Large, Long-Lived Convective Systems Over Subtropical South America and Their Relationships With Atmospheric Teleconnections

• Main Author: Mattingly, Kyle
• Format: Text
• Language: unknown
• Published: TopSCHOLAR® 2012
• Subjects: Climatology; Meteorology; South America; Mesoscale Convective Systems; Atmospheric Teleconnections; Atmospheric Sciences; Environmental Sciences; Antarctic; Austral; The Antarctic; Antarc*
• Online Access: https://digitalcommons.wku.edu/stu_hon_theses/353; https://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=1359&context=stu_hon_theses

This study provides a climatological assessment of persistent elongated convective systems (PECS) over subtropical South America during the austral warm seasons of 1998-2007 and a comparison of PECS frequency and physical characteristics to mesoscale convective complexes (MCCs) in the region. Relationships between the Antarctic Oscillation (AAO) and El Niño – Southern Oscillation (ENSO) teleconnections and large, long-lived convective systems (LLCSs) are explored. An average of 143 PECS and 37 MCCs occurred per warm season. PECS lasted longer on average than MCCs (17 hrs. vs. 14 hrs.) and reached a greater average maximum cloud-shield extent than MCCs (297,300 km2 vs. 256,500 km2). PECS frequency was maximized over the La Plata river basin during December – February. The relative frequency of LLCS occurrence was greatest during negative AAO phases (0.906 LLCSs/day) and positive ENSO phases (28.1 LLCS/month). LLCS maximum cloud-shield extent was greatest during negative AAO phases and positive ENSO phases. LLCSs tended to be displaced southward during negative AAO phases and neutral ENSO phases. These results suggest that AAO and ENSO phases have at least some influence on LLCSs over SSA. Additionally, the high relative frequency of PECS compared to MCCs suggests they may contribute substantially to yearly precipitation totals in the region.