Statistical properties of the atmosphere influencing long-range transport of air pollutants

Sammanfattning: This thesis deals with some statistical properties of the atmosphere of importance for the transport and removal of air pollutants. Clouds and precipitation can strongly influence the behaviour of atmospheric pollutants. Thus, we need to know the frequency of occurrence of cloud and rain events in order to estimate e.g. removal times of pollutants. The frequency of cloud and rain passages should be estimated in a Lagrangian frame of reference, i.e. moving with the wind. As these estimates are difficult to obtain, estimates made at fixed points in space are often used instead. When comparing estimates of frequency of rain events obtained in a Lagrangian frame of reference with estimates obtained at fixed points no systematic difference was found.To estimate the residence time of atmospheric gases one normally needs to know the sources and sinks. An alternative approach is to use the information contained in the atmospheric variability of these gases. The estimate of the residence time obtained from the variability will have an uncertainty of at least a factor of 10 if the source and sink distribution is unknown. If we know the location of the sources the estimate will be much improved bringing the uncertainty down to perhaps a factor of two.