On the study of three hotspots of rainfall on the eastern Andes

LLAMEDO, P.; HIERRO, R.; RAMEZANI, MARIAM; SCHMIDT, T.; DE LA TORRE, A.; ALEXANDER, P.

Rosario

Congreso; CONGREMET; 2018

Onthe basis of the period 1998-2015, 3hr accumulated rainfall data from TropicalRainfall Measuring Mission (TRMM) with 0.25x0.25 km resolution have been usedto detect extreme precipitation events at the east area of central Andes. Threestrong signals that appear in the mean accumulated rainfall field wereanalyzed. Enclosing them within three regions, spatial maxima were obtained andtheir behaviour studied. Extreme events within each of those regions, definedas the 99thpercentile of their daily mean accumulated rainfall, were detected andanalyzed. Austral summer is the period of the year presenting most frequentpeaks over these three regions. Daily statistics show that such spatial maxima,as well as their extreme events, are produced during the night. The hypothesisof nocturnal convection at the base of a mountain was tested using NCEP dataand WRF simulations. It implies cooling descending air from the mountains thatfinds unstable air at the surface, giving place to the development of stronglocal convection.