SEASONAL PRECIPITATION RECONSTRUCTION FOR NORTHWESTERN GUANAJUATO

Abstract

Tree rings constitute a high resolution proxy of climate and precipitation reconstructions can extend back in time instrumental climate records. Therefore, increment cores were collected from two populations of Pinus cembroides in the northwestern region of the state of Guanajuato and generated two ring-width chronologies for Ocampo and San Felipe municipalities. A correlation analysis determined that time series did not have common variance, thereby two single chronologies were produced, one of 223 years (1790 to 2007) for Ibarra site, and the other one, of 158 years (1850 to 2007), for Las Palomas del Cubo. The calibration analysis between the seasonal and annual precipitation indicated a significant response (p<0.05) and accounted for 51% and 48% of the total precipitation variability, respectively. The most intense drought was detected in 1999 for the Ibarra chronology and 1956 and 2006 for Las Palomas chronology. Wet episodes produced severe flooding problems from 1785 to 1788 in Ibarra and in the years 1865, 1871, 1877, 1941, 1966-1967 and 1980 in Las Palomas. The effect of circulatory patterns showed no significant influence, except during very strong ENSO events. Therefore, it is recommended to expand the network of tree ring chronologies in this region in order to improve the analysis of the impact of this atmospheric circulatory pattern.