Tree-ring reconstructed winter precipitation and tropical teleconnections in Durango, Mexico

Earlywood width chronologies from Douglas-fir tree rings were used to reconstruct winter ( November - March) precipitation for more than 600 years over Durango, Mexico. The tree-ring data were obtained from two sites of long-lived Douglas-fir in northern and southern Durango and the seasonal climatic precipitation data were regionally averaged from five weather stations well distributed across the state. The averaged earlywood chronology accounted for 56% of the variance in instrumental November - March precipitation 1942 - 1983. We validated the reconstruction against independent precipitation records. The worst winter drought of the 20th century in Durango occurred 1950 - 1965. However, the reconstruction indicates droughts more severe than any witnessed in the 20th century, e. g., the 1850s - 1860s, and the megadrought in the mid- to late-16th century. Reconstructed winter precipitation 1540 - 1579 shows 33 of 40 years were dry. Persistent drought may be linked to extended La Nina episodes. The Tropical Rainfall Index (TRI) correlates well with instrumental and reconstructed winter precipitation (r = 0.49 and 0.55, respectively), reflecting the strong ENSO modulation of cool season climate over northern Mexico. The ENSO teleconnection varies through time, with TRI-reconstructed precipitation correlations ranging from 0.78 to 0.27 in five periods 1895 - 1993. The 1942 - 1983 winter observed and reconstructed Durango data correlate well with the corresponding seasonalization of the All-Mexico Rainfall Index (AMRI; r = 0.68, P < 0.0001 and r = 0.70, P < 0.001, respectively), indicating that both the observed and the reconstructed precipitation often reflect broad-scale precipitation anomalies across Mexico. New long Douglas-fir and baldcypress tree-ring chronologies are now available for central and southern Mexico near major population centers, allowing the exploration of relationships between drought, food scarcity, and social and political upheaval in Mexican history.