A multi-temporal and a multi-incidence angle polarimetric analysis over Samarra UNESCO site in danger

The present research is the prosecution of a previous study already presented and held in the frame of a PhD research that aims to carry out a methodology for the detection of surface and, possibly, subsurface archaeological structures by the use of the Canadian RADARSAT-2 satellite. The analysis focused on the use of six images taken in a period spanning from April 2012 and January 2013. All the images were acquired in fine polarimetric mode with different incidence angles varying from 26 to 43 deg, in order to test and verify the most suitable configuration for the detection of archaeological remains upon or beneath the surface. To test the validity of the methodology, Samarra area (Iraq) test site was selected primarily because of its location in a semi desert area, because of the bigness of the structures easier to be detected from SAR systems and, not secondarily, because of inscribed in the UNESCO site in danger list since 2007. This city has been the capital of the Abbasid Caliphate for a period of only 58 years (836-892 A.D) as Bagdad was the first. Mysteriously, it was suddenly abandoned and this rapid abandonment is the reason for which Samarra has today one of the best preserved plan of an ancient large city. The choice of using different incidence angles has been due to the possibility of individuation of the most suitable configuration for archaeological purposes in order to identify different scattering mechanisms recognisable thanks to the polarimetric technique. Additive information, such as meteorological conditions, archaeological maps and photographs, were used as support for a likely interpretation of the archaeological areas, as surveys in situ are still not allowed in Iraq.