Variations in the stable isotope compositions of water vapor and precipitation in New Mexico : links to synoptic-scale weather

The D content of atmospheric water vapor over Albuquerque, New Mexico was measured for 30 months with air samples captured one to three times daily on the roof of a three story building. In addition, the D and O isotopes for 106 samples of surface water vapor and 40 samples of precipitation from the southwestern US were also measured. The relationship between the isotopic ratios of water vapor (δDv) and humidity, in the form of vertically integrated precipitable water (PW), is explored. Midlatitude waves are responsible for a great deal of δDv variation throughout the fall, winter, and spring. As the wave passes over NM, advection shifts to a westerly to northwesterly flow with subsidence aloft, which decreases δDv and PW. Variations in δDv throughout the summer monsoon season are due to a combination of factors but are primarily the result of circulation around a dominant high pressure system over North America. Periods of anticorrelated δDv - PW in the summer occur when Albuquerque is downwind of vigorous convective activity. The deuterium excess (d) of Albuquerque's vapor samples are remarkably consistent, especially when compared to reported values of d from other studies of water vapor. Our water vapor samples plot parallel to the Global Meteoric Water Line with an average d of 13.5‰, while higher values of d (up to 24‰) are observed in water vapor from AZ and eastern NM. Highly variable d is observed in precipitation samples; this variability is due to evaporation during precipitation events and is not related to variations of the d of the source vapor. Vertical profiles of δDv 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 δDv and vertical variations of δDv are primarily due to advection of water from different source regions.Earth and Planetary SciencesDoctoralUniversity of New Mexico. Dept. of Earth and Planetary SciencesGutzler, DavidSharp, ZacharyGalewsky, JoeFawcett, PeterKann, Deirdr