North American Monsoonal Moisture Sources and Climatic Teleconnections Revealed Using Precipitation Stable Isotope Timeseries.

Results of analyses using a stable isotope timeseries from Tucson, Arizona, summer precipitation have revealed stationarity in certain North American Monsoonal teleconnections to the U.S. Southwest. Significant correlations are noted between the isotope timeseries and (1) Tucson precipitation amount, (2) Tucson air temperatures, (3) regional and extra-regional specific humidity, and (4) Eastern Pacific SSTs near the Mexican coast. Separation of extra-regional wind vector datasets into groups of years matching relative isotopic depletion or enrichment of the Tucson July-August precipitation suggest two distinct low-level summer circulation modes resulting in a dominantly Pacific/Gulf of California summer moisture source.