Reconciling tracked atmospheric water flows to close the global freshwater cycle

Abstract

Atmospheric moisture plays a vital role in the hydrological cycle, connecting evap oration sources to precipitation sinks. While high-resolution moisture-tracking models offer valuable insight, discrepancies to atmospheric re-analysis data emerge. In this study, we reconcile tracked atmospheric water flows with reanal ysis data, using the Iterative Proportional Fitting procedure (IPF). We apply IPF to the atmospheric moisture flows from the UTrack dataset (averaged over 2008-2017), aggregated within countries and ocean boundaries. This reconciled dataset ensures that the total tracked atmospheric moisture equals the total precipitation at the sink and evaporation at the source on an annual basis. Country-scale discrepancies of up to 275% in precipitation and 225% in evapo ration are amended, correcting fluxes by 0˜.07%, on average. We find 45% of the total terrestrial precipitation (˜1.5 ·105 km3yr−1) originates from land evaporation (9.8 ·104 km3yr−1). Our reconciled country-scale dataset offers new ground to investigate transboundary atmospheric water flows which connect us globally.