Tracking cloud patterns by METEOSAT rapid scan imagery in complex terrain

During the field phase of the Mesoscale Alpine Programme (MAP) in autumn 1999 Meteosat-6 performed 5-minute rapid scans of a region centred over the Alpine area. This dataset was used to implement a tracking technique based on the standard pattern correlation technique for tracking cloud patterns. Sensitivity studies with respect to the size of the tracked cloud regions, their textural characteristics and persistence were carried out. The big advantage of satellite imagery of high temporal resolution for tracking purposes is demonstrated. The rapid scans favour a continuous tracking of smaller-sized geographical windows (e.g. 15 x 15 pixels) with a high tracking quality expressed in terms of correlation. This is true for rapidly developing convective cells or weakly-textured stratiform cloud areas. Besides the temporal resolution of the images the tracking results are dependent on the size of the initially defined target pattern and the rate of development.