Mean Annual Soil Temperature Estimation From Landsat-7 ETM+ In the Transylvanian Plain, RO.

The Transylvanian Plain (TP) is a hilly region of agronomic importance located in north-central Romania. Soil temperature was measured at 20 stations across the TP to evaluate soil temperature regimes. Previous work has identified the soil temperature regime of the TP as mesic. However, based on the elevation and aspect differences across the TP, isolated areas of other soi temperature regimes are likely. This study evaluated the use of band 6 (thermal band) from Landsat–7 Enhanced Thematic Mapper-Plus (ETM+) images to evaluate mean annual soil temperature (MAST). Band 6 can be converted to spectral radiance, and then to temperature in degrees Celsius or Kelvin. Landsat-7 ETM+ images from August and December of 2002 were used to calculate mean surface temperature (MST). A simple linear regression was then performed between the calculated MAST from 2009 for the 20 stations and pixel values from the MST. Initial evaluation showed that some areas were thermic and frigid. It is thought that locally thermic areas are associated with locations where mass wasting has occurred and the lack of vegetation has increased MAST. The use of Landsat-7 ETM+ could provide a cost effective way of determining MAST in hilly regions.