The impact of rain, frost, seasonal cycle, and wind on sequences of high resolution urban SAR images

The TerraSAR-X satellite has been fully operational since nearly 6 years and has delivered a very large quantity of high resolution SAR images. Among these images one can find a number of repeated acquisitions of selected target areas taken with nearly identical imaging parameters. These image time series data often cover the full seasonal cycle of a target area and lend themselves well to small-scale change detection; however, in the case of urban areas, we have to be aware of the quantitative impact of rain, frost and wind on high resolution SAR images. In particular, images of Western European cities are characterized by construction work concentrating on single buildings within a fully built-up city and by public green space changes. A quantitative analysis of urban time series data has to discriminate between definite changes of the urban landscape and the transient impacts of rain, frost and wind. The critical issue is how to identify and characterize these transient phenomena.