Diagnosing moisture transport using D/H ratios of water vapor

Water vapor transport paths into the American Southwest were deduced from a high temporal resolution record of hydrogen isotope compositions of atmospheric water vapor ( δ D wv ) collected over a six‐week period in late spring, 2005, at Albuquerque, New Mexico. Daily fluctuations of δ D wv routinely exceeded 20‰ in magnitude, while δ D wv variations up to 80‰ occurred on the time scale of weather (a few hours to ∼ a week). Vertical profiles of δ D wv in the lower troposphere exhibited considerable structure that cannot be ascertained from standard meteorological measurements. Trajectory analyses provide consistent evidence that the large temporal variations of surface δ D wv and vertical variations of δ D wv are primarily due to advection of water from different source regions. The lack of mixing inferred from our analyses indicates that δ D wv can be used as a sensitive tracer of the moisture transport history of air parcels.