Surface Ozone In Spain

This article presents an analysis of the surface ozone in five Spanish rural stations with the aim of studying the diurnal and seasonal variations of ozone concentration, the mechanisms that control it and its geographical sources. Results show diurnal cycles in three of the five considered stations, as well as spring maxima in four and summer maxima in three of them. The Conditional probability Functions (CPFs) are used to identify the geographical sources of O-3. The most important source areas are those with strong NOx emissions and far away the stations. Another objective of the article is to essay a method to identifify the temporal and spatial domain of the mechanisms to produce O-3. This method suggests that the photochemical production of O-3 from focal NOx seems to be the main mechanism to produce O-3 when the length of the trajectory of the air mass is short. When this length increases, NOx emission gains importance as the main mechanism controlling O-3 concentration. (C) 1999 Elsevier Science Ltd. All rights reserved.