Characterizing regional‐scale variations in monthly and seasonal surface air temperature over Mexico

Abstract Monthly and seasonal variations in surface air temperature (SAT) over Mexico have not received much research attention, a situation partly reflecting the lack of a coherent historical data set. As a step toward rectifying the data gap, this study outlines the development of a gridded monthly (2.5° × 2.5°lat.–long.) SAT data set (1940–2001) for Mexico. Using the data set, we investigate several basic dimensions of SAT variability. Our analysis demonstrates that much of the variability can be compactly expressed in terms of four regions which are physically plausible with respect to the country's climatology. Not surprisingly, persistence is an important component of regional SAT variability. Evaluated month to month, persistence tends to be greatest during the warm season, whereas across seasons there is evidence for persistence of warm season anomalies into the following cool season, behaviour that is consistent with positive feedback relationships between SAT, rainfall and land surface conditions. The regional time series display longer period variability that is partially linked to the state of the large‐scale, slowly evolving climate modes of the Atlantic multidecadal oscillation and the Pacific decadal oscillation. Analyses are also presented to describe teleconnections between SAT and the El Niño–southern oscillation phenomena, and SAT and other large‐scale atmospheric modes, such as the Pacific North American pattern and the North Atlantic oscillation. Copyright © 2004 Royal Meteorological Society