Variability of satellite-based land surface temperature and its relationship with vegetation indeces, topography, land cover and solar radiation.

Land Surface Temperature (LST) is the radiation temperature measured at the interface between surface materials (top of plant canopy, water, ground, ice, or snow surface) and the atmosphere. LST is a key indicator of geothermal and geological activities below the Earth and recently, there has been an increasingly interest in geothermal exploration relying on monitoring the anomalies of the surface temperature for searching alternative energy sources. Spaceborne sensors carried by polar orbiting satellites, such as the NOAA AVHRR (Advanced Very High Resolution Radiometer) series and the NASA Terra and Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) after the year 2000, with spectral bands in the TIR domain of the electromagnetic spectrum, allowed scientists to observe and monitor LST over large areas and long periods of time. The satellite synoptic view of large areas can consequently offer a unique help to geologists. The measurements collected directly on the field, forcedly spotty obtained, can be integrated with the satelliite data and consequently enlarged and spread over the whole area of interest. Ten years of MODIS day-time and nighttime 1 km Land Surface Temperature (LST) data over Southern Italy (2001-2010) have been analyzed to identify those factors that are influential on LST spatial and temporal variations. We first investigated the quality of the MODIS LST estimates and then quantified the amount of spatial and temporal variability explained by topography, land cover and incoming solar radiation. Further we analyzed the correlation between LST time series and the Vegetation Indices (VIs) (Normalized Difference vegetation Index, NDVI and Enhanced vegetation Index, EVI). These analyses are preliminary to investigate LST variability of surface temperature's due to the presence of anomalies related to geothermal sources of low enthalpy.