Validation of the SPEIbase for the Southeastern Brazil Region

Abstract

Drought is a natural phenomenon that cause severely impacts on different sectors of society. To assess drought, indices are used that allow comparing events in different regions and time scales. SPEIbase is a gridded database that provides global-scale SPEI estimates with an extensive temporal coverage (1901 to 2022), 0.5° x 0.5° spatial resolution, and is currently being updated. This study aimed to evaluate SPEIbase v2.9 in representing the spatio-temporal patterns of drought in the Southeastern Brazil Region. For this, SPEIbase values were compared to values calculated from data from eight conventional meteorological stations (CMS), for the period from 1961 to 2010. SPEIbase showed satisfactory results for the Southeastern Brazil Region. The gridded data presented a positive linear trend for all eight CMS in the study, with a strong correlation (0.70 < r < 0.90) for more than 50% of the stations. Additionally, SPEIbase performed satisfactorily in identifying the frequency and intensity of droughts. SPEIbase is an important tool for drought analysis in the Southeastern Brazil Region.

Keywords
climate; drought; gridded data; statistical methods