Temperature Trend Analysis in the North Pacific Watershed in Mexico

Through the monthly data of 71 meteorological stations of the North Pacific Watershed in northwest Mexico, the annual trends of nine temperature variables were estimated using the non-parametric Mann-Kendall test and the Q Sen’s slope estimator. Annual Q Sen’s slopes were analyzed in spatial terms using geographic variables as independent factors and likewise with Moran’s I index. Three major physiographic zones were used to perform a regional analysis using pooled data. The monthly trends were also analyzed. Divergent annual trends were found for the nine proposed variables and warming trends were predominant in almost all of them. Latitude is the most relevant factor in the spatial distribution of the Q Sen’s slopes. Four temperature variables were found statistically clustered, as depicted by the Moran’s I index. The largest regional Q Sen’s slopes values were found in the Coastal Plains. In this area a larger increase in minimum temperatures was observed, in contrast with the Sierra Madre regions, where the largest rate of increasing change was found in maximum temperatures. The monthly analysis indicates warming trends in the first six months of the year with a sudden decrease in July and also a noticeable decrease in the slope values in December.