How Much Did It Rain? A Comparison of Four Datasets for TC Beryl (2012)

Abstract The southeastern United States frequently experience significant precipitation from tropical cyclones (TCs), leading to wind damage, flooding, and related hazards. Understanding the precipitation characteristics of these storms is vital for hydrological assessments. This study aims to characterize the amount and spatial distribution of precipitation contributed to a region by TCs using various precipitation datasets. The analysis focuses on TC Beryl in 2012 during an active drought period. The datasets include near-real-time and postprocessed satellite data (IMERG), merged ground radar observations (Stage IV), interpolated gauge observations [geographic COOP (G-COOP)], and point-based data from Automated Surface Observing System (ASOS). Previous studies have identified significant differences in rainfall characteristics between these products. The analysis reveals that traditional evaluation approaches for quantitative precipitation forecast products (such as the rain rate or the amount or timing of the rain) may not be adequate to compare the TC rainfall data. Instead, an integrated comparison using rainfall intensity and spatial verification metrics provides a more comprehensive evaluation of precipitation estimates during TCs. The spatial verification metrics indicate substantial overlap (∼70%) between satellite-derived and gauge/radar-based precipitation products for the 90th percentile rainfall, highlighting areas of agreement in extreme precipitation estimates. A rainfall threshold of < 65 mm is spatially aligned with a median maximum interest score of > 0.85, suggesting the utility of satellite-derived estimates, particularly due to their global availability. This analysis informs future hydrological studies and highlights the importance of considering rainfall volume in understanding the impacts of landfalling TCs. The findings contribute to a broader perspective on hydrological characteristics derived from different precipitation products, paving the way for further research in this area. Significance Statement Extreme weather events have contributed to trillion dollar losses in the United States since 1980. The flooding caused by tropical cyclones contributes to 40%–50% of this loss. Precipitation being the critical parameter, this study highlights the differences among a few gridded precipitation data products for the case study of TC Beryl 2012. The results show that the volumetric precipitation is more representative of the storm than instantaneous rainfall rates. The study also focuses on the usability of satellite precipitation data for tropical cyclone cases in regions with few in situ precipitation observations.