A climatology of warm‐season mesoscale convective complexes in subtropical South America

Abstract

AbstractThis study extends investigations of mesoscale convective complexes (MCCs) over subtropical South America (SSA) by describing the physical characteristics of MCCs during the austral warm season (October–May) for 1998–2007 in SSA. Within the nine warm seasons, 330 events were documented. An average of 37 MCCs occurred each warm season and reached a maximum cloud‐shield size of 256 500 km2, and lasted 14 h on average. Although 85% of the MCC population occurred over the South American continent, the remaining systems that occurred over the adjacent Atlantic Ocean were significantly larger by nearly 30%. These findings show MCCs in SSA are larger and longer‐lived than shown in previous work. Compared to the United States, MCCs in SSA are significantly larger with longer durations. Unlike the US systems, these events do not exhibit much poleward migration throughout the warm season. The highest frequency and concentration of MCC cloud shields are centred east of the Andes Mountains between 20°S and 30°S over Paraguay, northern Argentina, and southern Brazil throughout the warm season. As a result, relationships between latitude, and MCC maximum extent or duration are weak or non‐existent, respectively. There is, however, a moderate positive relationship between duration and maximum extent. Ultimately, MCCs in SSA are large, long‐lasting events that possess great potential for contributing significantly to precipitation totals across the region. Copyright © 2009 Royal Meteorological Society