Contribution of evaporative sources and atmospheric circulation to the spatiotemporal variability of moisture transport

The coupling between land evaporation and precipitation is central to land-atmosphere interactions, yet remains one of the most poorly understood processes in the hydrological cycle. While evaporation is often viewed as having a predominantly local effect, growing evidence suggests that the land surface can significantly influence remote precipitation through atmospheric circulation and moisture transport. However, the sensitivity of precipitation to the interannual variability of its evaporative sources and atmospheric transport pathways remains largely unexplored.

 

Here, we employ the UTrack Lagrangian model driven by ERA5 reanalysis to perform a multi-annual moisture tracking analysis, identifying evaporative sources of precipitation and characterizing their variability over time. We develop statistical relationships to quantify the sensitivity of precipitation patterns to anomalies in both evaporative source strength and atmospheric moisture transport. Additionally, we investigate the correlation structure connecting evaporated moisture at the source, its transport through the atmosphere, and its contribution to precipitation at target locations.

 

Understanding the dominant factors driving moisture transport variability is crucial, as fluctuations in these pathways play a key role in the onset of droughts and extreme events and can be influenced by land uses and human activities. Furthermore, this work provides critical insights into the limitations of using climatological mean transport patterns compared to year-to-year analyses.