Synthetic Aperture Radar, Technology, Past and Future Applications to Archaeology

Abstract

Synthetic Aperture Radar (SAR) data are now widely available at resolutions better than 30 m for most locations on Earth. This imagery can be quite valuable for archaeological applications in diverse environments, as it is generally unaffected by cloud cover, making it useful in the tropics. In very arid environments, longer wavelength radar can penetrate thin sand cover.

Radar imagery is sensitive to evidence of human occupation, such as remains of walls. Multi-temporal radar coverage, and/or coverage at multiple wavelengths and polarizations are available for some areas, from which vegetation characteristics can be derived. Depending on observational parameters, Interferometric Synthetic Aperture Radar (InSAR) data can provide topographic data, or measure subtle topographic changes occurring in the time interval between observations.

SAR data has been found useful for a variety of archaeological applications, with future instruments and technology promising expanded usage. Applications have ranged from airborne and spaceborne studies of Angkor Wat, to the Egyptian Sahara, to focused studies at locations such as San Clemente Island. For archaeologists, successful analysis of the data requires an understanding of basic principles of SAR image interpretation, knowledge of data sources, and essential sensor characteristics. Fortunately, radar data is available for download through various websites, and there are many software tools available, some available at no charge, to assist with obtaining data, analysis and interpretation.