Spatial and time distribution of the flash rate over the central Andes

NICORA M.G.; BÜRGESSER R.; AVILA E. E.

Praga

Conferencia; 26th IUGG General Assembly of the International Union of Geodesy and Geophysics; 2015

The lowlands to the east of the central Andes exhibit a tropical continental climate, with a peak in rainfall at the height of the austral summer (December?January?February) when the South American Low Level Jet (SALLJ) transports warm, moist air from the Amazon Basin toward the subtropical part of the continent. Situated in the southwest of Bolivia there is a high-level plateau known as the Altiplano (15° and 22° S), about 250 km wide and at an average elevation of 4000 m. The Altiplano exhibits a distinctive climate, about 90% of the annual precipitation concentrates between October and March in the form of intense thunderstorms. The lightning flash rate over the central Andes in South America was analyzed using lightning data from two independent lightning detection systems, the Lightning Imaging Sensor (LIS) and the World Wide Lightning Location Network (WWLLN). Spatial and time distributions of lightning activity were studied using different spatial and temporal scales. We show that the lightning activity over this region presents a pattern with a localized center of high lightning activity located on the eastern foot of the Altiplano; this center is located between [16°; 17°]S of latitude and [65°; 66°]W of longitude and presents a steady flash rate throughout all seasons of the year. The maximum seasonal flash rate occurs in the September?November period with a lightning activity around 100 flashes km-2 yr-1. The lightning activities observed seem to be strongly influenced by the topography, the SALLJ and upper-level anticyclone established in the southeast of the central Andes, the so-called Bolivian high.