WHOI PO

Abstract: Arctic freshwater changes affect global climate. However, Arctic freshwater budgets are ill-constrained both due to observational challenges and methodological differences across studies. Here we derive observation-based freshwater budgets from volume and mass budgets for the Arctic Ocean and the Beaufort Gyre, the Arctic's freshwater reservoir, from 2003 to 2020. Our budgets include all sources and sinks (river runoff, precipitation minus evaporation, land ice melt, sea ice export, sea ice melt, and ocean fluxes) as well as volume and mass storage terms measured by satellite. We find that the seasonality in source and sink terms is greater than mass and volume storage measured by satellite. We use inverse methods to close the volume and mass budgets within observational uncertainty, and find that they are particularly sensitive to how ocean fluxes are accounted for. In fact, small changes to the ocean fluxes (smaller than we can measure) can account for all freshwater storage changes in the Arctic, highlighting the need for more careful accounting and detailed ocean observations in this rapidly changing environment.