Spatial extent of the North American Monsoon: increased cross-regional linkages via atmospheric pathways

The North American monsoon is a key feature affecting summer climate over Southwestern North America. During the monsoon, evapotranspiration from the southwest promotes transference of water to the atmosphere which is subsequently distributed across the continent - linking the SW to other regions via atmospheric hydrologic connectivity. However, the degree to which 18 atmospheric connectivity redistributes monsoonal terrestrial moisture through- out the continent and its sensitivity to climate disturbances such as drought is uncertain. We tracked the trajectory of moisture evapotranspired within the semiarid Southwest during the monsoon season using a Lagrangian analytical model. Southwest moisture was advected north-east accounting for 15% of precipitation in adjacent Great Plains regions. During recent drought (2000-2003), this amount decreased by 45%. Our results illustrate that the spatial extent of the North American monsoon is larger than normally considered when accounting for hydrologic connectivity via soil moisture redistribution through atmospheric pathways.