  Long-lived flow patterns in the atmosphere such as weather fronts,
mid-latitude blockings or tropical cyclones often induce extreme weather
conditions. As a consequence, their description, detection, and tracking has
received increasing attention in recent years. Similar objectives also arise in
diverse fields such as turbulence and combustion research, image analysis, and
medical diagnostics under the headlines of "feature tracking", "coherent
structure detection" or "image registration" - to name just a few. A host of
different approaches to addressing the underlying, often very similar, tasks
have been developed and successfully used. Here, several typical examples of
such approaches are summarized, further developed and applied to meteorological
data sets. Common abstract operational steps form the basis for a unifying
framework for the specification of "persistent structures" involving the
definition of the physical state of a system, the features of interest, and
means of measuring their persistence.
