A Correction Method for Use in Multidimensional Time-Splitting Advection Algorithms: Application to Two- and Three-Dimensional Transport

Meteorological and air quality models rely on accurately solving the advection equation in two and three dimensions. While a number of methods have been developed, all suffer from the formation and growth of errors during the solution procedure. Here, a correction method is developed and applied to the piecewise parabolic method for use in multidimensional modeling. This method is a time-split, alternating direction method with a flux correction to account for diagonal advection. The correction removes over- and undershooting while maintaining the method’s accuracy. The analysis also indicates that some methods will have errors that grow significantly in time, while the corrections developed minimize the problem. This analysis found that the buildup of errors was more pronounced in three-dimensional tests, suggesting that this is an import evaluation criteria for other advection algorithms as well

Analyse exploratoire d'un jeu de données de concentrations en ozone troposphérique; Application à la Zone Métropolitaine de la Vallée de Mexico

L'ozone troposphérique est une problématique environnementale de plus en plus répandue à l'échelle de la planète. L'augmentation démesurée de la taille des agglomérations, la croissance démographique et l'augmentation des émissions sont autant de facteurs qui contribuent à cette pollution de nature urbaine

Source apportionment to support air quality management practices: A fitness-for-purpose guide (V 3.1)

Information on the origin of pollution constitutes an essential step of air quality management as it helps identifying measures to control air pollution. In this document, we review the most widely used source-apportionment methods for air quality management. Using simple theoretical examples we highlight the differences among these methods and explain why and under which circunstances they lead to different results and therefore different conclusions in the context of air quality management. These differences are a consequence of the intrinsic assumptions that underpin the different methodologies and determine/limit their range of applicability. We show that ignoring their underlying assumptions is a risk for efficient/successful air quality management as these methods are sometimes used beyond their scope and range of applicability. The simplest approach based on increments, contributions obtained through receptor models or tagging approaches built in air quality models as well impacts obtained via “brute-force” methods are discussed. The guide is organised as follows: the different source apportionment approaches and their associated properties are presented in Part I, simple examples are introduced in Part II to illustrate the main differences in terms of results while Part III focuses on the fitness-for-purpose aspects of the different methods. Finally Part IV lists and briefly discusses a series of open issues.JRC.C.5-Air and Climat