Abstract
Extreme precipitation estimation commonly assumes stationarity, although climate variabili-ty can modify its temporal distribution. This study assessed nonstationarity in annual maxima of daily precipitation across three climatic regions of Ecuador using extreme-value models. Hourly ERA5-Land series were processed, the Relative Oceanic Niño Index was incorporated as a covariate, and stationa-ry and nonstationary formulations were compared through maximum likelihood, information criteria, likelihood-ratio tests, and parametric bootstrap. Guayaquil showed joint dependence on time and El Niño-Southern Oscillation variability; Puyo exhibited a temporal signal sensitive to the precipitation product; Quito remained compatible with stationarity. A CHIRPS robustness analysis showed that evidence of change is not spatially uniform and should be interpreted together with uncertainty associated with gridded precipitation products.
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