Quality of INTA-AHS Images for Estimating Apparent Thermal Inertia in Soils

Using remote sensing is an ideal solution to monitor thermal inertia over wide areas. This requires modelling it in terms of quantities derived from radiometry, usually albedo and change in surface temperature along the diurnal cycle. This allows to estimate the so-called apparent thermal inertia (ATI). The quality of a remote sensing image for estimating ATI depends on different factors. The first is radiometric noise which sets the minimum temperature difference that can be meaningfully observed. The second is spatial coregistration, which is critical for any study based on the temporal evolution of a variable. Finally, the accuracy of the estimation of albedo for a pixel in the image is essential. In this work, we analyze the quality of AHS airborne remote sensing images acquired by INTA for mapping ATI at high spatial resolution in an operational case. The results show that AHS noise enables the monitoring of ATI from temperature changes with images acquired as close in time as one hour. Spatial coregistration is below one pixel when using the same observing geometry. This figure is satisfactory for accurate mapping of temperature evolution in natural areas. Finally, albedo derived from AHS images is a good proxy of total albedo, but a correction factor depending on the soil type might be needed for high-accuracy estimations of ATI.