Probabilistic Modeling of Hourly Precipitation Jointly with ERA5-Land: Application of Geostatistical Simulations
摘要
Accurate estimation of hourly precipitation is critical for hydrological forecasting and hydroelectric operations. This study develops a multivariate geostatistical framework that integrates irregularly positioned meteorological station measurements with the regularly gridded ERA5-Land reanalysis data for southern Quebec, Canada. The workflow addresses the zero-inflation challenge by separating precipitation occurrences from intensity. The occurrences are modeled using sequential indicator simulation (SIS), while the precipitation intensity is simulated conditionally through multivariate turning bands simulation (TBS) with ERA5-Land as an auxiliary collocated variable. The method generates 100 scenarios per hour, allowing uncertainty quantification via probability and quantile maps. Cross-validation results show coefficients of 0.65 to 0.82 for the model of occurrences and mean absolute errors of 0.8 to 1.5 mm for hourly intensities. Integrating ERA5-Land reduces kriging variance by 25% to 40% relative to univariate approaches, particularly where station coverage is sparse. The 9 km resolution probabilistic outputs offer operational value for regional hydrological modeling and hydropower risk management.