AN ENHANCED SYNOPTIC CLIMATOLOGY OF OZONE USING A SEQUENCING TECHNIQUE

Abstract

A synoptic classification scheme is derived to examine basic associations between surface ozone pollution and the atmospheric circulation. Nine weather types are related to the daily maximum ozone concentration in Pittsburgh, Pennsylvania, for the years 1978–1987. A sequencing technique is developed to extract the maximum utility from the classification scheme. An analysis of the sequences of synoptic weather types highlights additional spatial and temporal information, such as air mass origins, system speed, and seasonal variations. Low concentrations of ozone are experienced in winter during lake-effect and cyclonic storms, which move in rapidly from the north-west, bringing cold, cloudy, windy conditions with precipitation. High concentrations occur during summer in slow-moving anticyclones, with southwesterly transport and warm, sunny conditions that are favorable for photochemical formation of ozone. The study demonstrates that the use of a sequencing technique in conjunction with a synoptic classification scheme enables a more thorough analysis of the data. [Key words: synoptic climatology, weather types, air pollution, ozone, applied climatology, weather sequences.]