Temporal Linkages Between Moisture Transport and Atmospheric Water Availability: Implications for Extreme Precipitation

Atmospheric moisture availability plays a central role in regulating the occurrence and persistence of extreme precipitation, but its temporal linkage with large-scale moisture transport remains insufficiently quantified at the global scale. This study examines the lagged relationship between moisture transport across the land–ocean interface and extreme precipitation using ERA5 reanalysis data for the period 1979–2020. Extreme precipitation is characterized using the R95pTOT index, which measures the total precipitation accumulated during very wet periods. Vertically integrated moisture fluxes are projected onto coastal boundaries to quantify inflow, outflow, and netflow components of moisture transport. Lagged Pearson correlations as well as the p-value between these components and R95pTOT are evaluated globally and for four representative regions: the Asian Monsoon, the Amazon Basin, the Gulf of Mexico and North America, and West Africa. The results show that moisture inflow is positively associated with extreme precipitation across most regions, indicating that enhanced ocean-to-land moisture transport supports increased atmospheric moisture availability during extreme events. The strongest and most persistent relationships are found in tropical regions, where significant inflow–precipitation correlations persist for approximately 5–10 days. In contrast, mid-latitude coastal regions exhibit weaker and more transient relationships, consistent with the influence of rapidly evolving synoptic systems. Netflow correlations generally display weaker and more regionally dependent associations with extreme precipitation, with outflow showing weak or negative relationships in some regions, particularly in West Africa. Overall, the findings demonstrate that both the direction and temporal persistence of moisture transport play an important role in shaping regional differences in extreme precipitation.