Regional flow climatology for central Mexico (Querétaro): A first case study

Abstract

A flow climatology was established for the Metropolitan Area of Querétaro (MAQ) in central Mexico, by analyzing four years (2014-2017) of back-trajectories generated using the HYSPLIT model. Two flow regimes were found: one from June until September (rainy regime); the other from December to May (dry regime). October and November were considered transition months. Northeasterly flows were present throughout the year; in contrast, trajectories from the southwest were much less frequent and observed mainly during the dry regime. An analysis of the wind fields from the North American Regional Reanalysis (NARR) database for a longer period of time (1979-2019) suggests that these results are representative of the average conditions of the atmosphere at the study site. Some of the northeasterly trajectories observed originate within a dessert region of the state of Querétaro, where several limestone mines are located. During the dry regime and transition months some clusters originate at the industrial area in Guanajuato, which includes the Salamanca refinery. As air transport of pollutants follow these paths, this analysis could be useful for identifying regional sources that affect the MAQ and possibly increase its air pollution load. In fact, the variability of criteria pollutants concentrations matched the flow regimes described above.