Changes in Atmospheric River, Tropical Cyclone, and Extreme IVT-Related Extreme Precipitation Events in a Multi-Source Global Precipitation Dataset

Using Multi-Source Weighted-Ensemble Precipitation (MSWEP), MERRA-2 atmospheric reanalysis, and IBTrACS best-track data, we assess means and trends in global atmospheric river (AR), tropical cyclone (TC), and extreme integrated vapor transport (IVT)-related extreme daily and multi-day precipitation. Initial AR and extreme IVT detection are based on a geographically-varying IVT threshold capable of identifying anomalous moisture transport across a range of latitudes and land types. Then, quasi-connected extreme precipitation objects (EPOs) are classified by area, intensity, and dominant weather type. Finally, trends in different types of extreme precipitation are linked to changes in the ambient synoptic environment, including (1) thermodynamic changes (increasing moisture availability as dictated by the Clausius-Clapeyron relation) and (2) dynamic changes (intensification, shifting, or weakening of prevailing atmospheric circulations). Globally, ARs account for the vast majority of overall extreme precipitation and large-scale EPOs outside of the tropics, while non-AR extreme IVT accounts for the majority in the tropics. Both AR- and TC-related extreme precipitation have increased significantly, though TC-related changes are more variable. Spatially larger events exhibit larger percentage increases in frequency, with those above 40,000 km² seeing the largest relative changes. This suggests that large storm systems – which pose especially widespread and multifaceted hazards – are experiencing some of the fastest rates of precipitation intensification.