On the need for improved knowledge on the regional-to-local precipitation variability in eastern Spain under climate change
Pau Benetó, Samira Khodayar
Abstract
The Western Mediterranean is a climate change hotspot subject to generalized drying together with an increased torrentiality in precipitation with future scenarios pointing toward an extremization of these conditions. Projections indicate a further enhancement of differences between dry summers and wet autumns that already characterize this region. However, relevant uncertainties and discrepancies among projections exist including contrasting results complicating planification for future adaptation to climate change impacts in the Western Mediterranean. Both, the water supply for ecosystems and communities as well as the safety and well-being of the inhabitants are in danger. Detailed knowledge of the regional-to-local precipitation variability and evolution in the present climate together with an improved understanding of the underlying mechanisms, which is the objective of this investigation, will provide a better comprehension of projected future trends in the region. In this context, the present study provides a comprehensive evaluation of precipitation spatiotemporal characteristics and trends for the period 1951–2020 employing novel high-resolution gridded observations (SPAIN02) with a focus in eastern Spain, Hydrographic Confederations of Ebro (EBRO), Júcar-Segura (CHJS) and the Mediterranean Basins of Andalusia (CMA) that conform it from north to south. Particular attention is on the analysis of the Júcar-Segura (CHJS) basin. Results indicate a marked precipitation seasonality along the Spanish Mediterranean coast, with localized areas showing increasing trends, and a substantial drying during summer in the last seven decades reinforcing the already remarkable interseasonal variability characterizing the region. In contrast, moderate-to-heavy precipitation events have intensified in the last three decades for all seasons over central regions. Non-significant seasonal trends are identified for the winter, spring and autumn for the period under study, however, substantial intraseasonal variability dominates precipitation changes in these periods, particularly a significant mean precipitation decrease is observed in March and June. Interestingly, in the last two decades, summer precipitation presents a non-significant negative trend, with some areas over central regions showing an increase in precipitation contrasting with the general mean decrease observed during the period 1951–2020. The detailed analysis of the underlying mechanisms responsible for interseasonal and intraseasonal precipitation variations in the period 2000–2020 indicates that a frequency increase and intensification of orographically induced summer storms drive the observed summer precipitation increase in the Júcar-Segura basin. While the main changes during winter, spring, and autumn are principally linked to an intensification of precipitation events as a consequence of changes in moisture advection from the Mediterranean. Ongoing variability in this region can represent a mirror of the changes to come over similar areas around the world as a consequence of global warming.