Surface ozone in Spain

This article presents an analysis of the surface ozone in five Spanish rura l stations with the aim of studying the diurnal and seasonal variations of ozone concentration, the mechanisms that control it and its geographical so urces. 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 geographi cal sources of O-3. The most important source areas are those with strong N Ox 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 mec hanisms to produce O-3. This method suggests that the photochemical product ion of O-3 from focal NOx seems to be the main mechanism to produce O-3 whe n the length of the trajectory of the air mass is short. When this length i ncreases, NOx emission gains importance as the main mechanism controlling O -3 concentration. (C) 1999 Elsevier Science Ltd. All rights reserved.