Monsoonal moisture sources revealed using temperature, precipitation, and precipitation stable isotope timeseries

Results of analyses using timeseries of mean temperature, precipitation amo unt, and stable isotopes from precipitation from July-August in Tucson, Ari zona, have revealed atmospheric circulation patterns related to the North A merican Monsoon in the U.S. Southwest. The isotope timeseries and Tucson ai r temperatures and precipitation amount are significantly correlated. The t emperature and isotope timeseries also correlate significantly with regiona l and extra-regional specific humidity, and with Eastern Pacific SSTs near the Mexican coast, evidence for a dominantly Pacific/Gulf of California sum mer moisture source for the period 1983-1999. Separation of extra-regional wind vector datasets into groups of years matching relative isotopic deplet ion or enrichment of the Tucson July-August precipitation seasonal means fo r the stable isotope timeseries (usually the extreme years in the Tucson se asonal temperature means) suggest circulation patterns entraining more trop ical moisture in cooler/isotopically depleted years, and entraining less tr opical moisture in hotter/isotopically enriched years.