A new view of global freshwater interconnectivity is emerging, where we understand that our collective pressure on the climate and biosphere impacts the stability of the entire global hydrological cycle . Any aspirations for sustainable water stewardship and governance must be based upon an understanding of how hydrological flows interact at local to global scales to shape the global freshwater cycle. Such understanding implies reliable confidence in the estimation of freshwater teleconnections, making it crucial to frame atmospheric moisture flows within the global hydrological cycle.

To this aim, growing efforts focused on tracking atmospheric moisture flows and understanding the the socio-hydrological implications of this global network. However, less attention has been given to guarantee the closure of the hydrological balance (i.e. the closure of the hydrological balance for its atmospheric component) on an annual scale and the consistency of the tracked moisture volumes with reanalysis data of precipitation (moisture reaching target cells) and evaporation (moisture departing from source cells).
In this study, we propose a framework to reconcile tracked atmospheric moisture flows from the U-Track dataset (), aggregated into a matrix  of bilateral connections between sources and sinks (at the country and subcontinental scale, including oceans), with reanalysis data (i.e., a combination of past observations with weather forecasting models to generate consistent time series of multiple climate variables) through the Iterative Proportional Fitting procedure. The methodolgy is further in-depth presented in the cell-scale application (https://doi.org/10.1038/s41597-025-04964-3).

Results provide  a novel dataset of up-to-date bilateral moisture connections between countries, including oceans, aimed at helping countries manage their portion of the global water cycle available at 10.5281/zenodo.10400695. This information enhances the exploration of the role countries and regions play in the international network of atmospheric water flows and the global hydrological cycle, thus supporting global water governance with consistent and reliable data.

The IPF procedure corrects country-scale discrepancies of up to 275% in precipitation and 225% in evaporation, adjusting bilateral flows by ~ 0.07 %, on average. This meaning, that the resulting dataset ensures that the total tracked moisture matches total precipitation at the sink and evaporation at the source annually while maintainig the structure of the global atmospheric network modeled by the lagrangian tracking U-Track. Remarkably, this procedure can be applied to any tracking model output and scale of analysis. The reconciled dataset enhances transboundary atmospheric water flows analysis, revealing that 45% of total terrestrial precipitation (~1.5 ⋅ 10⁵ km³yr⁻¹) originates from land evaporation (9.8 ⋅ 10⁴ km³yr⁻¹).

The study is open access at Communications Earth & Environment (https://doi.org/10.1038/s43247-025-02289-y).

The results from this work supported the Global Commission on the Economics of Water (GCEW) Report and Policy Brief 2024 presented at COP29. The GCEW was established in 2022 with the ambition to redefine how water flows are assessed and governed as a common good, presenting evidence and pathways for changes in policy, business approaches, and global collaboration to support climate and water justice, sustainability, and food, energy, and water security. The GCEW is convened by the government of the Netherlands and is facilitated by the Organization for Economic Co-operation and Development (OECD), while it is carried out by an independent and diverse group of policymakers and researchers in fields that bring new perspectives to the water economy, aligning the planetary economy with the sustainable management of water resources.

The GCEW Report and Policy Brief 2024 seek to redefine global water governance by promoting the concept of water as a global common and urging policymakers around the world to adopt a more equitable and sustainable approach to water management.