Evolution of Heatwaves in Chile Since 1980

Abstract

Heatwaves (HWs)  episodes are highly dangerous threats to human and ecosystem health, as well as to many economic sectors around the world. At the present work located in Chile,  we use a novel high-resolution gridded product (CR2Met) of ~5 km to evaluate the distribution and spatio-temporal HWs trends in Chile. We analyze November to March daily maximum temperatures (corresponds to late spring and austral summer; Tx) to evaluate the HWs behavior during 1980 - 2020, focusing on three thresholds: i) three consecutive days with Tx > 30°C, ii) three consecutive days with Tx > 90th percentile (P90) and iii) three consecutive days with Tx > 95th percentile (P95). Our findings show positive P90 trends (> 1 events per decade) across the Andean areas between 20° to 36°S, and > 0.75 events per decade in the Central Valley between 34º - 43ºS. In addition, P90 and P95 exhibit positive trends (> 1 and 0.5 events per decade, respectively), throughout most of Chile, including Andean highlands and Patagonia. We validated our results with HWs statistics based on eighteen official meteorological stations, revealing a coherence mainly on the Central Valley and Andean highlands.Moreover, using all thresholds, we found an increase in frequency during the 2011 - 2020 megadrought interval (ranging from 1 to 4 HWs events/decade) with respect to the previous period (1980 - 2010). Climatic factors such as Puelche (Föhn-like) winds frecuency is an amplifier HWs mechanism in South-Central Chile.

Keywords: Heatwaves, megadrought interval, Climate extreme events, Puelche winds, Chile