Observed tendencies in maximum and minimum temperatures in Zacatecas, Mexico and possible causes

Abstract

AbstractAt a global level, warming caused by the increase in greenhouse gases has been reported in different parts of the world. This warming resulted in a reduction in the diurnal temperature range (DTR), caused by a faster rate of increase in minimum temperatures. However, the tendency toward warming is not obvious in Zacatecas, Mexico. The tendencies in maximum and minimum temperatures are partly linked to the state of the low frequency variability of large‐scale atmospheric flow patterns, as depicted by the 700‐mb geopotential height anomalies. Analyses of maximum and minimum temperatures from 23 climate stations, from 1963 to 2002, show that the DTR in southern Zacatecas is increasing from a rise in maximum temperatures and drop in minimum temperatures, while the DTR in northern Zacatecas is decreasing from a faster rate of decline in maximum temperatures than the increase in minimum temperatures. The regional series related to the F1 and F2 leading modes, after applying a Varimax‐rotated empirical orthogonal function analysis to the 23 DTR series, acceptably reproduce the north–south dipole of DTR changes, while the point‐correlation analysis between the two regional series, the 700‐mb geopotential height anomalies and the indices of Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation indicate that the DTR in Zacatecas, Mexico is related to fluctuations in subtropical and extratropical circulations. Copyright © 2008 Royal Meteorological Society