Inter- and intra-annual precipitation variability observed in the Navajo Nation
The drought conditions in the Navajo Nation are severe to exceptional, and observed across the more than 70,000 square kilometers. The Navajo Nation is the largest land-based tribe in the United States that experiences impacts brought on by subtle changes in precipitation. Evaluation of precipitation from 2002 to 2015 water years across at 90 precipitation sites in Arizona, Utah, and New Mexico was completed. Five sub-regions of differing precipitation climatology were identified using k-means clustering, a vector quantization method. Spatial and temporal trends of precipitation variability were conducted with three climate indices and showed strong winter precipitation association to the Pacific North American teleconnection pattern for all regions; less correlation between climate indices and summer precipitation were observed; however, modest correlations with Pacific Decadal Oscillation were witnessed. Inter- and intra- annual precipitation variability contributes to additional climate change impacts observed.