Evaluation and projections of total and maximum-daily rainfall in Northwestern Argentina by CMIP6 models

Abstract

In this study, daily precipitation data simulated by 16 global circulation models from the 6th phase of the Coupled Model Intercomparison Project (CMIP6) were analyzed. Initially, the models’ ability to represent the average climatological values of maximum daily precipitation (Rx1) and total precipitation (TOT) on a seasonal and annual basis in Northwestern Argentina (NWA) was evaluated. The aim was to assess the models’ performance and select models with a lower bias in simulating Rx1 and TOT in NWA. However, a lower bias does not imply overall model superiority, as the evaluation was limited to a specific region, two precipitation indices, and a single realization. Subsequently, precipitation projections up to the end of the 21st century were obtained under two shared socioeconomic pathways (SSP) corresponding to intermediate and high global warming scenarios. Results from the selected and non-selected models and for Rx1 and TOT were compared. Models tend to overestimate Rx1 and TOT values in NWA, with only the IPSL-CM6A-LR model showing lower bias for both precipitation metrics simultaneously. In some cases, agreement among models on projected changes improves when considering the high global warming scenario. By the end of the century, a general increase in Rx1 is projected for the region, implying a higher flood risk. Additionally, a decrease in TOT during winter and spring is projected, increasing the risk of water deficits during the dry-to-wet season transition. Comparatively, Rx1 is more sensitive to global warming, suggesting that its contribution to TOT will increase by the end of the century.