Thermophysical Properties of the North Polar Residual Cap using Mars Global Surveyor Thermal Emission Spectrometer

Using derived temperatures from thermal-infrared instruments aboard orbiting spacecraft, we constrain the thermophysical properties, in the upper few meters, of the north polar residual cap of Mars. In line with previous authors we test a homogeneous thermal model (i.e., depth-independent thermal properties), simulating water ice of varying porosity against observed temperatures. We find that high thermal inertia (>1,000Jm(-2)K(-1)s(1/2) or 40% porosity) that densifies with depth into a zero-porosity ice layer at shallow depths (<0.5m). We interpret this as evidence of recent water ice accumulation. Our results along the edge of the residual cap imply that denser (