Analysis of drop size distribution and rain characteristics of extreme events at different locations in the Tropical Andes

Abstract

Extreme rainfall events in the tropical Andes have been the cause of economic and social disturbances throughout the years. Furthermore, climate change increases the frequency of these kinds of events. A few spatiotemporal studies have been performed on the behaviour of extreme rainfall events, but never went into depth about their hydrometeors' microphysics. Even the definition of what can be considered an extreme rainfall event has yet to be concisely defined.

Thus, we have aimed to analyse, observe and compare how the drops of extreme and non- extreme events differentiate. This was done using data from three different sites in the tropical

Andes where hydrometeor data and drop size distribution (DSD) were acquired using laser disdrometers. The results show that the percentage of rainfall events that are extreme is similar across the tropical Andes (≈8%) and that if an event has an accumulation higher than 15 mm or lasts more than 3 hours, it’s likely an extreme event. Additionally, it was observed that the DSD of all extreme events shows that drops for all diameters during these events are bigger than during non-extreme rainfall events.