO) activity and partly due to higher-frequency transients, such as mid-latitude synoptic fronts and blocking events. Circulation features during active and inactive periods will also be described.