The Contribution of Local and Remote Transpiration, Ground Evaporation, and Canopy Evaporation to Precipitation Across North America

Land surface evapotranspiration (ET) is a major source of moisture for the global hydrologic cycle. Though the influence of the land surface is well documented, moisture tracking analyses aimed at quantifying the contribution of the land surface to precipitation have often relied on offline tracking approaches that require simplifying assumptions and can bias results. Additionally, the contribution of the ET components (transpiration (T), canopy evaporation (C), and ground evaporation (E)) individually to precipitation is not well understood, inhibiting our understanding of moisture teleconnections in both the current and future climate. Here, we use the Community Earth System Model version 1.2 with online numerical water tracers to examine the contribution of local and remote land surface ET, including the contribution from each individual ET component, to precipitation across North America. Much of northern and northeastern North America receives up to 80% of summertime precipitation from land surface ET, and over 50% of that moisture originates from transpiration alone. Local moisture recycling constitutes an essential source of precipitation across much of the southern and western regions of North America, suggesting precipitation across the region is sensitive to local land surface conditions, including soil moisture and vegetation state. The reliance on locally recycled moisture is far less pronounced across northern and eastern North America, where remotely sourced moisture, particularly from transpiration, dominates precipitation contributions. The results highlight regions that are especially sensitive to land cover and hydrologic changes in local and upwind areas, providing key insights for drought prediction and water resource management.